ToxSTAR: drug-induced liver injury prediction tool for the web environment.

SUMMARY: Drug-induced liver injury (DILI) is a challenging endpoint in predictive toxicology because of the complex reactive metabolites that cause liver damage and the wide range of mechanisms involved in the development of the disease. ToxSTAR provides structural similarity-based DILI analysis and in-house DILI prediction models that predict four DILI subtypes (cholestasis, cirrhosis, hepatitis and steatosis) based on drug and drug metabolite molecules. AVAILABILITY AND IMPLEMENTATION: ToxSTAR is freely available at https://toxstar.kitox.re.kr/. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Medicarpin and Homopterocarpin Isolated from Canavalia lineata as Potent and Competitive Reversible Inhibitors of Human Monoamine Oxidase-B.

Thirteen compounds were isolated from the Canavalia lineata pods and their inhibitory activities against human monoamine oxidase-A (hMAO-A) and -B (hMAO-B) were evaluated. Among them, compounds 8 (medicarpin) and 13 (homopterocarpin) showed potent inhibitory activity against hMAO-B (IC50 = 0.45 and 0.72 µM, respectively) with selectivity index (SI) values of 44.2 and 2.07, respectively. Most of the compounds weakly inhibited MAO-A, except 9 (prunetin) and 13. Compounds 8 and 13 were reversible competitive inhibitors against hMAO-B (Ki = 0.27 and 0.21 µM, respectively). Structurally, the 3-OH group at A-ring of 8 showed higher hMAO-B inhibitory activity than 3-OCH3 group at the A-ring of 13. However, the 9-OCH3 group at B-ring of 13 showed higher hMAO-B inhibitory activity than 8,9-methylenedioxygroup at the B-ring of 12 (pterocarpin). In cytotoxicity study, 8 and 13 showed non-toxicity to the normal (MDCK) and cancer (HL-60) cells and moderate toxicity to neuroblastoma (SH-SY5Y) cell. Molecular docking simulation revealed that the binding affinities of 8 and 13 for hMAO-B (-8.7 and -7.7 kcal/mol, respectively) were higher than those for hMAO-A (-3.4 and -7.1 kcal/mol, respectively). These findings suggest that compounds 8 and 13 be considered potent reversible hMAO-B inhibitors to be used for the treatment of neurological disorders.

Predictive Model for Drug-Induced Liver Injury Using Deep Neural Networks Based on Substructure Space.

Drug-induced liver injury (DILI) is a major concern for drug developers, regulators, and clinicians. However, there is no adequate model system to assess drug-associated DILI risk in humans. In the big data era, computational models are expected to play a revolutionary role in this field. This study aimed to develop a deep neural network (DNN)-based model using extended connectivity fingerprints of diameter 4 (ECFP4) to predict DILI risk. Each data set for the predictive model was retrieved and curated from DILIrank, LiverTox, and other literature. The best model was constructed through ten iterations of stratified 10-fold cross-validation, and the applicability domain was defined based on integer ECFP4 bits of the training set which represented substructures. For the robustness test, we employed the concept of the endurance level. The best model showed an accuracy of 0.731, a sensitivity of 0.714, and a specificity of 0.750 on the validation data set in the complete applicability domain. The model was further evaluated with four external data sets and attained an accuracy of 0.867 on 15 drugs with DILI cases reported since 2019. Overall, the results suggested that the ECFP4-based DNN model represents a new tool to identify DILI risk for the evaluation of drug safety.

Anti-Inflammatory Activity and ROS Regulation Effect of Sinapaldehyde in LPS-Stimulated RAW 264.7 Macrophages.

We evaluated the anti-inflammatory effects of SNAH in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages by performing nitric oxide (NO) assays, cytokine enzyme-linked immunosorbent assays, Western blotting, and real-time reverse transcription-polymerase chain reaction analysis. SNAH inhibited the production of NO (nitric oxide), reactive oxygen species (ROS), tumor necrosis factor (TNF)-α, and interleukin (IL)-6. Additionally, 100 µM SNAH significantly inhibited total NO and ROS inhibitory activity by 93% (p < 0.001) and 34% (p < 0.05), respectively. Protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) stimulated by LPS were also decreased by SNAH. Moreover, SNAH significantly (p < 0.001) downregulated the TNF-α, IL-6, and iNOS mRNA expression upon LPS stimulation. In addition, 3-100 µM SNAH was not cytotoxic. Docking simulations and enzyme inhibitory assays with COX-2 revealed binding scores of -6.4 kcal/mol (IC50 = 47.8 µM) with SNAH compared to -11.1 kcal/mol (IC50 = 0.45 µM) with celecoxib, a known selective COX-2 inhibitor. Our results demonstrate that SNAH exerts anti-inflammatory effects via suppression of ROS and NO by COX-2 inhibition. Thus, SNAH may be useful as a pharmacological agent for treating inflammation-related diseases.

Inhibition of Butyrylcholinesterase and Human Monoamine Oxidase-B by the Coumarin Glycyrol and Liquiritigenin Isolated from Glycyrrhiza uralensis.

Eight compounds were isolated from the roots of Glycyrrhiza uralensis and tested for cholinesterase (ChE) and monoamine oxidase (MAO) inhibitory activities. The coumarin glycyrol (GC) effectively inhibited butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) with IC50 values of 7.22 and 14.77 µM, respectively, and also moderately inhibited MAO-B (29.48 µM). Six of the other seven compounds only weakly inhibited AChE and BChE, whereas liquiritin apioside moderately inhibited AChE (IC50 = 36.68 µM). Liquiritigenin (LG) potently inhibited MAO-B (IC50 = 0.098 µM) and MAO-A (IC50 = 0.27 µM), and liquiritin, a glycoside of LG, weakly inhibited MAO-B (>40 µM). GC was a reversible, noncompetitive inhibitor of BChE with a Ki value of 4.47 µM, and LG was a reversible competitive inhibitor of MAO-B with a Ki value of 0.024 µM. Docking simulations showed that the binding affinity of GC for BChE (-7.8 kcal/mol) was greater than its affinity for AChE (-7.1 kcal/mol), and suggested that GC interacted with BChE at Thr284 and Val288 by hydrogen bonds (distances: 2.42 and 1.92 Å, respectively) beyond the ligand binding site of BChE, but that GC did not form hydrogen bond with AChE. The binding affinity of LG for MAO-B (-8.8 kcal/mol) was greater than its affinity for MAO-A (-7.9 kcal/mol). These findings suggest GC and LG should be considered promising compounds for the treatment of Alzheimer's disease with multi-targeting activities.

Osthenol, a prenylated coumarin, as a monoamine oxidase A inhibitor with high selectivity.

Osthenol (6), a prenylated coumarin isolated from the dried roots of Angelica pubescens, potently and selectively inhibited recombinant human monoamine oxidase-A (hMAO-A) with an IC50 value of 0.74 µM and showed a high selectivity index (SI > 81.1) for hMAO-A versus hMAO-B. Compound 6 was a reversible competitive hMAO-A inhibitor (Ki = 0.26 µM) with a potency greater than toloxatone (IC50 = 0.93 µM), a marketed drug. Isopsoralen (3) and bakuchicin (1), furanocoumarin derivatives isolated from Psoralea corylifolia L., showed slightly higher IC50 values (0.88 and 1.78 µM, respectively) for hMAO-A than 6, but had low SI values (3.1 for both). Other coumarins tested did not effectively inhibit hMAO-A or hMAO-B. A structural comparison suggested that the 8-(3,3-dimethylallyl) group of 6 increased its inhibitory activity against hMAO-A compared with the 6-methoxy group of scopoletin (4). Molecular docking simulations revealed that the binding affinity of 6 for hMAO-A (-8.5 kcal/mol) was greater than that for hMAO-B (-5.6 kcal/mol) and that of 4 for hMAO-A (-7.3 kcal/mol). Docking simulations also implied that 6 interacted with hMAO-A at Phe208 and with hMAO-B at Ile199 by carbon hydrogen bondings. Our findings suggest that osthenol, derived from natural products, is a selective and potent reversible inhibitor of MAO-A, and can be regarded a potential lead compound for the design of novel reversible MAO-A inhibitors.

Potent inhibition of acetylcholinesterase by sargachromanol I from Sargassum siliquastrum and by selected natural compounds.

Six hundred forty natural compounds were tested for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Of those, sargachromanol I (SCI) and G (SCG) isolated from the brown alga Sargassum siliquastrum, dihydroberberine (DB) isolated from Coptis chinensis, and macelignan (ML) isolated from Myristica fragrans, potently and effectively inhibited AChE with IC50 values of 0.79, 1.81, 1.18, and 4.16 µM, respectively. SCI, DB, and ML reversibly inhibited AChE and showed mixed, competitive, and noncompetitive inhibition, respectively, with Ki values of 0.63, 0.77, and 4.46 µM, respectively. Broussonin A most potently inhibited BChE (IC50 = 4.16 µM), followed by ML, SCG, and SCI (9.69, 10.79, and 13.69 µM, respectively). In dual-targeting experiments, ML effectively inhibited monoamine oxidase B with the greatest potency (IC50 = 7.42 µM). Molecular docking simulation suggested the binding affinity of SCI (-8.6 kcal/mol) with AChE was greater than those of SCG (-7.9 kcal/mol) and DB (-8.2 kcal/mol). Docking simulation indicated SCI interacts with AChE at Trp81, and that SCG interacts at Ser119. No hydrogen bond was predicted for the interaction between AChE and DB. This study suggests SCI, SCG, DB, and ML be viewed as new reversible AChE inhibitors and useful lead compounds for the development for the treatment of Alzheimer's disease.

Rhamnocitrin isolated from Prunus padus var. seoulensis: A potent and selective reversible inhibitor of human monoamine oxidase A.

Three flavanones and two flavones were isolated from the leaves of Prunus padus var. seoulensis by the activity-guided screening for new monoamine oxidase (MAO) inhibitors. Among the compounds isolated, rhamnocitrin (5) was found to potently and selectively inhibit human MAO-A (hMAO-A, IC50 = 0.051 µM) and effectively inhibit hMAO-B (IC50 = 2.97 µM). The IC50 value of 5 for hMAO-A was the lowest amongst all natural flavonoids reported to date, and the potency was 20.2 times higher than that of toloxatone (1.03 µM), a marketed drug. In addition, 5 reversibly and competitively inhibited hMAO-A and hMAO-B with Ki values of 0.030 and 0.91 µM, respectively. Genkwanin (4) was also observed to strongly inhibit hMAO-A and hMAO-B (IC50 = 0.14 and 0.35 µM, respectively), and competitively inhibit hMAO-A and hMAO-B (Ki = 0.097 and 0.12 µM, respectively). Molecular docking simulation reveals that the binding affinity of 5 with hMAO-A (-18.49 kcal/mol) is higher than that observed with hMAO-B (0.19 kcal/mol). Compound 5 interacts with hMAO-A at four possible residues (Asn181, Gln215, Thr336, and Tyr444), while hMAO-B forms a single hydrogen bond at Glu84. These findings suggest that compound 5 as well as 4 can be considered as novel potent and reversible hMAO-A and/or hMAO-B inhibitors or useful lead compounds for future development of hMAO inhibitors in neurological disorder therapies.

Selective inhibition of monoamine oxidase A by hispidol.

Hispidol, an aurone, isolated from Glycine max Merrill, was found to potently and selectively inhibit an isoform of recombinant human monoamine oxidase-A (MAO-A), with an IC50 value of 0.26 µM, and to inhibit MAO-B, but with lower potency (IC50 = 2.45 µM). Hispidol reversibly and competitively inhibited MAO-A with a Ki value of 0.10 µM with a potency much greater than toloxatone (IC50 = 1.10 µM), a marketed drug. It also reversibly and competitively inhibited MAO-B (Ki = 0.51 µM). Sulfuretin, an analog of hispidol, effectively inhibited MAO-A (IC50 = 4.16 µM) but not MAO-B (IC50 > 80 µM). A comparison of their chemical structures showed that the 3'-hydroxyl group of sulfuretin might reduce its inhibitory activities against MAO-A and MAO-B. Flexible docking simulation revealed that the binding affinity of hispidol for MAO-A (-9.1 kcal/mol) was greater than its affinity for MAO-B (-8.7 kcal/mol). The docking simulation showed hispidol binds to the major pocket of MAO-A or MAO-B. The findings suggest hispidol is a potent, selective, reversible inhibitor of MAO-A, and that it be considered a novel lead compound for development of novel reversible inhibitors of MAO-A.

Selective inhibition of monoamine oxidase A by chelerythrine, an isoquinoline alkaloid.

Chelerythrine, an isoquinoline alkaloid isolated from the herbaceous perennial Chelidonium majus, was found to potently and selectively inhibit an isoform of recombinant human monoamine oxidase-A (MAO-A) with an IC50 value of 0.55 µM. Chelerythrine was a reversible competitive MAO-A inhibitor (Ki = 0.22 µM) with a potency much greater than toloxatone (IC50 = 1.10 µM), a marketed drug. Other isoquinoline alkaloids tested did not effectively inhibit MAO-A or MAO-B. A structural comparison with corynoline suggested the 1- and/or 2-methoxy groups of chelerythrine increase its inhibitory activity against MAO-A. Molecular docking simulations revealed that the binding affinity of chelerythrine for MAO-A (-9.7 kcal/mol) was greater than that for MAO-B (-4.6 kcal/mol). Docking simulation implied that Cys323 and Tyr444 of MAO-A are key residues for hydrogen-bond interaction with chelerythrine. Our findings suggest chelerythrine is one of the most reversible selective and potent natural inhibitor of MAO-A, and that it be regarded a potential lead compound for the design of novel reversible MAO-A inhibitors.

Assessing the safety of an Ephedrae Herba aqueous extract in rats: A repeat dose toxicity study.

Ephedrae Herba (EH) has been used in Asian traditional herbal medicine to cure bronchial asthma, cold, flu, chills, fever, headache, nasal congestion, and cough. In this study, we evaluated the subchronic toxicity of an Ephedrae Herba aqueous extract (EHAE) in male and female F344 rats. The EHAE was administered orally daily at doses of 0, 125, 250, 500, and 1000 mg/kg bw/day for 13 weeks. Toxicological assessment was performed to determine mortality, clinical signs, and changes in body weight, food consumption, ophthalmological, urinary, hematological, and serum biochemical parameters, macroscopic and microscopic evaluations, and organ weights. We found that oral administration of EHAE to F344 rats for 13 weeks resulted in histopathological changes in the kidneys and salivary glands. In the kidneys, increased incidence and severity of tubular basophilia were observed in females administered 1000 mg/kg bw/day of the extract. In the salivary glands, acinar cell hypertrophy was observed in males administered 500 mg/kg bw/day and in both sexes administered 1000 mg/kg bw/day of the extract. All test article-treated groups of males and females administered ≥250 mg/kg bw/day showed increased absolute and relative salivary gland weights. Therefore, the NOAEL (No Observed Adverse Effect Level) was determined as 125 mg/kg bw/day for both sexes of rats under the present experimental conditions.

Selective inhibition of monoamine oxidase A by purpurin, an anthraquinone.

Monoamine oxidase (MAO) catalyzes the oxidation of monoamines that act as neurotransmitters. During a target-based screening of natural products using two isoforms of recombinant human MAO-A and MAO-B, purpurin (an anthraquinone derivative) was found to potently and selectively inhibit MAO-A, with an IC50 value of 2.50µM, and not to inhibit MAO-B. Alizarin (also an anthraquinone) inhibited MAO-A less potently with an IC50 value of 30.1µM. Furthermore, purpurin was a reversible and competitive inhibitor of MAO-A with a Ki value of 0.422µM. A comparison of their chemical structures suggested the 4-hydroxy group of purpurin might play an important role in its inhibition of MAO-A. Molecular docking simulation showed that the binding affinity of purpurin for MAO-A (-40.0kcal/mol) was higher than its affinity for MAO-B (-33.9kcal/mol), and that Ile 207 and Gly 443 of MAO-A were key residues for hydrogen bonding with purpurin. The findings of this study suggest purpurin is a potent, selective, reversible inhibitor of MAO-A, and that it be considered a new potential lead compound for development of novel reversible inhibitors of MAO-A (RIMAs).

Potent selective monoamine oxidase B inhibition by maackiain, a pterocarpan from the roots of Sophora flavescens.

Monoamine oxidase (MAO) catalyzes the oxidation of monoamines and its two isoforms, MAO-A and MAO-B, break down neurotransmitter amines. Of the compounds isolated from the roots of Sophora flavescens, (-)-maackiain (4), a pterocarpan, was found to potently and selectively inhibit human MAO-B, with an IC50 of 0.68µM, and to have a selectivity index of 126.2 for MAO-B. As compared with other herbal natural products, the IC50 value of 4 for MAO-B is one of the lowest reported to date. Genistein (1) highly, effectively and non-selectively inhibited MAO-A and MAO-B with IC50 values of 3.9µM and 4.1µM, respectively. (-)-4-Hydroxy-3-methoxy-8,9-methylenedioxypterocarpan (2) effectively and non-selectively inhibited MAO-A and MAO-B with IC50 values of 20.3µM and 10.3µM, respectively. In addition, compound 4 reversibly and competitively inhibited MAO-B with a Ki value of 0.054µM. Molecular docking simulation revealed that the binding affinity of 4 for MAO-B (-26.6kcal/mol) was greater than its affinity for MAO-A (-8.3kcal/mol), which was in-line with our inhibitory activity findings. Furthermore, Cys172 of MAO-B was found to be a key residue for hydrogen bonding with compound 4. The findings of this study suggest compound 4 be viewed as a new potent, selective, and reversible MAO-B inhibitor, and that compounds 1 and 2 be considered useful lead compounds for the developments of nonselective and reversible MAO inhibitors for the treatment of disorders like Parkinson's disease, Alzheimer disease, and depression.

Trovafloxacin drives inflammation-associated drug-induced adverse hepatic reaction by changing macrophage polarization.

Drug-induced liver injury (DILI) is an adverse hepatic reaction and a serious concern for public healthcare systems and pharmaceutical companies. DILI is frequently caused by a combination of direct toxic stresses and subsequent immune damage to hepatocytes. However, little is known about the mechanism by which drugs facilitate the activation of the innate immune system. Here, we aimed to decipher the inflammatory events in trovafloxacin (TVX)-induced reactions using liver macrophages. We showed that proinflammatory M1-like macrophages mainly contributed to hepatotoxicity mediated by TVX, a DILI drug. Additionally, transcriptome results showed that the interferon type I pathway, cytokines, and apoptosis pathway were involved in the initiation of synergistic effects resulting in TVX-induced liver injury. We hypothesized that DILI drugs could drive liver injury by altering the activation and phenotype of hepatic macrophages. Furthermore, drug treatment-induced transcriptional changes such as Traf1 and 2, Socs3, and Hbegf in macrophage polarization could be used to assess drug-specific immune-mediated reactions. Therefore, we proposed that transcriptional change in the genes related to macrophage polarization index could be an indicator to reflect the severity of DILI in a preclinical setting during drug development.

Semi-automated approach for generation of biological networks on drug-induced cholestasis, steatosis, hepatitis, and cirrhosis.

Drug-induced liver injury (DILI) is one of the leading reasons for discontinuation of a new drug development project. Diverse machine learning or deep learning models have been developed to predict DILI. However, these models have not provided an adequate understanding of the mechanisms leading to DILI. The development of safer drugs requires novel computational approaches that enable the prompt understanding of the mechanism of DILI. In this study, the mechanisms leading to the development of cholestasis, steatosis, hepatitis, and cirrhosis were explored using a semi-automated approach for data gathering and associations. Diverse data from ToxCast, Comparative Toxicogenomic Database (CTD), Reactome, and Open TG-GATEs on reference molecules leading to the development of the respective diseases were extracted. The data were used to create biological networks of the four diseases. As expected, the four networks had several common pathways, and a joint DILI network was assembled. Such biological networks could be used in drug discovery to identify possible molecules of concern as they provide a better understanding of the disease-specific key events. The events can be target-tested to provide indications for potential DILI effects. Supplementary Information: The online version contains supplementary material available at 10.1007/s43188-022-00124-6.

Potent and Selective Inhibitors of Human Monoamine Oxidase A from an Endogenous Lichen Fungus Diaporthe mahothocarpus.

Using 126 endogenous lichen fungus (ELF) extracts, inhibitory activities against monoamine oxidases (MAOs) and cholinesterases (ChEs) were evaluated. Among them, extract ELF29 of the endogenous fungus Diaporthe mahothocarpus of the lichen Cladonia symphycarpia showed the highest inhibitory activity against hMAO-A. Compounds alternariol (AT), 5'-hydroxy-alternariol (HAT), and mycoepoxydiene (MED), isolated from the extract, had potent inhibitory activities against hMAO-A with IC50 values of 0.020, 0.31, and 8.68 µM, respectively. AT, HAT, and MED are reversible competitive inhibitors of hMAO-A with Ki values of 0.0075, 0.116, and 3.76 µM, respectively. The molecular docking studies suggested that AT, HAT, and MED had higher binding affinities for hMAO-A (-9.1, -6.9, and -5.6 kcal/mol, respectively) than for hMAO-B (-6.3, -5.2, and -3.7 kcal/mol, respectively). The relative tight binding might result from a hydrogen bond interaction of the three compounds with a Tyr444 residue in hMAO-A, whereas no hydrogen bond interaction was proposed in hMAO-B. In silico pharmacokinetics, the three compounds showed high gastrointestinal absorption without violating Lipinski's five rules, but only MED showed high probability to cross the blood-brain barrier. These results suggest that AT, HAT, and MED are candidates for treating neuropsychiatric disorders, such as depression and cardiovascular disease.

Development of blood brain barrier permeation prediction models for organic and inorganic biocidal active substances.

Biocidal products are broadly used in homes and industries. However, the safety of biocidal active substances (BASs) is not yet fully understood. In particular, the neurotoxic action of BASs needs to be studied as diverse epidemiological studies have reported associations between exposure to BASs and neural diseases. In this study, we developed in silico models to predict the blood-brain barrier (BBB) permeation of organic and inorganic BASs. Due to a lack of BBB data for BASs, the chemical space of BASs and BBB dataset were compared in order to select BBB data that were structurally similar to BASs. In silico models to predict log-scaled BBB penetration were developed using support vector regression for organic BASs and multiple linear regression for inorganic BASs. The model for organic BASs was developed with 231 compounds (training set: 153 and test set: 78) and achieved good prediction accuracy on an external test set (R2 = 0.64), and the model outperformed the model for pharmaceuticals. The model for inorganic BASs was developed with 11 compounds (R2 = 0.51). Applicability domain (AD) analysis of the models clarified molecular structures reliably predicted by the models. Therefore, the models developed in this study can be used for predicting BBB permeable BASs in human. These models were developed according to the Quantitative Structure-Activity Relationship validation principles proposed by the Organization for Economic Cooperation and Development.

Acetylcholinesterase and monoamine oxidase-B inhibitory activities by ellagic acid derivatives isolated from Castanopsis cuspidata var. sieboldii.

Among 276 herbal extracts, a methanol extract of Castanopsis cuspidata var. sieboldii stems was selected as an experimental source for novel acetylcholinesterase (AChE) inhibitors. Five compounds were isolated from the extract by activity-guided screening, and their inhibitory activities against butyrylcholinesterase (BChE), monoamine oxidases (MAOs), and ß-site amyloid precursor protein cleaving enzyme 1 (BACE-1) were also evaluated. Of these compounds, 4'-O-(α-L-rhamnopyranosyl)-3,3',4-tri-O-methylellagic acid (3) and 3,3',4-tri-O-methylellagic acid (4) effectively inhibited AChE with IC50 values of 10.1 and 10.7 µM, respectively. Ellagic acid (5) inhibited AChE (IC50 = 41.7 µM) less than 3 and 4. In addition, 3 effectively inhibited MAO-B (IC50 = 7.27 µM) followed by 5 (IC50 = 9.21 µM). All five compounds weakly inhibited BChE and BACE-1. Compounds 3, 4, and 5 reversibly and competitively inhibited AChE, and were slightly or non-toxic to MDCK cells. The binding energies of 3 and 4 (- 8.5 and - 9.2 kcal/mol, respectively) for AChE were greater than that of 5 (- 8.3 kcal/mol), and 3 and 4 formed a hydrogen bond with Tyr124 in AChE. These results suggest 3 is a dual-targeting inhibitor of AChE and MAO-B, and that these compounds should be viewed as potential therapeutics for the treatment of Alzheimer's disease.

Selective Inhibition of Human Monoamine Oxidase B by 5-hydroxy-2-methyl-chroman-4-one Isolated from an Endogenous Lichen Fungus Daldinia fissa.

Inhibitory activities against monoamine oxidases (MAOs) and cholinesterases (ChEs) and antioxidant activity were evaluated for 195 extracts from Ukraine-derived endogenous lichen fungi (ELF). Among them, an ELF13 (identified as Daldinia fissa) extract showed the highest inhibitory activity against MAO-B, and 5-hydroxy-2-methyl-chroman-4-one (HMC) was isolated as a ~ 4-fold selective inhibitor of MAO-B (IC50 = 3.23 µM) compared to MAO-A (IC50 = 13.97 µM). HMC is a reversible competitive inhibitor with a Ki value of 0.896 µM. No cytotoxicity was observed in normal and cancer cells at 50 µM of HMC. HMC showed blood-brain barrier permeability and high gastrointestinal absorption in silico pharmacokinetics. The docking simulation results showed that the binding affinity of HMC for MAO-B (-7.3 kcal/mol) was higher than that of MAO-A (-6.1 kcal/mol) and that HMC formed a hydrogen bond interaction with Cys172 of MAO-B (distance: 3.656 Å), whereas no hydrogen bonding was predicted with MAO-A. These results suggest that HMC can be considered a candidate for the treatment of neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease.

Inhibitory Effect of Sesamolin on Melanogenesis in B16F10 Cells Determined by In Vitro and Molecular Docking Analyses.

BACKGROUND: Melanin protects the skin against the harmful effects of ultraviolet irradiation. However, melanin overproduction can result in several aesthetic problems, including melasma, freckles, age spots and chloasma. Therefore, development of anti-melanogenic agents is important for the prevention of serious hyperpigmentation diseases. Sesamolin is a lignan compound isolated from sesame seeds with several beneficial properties, including potential for melanin inhibition. OBJECTIVE: The aim of this study was to evaluate the anti-melanogenic effect of sesamolin in cell culture in vitro and the underlying mechanism of inhibition using molecular docking simulation. METHODS: Melanogenesis was induced by 3-isobutyl-1-methylxanthine in B16F10 melanoma cells, and the inhibitory effects of sesamolin were evaluated using zymography, a tyrosinase inhibitory activity assay, western blotting, and real-time reverse transcription-polymerase chain reaction analysis. Docking simulations between sesamolin and tyrosinase were performed using Autodock vina. RESULTS: Sesamolin significantly inhibited the expression of melanogenesis-related factors tyrosinase, and tyrosinase-related proteins 1 and 2 at the mRNA and protein levels. Treatment of melanoma cells with 50 µM sesamolin demonstrated the strongest inhibition against intercellular tyrosinase and melanin synthesis without exerting cytotoxic effects. Sesamolin significantly reduced mushroom tyrosinase activity in a dose-dependent manner via a competitive inhibition mechanism. Tyrosinase docking simulations supported that sesamolin (-6.5 kcal/mol) bound to the active site of tyrosinase more strongly than the positive control (arbutin, -5.7 kcal/mol). CONCLUSION: Sesamolin could be developed as a melanogenesis inhibiting agent owing to its dual function in blocking the generation of melanogenesis-related enzymes and inhibiting the enzymatic response of tyrosinase.