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Ethnopharmacological Relevance: Moringa oleifera Lam. leaf (MOL), a rich source of protein and phenolics, was traditionally used to treat various diseases including headaches, fevers, sore throat and dyslipidemia. Recently, MOL was reported to possess antioxidant, anti-dyslipidemia and hepato-renal protective activities, indicating that MOL could become a potential agent to improve metabolic disorders associated with hyperuricemia. The antihyperuricemic effect of MOL hydrolysate (MOLH) with high contents of phenolics and peptides remains unknown., Aim of the Study: The aim of this study is to investigate xanthine oxidase (XO) inhibitory activity of MOLH, to clarify phenolic and peptide profiles of MOLH, and to evaluate possible mechanism underlying the antihyperuricemic effect of MOLH., Materials and Methods: MOLH was prepared by enzymatic hydrolysis using commercial trypsin. XO inhibitory activity was determined by XO reaction-UPLC-MS coupling method. The chemical profiles of the phenolic and peptide fractions of MOLH were determined by UPLC-QTOF-MS/MS. The antihyperuricemic effect of MOLH was evaluated in a potassium oxonate-induced hyperuricemic rat model at doses of 200 and 500 mg/kg. Serum uric acid (UA), urea nitrogen, creatinine (CRE), triglyceride (TG), total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol levels, serum XO activity, liver malondialdehyde (MDA) equivalent level, renal tumor necrosis factor-α and interleukin-1β levels, and protein expression of renal urate-anion transporter 1, glucose transporter 9 and ATP-binding cassette transporter G2 were determined., Results: The phenolic and peptide fractions played key roles in inhibiting XO activity and blocking uric acid production. Five flavonoids and sixteen polypeptides were identified in the phenolic and peptide fractions of MOLH, respectively. MOLH (200 and 500 mg/kg) could effectively reduce the serum UA level of hyperuricemic rats (p < 0.001) by regulation of serum XO activity (p < 0.05 at 200 mg/kg, p < 0.01 at 500 mg/kg) and renal urate transporters. Besides, MOLH could improve metabolic disorders associated with hyperuricemia by its multiple actions on liver MDA (p < 0.001), serum CRE (p < 0.05 at 500 mg/kg) and serum TG (p < 0.001)., Conclusion: The results provided scientific evidence that MOLH rich in phenolics and peptides ameliorated hyperuricemia and metabolic disorders. This study validated the potential use of MOLH for regulation of hyperuricemia., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Galangal extract (GE)-based hypouricemic functional food is under-developed due to ambiguous quality control standard that is closely associated with action mechanisms and interaction of key xanthine oxidase (XO) inhibitors (kaempferide and galangin) in GE. In terms of kinetics analysis, fluorescence quenching and molecular docking, kaempferide and galangin showed similar docking posture to xanthine in molybdopterin center, and formed flavonol-XO complexes driven by hydrogen bonding, hydrophobic interaction and van der Waals force, competitively inhibiting XO. Kaempferide, had stronger binding affinity for XO and three more hydrogen bonds with XO than galangin, interacting with critical amino acid residues (Arg880 and Glu802) in catalysis reaction of XO and showing stronger XO inhibitory activity than galangin. The combination of kaempferide and galangin enhanced their binding affinities for XO, showing synergistic inhibition on XO at optimal molar ratio 1:4 that could be quality control standard for GE. This study provided new insights into structure-XO inhibitory activity relationship of methoxylated flavonoids and quality control standard for GE-based hypouricemic functional food., 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 © 2020 Elsevier B.V. All rights reserved.)

Adlay bran free phenolic extract has been previously demonstrated to possess potent xanthine oxidase (XOD) inhibitory activity. The aims of this study were to characterize the free phenolic profile of adlay bran and investigate the structure-activity relationship, underlying mechanism and interaction of phenolic acids as XOD inhibitors. A total of twenty phenolics including ten phenolic acids, two coumarins, two phenolic aldedhyes and six flavonoids were identified in a phenolic compound-guided separation by UPLC-QTOF-MS/MS. Adlay bran free phenolic extract possessed strong XOD inhibitory activity related to hydroxycinnamic acids with methoxyl groups. The hydrogen bonding and hydrophobic interactions were the main forces in the binding of adlay phenolics to XOD. Sinapic acid, identified in adlay bran for the first time, possessed strong XOD inhibitory activity in a mixed non-competitive manner, and synergistic effects with other adlay phenolic acids at low concentrations, and would be a promising agent for preventing and treating hyperuricemia., (Copyright © 2018. Published by Elsevier Ltd.)

This is the first report on the ability of soy sauce to effectively reduce the serum uric acid levels and xanthine oxidase (XOD) activities of hyperuricemic rats. Soy sauce was partitioned sequentially into ethyl acetate and water fractions. The ethyl acetate fraction with strong XOD inhibition effect was purified further. On the basis of xanthine oxidase inhibitory (XOI) activity-guided purification, nine compounds including 3,4-dihydroxy ethyl cinnamate, diisobutyl terephthalate, harman, daidzein, flazin, catechol, thymine, genistein, and uracil were obtained. It was the first time that 3,4-dihydroxy ethyl cinnamate and diisobutyl terephthalate had been identified from soy sauce. Flazin with hydroxymethyl furan ketone group at C-1 and carboxyl at C-3 exhibited the strongest XOI activity (IC50 = 0.51 ± 0.05 mM). According to fluorescence quenching and molecular docking experiments, flazin could enter into the catalytic center of XOD to interact with Lys1045, Gln1194, and Arg912 mainly by hydrophobic forces and hydrogen bonds. Flazin, catechol, and genistein not only were potent XOD inhibitors but also held certain antioxidant activities. According to ADME (absorption, distribution, metabolism, and excretion) simulation in silico, flazin had good oral bioavailability in vivo.

This study aimed to explore the potential of polished adlay, brown adlay, adlay bran, and adlay hull to prevent and treat hyperuricemia. Brown adlay extract effectively decreased the serum uric acid levels of oxonate-induced hyperuricemic rats. Free and bound phenolic extracts from these materials contained significant amounts of phenolics, with free phenolics dominated by chlorogenic acid and p-coumaric acid while bound phenolics dominated by p-coumaric acid and ferulic acid. Free and bound phenolics of adlay bran exhibited significant xanthine oxidase inhibition activities, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, oxygen radical absorbance capacities, and superoxide radical scavenging activities. Adlay bran phenolics could be effective xanthine oxidase inhibitors and radical scavengers. p-Coumaric acid is a xanthine oxidase inhibitor with strong superoxide radical scavenging activity. However, ferulic acid is a xanthine oxidase inhibitor with weak superoxide radical scavenging activity. Chlorogenic acid is a superoxide radical scavenger with weak xanthine oxidase inhibitory activity.

Hyperuricemia is a common metabolic disorder disease in human and is associated with increased xanthine oxidase (XOD) activity. This study was aimed to evaluate the antihyperuricemic activities of an ethanolic and aqueous extract of walnut ( Juglans regia L.) shell in vivo and obtain active compounds with high xanthine oxidase inhibitory (XOI) activities and distinct chemical structures form allopurinol in vitro. Finally, the structure-XOI activity relationship of the active compound was further discussed based on the molecular docking. The in vivo antihyperuricemic study indicated that the walnut shell extract (WSE) could decrease the serum uric acid levels significantly (20-days treatment, P < 0.05; 30-days treatment, P < 0.01). And a new aldehyde XOD inhibitor with high XOI activity was obtained through XOI activity-guided purification in vitro. The studies of structure-XOI activity relationship and molecular docking indicated that the synergy of aldehyde group, double bond and hydroxyl group at C-4 in p-coumaric aldehyde was the critical contributor for its high XOI activity. [ABSTRACT FROM AUTHOR]

The antioxidant activities and xanthine oxidase inhibition effects of walnut fruit, stem and leaf were studied in this work. The total phenolic contents were in a descending sequence: shell extract > leaf extract > stem extract > defatted walnut kernel ( DWK) extract > green husk extract ( GHE). The sequence of total phenolic contents was in agreement with the sequence of antioxidant capacities evaluated by ferric reducing antioxidant power and oxygen radical absorbance capacity ( ORAC) assays except for DWK extract. The walnut shell extract showed the highest phenolic content (14.81 gallic acid equivalent g/100 g dry extract) and the best antioxidant activity (the ORAC value was 3423.44 ± 142.52 μmol Trolox equivalents g−1). All tested samples possessed xanthine oxidase inhibitory ( XOI) effects, the inhibition percentages of which were >50% at 2 mg mL−1 except for stem and DWK extracts. The contents of the major compound (hydrojuglone) in all extracts were in a descending order: GHE > walnut stem extract > walnut shell extract > walnut leaf extract > DWK extract. [ABSTRACT FROM AUTHOR]

In the present study, various lotus leaf extracts were prepared by multiple methods, characterized by 12 alkaloids, 14 flavonoids, and superoxide anion radical scavenging (OS) and xanthine oxidase inhibitory (XOI) activities, and divided into 3/4 groups with different characteristics. Both alkaloids and flavonoids contributed to XOI activity of representative lotus leaf extract. Norcoclaurine, O -nornuciferine, N -nornuciferine, nuciferine, luteolin, diosmetin, quercetin, and quercetin-3- O -glucuronide were defined as quality control standards for lotus leaf extracts with dual OS and XOI activities. Enzymatic hydrolysis coupled with ultrasound-assisted extraction method using 50% (v/v) ethanol was the most favorable approach for preparing food-grade lotus leaf extract with dual functions. Network pharmacology revealed that this extract having abundant alkaloids and flavonoids (especially flavonoid aglycones) could improve hyperuricemia by multiple actions on uric acid synthesis and transport, inflammation response, oxidative stress and lipid metabolism. Our study provided crucial data about clear quality control standards for plant-based functional food with potential hypouricemic effect. [Display omitted] • Antioxidant and XOI activities of various lotus leaf extracts were characterized. • It was the first time that hesperetin had been identified in lotus leaf. • Lotus leaf extracts were classified via chemical compositions and dual functions. • Lotus leaf extract with dual functions had potential hypouricemic effect. • Quality control standards for lotus leaf-based hypouricemic food were confirmed. [ABSTRACT FROM AUTHOR]

• Volatiles and phenolics of 31 batches of C. morifolium ' Boju ' were characterized. • Minority of ' Boju ' had abundant monoterpenoids and flavonoid aglycones. • Xanthine oxidase inhibitory effect-related phenolics and volatiles were screened. • Three flavonoid aglycones were identified as quality control standards of ' Boju '. • Four key monoterpenoids were identified as quality control standards of ' Boju '. This study aimed at obtaining precise quality control standards to efficiently screen Chrysanthemum morifolium Ramat. ' Boju ' with strong xanthine oxidase (XO) inhibitory activity for developing C. morifolium ' Boju ' extract based-hypouricemic functional food. The results indicated significant differences in volatile and phenolic profiles and XO inhibitory (XOI) activities of 31 batches of C. morifolium ' Boju ' collected in herb/tea market. The minority of C. morifolium ' Boju ' having abundant characteristic monoterpenoids and flavonoid aglycones showed strong XOI activities, while the majority of C. morifolium ' Boju ' possessing few corresponding monoterpenoids and flavonoid aglycones exhibited moderate XOI activities. Seven XOI activity-directly related phenolics and ten XOI activity-indirectly related volatiles were identified by UPLC-ESI-QTOF/MS-based and HS-SPME-GC/MS-based spectrum-effect relationships, respectively. Three flavonoids (luteolin, apigenin and acacetin) identified as key XO inhibitors and four monoterpenoids (filifolone, α-terpineol, thymol and piperitenone) closely related to key XO inhibitors were screened for XOI activity-oriented quality control of C. morifolium ' Boju '. [ABSTRACT FROM AUTHOR]