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Background: Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of (+)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait. Methods: (+)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the (+)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3). Results: There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml (+)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed. Conclusions: The results of this study indicate that (+)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. (+)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa. [ABSTRACT FROM AUTHOR]

Objective: Usnic acid, one of the most common and famous lichen acid and its Schiff base derivatives have various pharmacological activities such as analgesic, antibacterial, antiprotozoal, anti-inflammatory, anticholinergic, antiulcer, antioxidant, antiproliferative, and apoptotic properties. Dopamine, histamine and vanillylamine are the molecules that have important physiological properties in living organisms. Thus, in the current study, we aim to explore the potential pharmacological activities of novel Schiff base derivatives of usnic acid (I). Methods: Three novel Schiff base derivatives (II–IV) of usnic acid (I) were synthesized via the condensation of dopamine, histamine and vanillylamine. In vitro enzyme inhibitory effects on α-glycosidase, α-amylase, monoamine oxidases (MAO-A and MAO-B), and cholinesterase's (AChE and BChE) and antioxidant potentials of the compounds (I–IV) were evaluated. Results and Discussion: Among the tested compounds, only ligand (II) has an antidiabetic potential inhibiting strongly both α-glycosidase and α-amylase enzymes. All of the tested molecules exhibited a remarkable antidepressant effect by inhibiting MAO-A activity; however their effects were determined to be lower than that of clorgyline. On the other hand, the antiparkinson's and neuroprotective capabilities of (I–IV) were found to be much weaker as compared with those of pargyline and galantamine. The antioxidant potencies of (I–IV) were carried out and the compounds, (II) and (IV) acted as potent antioxidant agents by scavenging the ABTS and DPPH radicals more strongly than BHA and trolox. Conclusions: Our results point out the compound (II) is a candidate molecule for further in vitro and in vivo pharmacological studies due to its potent antidiabetic, antioxidant as well as remarkable antidepressant potentials. [ABSTRACT FROM AUTHOR]

Background/aim: Melanoma is one of the most aggressive cancers and treatment methods commonly used for patients with skin cancer include checkpoint and BRAF/MEK inhibitors, traditional chemotherapy drugs, radiation, and adjuvant treatment methods. Due to the resistance and toxic effects that patients develop against the drugs, an effective treatment method has not been developed for melanoma yet. In this study we evaluated the anticancer effect of usnic acid (UA) on A-375 melanoma cells and human epidermal melanocytes using the xCELLigence real-time cell analysis system. Materials and methods: To determine the cell death pathway through which UA exerts its antiproliferative effect, its potential for apoptotic effects was investigated. Caspase-3 and caspase-9 enzyme assays and the expression analysis of 84 genes from the apoptosis pathway were carried out in UA-treated and nontreated A-375 cells. Results: UA was found to have an antiproliferative effect on A-375 cells while it did not have a cytotoxic effect on human epidermal melanocytes. UA treatment led to statistically significant increases in both caspase-3 and caspase-9 enzyme activities. Moreover, the expression levels of 61 genes (mainly proapoptotic genes) were increased and the expression levels of 23 genes (mainly antiapoptotic genes) were decreased in response to UA treatment. This effect might have developed through both the extrinsic and intrinsic apoptosis pathways; however, the extrinsic pathway was more pronounced. Conclusion: As a result of the obtained findings, it could be concluded that UA might be a promising candidate drug molecule for melanoma treatment in the future through topical application or encapsulation with nanocarriers. [ABSTRACT FROM AUTHOR]

Dietary supplements containing usnic acid have been increasingly marketed for weight loss over the past decades, even though incidences of severe hepatotoxicity and acute liver failure due to their overuse have been reported. To date, the toxic mechanism of usnic acid‐induced liver injury at the molecular level still remains to be fully elucidated. Here, we conducted a transcriptomic study on usnic acid using a novel in vitro hepatotoxicity model employing human induced pluripotent stem cell (iPSC)‐derived hepatocytes. Treatment with 20 μM usnic acid for 24 h caused 4272 differentially expressed genes (DEGs) in the cells. Ingenuity Pathway Analysis (IPA) based on the DEGs and gene set enrichment analysis (GSEA) using the whole transcriptome expression data concordantly revealed several signaling pathways and biological processes that, when taken together, suggest that usnic acid caused oxidative stress and DNA damage in the cells, which further led to cell cycle arrest and eventually resulted in cell death through apoptosis. These transcriptomic findings were subsequently corroborated by a variety of cellular assays, including reactive oxygen species (ROS) generation and glutathione (GSH) depletion, DNA damage (pH2AX detection and 8‐hydroxy‐2′‐deoxyguanosine [8‐OH‐dg] assay), cell cycle analysis, and caspase 3/7 activity. Collectively, the results of the current study accord with previous in vivo and in vitro findings, provide further evidence that oxidative stress‐caused DNA damage contributes to usnic acid‐induced hepatotoxicity, shed new light on molecular mechanisms of usnic acid‐induced hepatotoxicity, and demonstrate the usefulness of iPSC‐derived hepatocytes as an in vitro model for hepatotoxicity testing and prediction. Treatment with 20 μM usnic acid for 24 h caused 4272 differentially expressed genes (DEGs) in human iPSC‐derived hepatocytes. Functional analysis of the transcriptomic data revealed signaling pathways and biological processes suggesting that usnic acid caused cellular oxidative stress and DNA damage, which further led to cell cycle arrest and eventually resulted in apoptosis. Results of a variety of cellular assays corroborated these transcriptomic findings, including ROS generation, GSH depletion, DNA damage, cell cycle arrest, and increased caspase 3/7 activity. Treatment with 20 μM usnic acid for 24 h caused 4272 differentially expressed genes (DEGs) in human iPSC‐derived hepatocytes. Functional analysis of the transcriptomic data revealed signaling pathways and biological processes suggesting that usnic acid caused cellular oxidative stress and DNA damage, which further led to cell cycle arrest and eventually resulted in apoptosis. Results of a variety of cellular assays corroborated these transcriptomic findings, including ROS generation, GSH depletion, DNA damage, cell cycle arrest, and increased caspase 3/7 activity. [ABSTRACT FROM AUTHOR]

Abstract Background Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of ( +)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait. Methods ( +)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the ( +)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3). Results There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml ( +)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed. Conclusions The results of this study indicate that ( +)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. ( +)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa.

Objective: To investigate impacts of usnic acid （UA） on malignant behavior of gastric cancer cells by regulating the chemokine （C-C motif） ligand 2 （CCL2）-CCL2 receptor （CCR2） signal axis. Methods: SGC-7901 cells, a well growing human gastric cancer cell line, were treated with different concentrations of UA, which were grouped into low concentration （UA-L） group （62.5 μmol/L UA）, medium concentration （UA-M） group （125 μmol/L UA） and high concentration （UA-H） group （250 μmol/L UA）; meantime, the cells were transfected with CCL2 overexpression vector （pc DNA3.1 CCL2）, empty vector （pc DNA3.1）, silenced CCL2 （si CCL2） and negative control （si control）, and SGC-7901 cells were treated with 250 μmol/L UA, labeled as UA-H+pc DNA3.1 CCL2 group, UA-H+pc DNA3.1 group, UA-H+si control group and UA-H+si CCL2 group, another untreated SGC-7901 cells were taken as the control group. Flow cytometry, MTT and qRT-PCR were applied to detect cell apoptosis, proliferation, and expression levels of CCL2 and CCR2 mRNA; Western blot was applied to detect expression levels of PD-L1, apoptotic protein（ Bax）, proliferative protein （CyclinD1, CCL2, CCR2） and immune escape related protein （B7H1）; after co-culturing with CD8+T cells isolated and cultured in vitro, ELISA was applied to detect levels of IL-4, IFN-γ and IL-10 in the supernatant. Gastric cancer cells in each group were co-cultured with activated peripheral blood mononuclear cell （PBMC） 1∶1 for 72 hours, and the sensitivity of gastric cancer cells in each group to T-cell-mediated killing was compared. Results: Compared with control group, cell proliferation rate, IL-10 level, CyclinD1, PD-L1, CCL2, CCR2 and B7H1 protein and mRNA expressions, cell counts after co-culturing with activated PBMC 1∶1 for 72 hours in UA-L group, UA-M group and UA-H group were obviously reduced, while apoptosis rate, IL-4 and IFN-γ levels, Bax protein expression were obviously increased （P<0.05）; compared with UA-H+pc DNA3.1 group, cell proliferation rate, IL-10 level, CyclinD1, PD-L1, CCL2, CCR2 protein and mRNA expressions, cell counts after co-culturing with activated PBMC 1∶1 for 72 hours in UA-H+pc DNA3.1 CCL2 group were obviously increased, while apoptosis rate, IL-4 and IFN-γ levels, and Bax protein expression were obviously reduced （P<0.05）; compared with UA-H+si control group, cell proliferation rate, IL-10 level, CyclinD1, PD-L1, CCL2, CCR2 and B7H1 protein and mRNA expressions, cell counts after co-culturing with activated PBMC 1∶1 for 72 hours in UA-H+si CCL2 group were obviously reduced, while apoptosis rate, IL-4 and IFN-γ levels and Bax protein expression were obviously increased（ P<0.05）. Conclusion: UA can inhibit gastric cancer cells proliferation, immune escape, and induce apoptosis, which may be related to the inhibition of the CCL2-CCR2 signaling axis. [ABSTRACT FROM AUTHOR]

6‐phosphogluconate dehydrogenase (6PGD) and Glucose‐6‐phosphate dehydrogenase (G6PD) are crucial enzymes involved in generating cellular reducing power. Modifying the balance of reduced NADPH is considered essential for cancer advancement and combined therapeutic strategies. Usnic acid (UA) is a physiologically active dibenzofuran derivative. Carnosic acid (CA) is a phenolic diterpene that has been isolated from several plants. This work evaluated the inhibitory effects of UA and CA on G6PD and 6PGD by in vitro tests. Molecular docking studies were employed to predict the mechanisms of inhibition. IC50 values for UA and CA were determined to be 49.50 μM and 77.00 μM for G6PD, and 69.30 μM and 57.75 μM for 6PGD, respectively. The Ki values for UA and CA were determined to be 35.01±7.69 μM and 43.46±10.48 μM for G6PD, and 104.87±11.86 μM and 31.17±2.55 μM for 6PGD, respectively. UA was identified as the most effective inhibitor against G6PD, whereas CA exhibited the best inhibitory activity against 6PGD, with estimated binding energies of −8.0 and −7.8 kcal/mol, respectively, in molecular docking studies. Ultimately, it was shown that the results obtained from in vitro and in silico methods in the study were strongly associated. These chemicals′ structure might assist in creating medications that focus on the pentose phosphate pathway. [ABSTRACT FROM AUTHOR]

Diabetic foot ulcer caused by vancomycin-resistant Enterococcus strains is a troublesome concern that threatens public health. Due to the few treatment options, it is essential to develop a new alternative antibacterial agent with high efficacy. In the current study, we evaluated the antibacterial and antibiofilm properties of usnic acid (UA), a secondary metabolite of lichens. Microdilution broth and crystal violet methods were applied to determine the antibacterial and antibiofilm activities, respectively. To further elucidate the biofilm inhibition, scanning electron microscopy imaging was performed. In addition, the antioxidant activity of UA was investigated by 2, 2-diphenyl-1-picrylhydrazyl assay. The bacteriostatic and bactericidal activity of UA was observed as an amount of 23.02 and 312.5 μg/mL, respectively. UA suppressed biofilm formation and motivated the reduction of free oxygen radicals. The present study may open up a new perspective to combat biofilm-forming enterococci. [ABSTRACT FROM AUTHOR]

With the increasing use of invasive, interventional, indwelling, and implanted medical devices, healthcare-associated infections caused by pathogenic biofilms have become a major cause of morbidity and mortality. Herein, we present the fabrication, characterization, and in vitro evaluation of biocompatibility and anti-biofilm properties of new coatings based on Fe3O4 nanoparticles (NPs) loaded with usnic acid (UA) and ceftriaxone (CEF). Sodium lauryl sulfate (SLS) was employed as a stabilizer and modulator of the polarity, dispersibility, shape, and anti-biofilm properties of the magnetite nanoparticles. The resulting Fe3O4 functionalized NPs, namely Fe3O4@SLS, Fe3O4@SLS/UA, and Fe3O4@SLS/CEF, respectively, were prepared by co-precipitation method and fully characterized by XRD, TEM, SAED, SEM, FTIR, and TGA. They were further used to produce nanostructured coatings by matrix-assisted pulsed laser evaporation (MAPLE) technique. The biocompatibility of the coatings was assessed by measuring the cell viability, lactate dehydrogenase release, and nitric oxide level in the culture medium and by evaluating the actin cytoskeleton morphology of murine pre-osteoblasts. All prepared nanostructured coatings exhibited good biocompatibility. Biofilm growth inhibition ability was tested at 24 h and 48 h against Staphylococcus aureus and Pseudomonas aeruginosa as representative models for Gram-positive and Gram-negative bacteria. The coatings demonstrated good biocompatibility, promoting osteoblast adhesion, migration, and growth without significant impact on cell viability or morphology, highlighting their potential for developing safe and effective antibacterial surfaces. [ABSTRACT FROM AUTHOR]

The rapid spread of SARS-CoV-2 and its infection severity require an urgent development of antiviral agents. In this respect, Usnic acid (UA), a natural dibenzofuran derivative, exerts antiviral activity against several viruses, though presenting very low solubility and high cytotoxicity. Here, UA was complexed with β-cyclodextrins (β-CDs), a pharmaceutical excipient used to improve drug solubility. The cytotoxic activity, tested on Vero E6 cells, revealed no effect for β-CDs alone whereas significant cytotoxicity for the UA/β-CDs complex was recorded at concentrations ≥ 0.05%. The neutralizing activity towards the fusion of SARS-CoV-2 Spike Pseudovirus showed no effects for β-CDs alone whereas the UA/β-CDs complex, when pre-incubated with the viral particles, efficiently inhibited the Pseudoviral fusion of about 90 and 82% at non-cytotoxic concentrations of 0.03 and 0.01%, respectively. In conclusion, although further evidences are needed to clarify the exact inhibition mechanism, UA/β-CDs complex could be useful in SARS-CoV-2 infection. [ABSTRACT FROM AUTHOR]

Objectives: Lichens are complex symbiotic organisms that generate various bioactive compounds with significant therapeutic value. We investigated the chemical composition and bioactivity of the acetone extract of the Algerian lichen Physconia venusta (Ach.) poet. Materials and Methods: Phytochemical screening was performed using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was assessed against Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, Salmonella typhi, Staphylococcus aureus, Listeria monocytogenes, and Bacillus subtilis using an agar diffusion test with the determination of the minimal inhibition concentration (MIC), while the antioxidant activity was determined using different chemical methods (DPPH, ABTS, CUPRAC, reducing power, superoxide anion scavenging, ß-carotene bleaching, and metal chelate). In addition, cytotoxic activity was tested using Artemia salina (Brine shrimp) bioassay. Results: The studied extract exhibited intense antibacterial activity against E. coli and S. aureus with inhibition diameters of 28 ± 0.01 and 22 ± 0.01 mm, respectively, with a MIC value of 6.25 mg/mL and a selectivity index of 2.8. The obtained extract showed different antioxidant trends depending on the selected assay. GC-MS analysis revealed many secondary metabolites. Conclusion: P. venusta, a type of lichen, is a potential source of bioactive substances that could be used in pharmaceuticals. [ABSTRACT FROM AUTHOR]

Usnic acid, a secondary metabolite of lichen Usnea sp., has several pharmacological activities, but it is poorly soluble in water. This study aimed to improve the solubility and dissolution rate of usnic acid loaded in mesoporous silica SBA-15 at a mass ratio of 1:1. and evaluate its physical stability. Physicochemical characterization was carried out via the nitrogen adsorption desorption isotherm, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and powder X-ray diffraction (PXRD). Usnic acid-loaded SBA-15 was stored at 40 °C with various relative humidities (RH) and then analyzed by PXRD for the physical stability. Usnic acid adsorbed well in the pores of SBA-15, as shown by a decrease in the volume pore and surface area of SBA-15 according to the nitrogen adsorption. Moreover, usnic acid-SBA-15 showed a decrease in the degree of crystallinity according to PXRD analysis and no melting point based on DSC analysis. The FTIR spectrum of usnic acid–SBA-15 corresponds to the spectra of each raw material. The solubility of usnic acid increased 5.15 times after adsorbed on SBA-15. The dissolution rate also showed a significant increase (p < 0.05) from 19.51% to 84.27%. Usnic acid–SBA-15 was relatively stable at RH 75%. Thus, the adsorption of usnic acid on SBA-15 can increase its solubility, dissolution rate, and physical stability.

Ramalina sp. (Ramalinaceae) is a type of lichen known to contain many active secondary metabolite compounds that have the potential to be used as medicine or medicinal raw materials. One of the biological activities possessed by Ramalina sp. lichen is its anticancer activity. This research aims to isolate and identify active secondary metabolite compounds from the methanol extract of the Ramalina sp. lichen and to find out the cytotoxic activity of the isolated compound against MCF7 breast cancer cells. Compound 1 (usnic acid) was successfully isolated from fraction A. The isolation and purification process was carried out starting with a maceration process using acetone solvent, followed by silica gel column chromatography using a gradient solvent system consisting of n-hexane, n-hexane:EtOAc, EtOAc, EtOAc:MeOH, and MeOH with 5% increment of polarity to obtain 17 fractions (F- 1 to F-17). From the 17 fractions obtained, fraction 3 (F-3) and fraction 4 (F-4) (eluted with n-hexane:EtOAc 30%), which had the same TLC profile, were combined and named as fraction A. Compound 1 (50 mg) is a yellow needle crystal that was formed in a bottle of fraction A, which was obtained after the process of combining fractions F-3 and F-4 and solvent evaporation process. The crystals were then separated and purified with CHCl3 and MeOH. Compound 1 was then characterized based on spectroscopic data. Various spectroscopic analysis data, including FTIR, 1D- and 2D-NMR, and LC-ESI-MS, show that Compound 1 is a dibenzofuran derivative compound with 18 carbons (3 from carbonyl groups (C=O) and 3 from methyl groups) and 2 hydroxyl (-OH). Cytotoxicity assay showed that at a low concentration of 18.75 ug/mL, Compound 1 caused a 67.06% decrease in MCF7 viability [ABSTRACT FROM AUTHOR]

Although the COVID-19 pandemic caused by SARS-CoV-2 viruses is officially over, the search for new effective agents with activity against a wide range of coronaviruses is still an important task for medical chemists and virologists. We synthesized a series of thiazolo-thiophenes based on (+)- and (−)-usnic acid and studied their ability to inhibit the main protease of SARS-CoV-2. Substances containing unsubstituted thiophene groups or methyl- or bromo-substituted thiophene moieties showed moderate activity. Derivatives containing nitro substituents in the thiophene heterocycle—just as pure (+)- and (−)-usnic acids—showed no anti-3CLpro activity. Kinetic parameters of the most active compound, (+)-3e, were investigated, and molecular modeling of the possible interaction of the new thiazolo-thiophenes with the active site of the main protease was carried out. We evaluated the binding energies of the ligand and protein in a ligand–protein complex. Active compound (+)-3e was found to bind with minimum free energy; the binding of inactive compound (+)-3g is characterized by higher values of minimum free energy; the positioning of pure (+)-usnic acid proved to be unstable and is accompanied by the formation of intermolecular contacts with many amino acids of the catalytic binding site. Thus, the molecular dynamics results were consistent with the experimental data. In an in vitro antiviral assay against six strains (Wuhan, Delta, and four Omicron sublineages) of SARS-CoV-2, (+)-3e demonstrated pronounced antiviral activity against all the strains. [ABSTRACT FROM AUTHOR]

The present study investigates the utilization of nanoparticles based on poly-l-lactide (PLLA) and polyglycerol adipate (PGA), alone and blended, for the encapsulation of usnic acid (UA), a potent natural compound with various therapeutic properties including antimicrobial and anticancer activities. The development of these carriers offers an innovative approach to overcome the challenges associated with usnic acid's limited aqueous solubility, bioavailability, and hepatotoxicity. The nanosystems were characterized according to their physicochemical properties (among others, size, zeta potential, thermal properties), apparent aqueous solubility, and in vitro cytotoxicity. Interestingly, the nanocarrier obtained with the PLLA-PGA 50/50 weight ratio blend showed both the lowest size and the highest UA apparent solubility as well as the ability to decrease UA cytotoxicity towards human hepatocytes (HepG2 cells). This research opens new avenues for the effective utilization of these highly degradable and biocompatible PLLA-PGA blends as nanocarriers for reducing the cytotoxicity of usnic acid. [ABSTRACT FROM AUTHOR]

The mat-forming fruticose lichens Cladonia stellaris and Cetraria islandica frequently co-occur on soils in sun-exposed boreal, subarctic, and alpine ecosystems. While the dominant reindeer lichen Cladonia lacks a cortex but produces the light-reflecting pale pigment usnic acid on its surface, the common but patchier Cetraria has a firm cortex sealed by the light-absorbing pigment melanin. By measuring reflectance spectra, high-light tolerance, photosynthetic responses, and chlorophyll fluorescence in sympatric populations of these lichens differing in fungal pigments, we aimed to study how they cope with high light while hydrated. Specimens of the two species tolerated high light equally well but with different protective mechanisms. The mycobiont of the melanic species efficiently absorbed excess light, consistent with a lower need for its photobiont to protect itself by non-photochemical quenching (NPQ). By contrast, usnic acid screened light at 450–700 nm by reflectance and absorbed shorter wavelengths. The ecorticate usnic species with less efficient fungal light screening exhibited a consistently lower light compensation point and higher CO2 uptake rates than the melanic lichen. In both species, steady state NPQ rapidly increased at increasing light with no signs of light saturation. To compensate for less internal shading causing light fluctuations with a larger amplitude, the usnic lichen photobiont adjusted to changing light by faster induction and faster relaxation of NPQ rapidly transforming excess excitation energy to less damaging heat. The high and flexible NPQ tracking fluctuations in solar radiation probably contributes to the strong dominance of the usnic mat-forming Cladonia in open lichen-dominated heaths. [ABSTRACT FROM AUTHOR]

In this study, we investigated the chemopreventive efficacy of usnic acid (UA), an effective secondary metabolite component of lichens, against 7,12‐dimethylbenz[a]anthracene (DMBA)‐induced oral squamous cell carcinoma (OSCC) in the hamster model. Initially, the buccal pouch carcinogenesis was induced by administering 0.5% DMBA to the HBP (hamster buccal pouch) region about three times a week until the 10th week. Then, UA was orally treated with different concentrations (25, 50, 100 mg/kg b.wt) on alternative days of DMBA exposure, and the experimental process ended in the 16th week. After animal experimentation, we observed 100% tumor incidence with well‐differentiated OSCC, dysplasia, and hyperplasia lesions in the DMBA‐induced HBP region. Furthermore, the UA treatment of DMBA‐induced hamster effectively inhibited tumor growth. In addition, UA upregulated antioxidant levels, interfered with the elevated lipid peroxidation by‐product of thiobarbituric acid reactive substances, and changed the activities of the liver detoxification enzyme (Phase I and II) in DMBA‐induced hamsters. Furthermore, immunohistochemical staining of inflammatory markers (iNOS and COX‐2) and proliferative cell markers (cyclin‐D1 and PCNA) were upregulated in the buccal pouch part of hamster animals induced with DMBA. Notably, the oral administration of UA significantly suppressed these markers during DMBA‐induced hamsters. Collectively, our findings revealed that UA exhibits antioxidant, anti‐inflammatory, antitumor, and apoptosis‐inducing characteristics, demonstrating UA's protective properties against DMBA‐induced HBP carcinogenesis. [ABSTRACT FROM AUTHOR]

Usnic acid is a potential active pharmaceutical ingredient derived from Usnea sp. It has a low bioavailability because of poor aqueous solubility. Particle size reduction by nanosizing has been applied to improve the solubility of active pharmaceutical ingredients which is achieved by preparation of nanocrystals. This study aimed to prepare usnic acid nanocrystals by employing a wet grinding method with a planetary ball mill and using Poloxamer 188 as a stabilizer. The solid state properties of the resulting usnic acid nanocrystals were characterized with a particle size analyzer, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dissolution rate profile. Usnic acid nanocrystals had a particle size of 358.77 ± 21.18 nm, evenly distributed with a polydispersity index of 0.591±0.02 and a zeta potential of -24.4 ± 0.1. The DSC thermogram showed a sharp endothermic peak at 193.413°C. The XRD pattern contained a high-intensity crystalline peak at 2O=10.213°. The dissolution rate of the usnic acid nanocrystals was 2.7 fold faster than that of the intact usnic acid. This study concluded that nanocrystals of usnic acid have improved physicochemical properties and a significantly increased dissolution rate. [ABSTRACT FROM AUTHOR]

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With the increasing use of invasive, interventional, indwelling, and implanted medical devices, healthcare-associated infections caused by pathogenic biofilms have become a major cause of morbidity and mortality. Herein, we present the fabrication, characterization, and in vitro evaluation of biocompatibility and anti-biofilm properties of new coatings based on Fe3O4 nanoparticles (NPs) loaded with usnic acid (UA) and ceftriaxone (CEF). Sodium lauryl sulfate (SLS) was employed as a stabilizer and modulator of the polarity, dispersibility, shape, and anti-biofilm properties of the magnetite nanoparticles. The resulting Fe3O4 functionalized NPs, namely Fe3O4@SLS, Fe3O4@SLS/UA, and Fe3O4@SLS/CEF, respectively, were prepared by co-precipitation method and fully characterized by XRD, TEM, SAED, SEM, FTIR, and TGA. They were further used to produce nanostructured coatings by matrix-assisted pulsed laser evaporation (MAPLE) technique. The biocompatibility of the coatings was assessed by measuring the cell viability, lactate dehydrogenase release, and nitric oxide level in the culture medium and by evaluating the actin cytoskeleton morphology of murine pre-osteoblasts. All prepared nanostructured coatings exhibited good biocompatibility. Biofilm growth inhibition ability was tested at 24 h and 48 h against Staphylococcus aureus and Pseudomonas aeruginosa as representative models for Gram-positive and Gram-negative bacteria. The coatings demonstrated good biocompatibility, promoting osteoblast adhesion, migration, and growth without significant impact on cell viability or morphology, highlighting their potential for developing safe and effective antibacterial surfaces.

The present study investigates the utilization of nanoparticles based on poly-l-lactide (PLLA) and polyglycerol adipate (PGA), alone and blended, for the encapsulation of usnic acid (UA), a potent natural compound with various therapeutic properties including antimicrobial and anticancer activities. The development of these carriers offers an innovative approach to overcome the challenges associated with usnic acid’s limited aqueous solubility, bioavailability, and hepatotoxicity. The nanosystems were characterized according to their physicochemical properties (among others, size, zeta potential, thermal properties), apparent aqueous solubility, and in vitro cytotoxicity. Interestingly, the nanocarrier obtained with the PLLA-PGA 50/50 weight ratio blend showed both the lowest size and the highest UA apparent solubility as well as the ability to decrease UA cytotoxicity towards human hepatocytes (HepG2 cells). This research opens new avenues for the effective utilization of these highly degradable and biocompatible PLLA-PGA blends as nanocarriers for reducing the cytotoxicity of usnic acid.

Although the COVID-19 pandemic caused by SARS-CoV-2 viruses is officially over, the search for new effective agents with activity against a wide range of coronaviruses is still an important task for medical chemists and virologists. We synthesized a series of thiazolo-thiophenes based on (+)- and (−)-usnic acid and studied their ability to inhibit the main protease of SARS-CoV-2. Substances containing unsubstituted thiophene groups or methyl- or bromo-substituted thiophene moieties showed moderate activity. Derivatives containing nitro substituents in the thiophene heterocycle—just as pure (+)- and (−)-usnic acids—showed no anti-3CLpro activity. Kinetic parameters of the most active compound, (+)-3e, were investigated, and molecular modeling of the possible interaction of the new thiazolo-thiophenes with the active site of the main protease was carried out. We evaluated the binding energies of the ligand and protein in a ligand–protein complex. Active compound (+)-3e was found to bind with minimum free energy; the binding of inactive compound (+)-3g is characterized by higher values of minimum free energy; the positioning of pure (+)-usnic acid proved to be unstable and is accompanied by the formation of intermolecular contacts with many amino acids of the catalytic binding site. Thus, the molecular dynamics results were consistent with the experimental data. In an in vitro antiviral assay against six strains (Wuhan, Delta, and four Omicron sublineages) of SARS-CoV-2, (+)-3e demonstrated pronounced antiviral activity against all the strains.

Lichens have great potential as food, functional food additives or flavourings. The presence of specific substances with multiple biological activities is one of the characteristics of lichens. However, research on lichens as a food source or functional food additive is limited. The present study simulated, for the first time, the potential bioaccessibility of active compounds from 6 lichen species in simulated gastric and intestinal conditions. An in vitro digestion showed that the lichen substances had different bioaccessibility and stability during digestion. It was found that the application of some metabolic modulators significantly altered the accumulation of metabolites in most species. In addition, the study demonstrated the antimicrobial activity of the tested extracts as well as of 14 isolated lichen metabolites. These multi-directional studies demonstrate the potential of lichens in terms of their use as antimicrobial functional food additives. • H. physodes showed the highest content of lichen substances, reaching up to 15% DW • In vitro digestion revealed variable bioaccessibility and stability of compounds • Metabolic modulators may increase accumulation of lichen compounds • Lack of a common pattern of elicitor activity in different lichen species • Atranorin showed the highest antimicrobial activity [ABSTRACT FROM AUTHOR]

The following study deals with the preparation of starch and starch-cellulose aerogels. The addition of cellulose nanocrystals and bacterial nanocellulose to starch led to composite aerogels with remarkable properties, e.g., high surface areas, high adsorption capacities, and outstanding morphological characteristics. Specific surface areas up to 220 m2/g have been reached. As the content of the nanocellulose in the aerogels increased, the textural, thermal, and morphological properties improved significantly. The behavior of the starch and starch-cellulose aerogels was studied, to investigate their swelling behavior and stability in aqueous media. Lastly, the aerogels were impregnated with xanthohumol and usnic acid. The presence of cellulose improved the aerogel sorption capacity and the xanthohumol intake. The impregnated aerogels preserved highly porous and sophisticated structures. [Display omitted] • Starch and starch-cellulose aerogels with high specific surface areas were obtained. • The addition of nanocellulose to the starch aerogels enhanced their properties. • Successful impregnation of xanthohumol and usnic acid into starch and composite aerogels. • The aerogels with the highest cellulose content showed the best sorption capacity. • Preserved porous structures of the impregnated aerogels. [ABSTRACT FROM AUTHOR]

Testicular torsion (TT) is a urological condition that can result in infertility in men. The etiopathogenesis of TT includes ischemia/reperfusion injury (IRI) characterized by oxidative stress (OS), inflammation and apoptosis resulting from increased levels of free radicals. Usnic acid (UA), a dibenzofuran, is one of the most common metabolites found in lichens and is known to possess powerful antioxidant properties. The aim of this study was to investigate the potential protective activity of UA in an experimental testicular IRI model for the first time. A total of 18 rats were randomly assigned to three groups (n=6): sham control, IRI and IRI+UA. The IRI groups underwent a four-hour period of ischemia and a two-hour period of reperfusion. The OS, inflammation, endoplasmic reticulum stress (ERS) and apoptosis markers in testicular tissue were evaluated using colorimetric methods. Furthermore, tissue samples were subjected to histological examination, with staining using hematoxylin and eosin. Histopathological findings supported by increased OS, inflammation, ERS and apoptosis levels were obtained in IRI group compared with sham control group. However, UA treatment restored these pathological and biochemical changes. Although this study provides the first preliminary evidence that UA may be used as a useful molecule against testicular IRI, further extensive molecular preclinical studies should be performed before clinical use is considered. • Testicular torsion is one of the most serious urological emergencies. • There is a need for adjuvants in the treatment of torsioned testicle injury. • Usnic acid is a lichen metabolite and widely used in the food and drug industry. • Testicular torsion increased inflammation and endoplasmic reticulum stress in rats. • Usnic acid significantly restored this testicular damage. [ABSTRACT FROM AUTHOR]

Usnic acid is a marker compound produced from numerous lichens (symbiotic association of mycobiont and phycobiont) possessing higher bioavailability, potent and selective against cancer cells. Usnic acid is an underutilized and well-documented anti-cancer compound from lichens and its activity is not yet documented against cervical cancer. The main aim of the present research is to screen the anti-cancer potential of usnic acid against cervical cancer target proteins. The drug-likeness validation of usnic acid shows nil violations against all drug-likeness rules when compared with all three screened anti-cancer standard drugs and shows some violation in drug likeness prediction. Further, ADMET screening reveals usnic acids shows effective pharmacokinetic profiles with good bioactivity scores, essential for drug delivery and metabolism. DFT analysis of usnic acid reveals less energy gap (-0.1184), hardness (0.0592 eV), and high softness (16.8918 eV) scores against three anti-cancer drug DFT scores. Molecular docking study shows usnic acid possesses excellent binding affinity with all the nine screened cervical cancer target proteins with docking scores ranging from -6.9 to -9.1 kcal/mol. Three anti-cancer drugs showed docking scores with a range of -5.2 to -8.4 kcal/mol. Further, four top-scored complexes were taken for molecular dynamic simulation study reveal that usnic acid complexes (1KTZ-usnic acid and 2BIM-usnic acid) possess good simulation trajectories with cervical cancer target proteins than the selected anti-cancer drugs.Communicated by Ramaswamy H. Sarma.

This research is based on the incorporation of the methanolic extract of the Usnea ghattensis into poly (caprolactone) (PCL) nanofibers (NFs) to investigate the capacity in reducing reactive oxygen species (ROS). PCL-NFs were fabricated by the electrospinning technique and are investigated as potential dressing material focused on the release of usnic acid (PCL-USNIC NFs), and its encapsulation efficiency and kinetic release were analyzed by high performance liquid chromatography (HPLC). This investigation was performed by analyzing the usnic acid concentration as a function of the distance from the mat center point. The kinetic release analysis is also developed with the usnea ghattensis extract (PCL-USNEA NFs), performing a metabolomic analysis of the released molecules as a function of time by nuclear magnetic resonance (NMR). Usnic acid was revealed as the most relevant compound together with other molecules, such as sucrose, mannitol, arabitol or glycerol that generate a positive matrix effect on the release of usnic acid. Finally, we analize the cytotoxicity and the neuroprotective effect of PCL-USNEA and PCL-USNIC NFs using a human neuroblastoma cell line model. Negligible toxicity was appreciated for both polymeric systems, showing high protective effects in presence of highly oxidative environment (e.g. in presence of H 2 O 2 )., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Introduction: ABT-199 (venetoclax) is a BCL-2 suppressor with pronounced effects on acute myeloid leukemia (AML). However, its usefulness as a monotherapy or in combination with hypomethylating medicines like azacitidine is debatable due to acquired resistance. Usnic acid, a dibenzofuran extracted from lichen Usnea diffracta Vain, exhibits anticancer properties and may counteract multidrug resistance in leukemia cells., Objective: This study investigated whether usnic acid at low-cytotoxicity level could enhance sensitivity of AML cells with acquired resistance to ABT-199 by targeting the integrated stress response pathways., Methods: To investigate the combined effects on AML cells, we used a cell viability test, flow cytometry to quantify apoptosis, cell cycle analysis, and mitochondrial membrane potential measurement. RNA-seq and immunoblot were used to determine the potential mechanisms of ABT-199 + usnic acid combination., Results: Usnic acid, at a low cytotoxicity level, successfully restored ABT-199 sensitivity in AML cell lines that had developed ABT-199 resistance and increased ABT-199's antileukemic activity in a xenograft model. Mechanistically, the combination of usnic acid and ABT-199 cooperated to boost the expression of the integrated stress response (ISR)-associated genes ATF4, CHOP, and NOXA through the heme-regulated inhibitor kinase (HRI), while also promoting the degradation of the anti-apoptotic protein MCL-1. ISRIB, a compound that blocks the ISR, was able to reverse the growth suppression and cell death, the increase in expression of genes related with the ISR, and the inhibition of MCL-1 protein caused by combination therapy. Additionally, the downregulation of MCL-1 was linked to an increase in MCL-1 phosphorylation at serine 159 and subsequent destruction by the proteasome., Conclusion: In summary, usnic acid improves chemosensitivity to ABT-199 by triggering the integrated stress response, leading to decreased levels of MCL-1 protein, suggesting a potential treatment for AML cases resistant to Bcl-2 inhibitors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Production and hosting by Elsevier B.V.)

Background: The genus Usnea (Parmeliaceae; lichenized Ascomycetes) is pale grayish-green fruticose lichens which grow as leafless mini-shrubs and comprise about 360 species. Most of the Usnea species are edible and is utilized in preparation of traditional foods as well as in medicines to combat wide range of ailments., Objective: The goal of this work was to quantify usnic acid in three Usnea spp. [Usnea ghattensis (UG), Usnea orientalis (UO) and Usnea undulata (UU)] using HPTLC-MS and chemical profiling of acetone extracts using UPLC-QTof-MSE resulted in the identification of sixteen compounds based on their MS/MS fragmentation patterns., Methods: Hyphenated techniques, HPTLC-MS and UPLC-QTof-MSE have been proposed to quantify usnic acid and analysis of metabolites in the crude extracts qualitatively. This method allowed tentative characterization of metabolites from Usnea spp., Results: The quantification study showed the excellent linearity of the usnic acid at 0.25-1 µg/band with a correlation coefficient r  2>0.99, and LOD, LOQ was found to be 51.7 and 156.6 ng/band, respectively. Further, UPLC-QTof-MSE analysis of crude extract led identification of lichen substances through their exact molecular masses and MS/MS fragmentation studies., Conclusions: The present study summarizes HPTLC method for quantification of usnic acid in three different Usnea spp. Along with two herbal formulations containing Usnea spp. as the ingredient and developed method was validated as per the ICH guidelines and further UPLC-QTof-MSE analysis provides characterization of the sixteen different secondary metabolites based on their mass fragmentation studies., Highlights: Rapid HPTLC method for quantification of usnic acid in three different Usnea spp. along with two herbal formulations and metabolite profiling using UPLC-QTof-MSE., (© The Author(s) 2024. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Breast cancer is a heterogeneous type of disease in which genetic and environmental factors play a crucial role. There are several types of treatment for breast cancer (BC) patients. However, the biggest problem in the treatment of breast cancer is the resistance that occurs during the treatment with chemotherapeutic agents. Usnic acid, a secondary metabolite of lichen, has been identified as a drug candidate molecule in cancer treatment. The determination of miRNA target proteins is essential for the understanding of molecular mechanisms of miRNA-related tumorigenesis., Objectives: We determined that mir-185-5p has therapeutic potential at the miRNA level by applying usnic acid to BT-474 breast cancer cells in a previous study. Herein, we aimed to investigate the molecular mechanisms of miR-185-5p on BT-474 breast cancer cells using a proteomics approach. We explored the changes in the protein expression level of BT-474 breast cancer cells in response to the up-regulation of miR-185-5p after applying usnic acid as a novel candidate anti-- cancer drug molecule., Methods: We performed quantitative proteome analysis based on an LC-MS/MS assay, which was validated by western blotting. The differentially expressed proteins were analyzed using the latest data available in bioinformatics tools. The up-regulated expression of YWHAE, Cathepsin D, and the down-regulated levels of PAK-1 were demonstrated by western blot assay., Results: According to the results, 86 proteins showing >2-fold change were identified as differentially expressed between breast cancer and normal breast epithelial cells. The apoptosis pathway was the main clade containing most of the proteins regulated by miR-185-5p. The results indicate that miR-185-5p modulates apoptosis signaling pathways in BT-474 breast cancer cells. Breast cancer inhibition due to increased expression of YWHAE, Cathepsin D, and decreased expression of PAK-1 is likely to be mediated by inducing miR-185-5p mediated apoptosis., Conclusion: In this study, the identification of miR-185-5p protein targets demonstrated the potential for the development of targeted therapy and the development of miRNA-based therapeutics and presented it as a biomarker for breast cancer diagnosis, prognosis, and treatment response. In this regard, proteome analyses provided an understanding of the molecular mechanism underlying the effect of miR-185-5p on breast cancer., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Preclinical and clinical studies have indicated that compromised blood-brain barrier (BBB) function contributes to Alzheimer's disease (AD) pathology. BBB breakdown ranged from mild disruption of tight junctions (TJs) with increased BBB permeability to chronic integrity loss, affecting transport across the BBB, reducing brain perfusion, and triggering inflammatory responses. We recently developed a high-throughput screening (HTS) assay to identify hit compounds that enhance the function of a cell-based BBB model. The HTS screen identified ( S , E )-2-acetyl-6-[3-(4'-fluorobiphenyl-4-yl)acryloyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo-[b,d]furan-1(9bH)-one (4-FPBUA), a semisynthetic analogue of naturally occurring usnic acid, which protected the in vitro model against Aβ toxicity. Usnic acid is a lichen-derived secondary metabolite with a unique dibenzofuran skeleton that is commonly found in lichenized fungi of the genera Usnea. In this study, we aimed to evaluate the effect of 4-FPBUA in vitro on the cell-based BBB model function and its in vivo ability to rectify BBB function and reduce brain Aβ in two AD mouse models, namely, 5xFAD and TgSwDI. Our findings demonstrated that 4-FPBUA enhanced cell-based BBB function, increased Aβ transport across the monolayer, and reversed BBB breakdown in vivo by enhancing autophagy as an mTOR inhibitor. Induced autophagy was associated with a significant reduction in Aβ accumulation and related pathologies and improved memory function. These results underscore the potential of 4-FPBUA as a candidate for further preclinical exploration to better understand its mechanisms of action and to optimize dosing strategies. Continued research may also elucidate additional pathways through which 4-FPBUA contributed to the amelioration of BBB dysfunction in AD. Collectively, our findings supported the development of 4-FPBUA as a therapeutic agent against AD.

A new series of usnic acid (UA) monoesterified derivatives 2-15 were designed and synthesised using UA ( 1 ) as starting material. The structural characterisation of all compounds was elucidated using 1 H-NMR and 13 C-NMR spectral data. In vitro studies demonstrated thatmost UA derivatives exhibited higher inhibitory activity against Candida albicans and Staphylococcus aureus . Among them, compound 7 displayed the highest inhibitory activity against C. albicans with a minimum inhibitory concentration (MIC) of 32 μg/mL. Compounds 5 , 8 , 9 , 11 and 13 demonstrated superior inhibition of S. aureus (MIC, 16 μg/mL) and biofilm formation in a concentration-dependent manner. With the exception of 11 , compounds 5 , 8 , 9 and 13 were all more effective than UA in inhibiting S. aureus biofilms. This research highlights the potential of UA monoesterified derivatives for the development of dual antimicrobial and antibiofilm agents.

Since usnic acid was first isolated in 1844 as a prominent secondary lichen metabolite, it has been used for various purposes worldwide. Usnic acid has been claimed to possess numerous therapeutic properties, including antimicrobial, anti-inflammatory, antiviral, anti-proliferative, and antipyretic activities. Approximately two decades ago, crude extracts of usnic acid or pure usnic acid were marketed in the United States as dietary supplements for aiding in weight loss as a "fat-burner" and gained popularity in the bodybuilding community; however, hepatotoxicity was documented for some usnic acid containing products. The US Food and Drug Administration (FDA) received numerous reports of liver toxicity associated with the use of dietary supplements containing usnic acid, leading the FDA to issue a warning letter in 2001 on a product, LipoKinetix. The FDA also sent a recommendation letter to the manufacturer of LipoKinetix, resulting in the withdrawal of LipoKinetix from the market. These events triggered investigations into the hepatotoxicity of usnic acid and its mechanisms. In 2008, we published a review article titled "Usnic Acid and Usnea Barbata Toxicity". This review is an updated version of our previous review article and incorporates additional data published since 2008. The purpose of this review is to provide a comprehensive summary of the understanding of the liver toxicity associated with usnic acid, with a particular focus on the current understanding of the putative mechanisms of usnic acid-related hepatotoxicity.

With the rapid improvement of power conversion efficiency (PCE), perovskite solar cells (PSCs) have broad application prospects and their industrialization will be the next step. Nevertheless, the performance and long-term stability of the devices are limited by the defect-induced nonradiative recombination centers and ions' migration inside the perovskite films. Here, usnic acid (UA), an easy-to-obtain and efficient natural biomaterial with a hydroxyl functional group (-OH) and four carbonyl groups (-C═O) was added to MAPbI 3 perovskite precursor to regulate the crystallization process by slowing the crystallization rate, thereby expanding the crystal size and preparing perovskite films with low defect density. In addition, UA anchors the uncoordinated Pb 2+ and suppresses the migration of I-ions, which enhances the stability of the perovskite film. Consequently, an impressive PCE exceeding 20% was achieved for inverted structure MAPbI 3 -based PSCs. More impressively, the optimized PSCs maintained 78% of the initial PCE under air with high humidity (RH ≈ 65%, 25-30 °C) for 1000 h. UA can be extracted from the plant, usnea, making it inexpensive and easy to obtain. Our work demonstrates the application of the plant material in PSCs and their industrialization, which is significant nowadays.

Bacterial cellulose is an extracellular polysaccharide produced by microorganisms, offering advantages such as high water-holding capacity, flexibility, and biocompatibility. However, its lack of bactericidal activity hampers its wide application. Usnic acid, a secondary metabolite derived from lichens of the Usnea genus, is recognized for its antibacterial and anti-biofilm efficiency, coupled with anti-inflammatory properties. Its water insolubility presents challenges for wide utilization and stable release. Sanxan gel, a novel polysaccharide, exhibits exceptional freeze-thaw stability, suspension properties, and high elasticity, rendering it effective as a suspending agent to improve the bioavailability of water-insoluble drugs. In this study, a hydrogel membrane is designed by combining bacterial cellulose and usnic acid suspended in sanxan gel through a simple in situ microorganism fermentation. The obtained membranes demonstrate excellent ability for sustained drug release, strong eradication capability against tested bacteria in both in vitro and in vivo experiments, effective inhibition of biofilm formation, and excellent hemocompatibility and cytocompatibility. Additionally, the composite membranes promote wound healing with reduced inflammation and bacterial infection in a full-thickness wound infection model in mice. This study provides innovative insights and strategies for the development of functional dressings for infected wounds in future clinical applications., (© 2024 Wiley‐VCH GmbH.)

Background: Reactive oxygen species (ROS) production and oxidative stress may be responsible for the onset of several chronic diseases. Usnic acid (UA) is a natural secondary metabolite of lichens with several healthful bioactivities, including antioxidant properties. However, UA is a hydrophobic compound known for its hepatic toxicity. These aspects limit its therapeutic applications. To overcome these drawbacks and improve the pharmacological use of hydrophobic compounds, nanotechnology is widely used. Therefore, the incorporation of UA into appropriate nanocarriers could enhance the bioactivity of UA by increasing its solubility., Objective: The aim of this work was to improve the solubility of UA and its bioactivity in the absence of cytotoxicity., Methods: In this study, UA loaded liposomes (UA-LP) were developed. The formulations were chemically and physically characterized, and an in vitro release study was performed. Free UA and UA-LP were tested on RAW 264.7 murine macrophages in terms of cytotoxicity, intracellular ROS production, and NO release in the absence or presence of pro-oxidant LPS stimulus., Results: UA-LP showed excellent physical and chemical stability during storage and improved solubility of UA. UA-LP showed an antioxidant effect in the absence of cytotoxicity compared with free UA on LPS-exposed macrophages., Conclusion: For the first time, liposomal formulation improved the beneficial action of UA in terms of solubility and antioxidant activity., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Usnic acid has a variety of biological activities, and has been widely studied in the fields of antibacterial, immune stimulation, antiviral, antifungal, anti-inflammatory and antiparasitic. Based on this, usnic acid is used as the lead compound for structural modification. In order to enhance the biological activity and solubility of usnic acid, scholars have carried out a large number of structural modifications, and found some usnic acid derivatives to be of more potential research value. In this paper, the structural modification, biological activity and structure-activity relationship of usnic acid were reviewed to provide reference for the development of usnic acid derivatives., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)