Insights into the inhibitory mechanism of purpurogallin on xanthine oxidase by multiple spectroscopic techniques and molecular docking

A Click-generated chalcone allied triazole sensor for Co (II) with INHIBIT logic gate construction and its antioxidant properties

This article presents the synthesis of chalcone allied 1,2,3-triazole via an aldol-click reaction. The newly synthesized compound chalcogenyl based 1,2,3-triazole (7) selectively detects Co (II) ion over other metal cations by UV-visible photophysical study with the limit of detection value of 1.24 × 10-8 M. Job's plot confirms that compound (7) and the Co (II) metal ion have 1:1 binding stoichiometry. The binding mechanism between Co (II) and sensor was confirmed by using 1H NMR spectroscopy, mass spectrometry and DFT studies. The reversible behaviour of 7 towards Co (II) was used to construct a molecular logic gate. The compound (7) demonstrated good antioxidant activity with an IC50 value of 3.04 µM in comparison to 1.31 µM of DPPḢ. Further, to explore the antioxidant effect of ligand 7, the molecular docking analysis was performed with xanthine oxidase protein and the obtained binding energy was -11.08 kcal/mol.

In Silico Prediction of Maize microRNA as a Xanthine Oxidase Inhibitor: A New Approach to Treating Hyperuricemia Patients

INTRODUCTION

Hyperuricemia is characterized by increased uric acid (UA) in the body. The ability to block xanthine oxidase (XO) is a useful way to check how different bioactive molecules affect hyperuricemia. Previous reports showed the significant effect of corn against hyperuricemia disorder with its anti-XO activity. The identification of stable Zea mays miRNA (zma-miR) in humans has opened up a new avenue for speculation about its part in regulating novel human gene targets.

AIMS

The aim of this study was to investigate the prospects of zma-miRs in XO gene regulation, the possible mechanism, and the interaction analysis of the zma-miR-XO mRNA transcript.

METHOD

Significant features of miRNA-mRNA interaction were revealed using two popular miRNA target prediction software-intaRNA (version 3.3.1) and RNA hybrid (version 2.2.1) Results: Only 12 zma-miR-156 variants, out of the 325 zma-miR's sequences reported in the miRNA database, efficiently interact with the 3'UTR of the XO gene. Characteristics of miRNA-mRNA interaction were as follows: the positioning of zma-miR-156 variants shows that they all have the same 11-mer binding sites, guanine (G), and uracil (U) loops at the 13th and 14th positions from the 5' end, and no G: U wobble pairing. These factors are related to the inhibition of functional mRNA expression. Additionally, the zma-miR-156 variants exhibit a single-base variation (SBV), which leads to distinct yet highly effective alterations in their interaction pattern with the XO mRNA transcript and the corresponding free energy values.

CONCLUSION

Therefore, we propose that zma-miR-156 variants may be a promising new bioactive compound against hyperuricemia and related diseases.

Identification and mechanistic study of piceatannol as a natural xanthine oxidase inhibitor

Natural Xanthine oxidase (XOD) inhibitors represent promising therapeutic agents for hyperuricemia (HUA) treatment due to their potent efficacy and favorable safety profiles. This study involved the construction of a comprehensive database of 315 XOD inhibitors and development of 28 machine learning-based QSAR models. The ChemoPy light gradient boosting machine model exhibited the best performance (AUC = 0.9371 and MCC = 0.7423). This model identified three potential XOD inhibitors from the FooDB database: daphnetin, 7-hydroxycoumarin, and piceatannol. Molecular docking and dynamics simulations revealed favorable interactions, with piceatannol showing a remarkable stability through hydrogen bonding and hydrophobic interactions. ADME predictions suggested that all three compounds possess desirable drug-like properties and safety characteristics. Subsequent in vitro enzyme inhibition assays validated computational predictions, with piceatannol exhibiting the strongest inhibitory activity (IC50 = 8.80 ± 0.05 μM). Multispectroscopic analyses revealed that piceatannol-XOD binding was predominantly mediated by hydrogen bonding and van der Waals forces, which induced conformational changes characterized by decreased α-helical content and increased proportions of β-sheets, β-turns, and random coils. This study presents an efficient strategy for the identification of natural XOD inhibitors, elucidates the molecular mechanism of piceatannol-mediated XOD inhibition, and establishes a foundation for its therapeutic application in HUA treatment.

Molecular Structure, Antioxidant Potential, and Pharmacokinetic Properties of Plant Flavonoid Blumeatin and Investigating Its Inhibition Mechanism on Xanthine Oxidase for Hyperuricemia by Molecular Modeling

Hyperuricemia, which usually results in metabolic syndrome symptoms, is increasing rapidly all over the world and becoming a global public health issue. Xanthine oxidase (XO) is regarded as a key drug target for the treatment of this disease. Therefore, finding natural, nontoxic, and highly active XO inhibitors is quite important. To get insights into inhibitory potential toward XO and determine antioxidant action mechanism depending on the molecular structure, plant flavonoid blumeatin was investigated for the first time by Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT), ADME/Tox (absorption, distribution, metabolism, excretion, and toxicity) analysis, and molecular docking study. Theoretical findings indicated that blumeatin has high radical scavenging activity due to its noncoplanarity and over twisted torsion angle (-94.64°) with respect to its flavanone skeleton could explain that there might be a correlation between antioxidant activity and planarity of blumeatin. Based on the ADME/Tox analysis, it is determined that blumeatin has a high absorption profile in the human intestine (81.93%), and this plant flavonoid is not carcinogenic or mutagenic. A molecular docking study showed that Thr1010, Val1011, Phe914, and Ala1078 are the main amino acid residues participating in XO's interaction with blumeatin via hydrogen bonds.

Pathology, target discovery, and the evolution of XO inhibitors from the first discovery to recent advances (2020-2023)

Hyperuricemia, a disease characterized by elevation of serum uric acid level beyond 6 mg/dL. This elevation led to appearance of symptoms from joint pain to gout and from gout to difficulty in mobility of the patient. So, in this review, we have summarized the pathology of hyperuricemia, discovery of target and discovery of first XO inhibitor. At last, this review provides in-sights about the recently discovered as natural XO inhibitors, followed by design, structure activity relationship and biological activity of synthetic compounds as XO inhibitors discovered between 2020 and 2023 years. At last, the pharmacophores generated in this study will guide new researchers to design and modify the structure of novel XO inhibitors.

Study on the interaction mechanism between luteoloside and xanthine oxidase by multi-spectroscopic and molecular docking methods

Gout is an inflammatory joint disease caused by urate crystal deposition, which is associated with hyperuricemia. Gout will take place when the uric acid accumulates. Xanthine oxidase (XO) is a crucial enzyme in the formation of uric acid. Inhibiting XO is one of the means to ameliorate gout. Luteoloside is a kind of natural flavonoid, which has an excellent prospect for relieving gout. But there are few reports on the interaction mechanism between luteoloside and XO currently. In this study, the interaction mechanism between luteoloside and XO was explored using spectroscopy and molecular docking. The fluorescence spectroscopy results indicated that luteoloside could make the intrinsic fluorescence of XO quenched, and the binding constant between luteoloside and XO was (1.85 ± 0.22) × 10³  L mol^-1 at 298 K. The synchronous fluorescence spectroscopy results showed that the absorption peaks of Tyr and Trp shifted blue, and the hydrophobicity of the microenvironment increased. Moreover, CD spectra showed that α-helix of XO decreased, β-sheet and β-turn increased after adding luteoloside. The results of molecular docking analysis showed that XO could combine with luteoloside through hydrogen bonds and hydrophobic force. The results indicated that luteoloside could remarkably interact with XO. Insights into the interaction mechanism provide a necessary basis for the search for low-toxic natural products as targets of XO. HIGHLIGHTS: Luteoloside and xanthine oxidase was a strong binding mode and had only one binding site. Luteoloside could cause α-helix reduced, β-sheet and β-turn increased, and change the secondary structure of XO. The binding between luteoloside and xanthine oxidase was a spontaneous process. The main binding force was hydrophobic force between luteoloside and xanthine oxidase.

Insights into the Inhibitory Mechanism of Viniferifuran on Xanthine Oxidase by Multiple Spectroscopic Techniques and Molecular Docking

Viniferifuran was investigated for its potential to inhibit the activity of xanthine oxidase (XO), a key enzyme catalyzing xanthine to uric acid. An enzyme kinetics analysis showed that viniferifuran possessed a strong inhibition on XO in a typical anti-competitive manner with an IC₅₀ value of 12.32 μM (IC₅₀ for the first-line clinical drug allopurinol: 29.72 μM). FT-IR and CD data analyses showed that viniferifuran could induce a conformational change of XO with a decrease in the α-helix and increases in the β-sheet, β-turn, and random coil structures. A molecular docking analysis revealed that viniferifuran bound to the amino acid residues located within the activity cavity of XO by a strong hydrophobic interaction (for Ser1214, Val1011, Phe914, Phe1009, Leu1014, and Phe649) and hydrogen bonding (for Asn768, Ser876, and Tyr735). These findings suggested that viniferifuran might be a promising XO inhibitor with a favorable mechanism of action.

Epicatechin Gallate as Xanthine Oxidase Inhibitor: Inhibitory Kinetics, Binding Characteristics, Synergistic Inhibition, and Action Mechanism

Epicatechin gallate (ECG) is one of the main components of catechins and has multiple bioactivities. In this work, the inhibitory ability and molecular mechanism of ECG on XO were investigated systematically. ECG was determined as a mixed xanthine oxidase (XO) inhibitor with an IC50 value of 19.33 ± 0.45 μM. The promotion of reduced XO and the inhibition of the formation of uric acid by ECG led to a decrease in O2- radical. The stable ECG-XO complex was formed by hydrogen bonds and van der Waals forces, with the binding constant of the magnitude of 104 L mol-1, and ECG influenced the stability of the polypeptide skeleton and resulted in a more compact conformation of XO. Computational simulations further characterized the binding characteristics and revealed that the inhibitory mechanism of ECG on XO was likely that ECG bound to the vicinity of flavin adenine dinucleotide (FAD) and altered the conformation of XO, hindering the entry of substrate and the diffusion of catalytic products. ECG and allopurinol bound to different active sites of XO and exerted a synergistic inhibitory effect through enhancing their binding stability with XO and changing the target amino acid residues of XO. These findings may provide a theoretical basis for the further application of ECG in the fields of food nutrition and functional foods.

α-Glucosidase inhibitory triterpenoids from Euonymus fortunei

α-Glucosidase plays an important role in catalyzing the hydrolytic cleavage of disaccharides into monosaccharides. In this study, a phytochemical investigation of the potential α-glucosidase inhibitory fraction from the aerial parts of Euonymus fortunei led to the isolation and identification of two new tetracyclic triterpenoids, fortunenones A and B (1-2), together with 11 known triterpenoids (3-13). Fortunenones A and B are rare C₃₂ triterpenoids possessing a 24,24-dimethyl group. The partial isolated compounds were evaluated their effects on α-glucosidase, of which echinochlorin D (5), lupenone (7), wilforlide B (12), and wilforlide A (13) exhibited remarkable inhibitory effects with the half inhibitory concentration ranged from 207.2 × 10^-6 M to 388.3 × 10^-6 M compared with the positive control, acarbose. An enzyme kinetics analysis by Lineweaver-Burk plots revealed that the inhibition types of the four active compounds were all mixed inhibition. Molecular docking further revealed that hydrophobic interactions and hydrogen bonds play an important role in the inhibition of α-glucosidase activity. Our results demonstrate the potential of E. fortunei extract and its constituents to inhibit α-glucosidase.