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Given the importance of high-mobility group box 1 (HMGB1) and 5-lipoxygenase (5-LO) signaling in vascular inflammation, we investigated the role of leukotriene signaling in monocytes on monocyte-to-macrophage differentiation (MMD) induced by HMGB1, and on vascular inflammation and subsequent intimal hyperplasia in a mouse model of wire-injured femoral artery. In cultured primary bone marrow-derived cells (BMDCs) stimulated with HMGB1, the number of cells with macrophage-like morphology was markedly increased in association with an increased expression of CD11b/Mac-1, which were attenuated in cells pre-treated with Zileuton, a 5-LO inhibitor as well as in 5-LO-deficient BMDCs. Of various leukotriene receptor inhibitors examined, which included leukotriene B4 receptors (BLTRs) and cysteinyl leukotriene receptors (cysLTRs), the BLTR1 inhibitor (U75302) exclusively suppressed MMD induction by HMGB1. The importance of BLTR1 in HMGB1-induced MMD was also observed in BMDCs isolated from BLTR1-deficient mice and BMDCs transfected with BLTR1 siRNA. Although leukotriene B4 (LTB4) had minimal direct effects on MMD in control and 5-LO-deficient BMDCs, MMD attenuation by HMGB1 in 5-LO-deficient BMDCs was significantly reversed by exogenous LTB4, but not in BLTR1-deficient BMDCs, suggesting that LTB4/BLTR1-mediated priming of monocytes is a prerequisite of HMGB1-induced MMD. In vivo , both macrophage infiltration and intimal hyperplasia in our wire-injured femoral artery were markedly attenuated in BLTR1-deficient mice as compared with wild-type controls, but these effects were reversed in BLTR1-deficient mice transplanted with monocytes from control mice. These results suggest that BLTR1 in monocytes is a pivotal player in MMD with subsequent macrophage infiltration into neointima, leading to vascular remodeling after vascular injury. [ABSTRACT FROM AUTHOR]

Leukotrienes (LTs) and prostaglandin (PG)E 2 , produced by 5-lipoxygenase (5-LO) and microsomal prostaglandin E 2 synthase-1 (mPGES-1), respectively, are key players in inflammation, and pharmacological suppression of these lipid mediators (LM) represents a strategy to intervene with inflammatory disorders. Previous studies revealed that the benzenesulfonamide scaffold displays efficient 5-LO-inhibitory properties. Here, we structurally optimized benzenesulfonamides which led to an N -phenylbenzenesulfonamide derivative (compound 47 ) with potent inhibitory activities (IC 50  = 2.3 and 0.4 μM for isolated 5-LO and 5-LO in intact cells, respectively). Compound 47 prevented the interaction of 5-LO with its activating protein (FLAP) at the nuclear envelope in transfected HEK293 cells as shown by in situ proximity ligation assay. Comprehensive assessment of the LM profile produced by human macrophages revealed the ability of 47 to selectively down-regulate pro-inflammatory LMs (i.e. LTs and PGE 2 ) in M1 but to enhance the formation of pro-resolving LMs (i.e. resolvins and maresins) in M2 macrophages. Moreover, 47 strongly inhibited LT formation and cell infiltration in two in vivo models of acute inflammation (i.e., peritonitis and air pouch sterile inflammation in mice). Together, 47 represents a novel LT biosynthesis inhibitor with an attractive pharmacological profile as anti-inflammatory drug that also promotes the biosynthesis of pro-resolving LM. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To explore the potential anti‐inflammatory activity of Bupleurum marginatum extracts using in vitro and in vivo studies supported by virtual screening. Methods: Antioxidant activity was assessed using the DPPH˙ and inhibition of 2‐deoxyribose degradation assays. Anti‐inflammatory activity was determined in vitro by measuring the suppression of prostaglandin E2 release (PGE2) in pancreatic cancer cells (MIA‐PaCa‐2) and the inhibition of 5‐lipoxygenase whereas the rat paw oedema was used in vivo. The major constituents were docked in 5‐lipoxygenase and cyclooxygenase‐II active sites. Key findings: Methanol and dichloromethane (DCM) extracts showed IC50 of 46.99 and 162.99 μg/ml in the DPPH˙, 1.52 and 2.12 μg/ml in inhibition of 2‐deoxyribose degradation assays, respectively. They reduced PGE2 release by 41.33 and 52.85% at 25 μg/ml and inhibited 5‐lipoxygenase with IC50 of 45.28 and 25.92 μg/ml, respectively. 50 and 70% reduction in the diameter of the carrageenan‐induced rat paws with methanol and DCM extracts, respectively, with a marked decline in the inflammation score was observed. Rutin, a predominating compound, showed a strong interaction with the key amino acids in 5‐LOX active site with interaction energy of −74.59 kcal/mol. Conclusions: Our study provides evidence for an interesting anti‐inflammatory activity of B. marginatum aerial parts offering a natural anti‐inflammatory agent. [ABSTRACT FROM AUTHOR]

Lipoxygenases (LOXs) are dioxygenases that catalyze the peroxidation of linoleic acid (LA) or arachidonic acid (AA), in the presence of molecular oxygen. The existence of inflammatory component in the tumor microenvironment intimately links the LOXs to gastrointestinal (GI) cancer progression. Amongst the six-different human LOX-isoforms, 5-LOX is the most vital enzyme for leukotriene (LT) biosynthesis, which is the main inflammation intermediaries. As recent investigations have shown the association of 5-LOX with tumor metastasis, there has also been significant progress in discovering the function of 5-LOX pathway in GI cancer. Studies on GI cancer cells using the pharmacological drugs targeting 5-LOX pathway have shown antiproliferative and proapoptotic effects. Pharmacogenetic discoveries in other diseases have revealed strong heritable basis for the leukotriene pathway, which helps in exploring the mechanistic source of genetic alteration within the leukotriene pathway and offer insights into GI cancer pathogenesis and future prospects for treatment and prevention. This review recapitulates the current research status of 5-LOX activity in GI malignancies. [ABSTRACT FROM AUTHOR]

Brain accumulation of increasing amount of phosphorylated microtubule associated tau protein is one the major hallmark lesions of Alzheimer’s disease (AD) and related tauopathies. Consistent evidence from clinical and animal studies has shown that neuroinflammation characterizes these diseases. The 5-lipoxygenase (5LO) is an enzyme protein whose metabolic products are lipids with potent inflammatory actions. Previously, we showed that blockade of 5LO activation ameliorates the phenotype of the htau transgenic mice. Here, by employing a vector system to overexpress 5LO in the brain of the same mouse model, we investigated its role and contribution to their behavioral deficits and development of tau neuropathology. Compared with controls, 5LO gene targeted mice manifested significant impairments in their memory and learning ability. On the other hand, brain tissues of the same mice had higher 5LO protein level and activity which resulted in intense neuroinflammation and synaptic pathology. Further, the same mice had a significant elevation of tau phosphorylation, which associated with the activation of the cdk5 kinase and an accumulation of insoluble tau. The functional involvement of this kinase in the 5LO-dependent tau phosphorylation was confirmed in neuronal cells. Taken together, our findings demonstrate that neuronal 5LO is directly involved in tau phosphorylation and tau neuropathology, and for this reason, it should be considered a good therapeutic target for tauopathies. [ABSTRACT FROM AUTHOR]

The products of 5-lipoxygenase are synthesized and released in the airway when an asthmatic reaction occurs. 5-lipoxygenase via arachidonic acid metabolism produces leukotrienes that mediate bronchoconstriction and inflammatory modifications essential in the pathophysiology of asthma. Until to now, only one approved 5-LO inhibitor, zileuton, can be found as a potential therapy for asthma. With the increasing number of indications for anti-leukotriene (anti-LT) drugs, the development of 5-LO inhibitor agents becomes increasingly important. The present MiniReview reports an update on 5-LO inhibitors currently under clinical investigation. In addition, the latest advances focused on the development of new 5-lipoxygenase inhibitors as asthma anti-inflammatory agents are also discussed. [ABSTRACT FROM AUTHOR]

5‑lipoxygenase (5‑LO) catalyzes the first step of arachidonic acid metabolism to inflammatory mediator leukotrienes. The present study assessed 5‑LO expression in esophageal squamous cell carcinoma (ESCC) tissue specimens for associations with clinicopathological and survival data from patients, then explored 5‑LO activity in ESCC cells in vitro. 5‑LO expression was detected in tissue microarrays containing 297 ESCC samples using immunohistochemistry. Kaplan‑Meier curves were used to analyze the survival significance of 5‑LO expression and relative risk was evaluated using the multivariate Cox proportional hazards model. Cultured tumor cells were subjected to gene transfection, western blotting, and cell migration and proliferation assays. 5‑LO protein was primarily expressed in normal cell cytoplasm and/or membrane, and never in the whole cytoplasm, whereas 5‑LO was expressed diffusely in ESCC tissues with nearly homogeneous whole‑cytoplasm staining. 5‑LO expression was significantly associated with tumor regional lymph node metastasis (P=0.013) and pTNM stage (P=0.004). 5‑LO expression was associated with poor overall survival (P=0.029). Multivariate analysis demonstrated that 5‑LO overexpression was an independent prognostic factor for ESCC patients (P=0.041). Furthermore, the inhibition of 5‑LO expression reduced ESCC cell viability and migration in vitro. These data provide further evidence that the upregulation of 5‑LO expression is associated with advanced stages of disease and poor ESCC prognosis, and that 5‑LO expression may independently predict overall survival in patients with ESCC. The inhibition of 5‑LO expression reduced ESCC malignant behavior in vitro. [ABSTRACT FROM AUTHOR]

Leukotrienes (LTs) and prostaglandin (PG)E 2 are enzymatically produced from arachidonic acid and represent highly bioactive lipid mediators with pro-inflammatory functions. Here, we report on novel multi-target inhibitors that potently and dually interfere with 5-lipoxygenase-activating protein (FLAP) and microsomal prostaglandin E 2 synthase (mPGES)-1 in LT and PGE 2 biosynthesis, based on the previously identified selective FLAP inhibitor BRP-7 ( 8 , IC 50  = 0.31 μM). C (5)-substitution of the benzimidazole ring of BRP-7 by carboxylic acid and its bioisosteres provided compounds, exemplified by 57 that potently suppress LT formation (IC 50  = 0.05 μM) by targeting FLAP along with inhibition of mPGES-1 (IC 50  = 0.42 μM). Besides FLAP, also 5-lipoxygenase (5-LO) and LTC 4 synthase activities were inhibited by 57 , albeit with lower potency (IC 50  = 0.6 and 6.2 μM) than FLAP. Docking studies and molecular dynamic simulations with FLAP, mPGES-1 and 5-LO provide valuable insights into potential binding interactions of the inhibitors with their targets. Together, these novel benzimidazole derivatives may possess potential as leads for development of effective anti-inflammatory drugs with multi-target properties for dually inhibiting LT and PGE 2 production. [ABSTRACT FROM AUTHOR]

Background: Agnimantha is a constituent of the bṛhatpañcamūla (the roots drugs of 5 tree species) which in turn is a part of daśamūla used in Ayurvedic pharmaceutical practices. Traditionally, the concept of bṛhatpañcamūla envisages the usage of root/ root bark of these tree species. By and large, use of stem bark came into vogue many decades ago for this sub-group of daśamūla. Going by descriptions in Ayurvedic lexicon of medicinal plants- two species are considered as Agnimantha viz. Clerodendrum phlomidis L.f. (Fam.: Lamiaceae) and Premna integrifolia L. (Syn. Premna serratifolia L) (Fam.: Lamiaceae). Objective: With an objective to address sustainability concerns associated with use of root or stem bark a comprehensive study was carried out on bṛhatpañcamūla group. This study kept the anti-inflammatory profile of candidate extracts in the centre-stage. As a part of this study, comparative assessment of two species used as Agnimantha was also carried out. Study Methodology: Different plant parts (Root bark, Stem bark, Leaves and Young roots) of C. phlomidis and P. integrifolia were collected from different parts of India. Each sample was extracted successively into four solvents. These extracts were evaluated for their anti-inflammatory profile using a battery of in-vitro assays, involving inhibition of regulatory enzymes like 5-lipoxygenase (5-LOX), cyclooxygenase 1&2 (COX-1 & COX-2) and analysis of the expression of pro- and anti-inflammatory cytokines in LPS-stimulated RAW 264.7 cells.Result and Conclusions: Both the species were observed to exhibit anti-inflammatory activity of varied degrees in this study. However, the sample of 12 months old roots of P. integrifolia was found to possess profound effect on all markers of inflammation. This sample was followed by 36 months old roots of C. phlomidis in terms of anti-inflammatory profile. Basing on these observations, the study suggests the use of 12 months roots of P. integrifolia (often referred to as Bṛhat-agnimantha) as part of daśamūla. Since the harvesting cycle is of 12 months, it is possible to produce the roots using High-Density Short-Term plantation protocols to address the sustainability concerns associated with use of root or stem bark. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of Cannabis sativa extract on the development of neuro- and hepato-toxicity caused by malathion injection in rats. Methods: The extract of Cannabis sativa was obtained from the plant resin by chloroform treatment. Δ-Tetrahydrocannabinol content of the extract (20%) was quantified using gas chromatography–mass spectrometry. The doses of cannabis extract were expressed as Δ -tetrahydrocannabinol content of 10 or 20 mg/kg. Malathion (150 mg/kg) was intraperitoneally administered followed after 30 min by the cannabis extract (10 or 20 mg/kg, subcutaneously). Rats were euthanized 4 h later. Malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide and paraoxonase-1 (PON-1) activity were determined in brain and liver. Brain 5-lipoxygenase and butyrylcholinesterase (BChE) activity were measured as well. Histopathological examination of brain and liver tissue was also performed. Results: Compared to controls, malathion resulted in increased oxidative stress in brain and liver. MDA and nitric oxide concentrations were significantly increased (P<0.05) and GSH significantly decreased with respect to control levels (P<0.05). Malathion also significantly inhibited PON-1 and BChE activities but had no effect on brain 5-lipoxygenase. Brain MDA concentrations were not altered by cannabis treatment. Cannabis at 20 mg/kg, however, caused significant increase in nitric oxide and restored the GSH and PON-1 activity. Brain BChE activity significantly decreased by 26.1% (P<0.05) after treatment with 10 mg/kg cannabis. Cannabis showed no effect on brain 5-lipoxygenase. On the other hand, rats treated with cannabis exhibited significantly higher levels of liver MDA, nitric oxide and PON-1 activity compared with the malathion control group. Rats treated with only malathion exhibited spongiform changes, neuronal damage in the cerebral cortex and degeneration of some Purkinje cells in the cerebellum. There were also hepatic vacuolar degeneration and dilated and congested portal vein. These histopthological changes induced by malathion in brain and liver were reduced to great extent by cannabis administration at 20 mg/kg. Conclusions: Our data suggest that acute treatment with cannabis alleviates the malathion-induced brain and hepatic injury in rats possibly by maintaining the levels of GSH and PON-1 activity. [ABSTRACT FROM AUTHOR]

Pancreatic glandular necrosis is rapid inflammation of the pancreas and contributes to severe acute pancreatitis in humans. The pathogenesis of pancreatic tissue inflammation during acute pancreatitis is still largely unknown. Recent studies suggest that 5-lipoxygenase (5-LOX) is an essential mediator in modulating cell death pathways in human diseases. In this study, we aimed to evaluate the effects of a 5-LOX inhibitor, zileuton, on tissue apoptosis and neutrophils activation in pancreatic tissues during acute necrotizing pancreatitis (ANP) in a rat model. In this present study, both mRNA and protein levels of 5-LOX are upregulated during ANP and zileuton treatment is shown to repress ANP-induced upregulation of 5-LOX levels. In addition, zileuton treatment is found to repress blood biomarkers of neutrophils activation such as soluble intercellular adhesive molecular 1 (ICAM-1), soluble E-selectin (E-selectin), soluble P-selectin (P-selectin), leukotriene B4 (LTB4), and myeloperoxidase (MPO). Also, zileuton treatment attenuates pancreatic tissue pathology, upregulates caspase-3, downregulates B-cell lymphoma 2 (Bcl-2), and activates tissue apoptosis evaluated by TUNEL staining. Our results show that 5-LOX plays an important role in activating apoptosis and repressing neutrophils activation during ANP. The current study suggests that 5-LOX can be used as a potential target for the treatment of ANP. [ABSTRACT FROM AUTHOR]

The inflammatory process plays a major role in the prognosis of dengue. In this context, the eicosanoids may have considerable influence on the regulation of the Dengue virus-induced inflammatory process. To quantify the molecules involved in the cyclooxygenase and lipoxygenase pathways during Dengue virus infection, plasma levels of thromboxane A2, prostaglandin E2 and leukotriene B4; mRNA levels of thromboxane A2 synthase, prostaglandin E2 synthase, leukotriene A4 hydrolase, cyclooxygenase-2 and 5-lipoxygenase; and the levels of lipid bodies in peripheral blood leukocytes collected from IgM-positive and IgM-negative volunteers with mild dengue, and non-infected volunteers, were evaluated. Dengue virus infection increases the levels of thromboxane A2 in IgM-positive individuals as well as the amount of lipid bodies in monocytes in IgM-negative individuals. We suggest that increased levels of thromboxane A2 in IgM-positive individuals plays a protective role against the development of severe symptoms of dengue, such as vascular leakage. [ABSTRACT FROM AUTHOR]

Age-related diseases, such as osteoarthritis, Alzheimer’s disease, diabetes, and cardiovascular disease, are often associated with chronic unresolved inflammation. Neutrophils play central roles in this process by releasing tissue-degenerative proteases, such as cathepsin G, as well as pro-inflammatory leukotrienes produced by the 5-lipoxygenase (5-LO) pathway. Boswellic acids (BAs) are pentacyclic triterpene acids contained in the gum resin of the anti-inflammatory remedy frankincense that target cathepsin G and 5-LO in neutrophils, and might thus represent suitable leads for intervention with age-associated diseases that have a chronic inflammatory component. Here, we investigated whether, in addition to BAs, other triterpene acids from frankincense interfere with 5-LO and cathepsin G. We provide a comprehensive analysis of 17 natural tetra- or pentacyclic triterpene acids for suppression of 5-LO product synthesis in human neutrophils. These triterpene acids were also investigated for their direct interference with 5-LO and cathepsin G in cell-free assays. Furthermore, our studies were expanded to 10 semi-synthetic BA derivatives. Our data reveal that besides BAs, several tetra- and pentacyclic triterpene acids are effective or even superior inhibitors of 5-LO product formation in human neutrophils, and in parallel, inhibit cathepsin G. Their beneficial target profile may qualify triterpene acids as anti-inflammatory natural products and pharmacological leads for intervention with diseases related to aging. [ABSTRACT FROM AUTHOR]

Summary: Progressive accumulation of highly phosphorylated tau protein isoforms is the main feature of a group of neurodegenerative diseases collectively called tauopathies. Data from human and animal models of these diseases have shown that neuroinflammation often accompanies their pathogenesis. The 5‐lipoxygenase (5LO) is an enzyme widely expressed in the brain and a source of potent pro‐inflammatory mediators, while its pharmacological inhibition modulates the phenotype of a tau transgenic mouse model, the htau mice. By employing an adeno‐associated viral vector system to over‐express 5LO in the brain, we examined its contribution to the behavioral deficits and neuropathology in a different transgenic mouse model of tauopathy, the P301S mouse line. Compared with controls, 5LO‐targeted gene brain over‐expression in these mice resulted in a worsening of behavioral and motor deficits. Over‐expression of 5LO resulted in microglia and astrocyte activation and significant synaptic pathology, which was associated with a significant elevation of tau phosphorylation at specific epitopes, tau insoluble fraction, and activation of the cdk5 kinase. In vitro studies confirmed that 5LO directly modulates tau phosphorylation at the same epitopes via the cdk5 kinase pathway. These data demonstrate that 5LO plays a direct role in tau phosphorylation and is an active player in the development of the entire tau phenotype. They provide further support to the hypothesis that 5LO is a viable therapeutic target for the treatment and/or prevention of human tauopathy. [ABSTRACT FROM AUTHOR]

Background: Recent studies demonstrated beneficial effects of zileuton, a 5-lipoxygenase (5LO) inhibitor, on some brain diseases in animal models, but the role of zileuton in the depression remains unknown.Methods: We investigated the effects of zileuton on depressive behaviors using tail suspension test (TST), forced swimming test (FST) and novelty-suppressed feeding test (NSFT) in mice injected with lipopolysaccharide (LPS). The 5LO level, activation of microglia, NF-κB p65, TNF-α, IL-1β, brain-derived neurotrophic factor (BDNF), and c-AMP response element-binding protein (CREB) were determined in the mouse hippocampus.Results: We firstly found that the expression of hippocampal 5LO was gradually increased over LPS exposure and was reversed by fluoxetine administration. Zileuton significantly suppressed LPS-induced depressive behaviors, evidenced by the decreases in immobility time in TST and FST, as well as the latency to feed in NSFT. This treatment pronouncedly alleviated LPS-induced neuroinflammatory response, characterized by decreased 5LO, suppressed activation of microglia, decreased NF-κB p65, TNF-α and IL-1β, and significantly increased the ratio of p-CREB/CREB or mBDNF/proBDNF in the hippocampus of the LPS-challenged mice.Conclusions: Zileuton abrogates LPS-induced depressive-like behaviors and neuroinflammation, and enhances CREB/BDNF signaling in the hippocampus, suggesting that zileuton could have potential therapeutic value for depression. [ABSTRACT FROM AUTHOR]

5-Lipoxygenase (5-LO) catalyzes the initial two steps of the conversion of arachidonic acid to leukotrienes which represent a group of pro-inflammatory lipid mediators involved in immune defense reactions as well as inflammation, allergy and cancer. Transforming growth factor-β (TGFβ) and calcitriol strongly upregulate 5-LO expression during myeloid cell differentiation and MLL-AF4 has been shown to strongly activate the 5-LO promoter. Here, we investigated the role of TGFβ/SMAD signalling in 5-LO promoter activation. We identified two functional SMAD binding elements in the proximal part of the 5-LO promoter which significantly induce 5-LO promoter activity via TGFβ and SMAD3/4. Since aberrant 5-LO gene expression has been linked with mixed lineage leukemia (MLL) which is characterized by the presence of MLL fusion proteins (e.g. MLL-AF4), we also investigated the influence of TGFβ/SMADs on MLL- and MLL-AF4-mediated 5-LO promoter activation. Our data show that induction of 5-LO promoter activity by SMAD3/4 is MLL-dependent and that knockdown of the MLL complex component MEN1 attenuates the SMAD effect. Our data suggest that induction of 5-LO gene expression by TGFβ is at least in part due to stimulation of transcript initiation. [ABSTRACT FROM AUTHOR]

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 PKC α -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. [Display omitted] • Clau reduced the motor impairment of PD model mice by inhibiting ferroptosis in dopaminergic neurons. • Clau inhibited lipid peroxidation and ferroptosis by blocking ALOX5 phosphorylation and nuclear translocation. • Clau interfered with ALOX5 function by binding to its Ser663 site and preventing the phosphorylation by PKCα. [ABSTRACT FROM AUTHOR]

The cysteinyl leukotrienes (CysLTs) have important functions in the regulation of inflammation and cellular stress. Blocking the CysLT receptors (CysLTRs) with specific antagonists is beneficial against progression of retinopathies (e.g. diabetic retinopathy, wet AMD). However, the exact cellular localization of the CysLTRs and their endogenous ligands in the eye have not been elucidated in detail yet. It is also not known whether the expression patterns differ between humans and animal models. Therefore, the present study aimed to describe and compare the distribution of two important enzymes in CysLT biosynthesis, 5-lipoxygenase (5-LOX) and 5-lipoxygenase-activating protein (FLAP), and of CysLTR1 and CysLTR2 in healthy human, rat and mouse eyes. Human donor eyes (n = 10) and eyes from adult Sprague Dawley rats (n = 5) and CD1 mice (n = 8) of both sexes were collected. The eyes were fixed in 4% paraformaldehyde and cross-sections were investigated by immunofluorescence with specific antibodies against 5-LOX, FLAP (human tissue only), CysLTR1 and CysLTR2. Flat-mounts of the human choroid were prepared and processed similarly. Expression patterns were assessed and semiquantitatively evaluated using a confocal fluorescence microscope (LSM710, Zeiss). We observed so far unreported expression sites for CysLT system components in various ocular tissues. Overall, we detected expression of 5-LOX, CysLTR1 and CysLTR2 in the human, rat and mouse cornea, conjunctiva, iris, lens, ciliary body, retina and choroid. Importantly, expression profiles of CysLTR1 and CysLTR2 were highly similar between human and rodent eyes. FLAP was expressed in all human ocular tissues except the lens. Largely weak immunoreactivity of FLAP and 5-LOX was observed in a few, yet unidentified, cells of diverse ocular tissues, indicating low levels of CysLT biosynthesis in healthy eyes. CysLTR1 was predominantly detected in ocular epithelial cells, supporting the involvement of CysLTR1 in stress and immune responses. CysLTR2 was predominantly expressed in neuronal structures, suggesting neuromodulatory roles of CysLTR2 in the eye and revealing disparate functions of CysLTRs in ocular tissues. Taken together, we provide a comprehensive protein expression atlas of CysLT system components in the human and rodent eye. While the current study is purely descriptive and therefore does not allow significant functional conclusions yet, it represents an important basis for future studies in diseased ocular tissues in which distribution patterns or expression levels of the CysLT system might be altered. Furthermore, this is the first comprehensive study to elucidate expression patterns of CysLT system components in human and animal models that will help to identify and understand functions of the system as well as mechanisms of action of potential CysLTR ligands in the eye. • Comprehensive expression atlas of CysLT system components in human and rodent eyes. • Description of novel expression sites for CysLT system components in ocular tissues. • Comparable distribution between species supports use of rodents in CysLT research. • CysLTR1 is predominantly expressed in ocular epithelia. • CysLTR2 is predominantly expressed in ocular nerve fibers. [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. [Display omitted] • Expression of 5-LOX is associated with the postoperative survival of HCC patients. • CD163(+) TAMs express 5-LOX and produce LTB4 and LTC/D/E4. • Inhibition of 5-LOX activity regulates HCC progression. • LTB4 and LTC/D/E4 promote cancer proliferative via phosphorylation of ERK1/2. • LTB4 and LTC/D/E4 enhance stem cell capacity through stem cell-associated genes. [ABSTRACT FROM AUTHOR]

Immune-suppressive cell populations impair anti-tumor immunity and can contribute to the failure of immune therapeutic approaches. We hypothesized that the non-steroidal anti-inflammatory drug (NSAID) licofelone, a dual COX-2/5-LO inhibitor, would improve therapeutic melanoma vaccination by reducing immune-suppressive cell populations. Therefore, licofelone was administered after tumor implantation, either alone or in combination with a peptide vaccine containing a long tyrosinase-related protein (TRP)2-peptide and the adjuvant α-galactosylceramide, all formulated into cationic liposomes. Mice immunized with the long-peptide vaccine and licofelone showed delayed tumor growth compared to mice given the vaccine alone. This protection was associated with a lower frequency of immature myeloid cells (IMCs) in the bone marrow (BM) and spleen of tumor-inoculated mice. When investigating the effect of licofelone on IMCs in vitro, we found that the prostaglandin E2-induced generation of IMCs was decreased in the presence of licofelone. Furthermore, pre-incubation of BM cells differentiated under IMC-inducing conditions with licofelone reduced the secretion of cytokines interleukin (IL)-10 and -6 upon LPS stimulation as compared to untreated cells. Interestingly, licofelone increased IL-6 and IL-10 secretion when administered after the LPS stimulus, demonstrating an environment-dependent effect of licofelone. Our findings support the use of licofelone to reduce tumor-promoting cell populations.

Given the importance of leukotrienes in vascular inflammation induced by local tissue injury, this study investigated the role for 5-lipoxygenase (5-LO) in monocytes in the development of intimal hyperplasia. As a mechanistic study, the importance of monocyte 5-LO in monocyte-macrophage differentiation with subsequent infiltration in neointima was evaluated. In a mouse model of wire-injured femoral artery, intimal hyperplasia started as early as 2 wks after injury, and luminal area and blood flow were reduced due to increased neointima formation. Time-dependent increases in macrophage infiltration were observed in neointima and showed a positive relationship with neointima volume. In 5-LO-deficient (KO) mice or wild-type (WT) mice treated with an inhibitor of 5-LO activating protein (MK886, 1 and 10 mg/kg), intimal hyperplasia and macrophage infiltration into neointima were reduced, but monocyte adhesion to injured luminal surface was not inhibited, which suggested 5-LO participates in monocyte-macrophage differentiation. In an in vitro study, monocyte-macrophage differentiation was found to be increased by high mobility group box 1 protein (HMGB1), but this effect was attenuated in cells isolated from 5-LO-KO mice. Furthermore, macrophage infiltration and intimal hyperplasia were more prominent in 5-LO-KO mice transplanted with monocytes from WT mice than in 5-LO-KO mice transplanted with monocytes from 5-LO-KO mice. Taken together, it was suggested that 5-LO in monocytes played a pivotal role in monocyte-macrophage differentiation and subsequent infiltration of macrophage in neointima, leading to vascular remodeling after vascular injury. [ABSTRACT FROM AUTHOR]

5-hydroxyeicosatetraenoic acid (5-HETE) and 5-hydroxyeicosapentaenoic acid (5-HEPE) are major metabolites produced by 5-lipoxygenase (5-LOX) from arachidonic acid (AA) and eicosapentaenoic acid (EPA). Effects of hydroxides on endothelial cells are unclear, although 5-LOX is known to increase at arteriosclerotic lesions. To investigate the effects of hydroxides on human umbilical vein endothelial cells (HUVECs), the cells were treated with 50 µM each of AA, EPA, 5-HETE, and 5-HEPE. Treatment of HUVECs with 5-HETE and 5-HEPE, rather than with AA and EPA, increased the nuclear translocation of NF-E2 related factor 2 (Nrf2) and upregulated the expression of heme oxygenase-1 and cystine/glutamate transporter regulated by Nrf2. Reactive oxygen species (ROS) generation was markedly elevated in HUVECs after treatment with 5-HETE and 5-HEPE, and the pretreatment with α-tocopherol abrogated ROS levels similar to those in the vehicle control. However, ROS generation was independent of Nrf2 activation induced by 5-HETE and 5-HEPE. 5-HETE was converted to 5-oxo-eicosatetraenoic acid (5-oxo-ETE) in HUVECs, and 5-oxo-ETE increased Nrf2 activation. These results suggest that 5-HETE works as an Nrf2 activator through the metabolite 5-oxo-ETE in HUVECs. Similarly, 5-HEPE works in the same way, because 5-HEPE is metabolized to 5-oxo-eicosapentaenoic acid through the same pathway as that for 5-HETE. [ABSTRACT FROM AUTHOR]

Aim Leukotrienes ( LTs) are pro-inflammatory lipid mediators formed by the enzyme 5-lipoxygenase (5- LO). The involvement of 5- LO metabolites in periodontal disease ( PD) is not well defined. This study aimed to assess the role of 5- LO in experimental PD induced by Aggregatibacter actinomycetemcomitans ( Aa). Material and Methods In vivo experiments were carried out using SV129 wild-type ( WT) and 5- LO-deficient ( 5lo-/-) mice inoculated with Aa. Osteoclasts were stimulated in vitro with Aa LPS in the presence or not of selective inhibitors of the 5- LO pathway, or LTB4 or platelet-activating factor ( PAF), as PAF has already been shown to increase osteoclast activity. Results In 5lo -/- mice, there were no loss of alveolar bone and less TRAP-positive osteoclasts in periodontal tissues, after Aa inoculation, despite local production of TNF-α and IL-6. The differentiation and activity of osteoclasts stimulated with Aa LPS were diminished in the presence of BLT1 antagonist or 5- LO inhibitor, but not in the presence of cysteinyl leukotriene receptor antagonist. The osteoclast differentiation induced by PAF was impaired by the BLT1 antagonism. Conclusion In conclusion, LTB4 but not Cys LTs is important for Aa-induced alveolar bone loss. Overall, LTB4 affects osteoclast differentiation and activity and is a key intermediate of PAF-induced osteoclastogenesis. [ABSTRACT FROM AUTHOR]

Previously undescribed chromenyl derivatives, characterized as 7-(2′-ethyl-1′-hydroxynonan-2′-yl)-6,7,8,8a-tetrahydro-3 H-isochromen-1-(5 H)-one ( 1) and 6-(3-(( E)-3-(furan-2′-yl)-prop-3-en-3-yl)-4a,5,6,8a-tetrahydro-8-methyl-2 H-chromen-6-yl)-ethyl-5′′-methyl-hexanoate ( 2) were isolated from ethyl acetate-methanol extract of yellow-foot bivalve clam, Paphia malabarica. Their structures have skeletons composed of isochromen-(5 H)-one and furanyl-2 H-chromenyl moieties, which are reported for the first time in marine organism. These were characterized by extensive one and two-dimensional nuclear magnetic resonance, infrared, and high-resolution mass spectroscopic experiments. The title compounds were evaluated for therapeutic potentials with regard to anti-inflammatory and antioxidant properties compared to known standards. These compounds exhibited comparable 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities with α-tocopherol (IC ~0.6-0.7 mg/mL). The significantly higher anti-5-lipoxygenase activity of the title compounds (IC 0.76-0.82 mg/mL) than ibuprofen (IC 0.93 mg/mL) indicated their potential anti-inflammatory properties. The selectivity indices (IC anti-cyclooxygenase-1/ICanti-cyclooxygenase-2) of compounds 1 (1.19) and 2 (1.31) well established its safety profiles as an anti-inflammatory when compared to known drug, ibuprofen (0.44). The target bioactivities of chromenyl derivatives were guided by hydrophobic and electronic parameters. These compounds can be used as potential bioactive leads in functional food and medicinal applications. [ABSTRACT FROM AUTHOR]

Glioblastoma multiforme (GBM) is an aggressive brain tumor that correlates with short patient survival and for which therapeutic options are limited. Polyphenolic compounds, including caffeic acid phenethyl ester (CAPE, 1a), have been investigated for their anticancer properties in several types of cancer. To further explore these properties in brain cancer cells, a series of caffeic and ferulic acid esters bearing additional oxygens moieties (OH or OCH3) were designed and synthesized. (CAPE, 1a), but not ferulic acid phenethyl ester (FAPE, 1b), displayed substantial cytotoxicity against two glioma cell lines. Some but not all selected compounds derived from both (CAPE, 1a) and (FAPE, 1b) also displayed cytotoxicity. All CAPE-derived compounds were able to significantly inhibit 5-lipoxygenase (5-LO), however FAPE-derived compounds were largely ineffective 5-LO inhibitors. Molecular docking revealed new hydrogen bonds and π-π interactions between the enzyme and some of the investigated compounds. Overall, this work highlights the relevance of exploring polyphenolic compounds in cancer models and provides additional leads in the development of novel therapeutic strategies in gliomas. [ABSTRACT FROM AUTHOR]

Anti-diabetic and anti-inflammatory activities of ethyl acetate-methanol extracts of cephalopods namely, Amphioctopus marginatus, Urothethis duvauceli, Sepia pharaonis, Sepiella inermis, and Cistopus indicus were evaluated. The ethyl acetate-methanol extracts of C. indicus exhibited significantly greater (p < 0.05) cyclooxygenase inhibition activities (IC90 ~ 1 mg/mL, respectively) compared to other cephalopod species. Likewise, C. indicus displayed greater 5-lipoxygenase inhibitory activity (IC90 1.69 mg/mL) compared to the other cephalopod species (IC90 > 2 mg/mL) considered in the present study. The solvent extracts derived from the members of the order Octopoda demonstrated fairly good α-amylase inhibitory activity (IC90 ≤ 2.5 mg/mL). Dipeptidyl peptidase-4 inhibitory activity of the ethyl acetate-methanol extract of C. indicus was found to be significantly greater (IC50 2.51 mg/mL) than other species of cephalopods (IC50 3.4–5.4 mg/mL; p < 0.05). The labeling of protons associated with different magnetic environments of the functional groups exhibited in the ethyl acetate-methanol extracts were analyzed by proton nuclear magnetic resonance spectroscopy that supported the in vitro anti-diabetic and anti-inflammatory results. The ethyl acetate-methanol extract of C. indicus and S. inermis displayed greater proton integrals (ΣH) of highly electronegative moieties appeared in the low-field region in the proton nuclear magnetic resonance spectroscopy spectra (C. indicus ΣHδ3.5–4.5 5.34, ΣHδ4.5–6.5 6.41; S. inermis ΣHδ3.5–4.5 6.52, and ΣHδ4.5–6.5 15.39) than other cephalopod species. A significant co-linearity was found between the electronegative groups present in the downfield position of nuclear magnetic resonance spectroscopy spectra vis-à-vis anti-diabetic and anti-inflammatory activities. [ABSTRACT FROM AUTHOR]

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy. [ABSTRACT FROM AUTHOR]

Ceruloplasmin, an acute-phase protein, can affect the activity of leukocytes through its various enzymatic activities and protein-protein interactions (with lactoferrin, myeloperoxidase, eosinophil peroxidase, serprocidins, and 5-lipoxygenase (5-LOX), among others). However, the molecular mechanisms of ceruloplasmin activity are not clearly understood. In this study, we tested the ability of two synthetic peptides, RPYLKVFNPR (883-892) (P1) and RRPYLKVFNPRR (882-893) (P2), corresponding to the indicated fragments of the ceruloplasmin sequence, to affect neutrophil activation. Leukotriene (LT) B4 is the primary eicosanoid product of polymorphonuclear leukocytes (PMNLs, neutrophils). We studied leukotriene synthesis in PMNLs upon interaction with Salmonella enterica serovar Typhimurium. Priming of neutrophils with phorbol 12-myristate 13-acetate (PMA) elicited the strong regulatory function of P2 peptide as a superoxide formation inducer and leukotriene synthesis inhibitor. Ceruloplasmin-derived P2 peptide appeared to be a strong inhibitor of 5-LOX product synthesis under conditions of oxidative stress. [ABSTRACT FROM AUTHOR]

The pentacyclic triterpenic acids isolated from the oleo gum resin of various Boswellia species are collectively called as Boswellic acids (BA). The oleo gum resin obtained from Indian variety i.e. Boswellia serrata (Family – Burseraceae) is commonly known as Salai guggal. The resin fraction of Salai guggal is rich in Boswellic acids and its essential oil is composed of a mixture of mono, di and sesquiterpenes while gum fraction chiefly contains pentose and hexose sugars. This oleo-gum resin is quite popular among traditional practitioners of traditional Chinese and Indian Systems of medicine owing to their wide range of useful biological properties such as anti-inflammatory, anti-arthritic, anti-rheumatic, anti-diarrheal, anti-hyperlipidemic, anti-asthmatic, anti-cancer, anti-microbial anti-fungal, anti-complementary and analgesic activity, etc. It has been used as a herbal medicine since the prehistoric time to cure acute and chronic ailments including inflammatory diseases. Phytochemical investigation of this herbal medicine lead to identification of Boswellic acids which are found to be novel, potent, specific anti-inflammatory agents due to non-redox inhibition of 5-lipoxygenase (5-LO) enzyme. However, the other important targets of Boswellic acids also include topoisomerases, angiogenesis, and cytochrome p450 enzymes. This review is a sincere attempt to discuss and present the current status of therapeutic potential, phytochemical as well as pharmacological profile of Boswellic acids primarily obtained from B. serrata . [ABSTRACT FROM AUTHOR]

Human 5-lipoxygenase (5-LO-WT) initiates the leukotriene (LT) biosynthesis. LTs play an important role in diseases like asthma, atherosclerosis and in many types of cancer. In this study, we investigated the 5-LO isoforms 5-LO∆13, 5-LO∆4 and 5-LOp12, lacking the exons 13, 4 or a part of exon 12, respectively. We were able to detect the mRNA of the isoforms 5-LO∆13 and 5-LOp12 in B and T cell lines as well as in primary B and T cells and monocytes. Furthermore, we found that expression of 5-LO and particularly of the 5-LO∆13 and 5-LOp12 isoforms is increased in monocytes from patients with rheumatoid arthritis and sepsis. Confocal microscopy of HEK293T cells stably transfected with tagged 5-LO-WT and/or the isoforms revealed that 5-LO-WT is localized in the nucleus whereas all isoforms are located in the cytosol. Additionally, all isoforms are catalytically inactive and do not seem to influence the specific activity of 5-LO-WT. S271A mutation in 5-LO-WT and treatment of the cells with sorbitol or KN-93/SB203580 changes the localization of the WT enzyme to the cytosol. Despite colocalization with the S271A mutant, the isoforms did not affect LT biosynthesis. Analysis of the phosphorylation pattern of 5-LO-WT and all the isoforms revealed that 5-LOp12 and 5-LO∆13 are highly phosphorylated at Ser271 and 5-LOp12 at Ser523. Furthermore, coexpression of the isoforms inhibited or stimulated 5-LO-WT expression in transiently and stably transfected HEK293T cells suggesting that the isoforms have other functions than canonical LT biosynthesis. [ABSTRACT FROM AUTHOR]

Background: Propolis and cerumen are plant-derived products found in honeybees and stingless bees, respectively. Although propolis is an ancient folk medicine, the bioactivities of cerumen obtained from Australian native stingless bees (Tetragonula carbonaria) have not been widely studied. Therefore, we investigated selected anti-oxidant and antiinflammatory properties of T. carbonaria cerumen. Methods: A methanolic extract was prepared from the combined cerumen of 40 T. carbonaria hives, and HPLC was used to screen for chemical constituents that scavenged 2,2-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The ability of cerumen extracts to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) and to interfere with leukotriene B4 (LTB4) production in ionomycin-stimulated human neutrophils was also examined. Results: The extract dose-dependently scavenged DPPH (EC50 = 27.0 ± 2.3 µg/mL); and inhibited the 5-lipoxygenase (5-LOX)-mediated oxidation of linoleic acid (IC50 = 67.1 ± 9.6 µg/mL). Pre-treatment of isolated human neutrophils with the methanolic cerumen extract additionally inhibited the ionomycin-stimulated production of LTB4 from these cells (IC50 = 13.3 ± 5.3 µg/mL). Following multi-solvent extraction, the free radical-scavenging and 5-LOX-inhibiting activities of the initial cerumen extract were retained in a polar, methanol-water extract, which contained gallic acid and a range of flavonone and phenolic natural products. Conclusions: The findings identify free radical scavenging activity, and interference by extracts of T. carbonaria cerumen in 5-LOX--LTB4 signaling. Further investigation is needed to determine whether the extracts will provide therapeutic benefits for medical conditions in which oxidative stress and inflammation are implicated, including cardiovascular disease and impaired wound healing. [ABSTRACT FROM AUTHOR]

Elevated levels of homocysteinemia (Hcy), a risk factor for late-onset Alzheimer's disease ( AD), have been associated with changes in cell methylation. Alzheimer's disease is characterized by an upregulation of the 5-lipoxygenase (5 LO), whose promoter is regulated by methylation. However, whether Hcy activates 5 LO enzymatic pathway by influencing the methylation status of its promoter remains unknown. Brains from mice with high Hcy were assessed for the 5 LO pathway and neuronal cells exposed to Hcy implemented to study the mechanism(s) regulating 5 LO expression levels and the effect on amyloid β formation. Diet- and genetically induced high Hcy resulted in 5 LO protein and mRNA upregulation, which was associated with a significant increase of the S-adenosylhomocysteine (SAH)/ S-adenosylmethionine ratio, and reduced DNA methyltrasferases and hypomethylation of 5-lipoxygenase DNA. In vitro studies confirmed these results and demonstrated that the mechanism involved in the Hcy-dependent 5 LO activation and amyloid β formation is DNA hypomethylation secondary to the elevated levels of SAH. Taken together these findings represent the first demonstration that Hcy directly influences 5 LO expression levels and establish a previously unknown cross talk between these two pathways, which is highly relevant for AD pathogenesis. The discovery of such a novel link not only provides new mechanistic insights in the neurobiology of Hcy, but most importantly new therapeutic opportunities for the individuals bearing this risk factor for the disease. [ABSTRACT FROM AUTHOR]

The arachidonic acid pathway consists of several enzymes and targeting them is favored for developing anti-inflammatory drugs. However, till date the current drugs are generally active against a single target, leading to undesirable side-effects. Phytochemicals are known to inhibit multiple targets simultaneously and hence, an attempt is made here to investigate their suitability. A pharmacophore based study is performed with three sets of reported phytochemicals namely, dual 5-LOX/mPGES1, alkaloids and FLAP inhibitors. The analysis indicated that phenylpropanoids (including ferulic acid) and benzoic acids derivatives, and berberine mapped onto these pharmacophores with three hydrophobic centroids and an acceptor feature. 2,4,5-trimethoxy ( 7 ) and 3,4-dimethoxy cinnamic acids ( 8 ) mapped onto all the three pharmacophores. Experimental studies indicated that berberine inhibited 5-LOX (100 μM) and PGE 2 (50 μM) production by 72.2 and 72.0% and ferulic acid by 74.3 and 54.4% respectively. This approach offers a promising theoretical combined with experimental strategy for designing novel molecules against inflammatory enzymes. [ABSTRACT FROM AUTHOR]

Myrica rubraSieb. et Zucc. is a valuable fruit tree that is used in Chinese, Japanese and Taiwanese traditional medicine. We investigated the anti-inflammatory activity ofM. rubraleaves extracted with four different solvents. Total phenolics were determined using the Folin–Ciocalteu method. Extracts were investigated for their inhibitory activity toward the pro-inflammatory enzymes cyclooxygenase-1 and -2 (COX-1, COX-2) and 5-lipoxygenase (5-LOX). The ethanol extract ofM. rubraleaves demonstrated a strong inhibition of prostaglandin E2(PGE2) biosynthesis catalyzed by both COX-1 (93.42%) and COX-2 (75.71%) and leukotriene B4(LTB4) formation catalyzed by 5-LOX (82.72%). Further we identified selective COX-1 inhibition by then-butanol and aqueous fractions of the ethanol extract (with an IC50for COX-1 inhibition of 1.07 and 0.71 µg mL−1,respectively) and dual 5-LOX/COX inhibition by the ethyl acetate fraction (with an IC50of 3.29 for COX-1, 2.54 for COX-2 and 8.30 µg mL−1for 5-LOX). [ABSTRACT FROM AUTHOR]

Two oleanenes, olean-18(19)-en-3β-yl-(3,6-dimethyl-3 E ,6 Z -dienoate) and (13α)-27- frido -olean-14(15)-en-(17α)-furanyl-3β-ol representing a class of rare natural pentacyclic triterpenoids were isolated from the chloroform extract of Asiatic mangrove, Rhizophora mucronata Lam. (Family: Rhizophoraceae). The furanyl oleanene exhibited significantly greater antioxidative activities (IC 50 0.73–0.76 mg/mL), than prenylated oleanene (IC 50 0.84–0.96 mg/mL) ( P < 0.05). No significant differences in anti-5-lipoxygenase activities of these compounds with the synthetic drug ibuprofen was discernable (IC 50 0.8–0.9 mg/mL), whilst furanyl oleanene demonstrated significantly greater anti-cyclooxygenase-2 (IC 50 0.84 mg/mL) and anti-5-lipoxygenase activities (IC 50 0.78 mg/mL) over prenylated oleanene (IC 50 > 0.90 mg/mL). These compounds exhibited lesser activity against cyclooxygenase-1 than cyclooxygenase-2 isoform, and therefore, their selectivity indices remained significantly greater (anti-cyclooxygenase-1 IC50 /anti-cyclooxygenase-2 IC50 > 1) than the aspirin (0.02) and ibuprofen (0.44). The lipophilic and steric molecular descriptors were found to occupy a prominent role in determining the bioactivities of the compounds. These previously undescribed oleanenes might serve as potential antioxidative and anti-inflammatory lead molecules in medicinal formulations and food industries. [ABSTRACT FROM AUTHOR]

Aiming to assess the biological activities of synthetic 1,4-benzoquinones, we previously synthesized different libraries of benzoquinones with lipophilic and bulky alkyl- or aryl-substituents that inhibited 5-lipoxygenase (5-LO). The high potency of 4,5-dimethoxy-3-alkyl-1,2-benzoquinones on 5-LO led to the idea to further modify the structures and thus to improve the inhibitory potential in vitro and in vivo as well as to investigate SARs. Systematic structural optimization through accurate structure-based design resulted in compound 30 (3-tridecyl-4,5-dimethoxybenzene-1,2-diol), an ubiquinol derivative that exhibited the strongest anti-inflammatory effect, with a 10-fold improved 5-LO inhibitory activity (IC 50 = 28 nM) in activated neutrophils. Moreover, 30 significantly reduced inflammatory reactions in the carrageenan-induced mouse paw oedema and in zymosan-induced peritonitis in mice. Compound 30 (1 mg/kg, i.p.) potently suppressed the levels of cysteinyl-LTs 30 min after zymosan, outperforming zileuton at a dose of 10 mg/kg. The binding patterns of the quinone- and hydroquinone-based 5-LO inhibitors were analyzed by molecular docking. Together, we elucidated the optimal alkyl chain pattern of quinones and corresponding hydroquinones and reveal a series of highly potent 5-LO inhibitors with effectiveness in vivo that might be useful as anti-inflammatory drugs. [ABSTRACT FROM AUTHOR]

A new series of 11-keto- β -boswellic acid and 3- O -acetyl-11-keto- β -boswellic acid analogs ( 5 , 7 , 8 , 10 , 13 , 18a-d , 27a-c , 28a-d ) were synthesized by modification of hydroxyl and acid functional moieties of boswellic acids. The structures of these analogs were confirmed by spectral data analysis ( 1 H, 13 C NMR and mass). Compounds 18b , 27a and 8 showed potent 5-lipoxygenase enzyme inhibitory activity (IC 50 : 19.53, 20.31 and 44.14 μg/mL). The computational studies revealed that selectivity of AKBA is due to its fitment into the 5-LOX receptor, which is missing for the other enzymes like 12-LOX, COX-1 and COX-2. Our study found potentiating effects of 2-formyl and 3-keto substituents in reviving inactive AKBA analogues possessing essential COOH group at 4th position. [ABSTRACT FROM AUTHOR]

5-lipoxygenase is an enzyme responsible for the synthesis of a range of bioactive lipids signalling molecules known collectively as eicosanoids. 5-lipoxygenase metabolites such as 5-hydroxyeicosatetraenoic acid (5-HETE) and a number of leukotrienes are mostly derived from arachidonic acid and have been shown to be lipid mediators of inflammation in different pathological states including cancer. Upregulated 5-lipoxygenase expression and metabolite production is found in a number of cancer types and has been shown to be associated with increased tumorigenesis. 5-lipoxygenase activity is present in a number of diverse cell types of the immune system and connective tissue. In this review, we discuss potential routes through which cancer cells may utilise the 5-lipoxygenase pathway to interact with the tumour microenvironment during the development and progression of a tumour. Furthermore, immune-derived 5-lipoxygenase signalling can drive both pro- and anti-tumour effects depending on the immune cell subtype and an overview of evidence for these opposing effects is presented. [ABSTRACT FROM AUTHOR]

The arachidonic acid cascade is a key player in inflammation, and numerous well-established drugs interfere with this pathway. Previous studies have suggested that simultaneous inhibition of 5-lipoxygenase (5-LO) and soluble epoxide hydrolase (sEH) results in synergistic anti-inflammatory effects. In this study, a novel prototype of a dual 5-LO/sEH inhibitor KM55 was rationally designed and synthesized. KM55 was evaluated in enzyme activity assays with recombinant enzymes. Furthermore, activity of KM55 in human whole blood and endothelial cells was investigated. KM55 potently inhibited both enzymes in vitro and attenuated the formation of leukotrienes in human whole blood. KM55 was also tested in a cell function-based assay. The compound significantly inhibited the LPS-induced adhesion of leukocytes to endothelial cells by blocking leukocyte activation. [ABSTRACT FROM AUTHOR]

5-Lipoxygenase (5-LO, EC1.13.11.34) has been implicated in the pathogenesis of inflammatory and immune diseases. Recently, aminothiazole comprising inhibitors have been discovered for this valuable target. Yet, the molecular mode of action of this class of substances is only poorly understood. Here, we present the detailed molecular mechanism of action of the compound class and the in vitro pharmacological profile of two lead compounds ST-1853 and ST-1906. Mechanistic studies with recombinant proteins as well as intact cell assays enabled us to define this class as a novel type of 5-LO inhibitors with unique characteristics. The parent compounds herein presented a certain reactivity concerning oxidation and thiol binding: Unsubstituted aminophenols bound covalently to C159 and C418 of human 5-LO. Yet, dimethyl substitution of the aminophenol prevented this reactivity and slowed down phase II metabolism. Both ST-1853 and ST-1906 confirmed their lead likeness by retaining their high potency in physiologically relevant 5-LO activity assays, high metabolic stability, high specificity and non-cytotoxicity. [ABSTRACT FROM AUTHOR]

We previously reported that the soy isoflavone daidzein (Dz) suppresses the intracellular replication of influenza virus and that arachidonic acid-derived oxidation product via lipid oxidase 5-lipoxygenase (5-LOX) is involved in its antiviral effect. The activation of 5-LOX by Dz triggers anti-influenza activity; however, the mechanism of activation of 5-LOX remains unclear. Therefore, in this study, we aimed to clarify the activation mechanism using human monocyte-derived THP-1 cells differentiated using phorbol 12-myristate 13-acetate. THP-1 cells expressed 5-LOX endogenously and Dz did not induce 5-LOX expression. However, 8 h after treatment with Dz, the amount of 5-hydroxyeicosatetraenoic acid (5-HETE), an arachidonic acid oxidation product via 5-LOX, increased significantly suggesting that the enzyme is activated regardless of changes in 5-LOX protein levels. Intracellular Ca2+ content, ATP concentration, 5-LOX protein phosphorylation, and 5-LOX intracellular localization are known 5-LOX activation factors. The intracellular Ca2+ and ATP concentrations were not affected by Dz treatment. The enzymatic activity of 5-LOX is regulated by the phosphorylation of three serine residues and four tyrosine residues. Pretreatment with inhibitors of each kinase revealed that Dz-induced 5-HETE production was suppressed by the MEK/ERK inhibitor. 5-LOX in which the Ser663 residue was phosphorylated was found to be increased in the nuclear fraction of Dz-treated THP-1 cells. Furthermore, immunocytochemistry showed that 5-LOX translocates to the nuclear envelope following Dz treatment. These results indicate that Dz activates 5-LOX by phosphorylating Ser663 via the MEK/ERK pathway. Thus, these results demonstrate that Dz exerts anti-influenza virus activity via the MEK/ERK signal transduction pathway. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] 5-Lipoxygenase (LO) catalyzes the first steps in the formation of pro-inflammatory leukotrienes (LT) that are pivotal lipid mediators contributing to allergic reactions and inflammatory disorders. Based on its key role in LT biosynthesis, 5-LO is an attractive drug target, demanding for effective and selective inhibitors with efficacy in vivo , which however, are still rare. Encouraged by the recent identification of the catechol 4-(3,4-dihydroxyphenyl)dibenzofuran 1 as 5-LO inhibitor, simple structural modifications were made to yield even more effective and selective catechol derivatives. Within this new series, the two most potent compounds 3,4-dihydroxy-3′-phenoxybiphenyl (6b) and 2-(3,4-dihydroxyphenyl)benzo[ b ]thiophene (6d) potently inhibited human 5-LO in cell-free (IC 50 6b and 6d = 20 nM) and cell-based assays (IC 50 6b = 70 nM, 6d = 60 nM). Inhibition of 5-LO was reversible, unaffected by exogenously added substrate arachidonic acid, and not primarily mediated via radical scavenging and antioxidant activities. Functional 5-LO mutants expressed in HEK293 cells were still prone to inhibition by 6b and 6d , and docking simulations revealed distinct binding of the catechol moiety to 5-LO at an allosteric site. Analysis of 5-LO nuclear membrane translocation and intracellular Ca2+ mobilization revealed that these 5-LO-activating events are hardly affected by the catechols. Importantly, the high inhibitory potency of 6b and 6d was confirmed in human blood and in a murine zymosan-induced peritonitis model in vivo. Our results enclose these novel catechol derivatives as highly potent, novel type inhibitors of 5-LO with high selectivity and with marked effectiveness under pathophysiological conditions. [ABSTRACT FROM AUTHOR]

We synthesized two series of new hydrazide harmine derivatives. The reaction of harmine1with ethyl acetate chloride afforded the corresponding ethyl ester2. The treatment of2with hydrazine hydrate gave the hydrazide3which further converted into hydrazones4a–jand dihydrazides5a–c. A series of new triazoles7a–fhas also been prepared from the suitable propargyl harmine6. The synthesized derivatives were characterized by1H-NMR,13C-NMR, and HRMS and evaluated for their activities against MCF7, HCT116 OVCAR-3, acetylcholinesterase and 5-lipoxygenase. The most hydrazones derivatives4a-jhave a good cytotoxic activity against all cell lines, when4a,4d,4fand4 gare more active than1(against OVCAR-3 IC5016.7–2.5 μM). The compound6was the most active (IC50 = 1.9 μM) against acetylcholinesterase. Some compounds exhibited significant activity against 5-lipoxygenase (IC50 = 30.9–63.1 μM). [ABSTRACT FROM AUTHOR]