The theoretical investigation of monohydroxy flavone: A combined DFT and molecular docking study

Structure-Activity Relationships and Changes in the Inhibition of Xanthine Oxidase by Polyphenols: A Review

Hyperuricemia (HUA), or elevated uric acid in the blood, has become more prevalent in recent years. Polyphenols, which are known to have good inhibitory activity on xanthine oxidoreductase (XOR), are effective in uric acid reduction. In this review, we address the structure-activity relationship of flavonoids that inhibit XOR activity from two perspectives: the key residues of XOR and the structural properties of flavonoids. Flavonoids' inhibitory effect is enhanced by their hydroxyl, methoxy, and planar structures, whereas glycosylation dramatically reduces their activity. The flavonoid structure-activity relationship informed subsequent discussions of the changes that occur in polyphenols' XOR inhibitory activity during their extraction, processing, gastrointestinal digestion, absorption, and interactions. Furthermore, gastrointestinal digestion and heat treatment during processing can boost the inhibition of XOR. Polyphenols with comparable structures may have a synergistic effect, and their synergy with allopurinol thus provides a promising future research direction.

Identification and molecular docking of xanthine oxidase and α-glucosidase inhibitors in Opuntia ficus-indica fruit

Opuntia ficus-indica fruit (OFI) is rich in bioactive compounds, which can promote human health. In this work, the purified OFI extract was prepared from OFI and its bioactivities were investigated. Xanthine oxidase (XOD) and α-glucosidase (α-Glu) inhibitors of the purified OFI extract were screened and identified by bio-affinity ultrafiltration combined with UPLC-QTRAP-MS/MS technology. The inhibitory effect of these inhibitors on enzymes were verified, and the potential mechanism of action and binding sites of inhibitors with enzymes were revealed based on molecular docking. The results showed that the total phenolic content of the purified OFI extract was 355.03 mg GAE/g DW, which had excellent antioxidant activity. Additionally, the extract had a certain inhibitory effect on XOD (IC50 = 199.00 ± 0.14 µg/mL) and α-Glu (IC50 = 159.67 ± 0.01 µg/mL). Seven XOD inhibitors and eight α-Glu inhibitors were identified. Furthermore, XOD and α-Glu inhibition experiments in vitro confirmed that inhibitors such as chlorogenic acid, taxifolin, and naringenin had significant inhibitory effects on XOD and α-Glu. The molecular docking results indicated that inhibitors could bind to the corresponding enzymes and had strong binding force. These findings demonstrate that OFI contains potential substances for the treatment of hyperuricemia and hyperglycemia.

Computational Chemistry Strategies to Investigate the Antioxidant Activity of Flavonoids-An Overview

Despite several decades of research, the beneficial effect of flavonoids on health is still enigmatic. Here, we focus on the antioxidant effect of flavonoids, which is elementary to their biological activity. A relatively new strategy for obtaining a more accurate understanding of this effect is to leverage computational chemistry. This review systematically presents various computational chemistry indicators employed over the past five years to investigate the antioxidant activity of flavonoids. We categorize these strategies into five aspects: electronic structure analysis, thermodynamic analysis, kinetic analysis, interaction analysis, and bioavailability analysis. The principles, characteristics, and limitations of these methods are discussed, along with current trends.

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.

Quinoa (Chenopodium quinoa Willd) Bran Saponins Alleviate Hyperuricemia and Inhibit Renal Injury by Regulating the PI3K/AKT/NFκB Signaling Pathway and Uric Acid Transport

Triterpenoids derived from natural products can exert antihyperuricemic effects. Here, we investigated the antihyperuricemic activity and mechanism of quinoa bran saponins (QBSs) in hyperuricemic mouse and cell models. The QBS4 fraction, with the highest saponin content, was used. Fourier-transform infrared, high-performance liquid chromatography, and ultrahigh-performance liquid chromatography-mass spectrometry identified 11 individual saponins in QBS4, of which the main components were hederagenin and oleanolic acid. The QBS4 effects on hyperuricemic mice (induced by adenine and potassium oxonate) were then studied. QBS4 reduced the levels of uric acid (UA), serum urea nitrogen, creatinine, and lipids in mice with hyperuricemia (HUA) and decreased renal inflammation and renal damage. Molecular analysis revealed that QBS4 may alleviate HUA by regulating the expression of key genes involved in the transport of UA and by inhibiting the activation of the PI3K/AKT/NFκB inflammatory signaling pathway. In conclusion, QBS4 has promise for using as a natural dietary supplement to treat and prevent HUA.

Lactobacillus fermentum F40-4 ameliorates hyperuricemia by modulating the gut microbiota and alleviating inflammation in mice

Hyperuricemia (HUA) is a systemic disease characterized by a disorder of purine metabolism and an abnormal increase in the serum level of uric acid (UA). Probiotics can exert potential therapeutic benefits against some metabolic diseases by regulating the intestinal microbiota. Lactobacillus fermentum F40-4 with UA-lowering activity of 87.40% was screened using purine as the target in vitro. The UA-lowering activity of L. fermentum F40-4 was further explored in a mouse model of HUA in vivo. L. fermentum F40-4 could downregulate serum levels of UA, blood urea nitrogen, creatinine, and xanthine oxidase by 40.84%, 11.61%, 57.66%, and 41.79%, respectively. L. fermentum F40-4 restored organ damage, and adjusted enzyme activity and transporter expression to promote the metabolic level of UA. In addition, L. fermentum F40-4 could reshape the gut microbiota and suppress inflammation to ameliorate HUA. An increment in intestinal UA excretion was documented. These findings suggest that L. fermentum F40-4 might serve as a potential probiotic for the prevention and treatment of HUA.

Investigation of the binding behavior of bioactive 7-methoxyflavone to human serum albumin by coupling multi-spectroscopic with computational approaches

The natural flavonoids with bioactivity as secondary plant metabolites are mostly found in fruits, vegetables, tea and herbs, the distribution and bioavailability of which in vivo depends on the interaction and successive binding with carrier proteins in the systemic circulation. In this paper, the binding behavior of bioactive 7-methoxyflavone (7-MF) with human serum albumin (HSA) was studied with the aid of the combination of multi-spectroscopic methods, molecular docking and molecular dynamic simulation. The results of multi-spectroscopic experiments revealed that 7-MF interacted with HSA predominantly via fluorescence static quenching and the microenvironment around the fluorophore Trp residues in HSA became more hydrophilicity with the binding of 7-MF. Thermodynamic analysis demonstrated that hydrogen bonds and van der Waals forces played a dominant role in stabilizing the HSA-7-MF complex. Moreover, the docking experiment and molecular dynamic simulation further confirmed that 7-MF could enter the active cavity of HSA and caused more stable conformation and change of secondary structure of HSA through forming hydrogen bond. The exploration of the mechanism of 7-MF binding to HSA lights a new avenue to understand the stability, transport and distribution of 7-MF and 7-MF may hold great potential to be extended as a promising alternative of dietary supplements or pharmaceutical agents.