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Objective: To explore the potential mechanism of lysionotin in treating glioma. Methods: First, target prediction based on Bernoulli Naïve Bayes profiling and pathway enrichment was used to predict the biological activity of lysionotin. The binding between 5-lipoxygenase (5-LO) and lysionotin was detected by surface plasmon resonance (SPR) and molecular docking, and the inhibitory effects of lysionotin on 5-LO and proliferation of glioma were determined using enzyme inhibition assay in vitro and cell viability analysis, respectively. Furthermore, the pharmaceutical effect of lysionotin was explored by cell survival rate analysis and liquid chromatography with tandem mass spectrometry (LC-MS/MS). The protein expression, intracellular calcium ion concentration and cytoskeleton detection were revealed by Western blot, flow cytometry and fluorescence labeling, respectively. Results: Target prediction and pathway enrichment revealed that lysionotin inhibited 5-LO, a key enzyme involved in the arachidonic acid metabolism pathway, to inhibit the proliferation of glioma. Molecular docking results demonstrated that 5-LO can be binding to lysionotin through hydrogen bonds, forming bonds with His600, Gln557, Asn554, and His372. SPR analysis further confirmed the interaction between 5-LO and lysionotin. Furthermore, enzyme inhibition assay in vitro and cell survival rate analysis revealed that 50% inhibition concentration of lysionotin and the median effective concentration of lysionotin were 90 and 16.58 µmol/L, respectively, and the results of LC-MS/MS showed that lysionotin inhibited the production of 5S-hydroperoxy-eicosatetraenoic acid (P<0.05), and moreover, the LC-MS/MS results indicated that lysionotin can enter glioma cells well (P<0.01) and inhibit their proliferation. Western blot analysis demonstrated that lysionotin can inhibit the expression of 5-LO (P<0.05) and downstream leukotriene B4 receptor (P<0.01). In addition, the results showed that lysionotin affected intracellular calcium ion concentration by inhibiting 5-LO to affect the cytoskeleton, as determined by flow cytometry and fluorescence labeling. Conclusion: Lysionotin binds to 5-LO could suppress glioma by inhibiting arachiodonic acid metabolism pathway. [ABSTRACT FROM AUTHOR]

Inflammation is a protective stress response triggered by external stimuli, with 5-lipoxygenase (5LOX) playing a pivotal role as a potent mediator of the leukotriene (Lts) inflammatory pathway. Nordihydroguaiaretic acid (NDGA) functions as a natural orthosteric inhibitor of 5LOX, while 3-acetyl-11-keto-β-boswellic acid (AKBA) acts as a natural allosteric inhibitor targeting 5LOX. However, the precise mechanisms of inhibition have remained unclear. In this study, Gaussian accelerated molecular dynamics (GaMD) simulation was employed to elucidate the inhibitory mechanisms of NDGA and AKBA on 5LOX. It was found that the orthosteric inhibitor NDGA was tightly bound in the protein's active pocket, occupying the active site and inhibiting the catalytic activity of the 5LOX enzyme through competitive inhibition. The binding of the allosteric inhibitor AKBA induced significant changes at the distal active site, leading to a conformational shift of residues 168–173 from a loop to an α-helix and significant negative correlated motions between residues 285–290 and 375–400, reducing the distance between these segments. In the simulation, the volume of the active cavity in the stable conformation of the protein was reduced, hindering the substrate's entry into the active cavity and, thereby, inhibiting protein activity through allosteric effects. Ultimately, Markov state models (MSM) were used to identify and classify the metastable states of proteins, revealing the transition times between different conformational states. In summary, this study provides theoretical insights into the inhibition mechanisms of 5LOX by AKBA and NDGA, offering new perspectives for the development of novel inhibitors specifically targeting 5LOX, with potential implications for anti-inflammatory drug development. [ABSTRACT FROM AUTHOR]

Background: The liver is anatomically divided into eight segments based on the distribution of Glisson's triad. However, the molecular mechanisms underlying each segment and its association with hepatocellular carcinoma (HCC) heterogeneity are not well understood. In this study, our objective is to conduct a comprehensive multiomics profiling of the segmentation atlas in order to investigate potential subtypes and therapeutic approaches for HCC. Methods: A high throughput liquid chromatography‐tandem mass spectrometer strategy was employed to comprehensively analyse proteome, lipidome and metabolome data, with a focus on segment‐resolved multiomics profiling. To classify HCC subtypes, the obtained data with normal reference profiling were integrated. Additionally, potential therapeutic targets for HCC were identified using immunohistochemistry assays. The effectiveness of these targets were further validated through patient‐derived organoid (PDO) assays. Results: A multiomics profiling of 8536 high‐confidence proteins, 1029 polar metabolites and 3381 nonredundant lipids was performed to analyse the segmentation atlas of HCC. The analysis of the data revealed that in normal adjacent tissues, the left lobe was primarily involved in energy metabolism, while the right lobe was associated with small molecule metabolism. Based on the normal reference atlas, HCC patients with segment‐resolved classification were divided into three subtypes. The C1 subtype showed enrichment in ribosome biogenesis, the C2 subtype exhibited an intermediate phenotype, while the C3 subtype was closely associated with neutrophil degranulation. Furthermore, using the PDO assay, exportin 1 (XPO1) and 5‐lipoxygenase (ALOX5) were identified as potential targets for the C1 and C3 subtypes, respectively. Conclusion: Our extensive analysis of the segmentation atlas in multiomics profiling defines molecular subtypes of HCC and uncovers potential therapeutic strategies that have the potential to enhance the prognosis of HCC. [ABSTRACT FROM AUTHOR]

Introduction: Pancreatic tumors and cell lines derived from them exhibit elevated expression of 5-lipoxygenase (5-Lox), whereas non-tumor glands or normal cells do not exhibit this overexpression. Arachidonic acid stimulates pancreatic cancer cell growth via metabolic conversion through the 5-Lox pathway, and inhibition of 5-Lox activity decreases the viability of pancreatic cancer cells. However, the downstream signaling mechanisms through which 5-Lox exerts its effects on the survival of pancreatic cancer cells remain to be elucidated. Methods: The effects of 5-Lox inhibition on cell proliferation, apoptosis, and invasive potential were investigated in pancreatic cancer cells. The protein expression was analyzed by Western blot. Apoptosis was analyzed by Annexin- V binding assay and by detecting the degradation of chromatin-DNA to nucleosomal fragments. The protein kinase C-epsilon (PKCε) activity was measured by an immunoprecipitation-kinase assay. The in vivo effects of MK591 were evaluated in pancreatic tumor xenograft model. Results: MK591, a specific inhibitor of 5-Lox activity, killed pancreatic cancer cells via induction of apoptosis, involving externalization of phosphatidylserine, cleavage of PARP (poly-ADP ribose polymerase) and degradation of chromatin DNA to nucleosomes. MK591 effectively blocked in vitro invasion and soft-agar colony formation by pancreatic cancer cells and decreased pancreatic tumor growth in nude mice xenografts. Furthermore, inhibition of 5-Lox downregulated K-Ras and inhibited phosphorylation of c-Raf and ERKs. Interestingly, 5-Lox inhibition induced apoptosis in pancreatic cancer cells without the inhibition of Akt but the protein level of PKCε was dramatically downregulated. Furthermore, inhibition of 5-Lox decreased the phosphorylation of Stat3 at Serine-727. Pretreatment of pancreatic cancer cells with peptide activators of PKCε prevented apoptosis induced by 5-Lox inhibition, suggesting that the mechanism by which 5-Lox inhibition causes cell death in pancreatic cancer involves downregulation of PKCε. The combination of low doses of MK591 and gemcitabine synergistically reduced the oncogenic phenotype and killed pancreatic cancer cells by inducing apoptosis. Discussion: These findings indicate that inhibition of 5-Lox interrupts an Aktindependent, PKCe-dependent survival mechanism in pancreatic cancer cells and suggest that metabolism of arachidonic acid through the 5-Lox pathway plays an integral part in the survival of pancreatic cancer cells via signaling through PKCε, an oncogenic, pro-survival serine/threonine kinase. [ABSTRACT FROM AUTHOR]

Pulmonary fibrosis (PF) is a progressive lung disease and has a bad prognosis with median survival ranging from 2.5 to 3.5 years. Leukotrienes which are eicosanoid lipid mediators synthesized from arachidonic acid by 5-lipoxygenase (5-LOX) enzyme have been associated with PF. REV-5901 is potent 5-LOX inhibitor; however, its role in PF has not been studied. We demonstrate that REV-5901 has an inhibitory effect on bleomycin (BLM)-induced PF in both in vitro and in vivo models. REV-5901 reduced expression of BLM induced key fibrotic markers in both cells and animal samples. Histopathological analysis of lung tissue demonstrated an alleviating effect on fibrosis with inhibitor treatment. We also observed downregulation of 5-LOX, pAkt and VEGF expressions upon treatment with inhibitor indicating involvement of both lipid and angiogenic pathways in the regulatory effect of REV-5901. Overall, our data suggests REV-5901 demonstrates an anti-fibrotic effect on BLM-induced PF, which warrants further investigation. [ABSTRACT FROM AUTHOR]

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ABSTRACT Cryptococcosis, caused by fungi of the genus Cryptococcus, manifests in a broad range of clinical presentations, including severe pneumonia and disease of the central nervous system (CNS) and other tissues (bone and skin). Immune deficiency or development of overexuberant inflammatory responses can result in increased susceptibility or host damage, respectively, during fungal encounters. Leukotrienes help regulate inflammatory responses against fungal infections. Nevertheless, studies showed that Cryptococcus exploits host 5-lipoxygenase (5-LO), an enzyme central to the metabolism of arachidonic acid into leukotrienes, to facilitate transmigration across the brain–blood barrier. To investigate the impact of host 5-LO on the development of protective host immune responses and mortality during cryptococcosis, wild-type (C57BL/6) and 5-lipoxygenase-deficient (5-LO−/−) mice were given experimental pulmonary and systemic Cryptococcus sp., infections. Our results showed that 5-LO−/− mice exhibited reduced pathology and better disease outcomes (i.e., no mortality or signs associated with cryptococcal meningoencephalitis) following pulmonary infection with C. deneoformans, despite having detectable yeast in the brain tissues. In contrast, C57BL/6 mice exhibited classical signs associated with cryptococcal meningoencephalitis. Additionally, brain tissues of 5-LO−/− mice exhibited lower levels of cytokines (CCL2 and CCL3) clinically associated with Cryptococcus-related immune reconstitution inflammatory syndrome (C-IRIS). In a systemic mouse model of cryptococcosis, 5-LO−/− mice and those treated with a Federal Drug Administration (FDA)-approved 5-LO synthesis inhibitor, zileuton, displayed significantly reduced mortality compared to C57BL/6 infected mice. These results suggest that therapeutics designed to inhibit host 5-LO signaling could reduce disease pathology and mortality associated with cryptococcal meningoencephalitis.IMPORTANCECryptococcosis is a mycosis with worldwide distribution and has a broad range of clinical manifestations, including diseases of the CNS. Globally, there is an estimated 179,000 cases of cryptococcal meningitis, resulting in approximately 112,000 fatalities per annum and 19% of AIDS-related deaths. Understanding how host immune responses are modulated during cryptococcosis is central to mitigating the morbidity and mortality associated with cryptococcosis. Leukotrienes (LTs) have been shown to modulate inflammatory responses during infection. In this study, we show that mice deficient in 5-lipoxygenase (5-LO), an enzyme central to the metabolism of arachidonic acid into leukotrienes, exhibit reduced pathology, disease, and neurological signs associated with cryptococcal meningitis. Additionally, mice given an experimental cryptococcal infection and subsequently treated with an FDA-approved 5-LO synthesis inhibitor exhibited significantly reduced mortality rates. These results suggest that therapeutics designed to inhibit host 5-LO activity could significantly reduce pathology and mortality rates associated with cryptococcal meningitis.

Many drugs can act on multiple targets or disease pathways, regardless of their original purpose. Drug repurposing involves reevaluating existing compounds for new medical uses. This can include repositioning approved drugs, redeveloping unapproved drugs, or repurposing any chemical, nutraceutical, or biotherapeutic product for new applications. Traditional drug development is slow, expensive, and has high failure rates. Drug repurposing can speed up the process, costing less and saving time. This approach can save 6–7 years of early-stage research time. Drug repurposing benefits from existing compounds with optimized structures and approved for clinical use with associated structure-activity relationship publications, supporting the development of new effective compounds. Drug repurposes can now utilize advanced in silico screening enabled by artificial intelligence (AI) and sophisticated tissue and organ-level in vitro models. These models more accurately replicate human physiology and improve the selection of existing drugs for further pre-clinical testing and, eventually, clinical trials for new indications. This mini-review discusses some examples of drug repurposing and novel strategies for further development of compounds for targets of the arachidonic acid cascade. In particular, we will delve into the prospect of repurposing antiplatelet agents for cancer prevention and addressing the emerging noncanonical functionalities of 5-lipoxygenase, potentially for leukemia therapy.

Abstract Background The liver is anatomically divided into eight segments based on the distribution of Glisson's triad. However, the molecular mechanisms underlying each segment and its association with hepatocellular carcinoma (HCC) heterogeneity are not well understood. In this study, our objective is to conduct a comprehensive multiomics profiling of the segmentation atlas in order to investigate potential subtypes and therapeutic approaches for HCC. Methods A high throughput liquid chromatography‐tandem mass spectrometer strategy was employed to comprehensively analyse proteome, lipidome and metabolome data, with a focus on segment‐resolved multiomics profiling. To classify HCC subtypes, the obtained data with normal reference profiling were integrated. Additionally, potential therapeutic targets for HCC were identified using immunohistochemistry assays. The effectiveness of these targets were further validated through patient‐derived organoid (PDO) assays. Results A multiomics profiling of 8536 high‐confidence proteins, 1029 polar metabolites and 3381 nonredundant lipids was performed to analyse the segmentation atlas of HCC. The analysis of the data revealed that in normal adjacent tissues, the left lobe was primarily involved in energy metabolism, while the right lobe was associated with small molecule metabolism. Based on the normal reference atlas, HCC patients with segment‐resolved classification were divided into three subtypes. The C1 subtype showed enrichment in ribosome biogenesis, the C2 subtype exhibited an intermediate phenotype, while the C3 subtype was closely associated with neutrophil degranulation. Furthermore, using the PDO assay, exportin 1 (XPO1) and 5‐lipoxygenase (ALOX5) were identified as potential targets for the C1 and C3 subtypes, respectively. Conclusion Our extensive analysis of the segmentation atlas in multiomics profiling defines molecular subtypes of HCC and uncovers potential therapeutic strategies that have the potential to enhance the prognosis of HCC.

Oxidative stress in muscles is closely related to the occurrence of insulin resistance, muscle weakness and atrophy, age-related sarcopenia, and cancer. Aldehydes, a primary oxidation intermediate of polyunsaturated fatty acids, have been proven to be an important trigger for oxidative stress. However, the potential role of linoleic acid (LA) as a donor for volatile aldehydes to trigger oxidative stress has not been reported. Here, we reported that excessive dietary LA caused muscle redox imbalance and volatile aldehydes containing hexanal, 2-hexenal, and nonanal were the main metabolites leading to oxidative stress. Importantly, we identified 5-lipoxygenase (5-LOX) as a key enzyme mediating LA peroxidation in crustaceans for the first time. The inhibition of 5-LOX significantly suppressed the content of aldehydes produced by excessive LA. Mechanistically, the activation of the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway facilitated the translocation of 5-LOX from the nucleus to the cytoplasm, where 5-LOX oxidized LA, leading to oxidative stress through the generation of aldehydes. This study suggests that 5-LOX is a potential target to prevent the production of harmful aldehydes.

IntroductionPancreatic tumors and cell lines derived from them exhibit elevated expression of 5-lipoxygenase (5-Lox), whereas non-tumor glands or normal cells do not exhibit this overexpression. Arachidonic acid stimulates pancreatic cancer cell growth via metabolic conversion through the 5-Lox pathway, and inhibition of 5-Lox activity decreases the viability of pancreatic cancer cells. However, the downstream signaling mechanisms through which 5-Lox exerts its effects on the survival of pancreatic cancer cells remain to be elucidated.MethodsThe effects of 5-Lox inhibition on cell proliferation, apoptosis, and invasive potential were investigated in pancreatic cancer cells. The protein expression was analyzed by Western blot. Apoptosis was analyzed by Annexin-V binding assay and by detecting the degradation of chromatin-DNA to nucleosomal fragments. The protein kinase C-epsilon (PKCε) activity was measured by an immunoprecipitation-kinase assay. The in vivo effects of MK591 were evaluated in pancreatic tumor xenograft model.ResultsMK591, a specific inhibitor of 5-Lox activity, killed pancreatic cancer cells via induction of apoptosis, involving externalization of phosphatidylserine, cleavage of PARP (poly-ADP ribose polymerase) and degradation of chromatin DNA to nucleosomes. MK591 effectively blocked in vitro invasion and soft-agar colony formation by pancreatic cancer cells and decreased pancreatic tumor growth in nude mice xenografts. Furthermore, inhibition of 5-Lox downregulated K-Ras and inhibited phosphorylation of c-Raf and ERKs. Interestingly, 5-Lox inhibition induced apoptosis in pancreatic cancer cells without the inhibition of Akt but the protein level of PKCε was dramatically downregulated. Furthermore, inhibition of 5-Lox decreased the phosphorylation of Stat3 at Serine-727. Pre-treatment of pancreatic cancer cells with peptide activators of PKCε prevented apoptosis induced by 5-Lox inhibition, suggesting that the mechanism by which 5-Lox inhibition causes cell death in pancreatic cancer involves downregulation of PKCε. The combination of low doses of MK591 and gemcitabine synergistically reduced the oncogenic phenotype and killed pancreatic cancer cells by inducing apoptosis.DiscussionThese findings indicate that inhibition of 5-Lox interrupts an Akt-independent, PKCε-dependent survival mechanism in pancreatic cancer cells and suggest that metabolism of arachidonic acid through the 5-Lox pathway plays an integral part in the survival of pancreatic cancer cells via signaling through PKCε, an oncogenic, pro-survival serine/threonine kinase.

Inflammation is a protective stress response triggered by external stimuli, with 5-lipoxygenase (5LOX) playing a pivotal role as a potent mediator of the leukotriene (Lts) inflammatory pathway. Nordihydroguaiaretic acid (NDGA) functions as a natural orthosteric inhibitor of 5LOX, while 3-acetyl-11-keto-β-boswellic acid (AKBA) acts as a natural allosteric inhibitor targeting 5LOX. However, the precise mechanisms of inhibition have remained unclear. In this study, Gaussian accelerated molecular dynamics (GaMD) simulation was employed to elucidate the inhibitory mechanisms of NDGA and AKBA on 5LOX. It was found that the orthosteric inhibitor NDGA was tightly bound in the protein’s active pocket, occupying the active site and inhibiting the catalytic activity of the 5LOX enzyme through competitive inhibition. The binding of the allosteric inhibitor AKBA induced significant changes at the distal active site, leading to a conformational shift of residues 168–173 from a loop to an α-helix and significant negative correlated motions between residues 285–290 and 375–400, reducing the distance between these segments. In the simulation, the volume of the active cavity in the stable conformation of the protein was reduced, hindering the substrate’s entry into the active cavity and, thereby, inhibiting protein activity through allosteric effects. Ultimately, Markov state models (MSM) were used to identify and classify the metastable states of proteins, revealing the transition times between different conformational states. In summary, this study provides theoretical insights into the inhibition mechanisms of 5LOX by AKBA and NDGA, offering new perspectives for the development of novel inhibitors specifically targeting 5LOX, with potential implications for anti-inflammatory drug development.

Leukotrienes (LTs) are derived from arachidonic acid metabolism by the 5‐lipoxygenase (5‐LO) enzyme. The production of LTs is stimulated in the pathogenesis of rheumatoid arthritis (RA), osteoarthritis, and periodontitis, with a relevant contribution to bone resorption. However, its role in bone turnover, particularly the suppression of bone formation by modulating the function of osteoclasts and osteoblasts, remains unclear. We investigated the effects of LTs on bone metabolism and their impact on osteogenic differentiation and osteoclastogenesis using a 5‐LO knockout (KO) mouse model. Results from micro‐computed tomography (μCT) analysis of femur from 8‐week‐old 5‐LO‐deficient mice showed increased cortical bone and medullary region in females and males and decreased trabecular bone in females. In the vertebra, we observed increased marrow area in both females and males 5‐LO KO and decreased trabecular bone only in females 5‐LO KO. Immunohistochemistry (IHC) analysis showed higher levels of osteogenic markers tissue‐nonspecific alkaline phosphatase (TNAP) and osteopontin (OPN) and lower expression of osteoclastogenic marker tartrate‐resistant acid phosphatase (TRAP) in the femurs of 5‐LO KO mice versus wild‐type (WT). Alkaline phosphatase activity and mineralization assay results showed that the 5‐LO absence enhances osteoblasts differentiation and mineralization but decreases the proliferation. Alkaline phosphatase (ALP), Bglap, and Sp7 gene expression were higher in 5‐LO KO osteoblasts compared to WT cells. Eicosanoids production was higher in 5‐LO KO osteoblasts except for thromboxane 2, which was lower in 5‐LO–deficient mice. Proteomic analysis identified the downregulation of proteins related to adenosine triphosphate (ATP) metabolism in 5‐LO KO osteoblasts, and the upregulation of transcription factors such as the adaptor‐related protein complex 1 (AP‐1 complex) in long bones from 5‐LO KO mice leading to an increased bone formation pattern in 5‐LO–deficient mice. We observed enormous differences in the morphology and function of osteoclasts with reduced bone resorption markers and impaired osteoclasts in 5‐LO KO compared to WT osteoclasts. Altogether, these results demonstrate that the absence of 5‐LO is related to the greater osteogenic profile. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). [ABSTRACT FROM AUTHOR]

Abstract Background To investigate if 5-LO selective inhibitor (MK-886) could be used for systemic treatment of experimentally induced apical periodontitis in a mouse model. Methods Twenty-four C57BL/6 mice were used. After coronal opening, a solution containing Escherichia coli LPS (1.0 µg/µL) was inoculated into the root canals of the lower and upper right first molars (n = 72 teeth). After 30 days apical periodontitis was established, and the animals were treated with MK-886 (5 mg/kg), a 5-LO inhibitor, for 7 and 14 days. The tissues were removed for histopathological and histometric analyses, evaluation of osteoclast number and gene expression for receptor activator of nuclear factor kappa-B (Tnfrsf11a), receptor activator of nuclear factor kappa-B ligand (Tnfsf11), osteoprotegerin (Tnfrsf11b), tartrate-resistant acid phosphatase (Acp5), matrix metalloproteinase-9 (Mmp9), cathepsin K (Ctsk) and calcitonin receptor (Calcr). Statistical data analysis was performed using Kruskal Wallis followed by Dunn’s tests (α = 0.05). Results Administration of MK-886 for 7 days exerted no effect on apical periodontitis progression compared to LPS inoculation without treatment (p = 0.3549), while treatment for 14 days exacerbated bone loss (p 0.9999). After 7 days of treatment, MK-886 induced mRNA expression for Acp5 (p = 0.0001), Calcr (p = 0.0003), Mmp9 (p = 0.0005) and Ctsk (p = 0.0008), however no effect in those gene expression was observed after 14 days (p > 0.05). Conclusion Systemic treatment with MK-886 exacerbated LPS-induced apical periodontitis in a mouse model.

Oxidative disruption of dopaminergic neurons is regarded as a crucial pathogenesis in Parkinson's disease (PD), eventually causing neurodegenerative progression. (-)-Clausenamide (Clau) is an alkaloid isolated from plant Clausena lansium (Lour.), which is well-known as a scavenger of lipid peroxide products and exhibiting neuroprotective activities both in vivo and in vitro, yet with the in-depth molecular mechanism unrevealed. In this study, we evaluated the protective effects and mechanisms of Clau on dopaminergic neuron. Our results showed that Clau directly interacted with the Ser663 of ALOX5, the PKCα-phosphorylation site, and thus prevented the nuclear translocation of ALOX5, which was essential for catalyzing the production of toxic lipids 5-HETE. LC-MS/MS-based phospholipidomics analysis demonstrated that the oxidized membrane lipids were involved in triggering ferroptotic death in dopaminergic neurons. Furthermore, the inhibition of ALOX5 was found to significantly improving behavioral defects in PD mouse model, which was confirmed associated with the effects of attenuating the accumulation of lipid peroxides and neuronal damages. Collectively, our findings provide an attractive strategy for PD therapy by targeting ALOX5 and preventing ferroptosis in dopaminergic neurons.

Diverse secondary metabolites are biosynthesized by plants via various enzymatic cascades. These have the capacity to interact with various human receptors, particularly enzymes implicated in the etiology of several diseases. The n-hexane fraction of the whole plant extract of the wild edible plant, Launaea capitata (Spreng.) Dandy was purified by column chromatography. Five polyacetylene derivatives were identified, including (3S,8E)-deca-8-en-4,6-diyne-1,3-diol (1A), (3S)-deca-4,6,8-triyne-1,3-diol (1B), (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (2), bidensyneoside (3), and (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1-ol-3-O-β-D-glucopyranoside (4). These compounds were investigated for their in vitro inhibitory activity against enzymes involved in neuroinflammatory disorders, including cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and butyrylcholinesterase (BchE) enzymes. All isolates recorded weak–moderate activities against COX-2. However, the polyacetylene glycoside (4) showed dual inhibition against BchE (IC50 14.77 ± 1.55 μM) and 5-LOX (IC50 34.59 ± 4.26 μM). Molecular docking experiments were conducted to explain these results, which showed that compound 4 exhibited greater binding affinity to 5-LOX (−8.132 kcal/mol) compared to the cocrystallized ligand (−6.218 kcal/mol). Similarly, 4 showed a good binding affinity to BchE (−7.305 kcal/mol), which was comparable to the cocrystallized ligand (−8.049 kcal/mol). Simultaneous docking was used to study the combinatorial affinity of the unresolved mixture 1A/1B to the active sites of the tested enzymes. Generally, the individual molecules showed lower docking scores against all the investigated targets compared to their combination, which was consistent with the in vitro results. This study demonstrated that the presence of a sugar moiety (in 3 and 4) resulted in dual inhibition of 5-LOX and BchE enzymes compared to their free polyacetylenes analogs. Thus, polyacetylene glycosides could be suggested as potential leads for developing new inhibitors against the enzymes involved in neuroinflammation. [ABSTRACT FROM AUTHOR]

The 5-lipoxygenase (5-LOX) pathway gives rise to bioactive inflammatory lipid mediators, such as leukotrienes (LTs). 5-LOX carries out the oxygenation of arachidonic acid to the 5-hydroperoxy derivative and then to the leukotriene A4 epoxide which is converted to a chemotactic leukotriene B4 (LTB4) by leukotriene A4 hydrolase (LTA4H). In addition, LTA4H possesses aminopeptidase activity to cleave the N-terminal proline of a pro-inflammatory tripeptide, prolyl-glycyl-proline (PGP). Based on the structural characteristics of LTA4H, it is possible to selectively inhibit the epoxide hydrolase activity while sparing the inactivating, peptidolytic, cleavage of PGP. In the current study, chalcogen-containing compounds, 4-(4-benzylphenyl) thiazol-2-amine (ARM1) and its selenazole (TTSe) and oxazole (TTO) derivatives were characterized regarding their inhibitory and binding properties. All three compounds selectively inhibit the epoxide hydrolase activity of LTA4H at low micromolar concentrations, while sparing the aminopeptidase activity. These inhibitors also block the 5-LOX activity in leukocytes and have distinct inhibition constants with recombinant 5-LOX. Furthermore, high-resolution structures of LTA4H with inhibitors were determined and potential binding sites to 5-LOX were proposed. In conclusion, we present chalcogen-containing inhibitors which differentially target essential steps in the biosynthetic route for LTB4 and can potentially be used as modulators of inflammatory response by the 5-LOX pathway. [ABSTRACT FROM AUTHOR]

Arnica montana is well known for its anti-inflammatory properties. While the anti-inflammatory activity of Arnica flowers (Arnicae flos) has been extensively studied, that of the whole plant (Arnicae planta tota) is less characterized. We compared the ability of Arnicae planta tota and Arnicae flos extracts to inhibit the pro-inflammatory NF-κB—eicosanoid pathway, using several in vitro and in vivo assays. We showed that Arnicae planta tota inhibited NF-κB reporter activation, with an IC50 of 15.4 μg/mL (vs. 52.5 μg/mL for Arnicae flos). Arnicae planta tota also inhibited LPS-induced expression of ALOX5 and PTGS2 genes in human differentiated macrophages. ALOX5 and PTGS2 encode the 5-lipoxygenase (5-LO) and cyclooxygenase-2 (COX-2) enzymes that initialize the conversion of arachidonic acid into leukotrienes and prostaglandins, respectively. Arnicae planta tota inhibited 5-LO and COX-2 enzymatic activity in vitro and in human primary peripheral blood cells, with lower IC50 compared to Arnicae flos. Finally, Arnicae planta tota applied topically reduced carrageenan-induced mouse paw oedema more efficiently than Arnicae flos. Altogether, Arnicae planta tota displayed a superior anti-inflammatory activity compared to Arnicae flos, suggesting that Arnicae-planta-tota-containing products might be more effective in alleviating the manifestations of acute inflammation than those based on Arnicae flos alone. [ABSTRACT FROM AUTHOR]

Metabolic activation of indirect-acting carcinogens in target organs is a recognized mechanism of carcinogenesis. This study aimed to determine the role of benzo[a]pyrene (BaP) metabolism enzymes lipoxygenase (LOX), cytochrome P4501A1 (CYP1A1), and prostaglandin synthetase (PGS) in the cytotoxicity and DNA damage induced by BaP in the human tracheobronchial epithelial cells (HBECs) using RNA interference strategy and metabolic enzyme inhibitors. Our results showed that in three epithelial cell lines (HBE, HTR-8/SVneo, and HaCat), BaP significantly upregulated 5-LOX protein expression. 15-LOX-2 expression also increased with increasing BaP concentration, but the change was less pronounced than that of 5-LOX. BaP caused significant cytotoxicity, DNA strand breaks, and 8-hydroxy-2'-deoxyguanosine formation in HBE, which was inhibited by 5-LOXshRNA, a specific inhibitor of 5-LOX (AA861), the CYP1A1 inhibitor α-naphthoflavone, and the PGS inhibitor naproxen. The protective effects of 5-LOXshRNA were stronger than AA861, naproxen and α-naphthoflavone. We conclude that BaP may be activated more by 5-LOX than by CYP1A1 and PGS to produce cytotoxicity and DNA damage in HBE. [ABSTRACT FROM AUTHOR]

In this study, an efficient method that employs 5‐lipoxygenase and acetylcholinesterase as biological target molecules in receptor–ligand affinity ultrafiltration–liquid chromatography was developed for the screening of enzyme inhibitors derived from the Astragalus membranaceus stems and leaves. The effects of the extraction time, number of extraction cycles, ethanol concentration, and liquid–solid ratio on the total yield of the target compounds were investigated using response surface methodology, and the bioactive components were isolated using a combination of semi‐preparative high‐performance liquid chromatography and high‐speed countercurrent chromatography via a two‐phase solvent system consisting of n‐hexane–ethyl acetate–methanol–water (1:6:2:6, v/v/v/v). Subsequently, 10 naturally‐occurring bioactive components in the Astragalus membranaceus stems and leaves, including wogonin, ononin, isoquercitrin, calycosin‐7‐glucoside, 3‐hydroxy‐9,10‐dimethoxyptercarpan, hyperoside, 7,2′‐dihydroxy‐3′,4′‐dimethoxyisoflavan, baicalein, calycosin, and soyasaponin, were screened using affinity ultrafiltration to determine their potential effects against Alzheimer's disease. Consequently, all target compounds had purities higher than 95.0%, and the potential anti‐Alzheimer's disease effect of the obtained bioactive compounds was verified using molecular docking analysis. Based on the results, the back‐to‐back screening of complex enzyme inhibitors and separation of the target bioactive compounds using complex chromatography could provide a new approach to the discovery and preparation of natural active ingredients. [ABSTRACT FROM AUTHOR]

Plant secondary metabolites have a long history of potential use in managing human diseases by inhibiting enzymes that are highly expressed due to various pathogenic conditions. Prostaglandins (PGs) and leukotrienes (LTs) are proinflammatory mediators synthesized from arachidonic acid (AA) by the action of cyclooxygenases (COXs) and lipoxygenases (LOXs), respectively. Particularly, COX-2/5-LOX enzymes play a significant role in inflammatory processes and the pain associated with them. Butyrylcholinesterase (BchE) was recently suggested as a more reliable potential target for sustaining normal cholinergic function. In an attempt to identify new potential COX-2/5-LOX and BchE inhibitors, a phytochemical investigation of Launaea capitata (Spreng.) Dandy (Asteraceae) was executed. This investigation led to the isolation of a new digalactosyldiacylglycerol isomer, namely 1,2-dilinolenoyl-3-O-(α-galactopyranosyl-(1,6)-O-α-D-galactopyranosyl)-sn-glycerol (1) in addition to 1-myristoyl-2-palmitoyl-3-O-(α-galactopyranosyl-(1,6)-O-β-D-galactopyranosyl)-sn-glycerol (2), which was isolated herein for the first time from nature. The structures of the two isolates were elucidated by using 1D-, 2D-NMR, and ESI-MS spectroscopy. Compounds 1 and 2 exhibited good in vitro inhibitory activities against 5-LOX (59.01 and 21.67 μg/mL) and BchE (13.37 and 24.32 μg/mL), respectively. However, they exhibited weak inhibition of COX-2 (110.44 and 179.63 μg/mL, respectively). These inhibitory activities were explained in silico using a computational docking study. The docking results were consistent with the in vitro enzyme inhibitory activity. The lowest binding affinity for 1 and 2 was observed against COX-2 (−7.360 and −5.723 kcal/mol), whereas they exhibited greater binding affinity to 5-LOX (−8.124 and −8.634 kcal/mol), respectively, compared to its natural substrate, AA (−5.830 kcal/mol). Additionally, 1 and 2 exhibited remarkable binding affinity to BchE (−8.313 kcal/mol and −7.502 kcal/mol, respectively), which was comparable to the co-crystallized ligand, thioflavin T (−8.107 kcal/mol). This was related to the multiple and crucial hydrogen bonding interactions of these compounds with the amino acid residues in the active sites of the investigated enzymes. This study demonstrated the role of plant galactolipids as potential leads in the development of new drugs that alleviate the neuroinflammatory conditions associated with various diseases, such as Alzheimer's disease and Type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

Simple Summary: Glioblastoma multiforme is a brain tumor with a very unfavorable prognosis, where the vast majority of patients do not survive a year after diagnosis. One line of research that may help in designing more successful therapeutic approaches is the synthesis and metabolism of arachidonic acid, which is then converted into a large number of different lipid mediators, including prostaglandins and leukotrienes (by cyclooxygenases and lipoxygenases, respectively). In this paper, we discuss the synthesis of arachidonic acid in glioblastoma multiforme tumors as well as the significance of lipid mediators synthesized from arachidonic acid, which can increase the proliferation of glioblastoma multiforme cancer cells, cause angiogenesis, inhibit the anti-tumor response of the immune system, and be responsible for resistance to treatment. Glioblastoma multiforme (GBM) is one of the most aggressive gliomas. New and more effective therapeutic approaches are being sought based on studies of the various mechanisms of GBM tumorigenesis, including the synthesis and metabolism of arachidonic acid (ARA), an omega-6 polyunsaturated fatty acid (PUFA). PubMed, GEPIA, and the transcriptomics analysis carried out by Seifert et al. were used in writing this paper. In this paper, we discuss in detail the biosynthesis of this acid in GBM tumors, with a special focus on certain enzymes: fatty acid desaturase (FADS)1, FADS2, and elongation of long-chain fatty acids family member 5 (ELOVL5). We also discuss ARA metabolism, particularly its release from cell membrane phospholipids by phospholipase A2 (cPLA2, iPLA2, and sPLA2) and its processing by cyclooxygenases (COX-1 and COX-2), lipoxygenases (5-LOX, 12-LOX, 15-LOX-1, and 15-LOX-2), and cytochrome P450. Next, we discuss the significance of lipid mediators synthesized from ARA in GBM cancer processes, including prostaglandins (PGE2, PGD2, and 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2)), thromboxane A2 (TxA2), oxo-eicosatetraenoic acids, leukotrienes (LTB4, LTC4, LTD4, and LTE4), lipoxins, and many others. These lipid mediators can increase the proliferation of GBM cancer cells, cause angiogenesis, inhibit the anti-tumor response of the immune system, and be responsible for resistance to treatment. [ABSTRACT FROM AUTHOR]

Background: To investigate if 5-LO selective inhibitor (MK-886) could be used for systemic treatment of experimentally induced apical periodontitis in a mouse model. Methods: Twenty-four C57BL/6 mice were used. After coronal opening, a solution containing Escherichiacoli LPS (1.0 µg/µL) was inoculated into the root canals of the lower and upper right first molars (n = 72 teeth). After 30 days apical periodontitis was established, and the animals were treated with MK-886 (5 mg/kg), a 5-LO inhibitor, for 7 and 14 days. The tissues were removed for histopathological and histometric analyses, evaluation of osteoclast number and gene expression for receptor activator of nuclear factor kappa-B (Tnfrsf11a), receptor activator of nuclear factor kappa-B ligand (Tnfsf11), osteoprotegerin (Tnfrsf11b), tartrate-resistant acid phosphatase (Acp5), matrix metalloproteinase-9 (Mmp9), cathepsin K (Ctsk) and calcitonin receptor (Calcr). Statistical data analysis was performed using Kruskal Wallis followed by Dunn's tests (α = 0.05). Results: Administration of MK-886 for 7 days exerted no effect on apical periodontitis progression compared to LPS inoculation without treatment (p = 0.3549), while treatment for 14 days exacerbated bone loss (p < 0.0001). Administration of MK-886 enhanced osteoclastogenesis signaling and osteoclast formation within 7 days (p = 0.0005), but exerted no effect at 14 days (p > 0.9999). After 7 days of treatment, MK-886 induced mRNA expression for Acp5 (p = 0.0001), Calcr (p = 0.0003), Mmp9 (p = 0.0005) and Ctsk (p = 0.0008), however no effect in those gene expression was observed after 14 days (p > 0.05). Conclusion: Systemic treatment with MK-886 exacerbated LPS-induced apical periodontitis in a mouse model. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID-19) is characterized by a broad spectrum of clinical symptoms. After acute infection, some subjects develop a post-COVID-19 syndrome known as long-COVID. This study aims to recognize the molecular and functional mechanisms that occur in COVID-19 and long-COVID patients and identify useful biomarkers for the management of patients with COVID-19 and long-COVID. Here, we profiled the response to COVID-19 by performing a proteomic analysis of lymphocytes isolated from patients. We identified significant changes in proteins involved in iron metabolism using different biochemical analyses, considering ceruloplasmin (Cp), transferrin (Tf), hemopexin (HPX), lipocalin 2 (LCN2), and superoxide dismutase 1 (SOD1). Moreover, our results show an activation of 5-lipoxygenase (5-LOX) in COVID-19 and in long-COVID possibly through an iron-dependent post-translational mechanism. Furthermore, this work defines leukotriene B4 (LTB4) and lipocalin 2 (LCN2) as possible markers of COVID-19 and long-COVID and suggests novel opportunities for prevention and treatment. [ABSTRACT FROM AUTHOR]

Arachidonic acid 5-lipoxygenase (5-LOX), an enzyme that synthesizes leukotrienes (LTs), is involved in cancer development including proliferation, invasion, metastasis and drug resistance. However, the functional role of 5-LOX in hepatocellular carcinoma (HCC) remains to be elucidated. In this study, we analyzed the contribution of 5-LOX in HCC progression and investigated the potential of targeted therapy. Analysis of 86 resected HCC specimens and the clinical data of 362 cases of liver cancer from The Cancer Genome Atlas Liver Hepatocellular Carcinoma dataset, showed that 5-LOX expression was associated with postoperative survival. The cancer proliferative and stem cell potential were correlated with the levels of 5-LOX in CD163(+) tumor-associated macrophages (TAMs). In an HCC mouse model, CD163(+) TAMs expressed 5-LOX and produced LTB4 and LTC/D/E4; the 5-LOX inhibitor, zileuton, suppressed HCC progression. LTB4 and LTC/D/E4 promoted cancer proliferation and stem cell capacity via phosphorylation of extracellular signal-regulated kinase 1/2 and stem cell-associated genes. Taken together, we identified a novel mechanism of HCC progression in which CD163(+) TAMs express 5-LOX and produce LTB4 and LTC/D/E4, thereby enhancing the proliferative and stem cell potential of HCC cells. Furthermore, inhibition of 5-LOX activity regulates HCC progression, suggesting it has potential as a new therapeutic target.

Inflammation is a complicated physiological process that results in a variety of disorders. Several inflammatory mediators are produced during this process, which is responsible for long-term inflammatory conditions like osteoarthritis, rheumatoid arthritis, asthma, cancer, and neurological disorders. Inflammatory mediators are produced by an arachidonic acid pathway that gives us several anti-inflammatory targets. The most commonly used medications are NSAIDs to treat inflammation by inhibiting cyclooxygenase (COX) and lipoxygenase enzymes (5-LOX). However, this therapy is associated with adverse events like gastrointestinal disorders, renal failure, etc., limiting its use. Therefore, novel, efficacious, and safer anti-inflammatory agents are prerequisites for inhibiting both cyclooxygenase and lipoxygenase pathways. Though several synthetic analogs are under development, natural products may act as a potential source to identify novel molecules and herbal remedies. Valuable contributions have been made in this direction by the scientific communities. This review article briefly discusses the implications of phytochemicals and bioactive fractions in the development of dual COX-LOX inhibitors while highlighting different classes of phytoconstituents such as tannins, steroids, flavonoids, alkaloids, terpenoids, among others, that showed significant dual COX-LOX inhibition.

Inflammation is a complicated disorder that is produced as a result of consecutive processes. 5-LOX (5-lipoxygenase) is accountable for various inflammation mediators and leukotrienes synthesis, and its inhibition is the target of anti-inflammation therapeutics. Fungi have acquired enormous attentiveness because of their capability to biosynthesize novel bio-metabolites that reveal diversified bio-activities. A new tetracyclic triterpenoid, integracide L (1), along with integracides B (2) and F (3), were separated from Mentha longifolia-associated Fusarium sp. (FS No. MAR2014). Their structures were verified utilizing varied spectral analyses. The isolated metabolites (1–3), alongside the earlier reported integracides G (4), H (5), and J (6), were inspected for 5-LOX inhibition capacity. Interestingly, 1–6 possessed marked 5-LOX inhibition potentials with IC50s ranging from 1.18 to 3.97 μM compared to zileuton (IC50 1.17 µM). Additionally, molecular docking was executed to examine the interaction among these metabolites and 5-LOX, as well as to validate the in vitro findings. The docking study revealed their inhibitory activity interactions in the binding pocket. These findings highlighted the potential of integracides as lead metabolites for anti-inflammation drug discovery. [ABSTRACT FROM AUTHOR]

Leukotrienes are among the most potent mediators of inflammation, and inhibition of their biosynthesis, is becoming increasingly important in the treatment of many pathologies. In this work, we demonstrated that preincubation of human neutrophils with the mitochondria targeted antioxidant SkQ1 (100 nM) strongly inhibits leukotriene synthesis induced by three different stimuli: the Ca2+ ionophore A23187, the chemotactic formylpeptide fMLP in combination with cytocholasin B, and opsonized zymosan. The SkQ1 analogue lacking the antioxidant quinone moiety (C12TPP) was ineffective, suggesting that mitochondrial production of reactive oxygen species (ROS) is critical for activating of leukotriene synthesis in human neutrophils. The uncoupler of oxidative phosphorylation FCCP also inhibits leukotriene synthesis, indicating that a high membrane potential is a prerequisite for stimulating leukotriene synthesis in neutrophils. Our data show that activation of mitogen-activated protein kinases p38 and ERK1/2, which is important for leukotriene synthesis in neutrophils is a target for SkQ1: 1) the selective p38 inhibitor SB203580 inhibited fMLP-induced leukotriene synthesis, while the ERK1/2 activation inhibitor U0126 suppressed leukotriene synthesis induced by any of the three stimuli; 2) SkQ1 effectively prevents p38 and ERK1/2 activation (accumulation of phosphorylated forms) induced by all three stimuli. This is the first study pointing to the involvement of mitochondrial reactive oxygen species in the activation of leukotriene synthesis in human neutrophils. The use of mitochondria-targeted antioxidants can be considered as a promising strategy for inhibiting leukotriene synthesis and treating various inflammatory pathologies. [ABSTRACT FROM AUTHOR]

Arachidonic acid (AA) plays a critical role in inflammatory regulation and secondary injury after spinal cord injury (SCI). However, the overall AA metabolism profile in the acute phase of SCI remains elusive. Here we quantified AA metabolomics by High Performance Liquid Chromatography−Tandem Mass Spectrometry-Based Method (LC−MS/MS) using spinal cord tissue collected at 4 h, 24 h and 48 h after contusive SCI in rats. Remarkably, Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4) were significantly increased throughout the acute SCI. Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX), the key enzymes involved in the production of PGE2 and LTB4, were elevated in the lesioned spinal cord tissue, validated by both western blot and immunofluorecnce. The spatial-temporal changes of COX-2 and 5-LOX mainly occurs in neurons both in epicenter and rostral and caudal spinal cord segments after SCI. Our study sheds light on the dynamic microenvironment changes in acute SCI by characterizing the profile of AA metabolism. The COX-2 and 5-LOX may be promising therapeutic target for SCI. [Display omitted] • Quantitative arachidonic acid metabolomics profiles based on LC-MS/MS were characterized in the acute spinal cord injury. • Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4) increased significantly after spinal cord injury. • Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) are the key mediators in the acute spinal cord injury. [ABSTRACT FROM AUTHOR]

As innate immune cells of the central nervous system (CNS), microglia are involved in the physiological processes of the CNS, including neural development and maintenance of homeostasis, and in the occurrence and development of most CNS diseases. Lipoxygenases (LOXs) are a family of non-heme, iron-containing enzymes that generate lipid mediators that regulate cellular inflammation by catalyzing the oxidation of polyunsaturated fatty acids. Many previous studies have demonstrated the indispensable role of the LOX pathway in microglia-mediated neuroinflammation, especially the 5-LOX and 12/15-LOX pathways. Emerging evidence indicates that the LOX pathway is also implicated in physiological processes, such as synaptic pruning and synaptic phagocytosis mediated by microglia, and that deficiency can contribute to neurodevelopmental disorders. The present review summarizes the impact of the LOX pathway on microglia-related physiological and pathological processes in the CNS and describes the potential for inhibition of the LOX pathway as a future strategy for the treatment of CNS diseases. [ABSTRACT FROM AUTHOR]

Introduction: Previous work of our group showed that lipoxygenase (LOX) pathways become activated upon surgical manipulation of the bowel wall and revealed a beneficial immune modulating role of the LOX-derived anti-inflammatory mediator protectin DX in postoperative ileus (POI). While we found a particular role of 12/15-LOX in the anti-inflammatory LOX action during POI, the role of 5-LOX, which produces the pro-inflammatory leukotriene B4 (LTB4), remained unknown. The purpose of this study was to investigate the role of 5-LOX within the pathogenesis of POI in a mouse model. Methods: POI was induced by intestinal manipulation (IM) of the small bowel in C57BL/6, 5-LOX−/−, and CX3CR1GFP/+. Mice were either treated with a vehicle or with the synthetic 5-LOX antagonist zileuton or were left untreated. Cellular localization of 5-LOX and LTB4 release were visualized by immunofluorescence or ELISA, respectively. POI severity was quantified by gastrointestinal transit (GIT) and leukocyte extravasation into the muscularis externa (ME) by immunohistochemistry. Results: 5-LOX expression was detected 24 h after IM within infiltrating leukocytes in the ME. LTB4 levels increased during POI in wild type but not in 5-LOX−/− after IM. POI was ameliorated in 5-LOX−/− as shown by decreased leukocyte numbers and normalized GIT. Zileuton normalized the postoperative GIT and reduced the numbers of infiltrating leukocytes into the ME. Discussion/Conclusion: Our data demonstrate that 5-LOX and its metabolite LTB4 play a crucial role in POI. Genetic deficiency of 5-LOX and pharmacological antagonism by zileuton protected mice from POI. 5-LOX antagonism might be a promising target for prevention of POI in surgical patients. [ABSTRACT FROM AUTHOR]

Cecropia pachystachya Tréc., popularly known as embaúba, belongs to the Cecropiaceae family and is used by the native population in the treatment of bronchitis, asthma, high blood pressure, fever, and as a diuretic. The pharmacological actions including anti-inflammatory, antioxidant, cardiotonic and sedative were previously reported. The objective of this study was to (1) isolate and identify bioactive compounds extracted from the ethanolic extract of C. pachystachya roots (ERCP), as well as (2) verify the affinity of these metabolites with the enzymes 5-lipoxygenase (5-LOX) and α-1-antitrypsin through in silico tests. Isolation and/or identification were performed using GC-MS, HPLC, Infrared (IR), and nuclear magnetic resonance (NMR) techniques. After isolation and identification of the active compounds, these substances were subjected to the in silico investigation that proceeded by performing PreADMET simulations and molecular docking calculations. The bioactive compounds identified were 1-(+)-ascorbic acid 2,6-dihexadecanoate, ethyl hexadecanoate, ethyl (9E,12E)-octadec-9,12-dienoate, ethyl (Z)-octadec-9-enoate and ethyl octadecanoate by GC-MS; chlorogenic acid, catechin, epicatechin, syringaldehyde by HPLC; β-sitosterol, sitostenone, beccaridiol, tormentic acid, lupeol, α- and β-amyrin by classical chromatography, IR, 1H and 13C NMR techniques. The ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties were determined for each bioactive compound. Tormentic acid demonstrated a greater affinity for 5-LOX enzyme while sitostenone demonstrated a higher affinity for the α-1-antitrypsin enzyme. Our findings demonstrated a diverse range of secondary metabolites isolated from C. pachystachya that showed relevant interactions with the enzymes 5-LOX and α-1-antitrypsin. Thus, "embaúba" may be employed in in vivo experimental studies as a form of alternative treatment for chronic lung diseases. Abbreviations: ADT: Autodock Tools; BBB: Blood-brain barrier; CaCo2: Human colonic adenocarcinoma cells; CC: Classic/open Column; TLC: Thin Layer Chromatography; CD40: Differentiation Cluster 40; CENAUREMN: Centro Nordestino de Aplicação e Uso da Ressonância Magnética Nuclear; GC-MS: Gas Chromatography coupled to mass spectrometry; HPLC: High-Perfomance Liquid Chromatography; CYP2C9, CYP2C19, CYP2D6 and CYP3A4: Cytochrome P450 isoenzymes; COPD: Chronic Obstructive Pulmonary Disease; DRX-500: X-Ray Diffraction – 500; ERCP: Ethanolic extract of the roots of C. pachystachya; FAPEPI: Fundação de Amparo à Pesquisa do Piauí; HIA: Human Intestinal Absorption; IR: Infrared; Ki: Inhibition constant; 5-LOX: 5-Lipoxygenase; mM: miliMolar; nM: nanoMolar; OECD423: acute toxic class method; PDB: Protein Data Bank; P-gP: P-glycoprotein; PM2,5: Small inhalable particles 2,5; PPB: Plasm Protein Binding; PreADMET: Prediction Absorption, Distribution, Metabolization, Excretion and Toxicity; NMR: Nuclear Magnetic Resonance; +S9: with metabolic activation; -S9: no metabolic activation; SisGen: Sistema Nacional de Gestão de Patrimônio Genético e do Conhecimento Tradicional Associado; RT: Retention time; TA100: Ames test with TA100 cells line; TA1535: Ames test with cells of the TA1535 cell line; UESPI: State University of Piauí; V79: lung fibroblast cells; ΔG: Gibbs free energy (Kcal/mol); μM: microMolar. [ABSTRACT FROM AUTHOR]

Arachidonate 5-lipoxygenase (ALOX5) is considered a prime target for drug discovery in the area of liver fibrosis, rheumatoid arthritis, atherosclerosis, cancer and asthma. To date, the lead rate in the discovery of drugs that inhibit ALOX5 for the treatment of the above diseases is not satisfactory. So, the development of powerful and effective ALOX5-targeted drugs is desired. In this regard, Quantitative Structure-Activity Relationship (QSAR) and molecular docking can have a major role in screening and designing drugs. In this work, 3D-QSAR models were proposed, which were built using the techniques like Multiple Linear Regression (MLR), and Partial Least Squares (PLS) for the pEC50(M) taking a diverse dataset of 112 molecules. The technique of the ‘Index of Ideality of Correlation (IIC)’ was also investigated to generate an optimal descriptor derived from the SMILES molecular structure. The effect of the number and nature of descriptors on the model were analyzed. The models can be helpful in providing better directions for the development of novel drug targets for 5-lipoxygenase. A significant improvement in the stability of the model was observed by the incorporation of the optimal descriptor. The molecular docking results showed that the ALOX5 receptor was well inhibited by the 112 ligands showing the least binding energy (-10.8 Kcal/mol). In order to validate the binding mode of the ligands docked with AutoDock Vina software, the top-scored compounds were re-docked using DockThor online docking server. The results obtained from docking suggest that the ligands with IDs 18, 20, 24, 30 and 44 are some of the potential inhibitors for ALOX5.

Leukotrienes are among the most potent mediators of inflammation, and inhibition of their biosynthesis, is becoming increasingly important in the treatment of many pathologies. In this work, we demonstrated that preincubation of human neutrophils with the mitochondria targeted antioxidant SkQ1 (100 nM) strongly inhibits leukotriene synthesis induced by three different stimuli: the Ca2+ ionophore A23187, the chemotactic formyl-peptide fMLP in combination with cytocholasin B, and opsonized zymosan. The SkQ1 analogue lacking the antioxidant quinone moiety (C12TPP) was ineffective, suggesting that mitochondrial production of reactive oxygen species (ROS) is critical for activating of leukotriene synthesis in human neutrophils. The uncoupler of oxidative phosphorylation FCCP also inhibits leukotriene synthesis, indicating that a high membrane potential is a prerequisite for stimulating leukotriene synthesis in neutrophils. Our data show that activation of mitogen-activated protein kinases p38 and ERK1/2, which is important for leukotriene synthesis in neutrophils is a target for SkQ1: 1) the selective p38 inhibitor SB203580 inhibited fMLP-induced leukotriene synthesis, while the ERK1/2 activation inhibitor U0126 suppressed leukotriene synthesis induced by any of the three stimuli; 2) SkQ1 effectively prevents p38 and ERK1/2 activation (accumulation of phosphorylated forms) induced by all three stimuli. This is the first study pointing to the involvement of mitochondrial reactive oxygen species in the activation of leukotriene synthesis in human neutrophils. The use of mitochondria-targeted antioxidants can be considered as a promising strategy for inhibiting leukotriene synthesis and treating various inflammatory pathologies.

To identify natural products as new prototypes for 5‐lipoxygenase (5‐LOX), 12 traditional Chinese medicines (TCMs) were selected for screening their 5‐LOX inhibition activities. The results showed that the methanol extracts of all selected TCMs (n = 12) possessed inhibitory activities against 5‐LOX at 200 μg/mL, of which six extracts of the TCMs showed significant inhibitory effects with IC50 values in the range from 33.2 ± 1.4 μg/mL to 153.5 ± 1.7 μg/mL, and the extract of Polygoni Cuspidati Rhizoma (RPC) was the most active sample. An on‐line ultra‐performance liquid chromatography–photodiode array–MSn–5‐LOX–fluorescence detector (UPLC–PDA–MSn–5‐LOX–FLD) method was applied to further identify the potential 5‐LOX inhibitory constituents in RPC extracts, which resulted in the identification of seven components with 5‐LOX‐binding activities. Finally, four compounds (polydatin, resveratrol, emodin‐8‐O‐glucoside, and emodin) were successfully purified from RPC extracts. The 5‐LOX inhibition action was assayed in vitro, and the results showed that these compounds possessed potent inhibitory effects against 5‐LOX with IC50 values of 15.3 ± 2.1, 4.5 ± 1.2, 23.8 ± 0.4, and 11.8 ± 1.5 μg/mL, respectively. This was the first study to reveal the 5‐LOX inhibitory constituents of RPC, and the present investigation might provide a valuable approach for the rapid discovery of natural inhibitors from TCMs. [ABSTRACT FROM AUTHOR]

Radiation-induced cutaneous ulcers are a challenging medical problem for patients receiving radiation therapy. The inhibition of cell senescence has been suggested as a prospective strategy to prevent radiation ulcers. However, there is no effective treatment for senescent cells in radiation ulcers. In this study, we investigated whether zileuton alleviated radiation-induced cutaneous ulcer by focusing on cell senescence. We demonstrate increased cell senescence and senescence-associated secretory phenotype (SASP) in irradiated dermal fibroblasts and skin tissue. The SASP secreted from senescent cells induces senescence in adjacent cells. In addition, 5-lipoxygenase (5-LO) expression increased in irradiated dermal fibroblasts and skin tissue, and SASP and cell senescence were regulated by 5-LO through p38 phosphorylation. Finally, the inhibition of 5-LO following treatment with zileuton inhibited SASP and mitigated radiation ulcers in animal models. Our results demonstrate that inhibition of SASP from senescent cells by zileuton can effectively mitigate radiation-induced cutaneous ulcers, indicating that inhibition of 5-LO might be a viable strategy for patients with this condition. [ABSTRACT FROM AUTHOR]

Lipoxygenases convert polyunsaturated fatty acids into biologically active metabolites such as inflammatory mediators—prostaglandins and leukotrienes. The inhibition of lipoxygenases is increasingly employed in the treatment of cancer. We evaluated the anticancer potential of two novel 5-lipoxygenase inhibitors, named CarbZDNaph and CarbZDChin, which are analogues of the commercially available inhibitor Rev-5901. The in vitro segment of this study was conducted on a mouse colorectal carcinoma cell line—CT26CL25. For an in vivo model, we induced tumors in BALB/c mice by the implantation of CT26CL25 cells, and we treated the animals with potential inhibitors. A 48 h treatment resulted in diminished cell viability. Calculated IC50 values (half-maximal inhibitory concentrations) were 25 μM, 15 μM and 30 μM for CarbZDNaph, CarbZDChin and Rev-5901, respectively. The detailed analysis of mechanism revealed an induction of caspase-dependent apoptosis and autophagy. In the presence of chloroquine, an autophagy inhibitor, we observed an increased mortality of cells, implying a cytoprotective role of autophagy. Our in vivo experiment reports tumor growth attenuation in animals treated with CarbZDChin. Compounds CarbZDNaph and Rev-5901 lacked an in vivo efficacy. The results presented in this study display a strong effect of compound CarbZDChin on malignant cell growth. Having in mind the important role of inflammation in cancer development, these results have a significant impact and are worthy of further evaluation. [ABSTRACT FROM AUTHOR]

Cephalopod cuttlefish, Sepia pharaonis, has been considered as a commercially important resource, which is widely regarded as nutritious food in the southwest of Indian and Mediterranean coasts. Chemical analysis of the crude extract of S. pharaonis resulted in the isolation of an undescribed 2H‐benzochromenone, pharachromenone, which was characterized as methyl‐2″‐(7‐hydroxy‐4‐(5′‐methylpent‐5′‐en‐1′‐yl‐oxy‐methyl)‐2‐oxo‐2H‐benzo[h]chromen‐5‐yl‐methyl)‐butanoate by mass and nuclear magnetic resonance spectral experiments. Pharachromenone revealed effective biopotency against 5‐lipoxygenase (IC50 1.85 mM) and cyclooxygenase‐2 (IC50 0.52 mM) than that displayed by nonsteroidal anti‐inflammatory drug ibuprofen (IC50 4.36 mM, p <.05). Promising antioxidant property for pharachromenone (IC50 1.42–1.61 mM) compared with those exhibited by antioxidative agents butylated hydroxyl anisole (BHA) and α‐tocopherol (IC50 1.40–1.90 mM) could conceivably validate its dual inhibition potential against 5‐lipoxygenase and cyclooxygenase‐2. Greater electronic parameters, lesser steric bulkiness, along with acceptable lipophilic–hydrophobic balance significantly contributed toward its promising anti‐inflammatory activities. Molecular docking studies showing significantly greater inhibition constant (Ki) 8.24 nM and binding energy (−11.03 kcal/mol) of pharachromenone than the standard ibuprofen (Ki 4.65 μM, binding energy −7.27 kcal/mol) at the binding site of 5‐lipoxygenase recognized its noncompetitive binding, which could describe the promising anti‐inflammatory potential. Pharachromenone could be developed as a functional food component against oxidative stress‐related inflammatory disorders. Practical applications: The cuttlefish Sepia pharaonis (family Sepiidae) comprises a major share in the global fishery sector due to its culinary delicacy and nutritionally valued high‐quality meat. Furthermore, cephalopod mollusks are gaining pharmaceutical acceptance as resources to derive bioactive compounds with therapeutic significance. Bioassay‐guided chromatographic fractionation of crude extract of S. pharaonis could result in the isolation of a 2H‐benzochromenone derivative, pharachromenone exhibiting potent antioxidant and anti‐inflammatory properties. This study recognized the therapeutic potential of a marine cuttlefish‐originated food constituent against inflammatory conditions, and could be anticipated as a high‐value functional food lead to minimize oxidative stress‐related inflammatory disorders. [ABSTRACT FROM AUTHOR]

Cryptococcosis, caused by fungi of the genus Cryptococcus , manifests in a broad range of clinical presentations, including severe pneumonia and disease of the central nervous system (CNS) and other tissues (bone and skin). Immune deficiency or development of overexuberant inflammatory responses can result in increased susceptibility or host damage, respectively, during fungal encounters. Leukotrienes help regulate inflammatory responses against fungal infections. Nevertheless, studies showed that Cryptococcus exploits host 5-lipoxygenase (5-LO), an enzyme central to the metabolism of arachidonic acid into leukotrienes, to facilitate transmigration across the brain-blood barrier. To investigate the impact of host 5-LO on the development of protective host immune responses and mortality during cryptococcosis, wild-type (C57BL/6) and 5-lipoxygenase-deficient (5-LO -/- ) mice were given experimental pulmonary and systemic Cryptococcus sp., infections. Our results showed that 5-LO -/- mice exhibited reduced pathology and better disease outcomes (i.e., no mortality or signs associated with cryptococcal meningoencephalitis) following pulmonary infection with C. deneoformans, despite having detectable yeast in the brain tissues. In contrast, C57BL/6 mice exhibited classical signs associated with cryptococcal meningoencephalitis. Additionally, brain tissues of 5-LO -/- mice exhibited lower levels of cytokines (CCL2 and CCL3) clinically associated with Cryptococcus -related immune reconstitution inflammatory syndrome (C-IRIS). In a systemic mouse model of cryptococcosis, 5-LO -/- mice and those treated with a Federal Drug Administration (FDA)-approved 5-LO synthesis inhibitor, zileuton, displayed significantly reduced mortality compared to C57BL/6 infected mice. These results suggest that therapeutics designed to inhibit host 5-LO signaling could reduce disease pathology and mortality associated with cryptococcal meningoencephalitis., Importance: Cryptococcosis is a mycosis with worldwide distribution and has a broad range of clinical manifestations, including diseases of the CNS. Globally, there is an estimated 179,000 cases of cryptococcal meningitis, resulting in approximately 112,000 fatalities per annum and 19% of AIDS-related deaths. Understanding how host immune responses are modulated during cryptococcosis is central to mitigating the morbidity and mortality associated with cryptococcosis. Leukotrienes (LTs) have been shown to modulate inflammatory responses during infection. In this study, we show that mice deficient in 5-lipoxygenase (5-LO), an enzyme central to the metabolism of arachidonic acid into leukotrienes, exhibit reduced pathology, disease, and neurological signs associated with cryptococcal meningitis. Additionally, mice given an experimental cryptococcal infection and subsequently treated with an FDA-approved 5-LO synthesis inhibitor exhibited significantly reduced mortality rates. These results suggest that therapeutics designed to inhibit host 5-LO activity could significantly reduce pathology and mortality rates associated with cryptococcal meningitis., Competing Interests: The authors declare no conflict of interest.

Many drugs can act on multiple targets or disease pathways, regardless of their original purpose. Drug repurposing involves reevaluating existing compounds for new medical uses. This can include repositioning approved drugs, redeveloping unapproved drugs, or repurposing any chemical, nutraceutical, or biotherapeutic product for new applications. Traditional drug development is slow, expensive, and has high failure rates. Drug repurposing can speed up the process, costing less and saving time. This approach can save 6-7 years of early-stage research time. Drug repurposing benefits from existing compounds with optimized structures and approved for clinical use with associated structure-activity relationship publications, supporting the development of new effective compounds. Drug repurposes can now utilize advanced in silico screening enabled by artificial intelligence (AI) and sophisticated tissue and organ-level in vitro models. These models more accurately replicate human physiology and improve the selection of existing drugs for further pre-clinical testing and, eventually, clinical trials for new indications. This mini-review discusses some examples of drug repurposing and novel strategies for further development of compounds for targets of the arachidonic acid cascade. In particular, we will delve into the prospect of repurposing antiplatelet agents for cancer prevention and addressing the emerging noncanonical functionalities of 5-lipoxygenase, potentially for leukemia therapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Patrignani, Contursi, Tacconelli and Steinhilber.)

Plant species from the genus Andrographis were used in Ayurveda and in other folklore medicines for treating ailments for centuries. In this study, we have hypothesized to evaluate the secondary metabolites as potent anti-inflammatory agents from the genus Andrographis. A library of secondary metabolites of the said genus was curated from the PubChem database and was subjected to energy minimization using UCSF Chimera software employing the AMBER force field. Initially, molecular docking was performed to evaluate the binding affinity of the curated library against the enzymes cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), and 5-Lipoxygenase (5-LOX) using AutoDock Vina. This resulted in shortlisting of two metabolites Echioidinin 5-O-glucoside was bound and 5,2',6'-Trihydroxy-6,7,8-trimethoxy flavone 2'-O-glucoside with high binding affinity than standard drugs Ibuprofen and Zileuton. In addition, molecular dynamic simulation studies confirm that these compounds form relatively more stable complexes than standard drugs with the above-said enzymes. The free binding energy values using MMGBSA of the above said ligands with COX-1, COX-2, and 5-LOX were found to be -49.18 kcal/mol, -38.60 kcal/mol, and -54.27 kcal/mol respectively, Whereas the standards have -21.77 kcal/mol, -9.96 kcal/mol, and -10.29 kcal/mol. Moreover, the in-silico ADMET analysis confirms the druggability of the shortlisted compounds. Later, this work will act as a base for in-vitro and in-vivo experimental studies to validate the anti-inflammatory potential of the same.Communicated by Ramaswamy H. Sarma.

The vitamin E family contains α-tocopherol (αT), βT, γT, and δT and α-tocotrienol (TE), βTE, γTE, and δTE. Research has revealed distinct roles of these vitamin E forms in prostate cancer (PCa). The ATBC trial showed that αT at a modest dose significantly decreased PCa mortality among heavy smokers. However, other randomized controlled trials including the Selenium and Vitamin E Cancer Prevention Trial (SELECT) indicate that supplementation of high-dose αT (≥400 IU) does not prevent PCa among nonsmokers. Preclinical cell and animal studies also do not support chemopreventive roles of high-dose αT and offer explanations for increased incidence of early-stage PCa reported in the SELECT. In contrast, accumulating animal studies have demonstrated that γT, δT, γTE, and δTE appear to be effective for preventing early-stage PCa from progression to adenocarcinoma in various PCa models. Existing evidence also support therapeutic roles of γTE and its related combinations against advanced PCa. Mechanistic and cell-based studies show that different forms of vitamin E display varied efficacy, that is, δTE ≥ γTE > δT ≥ γT >> αT, in inhibiting cancer hallmarks and enabling characteristics, including uncontrolled cell proliferation, angiogenesis, and inflammation possibly via blocking 5-lipoxygenase, nuclear factor κB, hypoxia-inducible factor-1α, modulating sphingolipids, and targeting PCa stem cells. Overall, existing evidence suggests that modest αT supplement may be beneficial to smokers and γT, δT, γTE, and δTE are promising agents for PCa prevention for modest-risk to relatively high-risk population. Despite encouraging preclinical evidence, clinical research testing γT, δT, γTE, and δTE for PCa prevention is sparse and should be considered., Competing Interests: Conflict of interest The author reports no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

The 5-lipoxygenase (5-LOX) pathway gives rise to bioactive inflammatory lipid mediators, such as leukotrienes (LTs). 5-LOX carries out the oxygenation of arachidonic acid to the 5-hydroperoxy derivative and then to the leukotriene A4 epoxide which is converted to a chemotactic leukotriene B4 (LTB4) by leukotriene A4 hydrolase (LTA4H). In addition, LTA4H possesses aminopeptidase activity to cleave the N-terminal proline of a pro-inflammatory tripeptide, prolyl-glycyl-proline (PGP). Based on the structural characteristics of LTA4H, it is possible to selectively inhibit the epoxide hydrolase activity while sparing the inactivating, peptidolytic, cleavage of PGP. In the current study, chalcogen-containing compounds, 4-(4-benzylphenyl) thiazol-2-amine (ARM1) and its selenazole (TTSe) and oxazole (TTO) derivatives were characterized regarding their inhibitory and binding properties. All three compounds selectively inhibit the epoxide hydrolase activity of LTA4H at low micromolar concentrations, while sparing the aminopeptidase activity. These inhibitors also block the 5-LOX activity in leukocytes and have distinct inhibition constants with recombinant 5-LOX. Furthermore, high-resolution structures of LTA4H with inhibitors were determined and potential binding sites to 5-LOX were proposed. In conclusion, we present chalcogen-containing inhibitors which differentially target essential steps in the biosynthetic route for LTB4 and can potentially be used as modulators of inflammatory response by the 5-LOX pathway.

Diverse secondary metabolites are biosynthesized by plants via various enzymatic cascades. These have the capacity to interact with various human receptors, particularly enzymes implicated in the etiology of several diseases. The n-hexane fraction of the whole plant extract of the wild edible plant, Launaea capitata (Spreng.) Dandy was purified by column chromatography. Five polyacetylene derivatives were identified, including (3S,8E)-deca-8-en-4,6-diyne-1,3-diol (1A), (3S)-deca-4,6,8-triyne-1,3-diol (1B), (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (2), bidensyneoside (3), and (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1-ol-3-O-β-D-glucopyranoside (4). These compounds were investigated for their in vitro inhibitory activity against enzymes involved in neuroinflammatory disorders, including cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and butyrylcholinesterase (BchE) enzymes. All isolates recorded weak–moderate activities against COX-2. However, the polyacetylene glycoside (4) showed dual inhibition against BchE (IC50 14.77 ± 1.55 μM) and 5-LOX (IC50 34.59 ± 4.26 μM). Molecular docking experiments were conducted to explain these results, which showed that compound 4 exhibited greater binding affinity to 5-LOX (−8.132 kcal/mol) compared to the cocrystallized ligand (−6.218 kcal/mol). Similarly, 4 showed a good binding affinity to BchE (−7.305 kcal/mol), which was comparable to the cocrystallized ligand (−8.049 kcal/mol). Simultaneous docking was used to study the combinatorial affinity of the unresolved mixture 1A/1B to the active sites of the tested enzymes. Generally, the individual molecules showed lower docking scores against all the investigated targets compared to their combination, which was consistent with the in vitro results. This study demonstrated that the presence of a sugar moiety (in 3 and 4) resulted in dual inhibition of 5-LOX and BchE enzymes compared to their free polyacetylenes analogs. Thus, polyacetylene glycosides could be suggested as potential leads for developing new inhibitors against the enzymes involved in neuroinflammation.

M1 microglia induce neuroinflammation-related neuronal death in animal models of spontaneous subarachnoid haemorrhage. Zileuton is a 5-lipoxygenase inhibitor that reduces the levels of downstream pro-inflammatory cytokines. This study aimed to investigate whether zileuton inhibits microglial activation and describe its underlying mechanisms. BV-2 cells were exposed to 1 mg/mL haemolysate for 30 min, followed by treatment with different concentrations (5, 10, 15, or 20 μM) of zileuton for 24 h. The cells were then assessed for viability, polarisation, and protein expression levels. Haemolysate increases the viability of BV-2 cells and induces M1 polarisation. Subsequent exposure to high concentrations of zileuton decreased the viability of BV-2 cells, shifted the polarisation to the M2 phenotype, suppressed the expression of 5-lipoxygenase, decreased tumour necrosis factor α levels, and increased interleukin-10 levels. Furthermore, high concentrations of zileuton suppressed the expression of myeloid differentiation primary response protein 88 and reduced the phosphorylated-nuclear factor-kappa B (NF-kB)/NF-kB ratio. Therefore, phenotype reversal from M1 to M2 is a possible mechanism by which zileuton attenuates haemolysate-induced neuroinflammation after spontaneous subarachnoid haemorrhage. [ABSTRACT FROM AUTHOR]

Persistent cognitive impairment is a primary central nervous system-related symptom in veterans afflicted with chronic Gulf War Illness (GWI). Previous studies in a rat model have revealed that cognitive dysfunction in chronic GWI is associated with neuroinflammation, typified by astrocyte hypertrophy, activated microglia, and enhanced proinflammatory cytokine levels. Studies in a mouse model of GWI have also shown upregulation of several phospholipids that serve as reservoirs of arachidonic acid, a precursor of leukotrienes (LTs). However, it is unknown whether altered LT signaling is a component of chronic neuroinflammatory conditions in GWI. Therefore, this study investigated changes in LT signaling in the brain of rats displaying significant cognitive impairments six months after exposure to GWI-related chemicals and moderate stress. The concentration of cysteinyl LTs (CysLTs), LTB4, and 5-Lipoxygenase (5-LOX), the synthesizing enzyme of LTs, were evaluated. CysLT and LTB4 concentrations were elevated in the hippocampus and the cerebral cortex, along with enhanced 5-LOX expression in neurons and microglia. Such changes were also associated with increased proinflammatory cytokine levels in the hippocampus and the cerebral cortex. Enhanced CysLT and LTB4 levels in the brain could also be gleaned from their concentrations in brain-derived extracellular vesicles in the circulating blood. The circulating blood in GWI rats displayed elevated proinflammatory cytokines with no alterations in CysLT and LTB4 concentrations. The results provide new evidence that a brain-specific increase in LT signaling is another adverse alteration that potentially contributes to the maintenance of chronic neuroinflammation in GWI. Therefore, drugs capable of modulating LT signaling may reduce neuroinflammation and improve cognitive function in GWI. Additional findings demonstrate that altered LT levels in the brain could be tracked efficiently by analyzing brain-derived EVs in the circulating blood. [ABSTRACT FROM AUTHOR]

Sec-O-glucosylhamaudol (SOG), an active flavonoid compound derived from the root of Saposhnikovia divaricata (Turcz. ex Ledeb.) Schischk., exhibits analgesic, anti-inflammatory, and high 5-lipoxygenase (5-LO) inhibitory effects. However, its effect on osteoclastogenesis was unclear. We demonstrated that SOG markedly attenuated RANKL-induced osteoclast formation, F-actin ring formation, and mineral resorption by reducing the induction of key transcription factors NFATc1, c-Fos, and their target genes such as TRAP , CTSK , and DC-STAMP during osteoclastogenesis. Western blotting showed that SOG significantly inhibited the phosphorylation of AKT and GSK3β at the middle–late stage of osteoclastogenesis without altering calcineurin catalytic subunit protein phosphatase-2β-Aα expression. Moreover, GSK3β inhibitor SB415286 partially reversed SOG-induced inhibition of osteoclastogenesis, suggesting that SOG inhibits RANKL-induced osteoclastogenesis by activating GSK3β, at least in part. 5-LO gene silencing by small interfering RNA in mouse bone marrow macrophages markedly reduced RANKL-induced osteoclastogenesis by inhibiting NFATc1. However, it did not affect the phosphorylation of AKT or GSK3β, indicating that SOG exerts its inhibitory effects on osteoclastogenesis by suppressing both the independent 5-LO pathway and AKT-mediated GSK3β inactivation. In support of this, SOG significantly improved bone destruction in a lipopolysaccharide-induced mouse model of bone loss. Taken together, these results suggest a potential therapeutic effect for SOG on osteoclast-related bone lysis disease. [ABSTRACT FROM AUTHOR]

Background: Traditionally, Usnea genus has significant uses in the treatment of swelling and tumors in Africa and Asia. The aim of the present study was to investigate the chemical constituents present in the acetone extract (AE) of Usnea subfloridana Stirton and also to evaluate their anti-inflammatory and anti-gout effects. Methods: Isolation and characterization of secondary metabolites from AE were evaluated by chromatography and spectral studies. Anti-inflammatory activities were assessed through cyclooxygenase (COX1 and COX2) and 5-lipooxygenase (5-LOX) enzyme inhibition assays, while anti-gout effects were evaluated by xanthine oxidase (XO) inhibition assay. Results: The existence of five known depsidones, identified as galbinic acid (1), conprotocetraricacid (2), constictic acid (3), salazinic acid (4), and lobaric acid (5), were exposed by chemical investigation of AE and confirmed by spectral data. Using in vitro enzyme inhibition assays, it was noticed that all the isolates showed dose-dependent activity against all the tested enzymes. Mainly, compounds 2 and 5 showed better inhibition efficiency on COX2 enzyme with the IC50of 7.17±1.07 and 7.01±0.94 nM, respectively, than the reference drug indomethacin (7.3±0.65nM). Furthermore, all isolates exhibited potent inhibition effects on the XO enzyme. Conclusion: The results indicated that U. subfloridana can be a favorable natural source for thetreatment of inflammation and gout. Compounds 2 and 5 were responsible for these biologicalactions by regulating pro-inflammatory enzymes, namely COXs, 5-LOX, and XO.

This mini-review addresses lipoxygenases and receptors for leukotrienes in hematological malignancies. Potential novel biomarkers and drug targets in leukemia and B-cell lymphoma are discussed. • B-cell chronic lymphocytic leukemia and B-cell lymphoma have high expression of 5-lipoxygenase. • Inhibition of the 5-lipoxygenase pathway or leukotriene B 4 receptor might inhibit the migration of malignant B cells. • Chronic myeloid leukemia cells possess high leukotriene C 4 synthase activity. • Hodgkin Reed-Sternberg cells express 15-lipoxygenase and cysteinyl-leukotriene receptor 1. • Potential novel biomarkers and drug targets in hematological malignancies are discussed. [ABSTRACT FROM AUTHOR]