Enzyme Xanthine Oxidase Research Articles

Phenolics profile, anti-nephrolithiasis, and antioxidant activities of Monodora myristica seed: impact of endogenous proteins and lipids

The bioactive compounds in a food matrix can exist either in their free form or bound to other endogenous compounds, which may affect their bioactivities. This study investigated the impact of endogenous proteins and lipids on the phenolics profile, anti-nephrolithiasis, and antioxidant activities of Monodora myristica (African nutmeg) seed. Endogenous proteins and lipids in M. myristica seed flour were removed by deproteinization and defatting, to obtain the deproteinized, defatted, and deproteinized-defatted flours. The native flour served as a control. Phenolics compounds in the flours were quantified using HPLC-DAD, while nephrolithiasis-associated enzymes (xanthine oxidase and urease) inhibitory and antioxidant activities were determined using a spectrophotometer. Nine phenolic compounds (gallic, chlorogenic, caffeic, p-coumaric, ellagic acids, catechin, rutin, quercetin and luteolin) were detected in the native flour, with quercetin as the most abundant. The concentrations of the phenolic compounds, nephrolithiasis-associated enzymes inhibitory, and antioxidant activities of the flour decreased significantly due to deproteinization and defatting. Overall, the native flour had the highest concentrations of phenolics and the most potent enzymes inhibitory and antioxidant activities, followed by the defatted, deproteinized, and deproteinized-defatted flours. Hence, endogenous proteins and lipids may enhance the phenolics profile, anti-nephrolithiasis and antioxidant activities of M. myristica seed. This could have application in the development of functional food products and nutraceuticals targeting nephrolithiasis.Graphical

Exploring the Antioxidant Properties of Caffeoylquinic and Feruloylquinic Acids: A Computational Study on Hydroperoxyl Radical Scavenging and Xanthine Oxidase Inhibition.

Caffeoylquinic (5-CQA) and feruloylquinic (5-FQA) acids, found in coffee and other plant sources, are known to exhibit diverse biological activities, including potential antioxidant effects. However, the underlying mechanisms of these phenolic compounds remain elusive. This paper investigates the capacity and mode of action of 5-CQA and 5-FQA as natural antioxidants acting as hydroperoxyl radical scavengers and xanthine oxidase (XO) inhibitors. The hydroperoxyl radical scavenging potential was investigated using thermodynamic and kinetic calculations based on the DFT method, taking into account the influence of physiological conditions. Blind docking and molecular dynamics simulations were used to investigate the inhibition capacity toward the XO enzyme. The results showed that 5-CQA and 5-FQA exhibit potent hydroperoxyl radical scavenging capacity in both polar and lipidic physiological media, with rate constants higher than those of common antioxidants, such as Trolox and BHT. 5-CQA carrying catechol moiety was found to be more potent than 5-FQA in both physiological environments. Furthermore, both compounds show good affinity with the active site of the XO enzyme and form stable complexes. The hydrogen atom transfer (HAT) mechanism was found to be exclusive in lipid media, while both HAT and SET (single electron transfer) mechanisms are possible in water. 5-CQA and 5-FQA may, therefore, be considered potent natural antioxidants with potential health benefits.

Chemical and biological characteristics of Sri Lankan white tea

White tea is the rarest of all kinds of tea and has numerous health benefits. Sri Lankan white tea fetches the highest premium price on the market because of its distinct color and flavor. This is the first report on the chemical and biological activities of Sri Lankan white tea. This study evaluated the total polyphenol content, major catechins, including, (+)-catechin, (-)-epigallo catechin-3-gallate (EGCG), epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC), (-)-epicatechin (EC), and caffeine content of white tea collected from different elevations in Sri Lanka. The inhibitory effects of white tea on α-amylase, α-glucosidase, lipase, acetylcholine esterase, xanthine oxidase, and tyrosinase enzymes were evaluated. Ferric reducing antioxidant power (FRAP), DPPH, and ABTS radical scavenging activities were performed to determine the antioxidant capacity. The total polyphenol and catechin contents of white tea ranged from 18.21 % to 22.52 % and 5.32–12.22 %, respectively. White tea exhibited xanthine oxidase, acetylcholine esterase, and α-glucosidase inhibitory activity with the IC50 values in the range of 2.51–48.96, 14.2–54.21 and 6.38–33.14 ppm., respectively. Sri Lankan white tea has strong antioxidant activity as well as acetylcholine esterase, α-glucosidase, and xanthine oxidase inhibitory activities. In addition, white tea showed moderately inhibiting activities of lipase and tyrosinase.

Phytochemical Analysis, Antioxidant and Enzyme-Inhibitory Activities, and Multivariate Analysis of Insect Gall Extracts of Picea koraiensis Nakai.

Picea koraiensis Nakai (PK) is an evergreen tree. It plays an important role in landscaping and road greening. Insect galls of PK are formed by parasitism of the adelgid Adelges laricis. Except for phenolics, other chemical constituents and biological activity of insect gall from PK are still unknown. Thus, here, we performed phytochemical and biological activity analyses of PK insect gall extracts, aiming to turn waste into treasure and serve human health. PK insect gall extracts were prepared using seven solvents. Antioxidant activities of the extracts were examined via antioxidant assays (radical and oxidizing substance quenching, metal chelating, and reducing power). The inhibitory activities of the extracts were determined toward the key human-disease-related enzymes α-glucosidase, α-amylase, cholinesterase, tyrosinase, urease, and xanthine oxidase. The content of numerous active constituents was high in the methanol and ethanol extracts of PK insect gall, and these extracts had the highest antioxidant and enzyme-inhibitory activities. They also showed excellent stability and low toxicity. These extracts have potential for use as stabilizers of olive and sunflower seed oils.

Xanthine oxidase, α-glucosidase and α-amylase inhibitory activities of the essential oil from Piper lolot: In vitro and in silico studies

IntroductionPiper lolot is a species of herb used as a popular food in Vietnam. Furthermore, the species has been used as a Vietnamese traditional medicine to treat many diseases. MethodsChemical constituents in the essential oil from leaves of Piper lolot were determined using GC/MS analysis. The anti-gout and anti-diabetic activities of the essential oil were determined through the inhibitory assays against xanthine oxidase, α-glucosidase and α-amylase enzymes. In addition, molecular docking simulations were used to elucidate the inhibitory mechanism between the main compounds and the enzymes. ResultsThe dominant constituents of the Piper lolot essential oils were determined as β-caryophyllene (20.6%), β-bisabolene (11.6%), β-selinene (8.4%), β-elemene (7.7%), trans-muurola-4(14),5-diene (7.4%), and (E)-β-ocimene (6.7%). The essential oil displayed xanthine oxidase, α-amylase, and α-glucosidase inhibitory activities with IC50 values of 28.4, 130.6, and 59.1 μg/mL, respectively. The anti-gout and anti-diabetic activities of the essential oil from the P. lolot species are reported for the first time. Furthermore, molecular docking simulation was consistent to in vitro experiments. ConclusionThe present study provides initial evidence that the essential oil of P. lolot may be a potential natural source to develop new diabetes preparations.

Synthesis, enzyme inhibition and molecular docking studies of pyrazolo[1,5-a][1,3,5] triazine derivatives as potential antioxidant agents

We developed and produced a series of pyrazolo[1,5-a][1,3,5]triazine derivatives (5a-l) in three stages using condensation, intramolecular ring annulation, and acylation processes under moderate conditions. Various spectroscopic techniques and elemental analyses were used to characterize all newly synthesized molecules. By using FRAP and DPPH radical scavenging assays, the antioxidant activity of these compounds was assessed. These conjugates were shown to have moderate to substantial antioxidant activity in both assays. In DPPH and FRAP experiments, compounds 5c, 5d, 5f, and 5 g had the highest levels of antioxidants, with IC50 values of 80.33–99.04 μM and 85.69–102.81 μM, respectively. The SAR study's findings indicate that compounds with electron-donating groups (5b-g) are more potent than those with electron-withdrawing groups (5h-l) and unsubstituted compound (5a). Additionally, the lipoxygenase (LOX) and xanthine oxidase (XO) enzymes were used to assess the potent compounds (5b-g) for their ability to suppress enzyme activity. With an IC50 value of 16.85–49.02 μM and 23.01–57.38 μM, respectively, these compounds significantly inhibited the activity of the LOX and XO enzymes. Particularly, a number of the designed compounds bearing hydroxyl substituted on phenyl ring linked to pyrazolo[1,5-a][1,3,5]triazine system showed excellent not only in antioxidant activity but also in LOX and XO enzyme inhibition. Among these compound 5f was proved to be the top one with an antioxidant and enzyme inhibition ability that was even comparable to that of the standards used. Finally, molecular docking studies of the most effective compounds have been carried out, and the results have shown that the docking scores obtained for compounds 5c, 5f, and 5 g have a significant correlation with the values of antioxidant and enzyme inhibition activity that were found through experimentation.

Potential of flavonol and sulfur compounds from Allium leaves as an antioxidant and xanthine oxidase inhibition in silico study

Antioxidant is the important agent to inhibit free radical reaction. One of the enzymes that trigger the formation of superoxide anion radicals is xanthine oxidase enzyme (XO). Excessive total of free radicals formed by the XO enzyme can cause oxidative stress which would influence the human body health. It is needed natural antioxidant agent that is safe for consumption. In this study focus on the prediction of antioxidant activity through ligand-protein interaction by molecular docking with test ligands which were compounds isolated from Allium sativum (garlic) and Allium cepa (onion) leaves. This study uses method by in silico (molecular docking) in prediction of antioxidant activity. The result of molecular docking presents that compound 2 has the best inhibition to protein XO activity with resulting the lowest binding energy -8.64 kcal/mol, ΔG of -9.75 kcal/mol and Ki of 0.70 μM when compared with allopurinol as a positive control. Based on in silico, compound that results the lowest binding energy means having the good affinity and stable conformation.

Phytochemical Screening And Test For Reducing Uric Acid Levels In Male Rats After Administration Of Ethanol Extract Of The Herb Binara (Artemisia vulgaris L.)

Hyperuricemia is a metabolic disease generally characterized by high uric acid levels in the blood. The general treatment strategy for hyperuricemia is to decrease uric acid production using xanthine oxidation reductase inhibitors such as allopurinol and uricosuric agents. However, the drugs showed side effects, including skin rashes, diarrhoea and liver damage. To overcome the side effects of synthetic drugs, alternatives are used, namely by researching to find plants that have activity in reducing uric acid levels. The activity of reducing uric acid levels in plants is likely due to the presence of flavonoid compounds as antioxidants. Flavonoids active in reducing uric acid levels are kaempferol through xanthine oxidase inhibitors. Quercetin also has the potential to reduce uric acid levels through inhibition of the xanthine oxidase enzyme. Binara plant (Artemisia vulgaris L.) has flavonoids, tannins, alkaloids, glycosides and saponins which have potential as antioxidants and analgesics, anti-inflammatory, immunomodulating, and hepatoprotective, through secondary metabolites of flavonoids, terpenes, and phenolic acids. The Karo people have traditionally used Binara leaves to treat wounds, diarrhoea and heartburn by chewing some of the leaves and then placing them on the wounds outside the body, such as cuts and for diarrhoea and stomach ulcers and placing them around the sick stomach. This study was conducted to know the anti-hyperuricemia effect of the Ethanol Extract of Herba Binara (Artemisia vulgaris L.) on gout rats; phytochemical screening was carried out first to determine the content of Herba Binara (Artemisia vulgaris L.) compounds. The results showed that Herb Binara fulfilled the simplicia characterization requirements and contained secondary metabolites such as alkaloids, flavonoids, tannins, glycosides, saponins and steroids. Herb Binara Ethanol Extract has been shown to reduce uric acid levels in hyperuricemia rats, with the best concentrations being 400 and 800 mg/kg body weight. This was based on significantly different results p>0.05 compared to the positive control group.

In Vitro and in Silico Study on the Interaction between Apigenin, Kaempferol and 4-Hydroxybenzoic Acid in Xanthine Oxidase Inhibition

Xanthine oxidase (XO) is a biological enzyme that takes part in purine catabolism. It catalyses the conversion of hypoxanthine to xanthine and eventually xanthine to uric acid. The catabolism reaction increases the level of uric acid and subsequently leads to hyperuricemia. Allopurinol is a XO inhibitor that is used clinically to prevent purine catabolism. Although it is an effective XO inhibitor, it causes some side effects. Therefore, a more effective inhibitor with fewer side effects is in an urgent need. Phenolic compounds have been identified as effective XO inhibitors in many studies. In vitro and in silico study were conducted to investigate the interaction between apigenin, kaempferol and 4-hydroxybenzoic acid in XO inhibition. Apigenin was found to be the most effective XO inhibitor among the compounds tested with the best docking score of -8.2 kcal/mol as demonstrated in the molecular docking simulation which indicated its favourable interaction with XO enzyme. Additive interactions between compounds namely apigenin-kaempferol, apigenin-4-hydroxybenzoic acid and 4-hydroxybenzoic acid-kaempferol were demonstrated in both in vitro and in silico studies. The results showed that 4-hydroxybenzoic acid- apigenin (-7.4 kcal/mol) was the most stable ligands combination docked to XO. The multiple ligands docking simulation showed independent ligands bound to the XO active site at non-interfering regional location. In conclusion, the combination of these three compounds can be explored further for their additive interaction in XO inhibition, which could be beneficial in terms of the enhanced effectiveness and lower side effects when each is used at lower dose to give the same effect.

Evaluation of Antioxidant Activities from a Sustainable Source of Okara Protein Hydrolysate Using Enzymatic Reaction

Okara is a solid byproduct created during the processing of soy milk. The production of protein hydrolysates utilizing enzymatic tests such as papain can result in the production of bioactive peptides (BPs), which are amino acid sequences that can also be produced from the okara protein by hydrolysis. The objective of this study was to investigate the antioxidant activities of okara hydrolysates using papain, based on the in silico and in vitro assays using the papain enzyme. We found that using the in silico assessment, the antioxidant peptides can be found from the precursor (glycinin and conglycinin) in okara. When used as a protease, papain provides the maximum degree of hydrolysis for antioxidative peptides. The highest-peptide-rank peptide sequence was predicted using peptide ranks such as proline–histidine–phenylalanine (PHF), alanine–aspartic acid–phenylalanine (ADF), tyrosine–tyrosine–leucine (YYL), proline–histidine–histidine (PHH), isoleucine–arginine (IR), and serine–valine–leucine (SVL). Molecular docking studies revealed that all peptides generated from the parent protein impeded substrate access to the active site of xanthine oxidase (XO). They have antioxidative properties and are employed in the in silico approach to the XO enzyme. We also use papain to evaluate the antioxidant activity by using in vitro tests for protein hydrolysate following proteolysis. The antioxidant properties of okara protein hydrolysates have been shown in vitro, utilizing DPPH and FRAP experiments. This study suggests that okara hydrolysates generated by papain can be employed as natural antioxidants in food and for further applications, such as active ingredients for antioxidants in packaging.

Synthesis and docking studies of pyrazole-benzamide-benzothiazole conjugates as xanthine oxidase inhibitor candidates

A series of benzothiazole bearing pyrazole derivatives (6a-j) were synthesized via mechanochemical synthesis through hand grinding using pestle and mortar, and their xanthine oxidase inhibition efficiency and antioxidant properties were evaluated. The 1H NMR, 13C NMR, FT-IR, and mass spectroscopy techniques were employed for the characterization of the synthesized molecules. Initially, the xanthine oxidase (XO) enzyme inhibitory activity for all the compounds (6a-j) was performed using standard reference. Further, for the potent compound (6h) with methyl sulphonyl substitution in the benzothiazole ring the kinetic analysis of XO was carried out. Later, anti-oxidant assays like DPPH, ABTS, and superoxide radical scavenging assays for title compounds were conducted. Also in these assays, the compound (6h) was found to exhibit good antioxidant activity, and the inhibitory constant of XO was found to be 1.78 µg. Furthermore, the docking and dynamic studies were carried out, and the compound (6h) was found to show the lowest binding energy. Also, the analysis of RMSD, RMSF, Rg, SASA, and the number of hydrogen bonds of the compound (6h) was conducted and the binding free energy of the compound (6h) was calculated.

Nanomaterial-Doped Xerogels for Biosensing Measurements of Xanthine in Clinical and Industrial Applications.

First-generation amperometric xanthine (XAN) biosensors, assembled via layer-by-layer methodology and featuring xerogels doped with gold nanoparticles (Au-NPs), were the focus of this study and involved both fundamental exploration of the materials as well as demonstrated usage of the biosensor in both clinical (disease diagnosis) and industrial (meat freshness) applications. Voltammetry and amperometry were used to characterize and optimize the functional layers of the biosensor design including a xerogel with and without embedded xanthine oxidase enzyme (XOx) and an outer, semi-permeable blended polyurethane (PU) layer. Specifically, the porosity/hydrophobicity of xerogels formed from silane precursors and different compositions of PU were examined for their impact on the XAN biosensing mechanism. Doping the xerogel layer with different alkanethiol protected Au-NPs was demonstrated as an effective means for enhancing biosensor performance including improved sensitivity, linear range, and response time, as well as stabilizing XAN sensitivity and discrimination against common interferent species (selectivity) over time-all attributes matching or exceeding most other reported XAN sensors. Part of the study focuses on deconvoluting the amperometric signal generated by the biosensor and determining the contribution from all of the possible electroactive species involved in natural purine metabolism (e.g., uric acid, hypoxanthine) as an important part of designing XAN sensors (schemes amenable to miniaturization, portability, or low production cost). Effective XAN sensors remain relevant as potential tools for both early diagnosis of diseases as well as for industrial food monitoring.

Molybdoenzymes isolated from S. glanis liver can produce nitric oxide from nitrates and nitrites

Nitric oxide (NO) plays numerous essential physiological functions in terrestrial animals. In mammals, NO production from l-arginine is catalysed by the enzyme NO synthase (NOS). In recent years, data have begun to emerge on NOS expression and the physiological significance of NO in ectothermic vertebrates such as fish. However, there are relatively fewer data compared to the mammalian system. Although it is already well known that animal molybdoenzymes can convert nitrate and nitrite into NO, there is almost no information on the content and properties of molybdoenzymes in fish organs in the scientific literature. In this regard, the objectives of the present work were to detect the activity of classical molybdoenzymes xanthine oxidase (XO) and aldehyde oxidase (AO) in the liver and to study their possible activity to reduce nitrate and nitrite to nitrogen monoxide. In this work, the intrinsic activity of XO and AO was examined by using their substrates. At the same time, their nitrate (NR) – and nitrite reductase (NiR) activity were determined. It was determined that XO and AO in the fish liver are mainly represented by the molybdenum-free forms. The presence of an additional source of molybdenum can activate both the intrinsic and the NR and NiR activities. The NiR activity of XO and AO was higher than their NR activity. The data shows that treatment at a concentration of sodium molybdate and glutathione of 1.0 mM increases all activities of XO and AO. The optimal conditions for maximum activation of exogenous molybdate for XO and AO were reached by heating at 70 °C for 5 minutes. The activity of XO increased almost 4.7 times, and the activity of AO 7.7 times compared with its intrinsic activity without heat treatment. NO is formed from nitrite by the enzymes XO and AO much more than from nitrate.

Simple assay for quantifying xanthine oxidase activity

This paper reports a sensitive method for assaying xanthine oxidase (XO) enzyme activity. XO produces hydrogen peroxide (H2O2) and superoxide anion radicals (O2•−), promoting the development of oxidative stress-related diseases, and is inhibited by various plant extracts. XO activity is quantified by incubating enzyme samples with an appropriate xanthine concentration as the substrate. The proposed method requires XO activity to be quantified based on H2O2 generation using a 3,3′,5,5′-tetramethylbenzidine (TMB)-H2O2 system catalyzed by cupric ions. After a 30-min incubation at 37 °C, sufficient cupric ion and TMB amounts are added. The assay produces optical signals that can be visually recognized or detected with a UV–visible spectrometer. A direct correlation was found between XO activity and the absorbance at 450 nm of the resulting di-imine (dication) yellow product. The proposed method uses sodium azide to prevent catalase enzyme interference. The new assay's function was confirmed using the TMB-XO assay and a Bland–Altman plot. The resulting correlation coefficient was 0.9976. The innovative assay was relatively precise and comparable to the comparison protocols. In conclusion, the presented method is very efficient at measuring XO activity.

Effect of Melinjo Seed Extract on GSH Levels of Hyperuricemic Wistar Rats

Background: Hyperuricemia is a condition where uric acid levels are above normal. The biosynthesis of uric acid by the enzyme xanthine oxidase (XO) produces free radicals that cause oxidative stress. Oxidative stress lowers cellular GSH levels. Gnetum gnemon L. or melinjo seeds contain stilbenoids and flavonoids that can act as natural XO inhibitors. Objective: To study the effect of melinjo seed extract on GSH levels.Methods: This research was a true experimental with pre and post-test controlled group design. Thirty six male wistar rats were randomly divided into 6 groups consisting of a healthy control (KS), negative control (K1), positive control (K2), treatment 1 (P1) extract 250 mg/kgBW, treatment 2 (P2) extract 500 mg/kgBW, treatment 3 (P3) extract 2000 mg/kgBW. Hyperuricemia was induced by the administration of Maggie® block broth and potassium oxonate. Measurement was carried out on the 21st and 35th day of treatment, then analyzed using Paired-Sample T Test, continued with One-Way Anova test and Post Hoc LSD test. Results: Administration of melinjo seed extract at P1, P2, and P3 significantly increased GSH levels (P<0.05) from 1.23±0.10 to 1.55±0.16; 1.22±0.06 to 1.73±0.16; and 1.21±0.08 to 1.88±0.08. There was significant difference between the three doses with a dose of 250 mg/kgBW melinjo seed extract being more effective than allopurinol 90 mg/kgBW. Conclusion: Melinjo seed extract could increase GSH levels with the most effective dose of 250 mg/kgBB.

Explored potential hypoglycemic, hypolipidemic, and anti‐hyperuricemic components from Rheum tanguticum combing affinity ultrafiltration with four enzyme targets

AbstractDue to its variety of biological activities, rhubarb has been widely applied worldwide with a long history. However, the potential bioactive compounds in Rheum tanguticum responsible for hypoglycemic, hypolipidemic, and anti‐hyperuricemic activities as well as their underlying mechanisms remain elusive. In order to explore these specific multifunctional ingredients, the in vitro α‐glucosidase and pancreatic lipase inhibitory assays were first determined, and the results indicated that R. tanguticum possessed remarkable hypoglycemic and hypolipidemic activities. Then, 14, 23, 15, and 10 active compounds in R. tanguticum were fast screened out by employing the bio‐affinity ultrafiltration with LC‐MS (Liquid Chromatograph‐Mass Spectrometer) strategy, which displayed various binding abilities to α‐glucosidase, α‐amylase, lipase, and xanthine oxidase enzymes, respectively. Further verifications of potential bioactive ingredients were implemented by molecule docking and the enzyme inhibitory assays in vitro. At last, the first interaction network between multifunctional components in R. tanguticum and their targets was further constructed facilitating to decipher the underlying mechanisms of action regarding R. tanguticum. The present work suggests that R. tanguticum may be a promising natural therapeutics and have good potential to be developed to prevent and treat diabetes, obesity, and gout in the near future.

Thioether-substituted Benzimidazolium Salts: Synthesis, Characterization, Crystal Structure, and Their Inhibitory Properties Against Acetylcholinesterase and Xanthine Oxidase

The sulfurous compounds are known as organosulfur, which has been associated with numerous biological activities in both natural products and synthetic organic compounds. In this work, we present the synthesis of a series of 4-(methylthio)benzyl substituted benzimidazolium salts. All compounds were characterized using NMR (1H and 13C) and FTIR spectroscopic methods as well as an elemental analysis technique. The molecular and crystal structures of the compound 1a were determined by X-ray crystallography revealing that the compound crystallized in the trigonal space group R-3. Enzyme inhibition studies demonstrated that a new series of sulfurous compounds precursors were highly potent inhibitors for xanthine oxidase (XO) and acetylcholinesterase (AChE) enzyme. The IC50 values were found in the range of 0.548 ± 0.033 to 0.725 ± 0.043 µM for XO promising strategy for the treatment from gout disease, while IC50 values were found in the range 0.813 ± 0.076 to 1.149 ± 0.072 µM toward AChE as the key enzyme promising strategy for the treatment of neurological disorders such as Alzheimer's disease (AD). Furthermore, pharmacodynamics studies prove the binding interaction patterns, structural orientations and drug potential of sulfide derivatives in the binding sites of xanthine oxidase (XO) and acetylcholinesterase (AChE) enzymes. Potential inhibitors (compounds 1d-f) were compared with standard compounds allopurinol (for XO) and donepezil (for AChE). Compared to the positive compound of target XO, the 4-vinylbenzyl group of potential compound 1f and the 4-methylbenzyl group of compound le more effectively formed electrostatic and hydrophobic interactions with the target's interaction site. While donepezil as standard compound interacts only at the peripheral anionic site of AChE, the related compounds interact with both regions (PAS and CAS sites) of the same target. These compounds were placed at the active sites of the respective targets by molecular docking method using AutoDock software. Binding energy, binding modes and interaction types were used to evaluate the series of 4-(methylthio)benzyl substituted benzimidazolium salts's ability to bind to each target. Binding energy lower than zero remarks spontaneous binding, and equal and/or lower than -5 kcal/mol remarks good binding. Besides XO, the related compounds show higher activity against the AChE enzyme. They can also be analyzed as strong candidate compounds in biological studies of related enzymes.

A consensual machine-learning-assisted QSAR model for effective bioactivity prediction of xanthine oxidase inhibitors using molecular fingerprints.

Xanthine oxidase inhibitors (XOIs) have been widely studied due to the promising potential as safe and effective therapeutics in hyperuricemia and gout. Currently, available XOI molecules have been developed from different experiments but they are with the wide structure diversity and significant varying bioactivities. So it is of great practical significance to present a consensual QSAR model for effective bioactivity prediction of XOIs based on a systematic compiling of these XOIs across different experiments. In this work, 249 XOIs belonging to 16 scaffolds were collected and were integrated into a consensual dataset by introducing the concept of IC50 values relative to allopurinol (RIC50). Here, extended connectivity fingerprints (ECFPs) were employed to represent XOI molecules. By performing effective feature selection by machine-learning method, 54 crucial fingerprints were indicated to be valuable for predicting the inhibitory potency (IP) of XOIs. The optimal predictor yields the promising performance by different cross-validation tests. Besides, an external validation of 43 XOIs and a case study on febuxostat also provide satisfactory results, indicating the powerful generalization of our predictor. Here, the predictor was interpreted by shapely additive explanation (SHAP) method which revealed several important substructures by mapping the featured fingerprints to molecular structures. Then, 15 new molecules were designed and predicted by our predictor to show superior IP than febuxostat. Finally, molecular docking simulation was performed to gain a deep insight into molecular binding mode with xanthine oxidase (XO) enzyme, showing that molecules with selenazole moiety, cyano group and isopropyl group tended to yield higher IP. The absorption, distribution, metabolism, excretion and toxicity (ADMET) prediction results further enhanced the potential of these novel XOIs as drug candidates. Overall, this work presents a QSAR model for accurate prediction of IP of XOIs, and is expected to provide new insights for further structure-guided design of novel XOIs.

The Compounds of Tuna-Shredded (<i>Thunnus</i> sp.) Fortified Banana Blossom Extracts’ Antioxidant Activity and Xanthine Oxidase Enzyme Inhibition Capacity: An <i>In Vitro-In Silico</i> Study

Tuna is one of the fish source of nutrition for humans because it contains high-quality protein and omega-3 fatty acids, which are beneficial for health. Tuna can be processed into various products, such as tuna-shredded. But it still has a drawback, i.e., the lower-fiber content. To enrich the fiber of tuna-shredded, fortification with banana blossoms can be developed as functional food such as preventing gout arthritis. The aims of this study were to develop a diversified product of tuna-shredded fortified banana blossoms and to determine the antioxidant activity in vitro and anti-arthritis gout through inhibition of the xanthine oxidase (XO) enzyme in silico. The method used was a simple, completely randomized design. The formulation of tuna-shredded used fortification and active compounds analyzed by LC-HRMS. The antioxidant activity was analyzed by the DPPH. Inhibition of the XO enzyme was analyzed by molecular docking in silico. The results showed that tuna-shredded extract contained 32 compounds, which had total phenolic was 0.00134 mg GAE/g, total flavonoid was 0.0006670 mg QE/g, and IC50 was 4.38 ppm. Ferulic acid had the potential to inhibit the XO enzyme with binding affinity was -9.70 kcal/mol through hydrogen bonds and hydrophobic interactions.

Probing the Interactions of 31 Mycotoxins with Xanthine Oxidase: Alternariol, Alternariol-3-Sulfate, and α-Zearalenol Are Allosteric Inhibitors of the Enzyme.

Mycotoxins are frequent toxic contaminants in foods and beverages, causing a significant health threat. Interactions of mycotoxins with biotransformation enzymes (e.g., cytochrome P450 enzymes, sulfotransferases, and uridine 5'-diphospho-glucuronosyltransferases) may be important due to their possible detoxification or toxic activation during enzymatic processes. Furthermore, mycotoxin-induced enzyme inhibition may affect the biotransformation of other molecules. A recent study described the strong inhibitory effects of alternariol and alternariol-9-methylether on the xanthine oxidase (XO) enzyme. Therefore, we aimed to test the impacts of 31 mycotoxins (including the masked/modified derivatives of alternariol and alternariol-9-methylether) on XO-catalyzed uric acid formation. Besides the in vitro enzyme incubation assays, mycotoxin depletion experiments and modeling studies were performed. Among the mycotoxins tested, alternariol, alternariol-3-sulfate, and α-zearalenol showed moderate inhibitory actions on the enzyme, representing more than tenfold weaker impacts compared with the positive control inhibitor allopurinol. In mycotoxin depletion assays, XO did not affect the concentrations of alternariol, alternariol-3-sulfate, and α-zearalenol in the incubates; thus, these compounds are inhibitors but not substrates of the enzyme. Experimental data and modeling studies suggest the reversible, allosteric inhibition of XO by these three mycotoxins. Our results help the better understanding of the toxicokinetic interactions of mycotoxins.