Xanthine Oxidase Inhibitory Activity Research Articles

Enhanced hypoxanthine utilization for cAMP salvage synthesis efficiently by Arthrobacter sp. CCTCC 2013431 via xanthine oxidase inhibition.

When hypoxanthine was utilized as the activator for the salvage pathway in cAMP synthesis, xanthine oxidase would generate in quantity leading to low hypoxanthine conversion ratios and cell viability. To enhance cAMP salvage synthesis, fermentations with citrate/luteolin and hypoxanthine coupling added were conducted in a 7 L bioreactor and then multiple physiological indicators of fermentation with luteolin addition were assayed. Due to hypoxanthine feeding, cAMP productivity reached 0.066g/(L·h) with 43.5% higher than control, however, cAMP synthesis, cell growth and glucose uptake all ceased at 50h which was shortened by 22h in comparison to control. The addition of citrate resulted in the cessation of fermentation at 61h, on the contrary, owing to luteolin addition, cAMP fermentation performance was enhanced significantly during the whole fermentation period (72h) with higher hypoxanthine conversion ratios and cAMP contents when compared with citrate and only hypoxanthine added batches. Multiple physiological indicators revealed that luteolin inhibited xanthine oxidase activity reducing hypoxanthine decomposition and ROS generation. ATP/AMP, NADH/NAD+ and NADPH/NADP+ were significantly increased especially at the late phase. Moreover, HPRT, PUP expression contents and corresponding gene transcription levels were also elevated. Luteolin could inhibit xanthine oxidase activity and further decrease hypoxanthine decomposition and ROS generation leading to higher hypoxanthine conversion and less cell damage for cAMP salvage synthesis efficiently.

Ilex cornuta leaves extracts ameliorate hyperuricemia by modulating uric acid transporters

Ethnopharmacological relevanceIlex cornuta is a valuable species of the Holly genus (Aquifoliaceae), and mainly distributed in eastern China. It is not only made into tea, namely Kudingcha, but also used as traditional medicine to relieve cough, headache, gout, and nourish liver and kidney. Aim of the studyThe purpose of this study was to explore the exact efficacy of different extracts from Ilex cornuta in the treatment of hyperuricemia in vitro and in vivo, and to explore its pharmacological mechanism, so as to bring new ideas for the development of new drugs for reducing uric acid (UA) and anti-gout. Materials and methodsFive crude extracts from Ilex cornuta leaves were extracted by different methods. Then, the xanthine oxidase inhibitory activity and antioxidant capacity of 5 extracts in vitro were compared to screen the extract with the most UA regulating potential. In vivo experiment, hyperuricemia model of mice was established by intragastric administration of potassium oxonate and feeding high yeast diet. Biochemical indexes such as serum UA level, xanthine oxidase activity, liver and kidney index of mice in each group were detected. The pathological sections of kidney and liver tissues were also observed and compared. The mechanism of Ilex cornuta leaves (western blotting, and RT-qPCR) in the treatment of hyperuricemia was further explored by targeting UA transporters ABCG2, GLUT9, and URAT1. ResultsThe in vitro results of inhibitory activity of xanthine oxidase showed that the crude saponin extract was the best, followed by crude flavonoids extract. Then, the in vivo results reflected that both crude saponins and crude flavonoids extracts could significantly reduce the serum UA level, inhibit the activity of xanthine oxidase in serum and liver, and maintain serum urea nitrogen and creatinine at normal level. Meanwhile, there was no liver and kidney injury in mice. Through the comparison of the mechanism results, it was found that both extracts could up-regulate the expression of ABCG2 protein and mRNA related to UA excretion, and down-regulate the expression of GLUT9 and URAT1 protein and mRNA. ConclusionThe crude flavonoids and saponins of Ilex cornuta leaves not only inhibited XOD activity in vitro, but also significantly controlled XOD activity and reduced UA level in hyperuricemia mice in vivo. One of the potential mechanisms was to regulate UA level in vivo by regulating ABCG2, GLUT9, and URAT1 transporters directly related to UA transport, thus achieving the effect of intervening hyperuricemia. This study provided a preliminary experimental basis for the development of new drugs of Ilex cornuta leaves for treating hyperuricemia.

Inhibitory mechanism of xanthine oxidase by 6-, 8- and 10-gingerol: Enzyme kinetics, multi-spectroscopy and molecular simulations

In this study, the inhibitory activity and mechanism of three gingerols (6-, 8- and 10-gingerol) on xanthine oxidase (XOD), a key enzyme responsible for the formation of uric acid, were evaluated. The three gingerols reversibly inhibited XOD activity in a mixed manner with IC50 values of (13.16 ± 0.41), (10.18 ± 0.22) and (6.88 ± 0.11) μM, respectively. 10-gingerol exhibited stronger inhibitory ability, which might contribute to its superior antioxidant properties, higher binding affinity and more significant conformational changes for XOD compared to other gingerols. Fluorescence quenching and molecular docking results indicated that gingerols acted in the vicinity of the flavin adenine dinucleotide in XOD, interacting with the surrounding key amino acid residues through hydrogen bonding and van der Waals forces, thereby preventing substrate entry and the release of catalytic products. Molecular dynamics simulations showed that the addition of gingerol decreased the stability and increased the structural density of XOD. These findings could provide valuable data for the application of gingerols in new XOD inhibitors and hypouricemic functional foods.

A study on the antioxidant, anti-inflammatory, and xanthine oxidase inhibitory activity of the Artemisia vulgaris L. extract and its fractions

Ethnopharmacological relevanceVietnamese people use mugwort (Artemisia vulgaris L.) to treat arthritis and gout. Our previous research shows that mugwort contains flavonoids, and its extract possesses antibacterial and anti-inflammatory activities. However, no publications have been on the xanthine oxidase inhibitory activity of mugwort and acute anti-inflammatory activity in vivo. Aim of the studyThe study aimed to verify the antioxidant, xanthine oxidase inhibitory, and anti-inflammatory capabilities of mugwort extract in vitro and in vivo, isolate phyto-compounds from potential bioactive fractions, and then evaluate their potential in inhibiting xanthine oxidase. MethodsAccording to established methods, the extract and the active flavonoids were obtained using different chromatographic techniques. DPPH, ABTS, reducing power, and H2O2 elimination were used to evaluate antioxidant activity. The model of LPS-induced RAW264.7 cells was used to measure the inhibition of NO production. The carrageenan-induced paw oedema model was used to assess acute inflammation in mice. In vitro, xanthine oxidase inhibition assay was applied to investigate the effects of extract/compounds on uric acid production. Chemical structures were identified by spectral analysis. ResultsThe assessment of the acute inflammatory model in mice revealed that both the 96% ethanol and the 50% ethanol extracts significantly decreased oedema in the mice's feet following carrageenan-induced inflammation. 96% ethanol extract exhibited a better reduction in oedema at the low dose. The analysis revealed that the ethyl acetate fraction had the highest levels of total polyphenols and flavonoids. Additionally, this fraction demonstrated significant antioxidant activity in various assays, such as DPPH, ABTS, reducing power, and H2O2 removal. Furthermore, it displayed the most potent inhibition of xanthine oxidase, an anti-inflammatory activity. Five phytochemicals were isolated and determined from the active fraction such as luteolin (1), rutin (2), apigenin (3), myricetin (4), and quercetin (5). Except for rutin, the other compounds demonstrated the ability to inhibit effective xanthine oxidase compared to standard (allopurinol). Moreover, quercetin (5) inhibited NO production (IC50 21.87 μM). ConclusionThe results indicate that extracts from A. vulgaris effectively suppressed the activity of xanthine oxidase and exhibited antioxidant and anti-inflammatory properties, potentially leading to a reduction in the production of uric acid in the body and eliminating ROS. The study identified mugwort extract and bioactive compounds derived from Artemisia vulgaris, specifically luteolin, apigenin, and quercetin, as promising xanthine oxidase inhibitors. These findings suggest that further development of these compounds is warranted. At the same time, the above results also strengthen the use of mugwort to treat gout disease in Vietnam.

A Review of Medicinal Plants and Phytochemicals for the Management of Gout.

Gout, characterized by elevated uric acid levels, is a common inflammatory joint disease associated with pain, joint swelling, and bone erosion. Existing treatments for gout often result in undesirable side effects, highlighting the need for new, safe, and cost-effective anti-gout drugs. Natural products, including medicinal plants and phytochemicals, have gained attention as potential sources of anti-gout compounds. In this review, we examined articles from 2000 to 2020 using PubMed and Google Scholar, focusing on the effectiveness of medicinal plants and phyto-chemicals in managing gout. Our findings identified 14 plants and nine phytochemicals with anti-gout properties. Notably, Teucrium polium, Prunus avium, Smilax riparia, Rhus coriaria, Foenic-ulum vulgare, Allium cepa, Camellia japonica, and Helianthus annuus exhibited the highest xa-thine oxidase inhibitory activity, attributed to their unique natural bioactive compounds such as phenolics, tannins, coumarins, terpenoids, and alkaloids. Herbal plants and their phytochemicals have demonstrated promising effects in reducing serum urate and inhibiting xanthine. This review aims to report recent studies on plants/phytochemicals derived from herbs beneficial in gout and their different mechanisms.

Identification of Anastatica hierochuntica L. Methanolic-Leaf-Extract-Derived Metabolites Exhibiting Xanthine Oxidase Inhibitory Activities: In Vitro and In Silico Approaches.

There is a growing interest in the discovery of novel xanthine oxidase inhibitors for gout prevention and treatment with fewer side effects. This study aimed to identify the xanthine oxidase (XO) inhibitory potential and drug-likeness of the metabolites present in the methanolic leaf extract of Anastatica (A.) hierochuntica L. using in vitro and in silico models. The extract-derived metabolites were identified by liquid-chromatography-quadrupole-time-of-flight-mass-spectrometry (LC-QTOF-MS). Molecular docking predicted the XO inhibitory activity of the identified metabolites and validated the best scored in vitro XO inhibitory activities for experimental verification, as well as predictions of their anticancer, pharmacokinetic, and toxic properties; oral bioavailability; and endocrine disruption using SwissADMET, PASS, ProTox-II, and Endocrine Disruptome web servers. A total of 12 metabolites, with a majority of flavonoids, were identified. Rutin, quercetin, and luteolin flavonoids demonstrated the highest ranked docking scores of -12.39, -11.15, and -10.43, respectively, while the half-maximal inhibitory concentration (IC50) values of these metabolites against XO activity were 11.35 µM, 11.1 µM, and 21.58 µM, respectively. In addition, SwissADMET generated data related to the physicochemical properties and drug-likeness of the metabolites. Similarly, the PASS, ProTox-II, and Endocrine Disruptome prediction models stated the safe and potential use of these natural compounds. However, in vivo studies are necessary to support the development of the prominent and promising therapeutic use of A. hierochuntica methanolic-leaf-extract-derived metabolites as XO inhibitors for the prevention and treatment of hyperuricemic and gout patients. Furthermore, the predicted findings of the present study open a new paradigm for these extract-derived metabolites by revealing novel oncogenic targets for the potential treatment of human malignancies.

Identification of aurones and chalcones as the main contributors to xanthine oxidase inhibitory activity of snow chrysanthemum

Snow chrysanthemum, the capitulum of Coreopsis tinctoria Nutt., was found to possess inhibitory activity on xanthine oxidase (XO), one of the key enzymes in the pathogenesis of gout. Assisted by bioactivity-oriented isolation, a total of 16 compounds containing a new compound were obtained from the active fractions of snow chrysanthemum extract, including two aurones (1, 2), four chalcones (3–6), a flavone (7), four flavonols (8-11), a flavanonol (12), three phenylpropanoids (13–15), and a new polyacetylene glycoside (16). All the isolated compounds were assayed for their inhibitory activity on XO, among which eight polyphenols (1–8) exhibited potent or moderate inhibitory activities with IC50 values from 0.65 to 29.11 μM. The structure-activity relationship was interpreted for polyphenols (1-12). Besides, the inhibition properties of compounds 1–4 against XO were comprehensively investigated through enzyme kinetics, fluorescence quenching, and docking simulation. Maritimetin (1) and sulfurein (2) reversibly inhibited XO by mixed type mechanism. Okanin-4′-O-(6″-acetyl)-β-d-glucopyranoside (3) and coreopsin (4) competitively inhibited XO in reversible and irreversible manners, respectively. In addition, fluorescence quenching studies suggested that all four compounds interacted with XO through a static quenching mechanism. Molecular docking inferred that hydrogen bonds and hydrophobic interaction played key roles in the binding process. This study revealed the XO-inhibitory activity of snow chrysanthemum and the contribution of containing aurones and chalcones to XO inhibition, making it a potential functional food ingredient for management of hyperuricemia.

Exploring the mechanism and inhibitory effect of robinin on xanthine oxidase using multi-spectroscopy and molecular dynamics simulation methods

Xanthine oxidase (XOD) is a key enzyme in purine metabolism that is tightly associated with hyperuricemia (HUA). Natural flavonoids can inhibit XOD activity. In this study, the inhibitory activity and mechanism of the novel flavonoid robinin on XOD were analyzed using enzyme inhibition kinetics, multispectral techniques, molecular docking, and molecular dynamics (MD) simulations. Robinin reversibly inhibited the activity of XOD in a mixed competitive manner, with an IC50 value of 31.79 ± 0.15 μg/mL. Moreover, robinin spontaneously binds to a specific site on XOD and effectively quenches its intrinsic fluorescence via a single static quenching mechanism. The combination of XOD and robinin induced secondary structure rearrangement and conformational changes in XOD and prevented the entry of substrates, thus producing a strong inhibitory effect. Molecular docking and MD simulation revealed that robinin mainly binds to XOD through hydrogen bonding and hydrophobic interactions to form more stable complexes with a binding energy of −7.4 kcal/mol. Overall, this study established a theoretical reference for robinin as a promising natural XOD inhibitor for relieving HUA.

Effects of Smilax China L. extracts on Hyperuricemia chicken model via inhibiting xanthine oxidase activity

Hyperuricemia (HUA) is a metabolic disorder caused by excessive production of uric acid (UA) or impaired uric acid metabolism. Smilax China L. has a wide range of pharmacological activities such as immunomodulatory, anti-inflammatory, and antioxidant. Its roots and rhizomes have been widely used for the treatment of HUA. However, its mechanisms for treating HUA and reducing renal impairment have not been fully elucidated. In the present study, we evaluated the effect of Smilax China L. extract (SC) on UA metabolism and further explored its mechanism of action by feeding a high-calcium and high-protein diet to chickens to induce a model of HUA in chickens. SC significantly reduced serum UA levels and improved renal function in hyperuricemic chickens. Meanwhile, SC was able to inhibit the activity of xanthine oxidase (XOD) in vivo and in vitro, reducing the production of uric acid. In addition, SC was able to increase the expression of Breast Cancer Resistance Protein (BCRP) in the kidney and ileum and increase uric acid excretion. Therefore, our results suggest that SC may be a candidate for anti-hyperuricemia.

Identification of Hyperuricemia Alleviating Peptides from Yellow Tuna Thunnus albacares.

The development of food-derived antihyperuricemic substances is important for alleviating hyperuricemia (HUA) and associated inflammation. Here, novel peptides fromThunnus albacares (TAP) with strong antihyperuricemic activity were prepared. TAP was prepared by alkaline protease (molecular weight <1000 Da), with an IC50 value of xanthine oxidase inhibitory activity of 2.498 mg/mL, and 5 mg/mL TAP could reduce uric acid (UA) by 33.62% in human kidney-2 (HK-2) cells (P < 0.01). Mice were fed a high-purine diet and injected with potassium oxonate to induce HUA. Oral administration of TAP (600 mg/kg/d) reduced serum UA significantly by 42.22% and increased urine UA by 79.02% (P < 0.01) via regulating urate transporters GLUT9, organic anion transporter 1, and ATP-binding cassette subfamily G2. Meantime, TAP exhibited hepatoprotective and nephroprotective effects, according to histological analysis. Besides, HUA mice treated with TAP showed anti-inflammatory activity by decreasing the levels of toll-like receptor 4, nuclear factors-κB p65, NLRP3, ASC, and Caspase-1 in the kidneys (P < 0.01). According to serum non-targeted metabolomics, 91 differential metabolites between the MC and TAP groups were identified, and purine metabolism was considered to be the main pathway for TAP alleviating HUA. In a word, TAP exhibited strong antihyperuricemic activity both in vitro and in vivo.

Inhibitory Activity of Quercetin, Rutin, and Hyperoside against Xanthine Oxidase: Kinetics, Fluorescence, and Molecular Docking.

Quercetin (Qc), rutin (Ru), and hyperoside (Hyp) are three common polyphenols widely distributed in the plant kingdom. This study explored the inhibition and mechanisms of Qc, Ru, and Hyp against xanthine oxidase (XOD) by enzyme kinetic analysis, fluorescence analysis, and molecular docking. The inhibitory activities of the three polyphenols on XOD showed the following trend: quercetin > hyperoside > rutin, with IC50 values of 8.327 ± 0.36 µmol/L, 35.215 ± 0.4 µmol/L and 60.811 ± 0.19 µmol/L, respectively. All three polyphenols inhibited xanthine oxidase activity in a mixed-competitive manner. Synchronous fluorescence results demonstrated that three polyphenols binding to XOD were spontaneous and showed static quenching. The binding of the three polyphenols to XOD is mainly driven by hydrogen bonding and van der Waals forces, resulting in the formation of an XOD-XA complex with only one affinity binding site. The binding sites of the three RSFQ phenolic compounds are close to those of tryptophan. Molecular docking showed that all three polyphenols enter the active pocket of XOD and maintain the stability of the complex through hydrogen bonding, hydrophobic interaction, and van der Waals forces. The results provide a theoretical basis for quercetin, rutin, and hyperoside to be used as function factors to prevent hyperuricemia.

Stilbene derivatives from Gnetum montanum Markgr. with their xanthine oxidase inhibition activity

AbstractPhytochemical study on the methanol extract of the trunks of Gnetum montanum Markgr. led to the isolation of one new stilbene derivative, (E)‐2′‐methoxy‐3,5,5′‐trihydroxystilbene (1) and six known compounds, lehmbachol (2), gnetulin (3), trans‐shegansu B (4), cis‐shegansu B (5), (+)‐hannokinol (6), and gnetol (7). Their chemical structures were determined by spectroscopic analyses including HR‐ESI‐MS, 1D and 2D NMR, and circular dichroism methods in comparison with the reported data. In addition, compounds 1–5 showed xanthine oxidase inhibitory activity with IC50 values of 13.6, 35.2, 38.7, 43.4, and 47.7 µm, respectively, compared to the positive control, allopurinol, which showed IC50 value of 2.9 µm.

Effect of Lacticaseibacillus rhamnosus L08 fermentation on xanthine oxidase inhibitory activity and flavour profile of honeysuckle (Lonicera japonica thunb.)

Xanthine oxidase (XOD) catalyses the oxidation of hypoxanthine and xanthine to uric acid, and inhibition of its activity has become the main strategy to reduce uric acid production. Honeysuckle (HON) which is rich in polyphenols potentially has the capacity to inhibit XOD activity. However, it carries the bitter and astringent flavor as well as many traditional Chinese medicines, along with that most of the polyphenols in HON exist in bound form, the exploitation and application of HON in food is limited. In this study, we investigated the effects of Lacticaseibacillus rhamnosus L08 fermentation on the bioactive components, XOD inhibitory activity and flavour characteristics of HON. The results showed that the XOD inhibitory activity was increased by 2.08 times after 96 h of fermentation. It was demonstrated that the increase in the total flavonoid content and total phenol content was the main reason for the enhancement of the fermentation solution's XOD inhibitory activity and antioxidant activity. Moreover, the fermentation also enriched the composition of volatile components of HON and reduced levels of undesirable flavour substances, which made the usage of fermented HON as functional food or in pharmaceutical use feasible and applicable.

A potential therapeutic agent for the treatment of hyperuricemia and gout: 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide

Uric acid, the metabolic product of purines, relies on xanthine oxidase (XOD) for production. XOD is a target for the development of drugs for hyperuricemia (HUA) and gout. Currently, treatment options remain limited for gout patients. 3, 4-Dihydroxy-5-nitrobenzaldehyde (DHNB) is a derivative of the natural product protocatechualdehyde with good biological activity. In this work, we identify a DHNB thiosemicarbazide class of compounds that targets XOD. 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazone can effectively inhibit XOD activity (IC50 value: 0.0437 μM) and exhibits a mixed inhibitory effect. In a mouse model of acute hyperuricemia, a moderate dose (10 mg/kg.w) of 3,4-dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide effectively controlled the serum uric acid content and significantly inhibited serum XOD activity. In addition, 3,4-Dihydroxy-5-nitrobenzaldehyde phenylthiosemicarbazide showed favorable safety profiles, and mice treated with the target compound did not show any symptoms of general toxicity following a single dose of 500 mg/kg. In the allopurinol group, 50 % of the mice died. These results provide a structural framework and mechanism of XOD inhibition that may facilitate the design of hyperuricemia and gout treatments.

Xanthine oxidase inhibitory constituents from the roots of Ampelopsis japonica

Bioassay-guided purification of the xanthine oxidase (XOD) inhibitory extract of the roots of Ampelopsis japonica resulted in the isolation of two new triterpenoids (1-2), designated Ampejaponoside A and B, along with sixteen known compounds (3-18). The structures of Ampejaposide A and B were elucidated by comprehensive analysis of spectroscopic data with the structures of the known compounds 3-18 confirmed by comparison the spectral data with corresponding values reported in literatures. All the isolates were evaluated for their XOD inhibitory activity in vitro. As a result, compounds 2, 8, and 14-16 displayed significant XOD inhibitory effect, particularly 16 being the most potent with an IC50 value of 0.21 μM, superior to positive substance allopurinol (IC50 1.95 μM). Molecular docking uncovered a unique interaction mode of 16 with the active site of XOD. The current study showed that the triterpenoids and polyphenols from A. japonica could serve as new lead compounds with the potential to speed up the development of novel XOD inhibitors with clinical potential to treat hyperuricaemia and gout.

Ellagitannins from pomegranate (Punica granatum L.) flower with xanthine oxidase and α-glucosidase inhibitory activities

In the course of our research on utilizing edible flower resources to promote health, five ellagitannins (1–5) were isolated from pomegranate (Punica granatum L.) flower by bioassay-guided fractionation. Among them, mallotusinin (1) and tercatain (2) were first isolated from pomegranate flower, and punicatannin D (4) was an unprecedented compound. Compounds 1–3 exhibited significant xanthine oxidase (XO) inhibitory activity compared with allopurinol, and a potent inhibition on α-glucosidase that was superior to acarbose was observed for compounds 1–4. The XO inhibitory activity is positively correlated with the amount of galloyl moiety (3 > 2 > 1). Presenting tetrahydroxydibenzofuranoyl substituent or increasing the number of galloyl group enhanced the inhibition capacity of α-glucosidase (1 > 3 > 2). The inhibitory mechanism was further clarified in terms of kinetic studies and molecular docking. This study revealed that the ellagitannins present in pomegranate flower might be promising functional food ingredients with anti-hyperuricemia and anti-hyperglycemia properties.

Xanthine oxidase and nitric oxide inhibitory activities of compounds isolated from Gomphrena celosioides

AbstractIn this study, the investigation of xanthine oxidase and nitric oxide formation inhibitory activities of three compounds isolated from aerial part of Gomphrena celosioides, a folk medicinal plant for treatment of gout disease, is reported. The isolated compounds were determined based on NMR and ESI‐MS spectra, they are umbellatosides B, 20‐hydroxyecdysone, and 20‐hydroxyecdysone‐20,22‐monoacetonide. Biological activity results indicated that three compounds showed great activities, in which, umbellatosides B has good activity with IC50 value of 33.78 ± 0.49 and 19.55 ± 0.61 µm for xanthine oxidase and nitric oxide inhibitory activities, respectively. This is the report on the xanthine oxidase and nitric oxide inhibitory activities of three compounds that were first time isolated from the G. celosioides.

Enzymatic Hydrolysis Optimization of Yak Whey Protein Concentrates and Bioactivity Evaluation of the Ultrafiltered Peptide Fractions.

Yak whey protein concentrates (YWPCs) have good functional properties, but there is still a gap in the study of their peptides. In this study, peptides were obtained by enzymatic hydrolysis, and the bioactivity of each ultrafiltration fraction was evaluated using an optimal process. YWPCs were isolated and purified from yak milk as the raw material. Alkaline protease, trypsin, and papain were used to hydrolyze YWPCs. The protease with the highest degree of hydrolysis (DH) and peptide concentration was selected as the most suitable enzyme. The effects of pH, temperature, time, and the enzyme-to-substrate ratio (E/S) on the DH and peptide concentration were investigated, and response surface methodology was utilized to optimize the hydrolysis process. The hydrolysate was separated using ultrafiltration membranes with molecular weight cut-offs of 10 kDa, 5 kDa, 3 kDa, and 1 kDa. The bioactivity of each ultrafiltration component was analyzed, including the inhibition rates of α-amylase and xanthine oxidase (XOD) activities and the scavenging rates of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radicals. The results indicated that alkaline protease was the best enzyme for hydrolyzing YWPCs. The peptide concentration in the YWPC hydrolysate was the highest (17.21 mg/mL) at a pH of 8 and a concentration of 7500 U/g, after 2.5 h at 62 °C. The enzymatic hydrolysate was ultrafiltered to yield four peptide fractions, of which the <1 kDa peptides exhibited the highest α-amylase inhibitory activity (22.06%), XOD inhibitory activity (17.15%), and ABTS cationic free radical scavenging rate (69.55%). This demonstrates the potential of YWPC hydrolyzed peptides for hypoglycemic, uric acid-lowering, and antioxidant applications, providing a theoretical basis for the high-value utilization of YWPCs.

In vivo and in vitro insights into the anti-hyperuricemic effects of sacha inchi (plukenetia volubilis l.) leaves extract rich in polyphenols

Sacha inchi (SI, Plukenetia volubilis L.) is a South American oleaginous crop with multiple health benefits and has been traditionally used to treat various ailments due to its bioactive ingredients such as polyphenols and flavonoids. In this study, a variety of compounds including three flavonoids (epigallocatechin, luteolin-3′,7-di-O-glucoside and cosmosiin), two polyphenols (gallic acid and 4-hydroxycoumarin) and three organic acids (malic acid, citric acid and 2-isopropylmalic acid) were firstly identified by UHPLC-QQQ-MS. Subsequently, in vitro results show that SI leaf aqueous extract (SILE) exhibit potential to lower uric acid (UA) by affecting mRNA levels of UA synthases (XO and HGPRT) with neglectable impacts on cell viability of liver cells (L02). In vivo experiments further suggest that SILE can effectively reduce the levels of serum UA and renal inflammatory cytokines (Il-1β, Il-6 and Tnf-α), and improve renal function indicators (serum Cr and BUN), thereby repairing kidney injury in both acute and chronic hyperuricemic (HUA) animal models. In addition, SILE also improve UA metabolism by inhibiting UA biosynthesis and reabsorption and promoting UA excretion. 1H NMR-based metabolomics reveals that SILE effectively regulate the levels of glucose, amino acid, purine and pyrimidine that are involved in UA metabolic pathway in kidney of HUA mice. These findings demonstrate that SILE rich in polyphenols and flavonoids has a great potential for HUA treatment by inhibiting xanthine oxidase activity and improving UA metabolism.

Screening and characterization of potential anti-gout components from Polygonum cuspidatum by integration off-line two-dimensional liquid chromatography-mass spectrometry with affinity ultrafiltration and on-line HPLC-ABTS

Polygonum cuspidatum (P. cuspidatum) is a traditional herbal medicine with a long history and proven efficacy in treating gout. However, due to the complexity of composition and extensive content distribution, the substance basis of its anti-gout effectiveness is still unclear. A strategy was proposed via integrating off-line two-dimensional liquid chromatography (2D-LC) and targeted rapid screening technology based on ultrafiltration-liquid chromatography-mass spectrometry (UF-LC/MS) and on-line high-performance liquid chromatography-2, 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (HPLC-ABTS) to accomplish high coverage and high throughput screening of anti-gout components from P. cuspidatum. As a result, twenty components were screened from P. cuspidatum extract with both xanthine oxidase (XOD) inhibitory activity and free radical scavenging activity, then were preliminarily identified by high-resolution electrospray ionization-quadrupole-time-of-flight mass spectrometer (ESI-Q-TOF/MS). The screened results were verified by the in vitro assays. Meanwhile, molecular docking further elucidated that the screened bioactive ingredients had favourable binding capabilities with XOD. The performance of this study can achieve high efficiency and high coverage screening of the anti-gout components from P. cuspidatum, which provides methodology and strategy support for the rapid screening of bioactive ingredients from complex medicinal plants.