Xanthine Oxidase Inhibitory Activity Research Articles

Constituents of Vernonia gratiosa Hance and their α‐glucosidase and xanthine oxidase inhibitory activities

AbstractEight compounds, including 11β,13‐dihydrovernolide (1), apigenin (2), kaempferol (3), quercetin 3‐O‐methyl ether (4), quercetin (5), syringaresinol‐β‐ᴅ‐glucoside (6), 3‐hydroxy‐1‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐[4‐(3‐hydroxy‐1‐(E)‐propenyl)‐2,6‐dimethoxyphenoxy]propyl‐β‐ᴅ‐glucopyranoside (7), and 5‐(methoxymethyl)‐1H‐pyrrole‐2‐carbaldehyde (8) were isolated from the aerial part of Vernonia gratiosa. Their chemical structures were identified by NMR experiments along with the comparison of their spectroscopic data with those reported in the literature. In addition, all compounds were evaluated for their inhibitory effects on α‐glucosidase and xanthine oxidase. Among them, only compound 7 showed the significant inhibition of α‐glucosidase with an IC50 value of 47.08 ± 3.98 μg/mL and xanthine oxidase activity with an IC50 value of 26.92 ± 1.04 μg/mL. Compounds 1‐5 were firstly isolated from V. gratiosa, while compounds 6‐8 were reported from the genus for the first time. This is the first study about this species growing in Vietnam.

Characterization of xanthine oxidase inhibitory activities of phenols from pickled radish with molecular simulation

Pickled radish is a general source of natural bioactive compounds that include phenols. Here, we used molecular docking, fluorescence quenching, circular dichroism spectroscopy and molecular dynamics simulations to identify potential inhibitors against xanthine oxidase from a library of pickled radish compounds. The most effective compounds were selected for validation through in vitro experiments including enzyme activity inhibition tests, and cell-based assays. Molecular docking results revealed that 2,6-Dihydroxyacetophenone, 4-Hydroxyphenethyl alcohol, and 4-Hydroxybenzaldehyde exhibited significant effects on xanthine oxidase inhibition. Three phenols have varying degrees of inhibition on xanthine oxidase, which is driven by hydrophobic interactions and hydrogen bonds and affects the secondary structure and hydrophobic homeostasis of xanthine oxidase. The stability of xanthine oxidase inhibition by three phenols was analyzed by molecular dynamics simulation. Finally, cellular experiments confirmed that three phenols reduced uric acid levels by inhibiting the xanthine oxidase enzyme activity of BRL 3A cells.

Synthesis and biological evaluation of thiazolidine-2-thione derivatives as novel xanthine oxidase inhibitors.

Xanthine oxidase (XO) is a key enzyme in the generation and development of hyperuricemia. Thiazolidine-2-thione, a typical heterocyclic compound, have been widely used in the field of drug synthesis. In this study, a series of novel thiazolidine-2-thione derivatives were synthesized as XO inhibitors, and the XO inhibitory potencies of obtained compounds were evaluated by in vitro enzyme catalysis. The result shown that compound 6k behaved the strongest XO inhibitory activity with an IC50 value of 3.56 μmol/L, which was approximately 2.5-fold more potent than allopurinol. The structure-activity relationship revealed that the phenyl-sulfonamide group was indispensable for thiazolidine-2-thione derivatives to produce XO inhibitory activity. The enzyme inhibition kinetics analyses confirmed that compound 6k exerted a mixed-type XO inhibition. Additionally, the molecular docking results suggested that the 4-fluorophenyl-sulfonyl moiety could interact with Gly260 and Ile264 in the innermost part of the active pocket through 2 hydrogen bonds, while the thiazolidinethione moiety could form two hydrogen bonds with Glu263 and Ser347 in hydrophobic pockets. In summary, the results described above suggested that compound 6k could be a valuable lead compound for the treatment of hyperuricemia as a novel XO inhibitor.

Novel peptides with xanthine oxidase inhibitory activity identified from macadamia nuts: integrated in silico and in vitro analysis

Novel peptides with xanthine oxidase inhibitory activity identified from macadamia nuts: integrated in silico and in vitro analysis

A flavonoid-rich fraction of Monolluma quadrangula inhibits xanthine oxidase and ameliorates potassium oxonate-induced hyperuricemia in rats.

Hyperuricemia represents a risk factor for the progression of chronic kidney disease. Oxidative stress and inflammation are implicated in the mechanisms underlying hyperuricemia-mediated kidney injury. Monolluma quadrangula possesses several beneficial effects; however, its effect on hyperuricemia has not been investigated. This study evaluated the renoprotective and xanthine oxidase (XO) inhibitory activity of M. quadrangula in hyperuricemic rats. Phytochemical investigation revealed the presence of six known flavonoid isolated for the first time from this species. The rats received M. quadrangula extract (MQE) and potassium oxonate (PO) for 7days. In vitro assays showed the radical scavenging and XO inhibitory activities of MQE, and in silico molecular docking revealed the inhibitory activity of the isolated flavonoids towards XO. Hyperuricemic rats showed elevated serum uric acid, creatinine, urea, and XO activity, and renal pro-inflammatory cytokines, MDA and NO, and decreased GSH, SOD, and catalase. MQE ameliorated serum uric acid, urea, creatinine, and XO activity, and renal pro-inflammatory cytokines. In addition, MQE attenuated renal oxidative stress, enhanced antioxidants, downregulated URAT-1, and GLUT-9 and upregulated OAT-1 in PO-induced rats. In conclusion, M. quadrangula attenuated hyperuricemia and kidney impairment by suppressing XO activity, oxidative stress and inflammation, and modulating urate transporters.

Synthesis and biological evaluation of geniposide derivatives as inhibitors of hyperuricemia, inflammatory and fibrosis

Hyperuricemia is a metabolic disease caused by abnormal purine metabolism in the body. Long-term high levels of uric acid in the body will lead to gout and kidney disease. Xanthine oxidase (XOD) is a key enzyme in the pathogenesis of hyperuricemia. In this context, a series of geniposide derivatives were designed, synthesized and evaluated as xanthine oxidase inhibitors. Most of these compounds exhibited potent XOD inhibitory activities in vitro, and representatives 6a, 6c, 6g and 6j were found to be the most potent inhibitors against the enzyme with IC50 values of 2.15 ± 1.03, 1.37± 0.26, 4.14± 0.79 and 1.86± 0.13 μM, which were 33.03–158.37 fold more active than geniposide, respectively. Compounds 6a, 6c, 6g and 6j were evaluated in hyperuricemia mice, and the results demonstrated that compound 6c showed the strongest anti-hyperuricemia and renal protective activity in vivo. Subsequently, the molecular mechanism of compound 6c was studied in this investigation. In vitro cell experiments showed that compound 6c inhibited the inflammation of HK-2 cells under high uric acid conditions by inhibiting the expressions of TGF-β, TNF-α and IL-1β, and reduced the cell fibrosis by decreasing the expressions of α-SMA and Collagen I. The results of the mice experiments indicated that compound 6c efficiently decreased the level of serum uric acid (SUA) in hyperuricemia mice by inhibiting the XOD activity. Moreover, compound 6c effectively reduced the urate accumulation in the kidney and simultaneously decreased inflammation by regulating the expression of the TLR4/IκBα/NF-κB signaling pathway. In addition, consistent with cell experiments, compound 6c also reduced renal fibrosis in hyperuricemia mice, which may be due to compound 6c inhibiting the expression of inflammatory factor TGF-β. Furthermore, a molecular docking study was performed to gain insight into the binding mode of compound 6c with XOD. These results suggest that compound 6c has the potential to be developed into a novel medicine to reduce blood uric acid and treat renal diseases caused by hyperuricemia.

Two New Seco-Abietanoids with Xanthine Oxidase Inhibitory Activity from Cryptomeria japonica D. Don

Two New Seco-Abietanoids with Xanthine Oxidase Inhibitory Activity from Cryptomeria japonica D. Don

Discovery of mycotoxin alternariol as a potential lead compound targeting xanthine oxidase

Xanthine oxidase (XO) catalyzes the oxidation of hypoxanthine to xanthine, which is further converted to uric acid. The excessive production or reduced excretion of the purine terminal metabolite may lead to hyperuricemia. In our ongoing search for new xanthine oxidase inhibitors, 14 endophytic fungi were isolated for the first time from a medicinal plant Callicarpa kwangtungensis Chun, and the ethyl acetate extracts of their culture filtrates were screened for XO inhibitory activity. The extract from an endophytic fungus, characterized as Alternaria alternata GDZZ-J6, exhibited the most potent inhibition of XO. Further fractionation of its secondary metabolites led to the isolation of six compounds. Among them, mycotoxin alternariol (AOH), a dibenzo-α-pyrone derivative, had strong inhibitory activity on XO, and the IC50 value was 0.23 ± 0.01 μM. The potency of XO inhibition by AOH was >12-fold higher as compared to allopurinol (2.98 ± 0.07 μM), a XO inhibitor that has been used clinically. The IC50 values of three dibenzo-α-pyrones from gut microbial metabolites of ellagic acid, urolithins A, B, and C, against XO were further compared, and their structure-activity relationships were discussed. Inhibition kinetic analysis by double-reciprocal Lineweaver-Burk plots demonstrated that AOH was an uncompetitive inhibitor. Follow-up docking studies showed that Gln957, Lys1257, and Phe1153 played an important role by forming hydrogen bonds with AOH. Our findings suggest that AOH may be used as a lead compound for further modification to develop future drug for treating hyperuricemia.

A Novel Hyaluronic Acid-Black Rice Anthocyanins Nanocomposite: Preparation, Characterization, and Its Xanthine Oxidase (XO)-Inhibiting Properties.

To promote the normal metabolism of human uric acid, high-performance hyaluronic acid-black rice anthocyanins (HAA) nanocomposite particles were successfully prepared by a simple crosslinking method as a novel xanthine oxidase inhibitor. Its structure and properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), and X-ray diffraction (XRD). SEM and TEM electron microscopy showed an obvious double-layer spherical structure with a particle size of ~298 nm. FT-IR and XRD analysis confirmed that black rice anthocyanins (ATC) had been successfully loaded into the hyaluronic acid (HA) structure. Nanocomposite particles (embedded form) showed higher stability in different environments than free black rice ATC (unembedded form). In addition, the preliminary study showed that the inhibition rate of the nanocomposite particles on Xanthine oxidase (XO) was increased by 40.08%. These results indicate that HAA nanocomposite particles can effectively improve black rice ATC's stability and activity, creating an ideal new material for inhibiting XO activity that has a broad application prospect.

In vitro xanthine oxidase inhibitory properties of Flos Sophorae Immaturus and potential mechanisms

Flos Sophorae Immaturus (FSI) possessed potential xanthine oxidase (XO) inhibitory activity as a uric acid-lowing natural product. The present work identified and quantified the free and bound polyphenols of FSI by UPLC-QTOF-MS. Then determined the primary polyphenols with XO inhibitory effect and clarified their potential mechanisms by omission experiment, interaction assay, inhibition type, and fluorescence measurements. The results revealed that nine polyphenols were detected in the free polyphenol extract and ten polyphenols were detected in the bound polyphenol extract. Meanwhile, seven polyphenols were identified as XO inhibitors, including quercetin, kaempferol, isorhamnetin, rutin, hyperoside, protocatechuic acid, and quercitrin with the IC50 values of 0.03, 0.11, 0.07, 5.62, 11.48, 22.13, and 367.82 mg/mL, but their inhibition stability was lower than 24 h. Although the content of quercetin (18.87 mg/g) was not the highest, it played a crucial role to the XO inhibitory effect of FSI. Furthermore, kaempferol and isorhamnetin alone revealed the sub-additive effect with quercetin, while the combination of other polyphenols with quercetin generated the interference or antagonism effects. Quercetin, isorhamnetin, and kaempferol were mixed-type and competitive inhibitors, which significantly quenched the fluorescence intensity of XO. Moreover, the binding processes of quercetin-XO, kaempferol-XO, and isorhamnetin-XO were spontaneous and endothermic, and the hydrophobic interaction was the key driving force. In general, quercetin, kaempferol, and isorhamnetin in FSI can be used as potential XO inhibitors.

Anti-Hyperuricemic Effect of Ethyl Acetate Sub-Fractions from Chrysanthemum morifolium Ramat. Dried Flowers on Potassium Oxonate-Induced Hyperuricemic Rats

Xanthine oxidase (XO) plays an important role in purine degradation in humans. The study aimed to determine the XO inhibitory potential of Chrysanthemum morifolium dried flower ethyl acetate sub-fractions and its anti-hyperuricemic effect in rat models. Bioassay-guided fractionation based on XO inhibitory assay was employed to obtain bioactive fractions and sub-fractions. In vitro cytotoxicity and cellular antioxidant capacity of the sub-fraction and its mode of XO inhibition were also investigated. The anti-hyperuricemic effect of the bioactive sub-fraction was investigated using rat models via oral consumption, and followed by an XO mRNA gene expression study. The compounds in the bioactive sub-fractions were identified putatively using HPLC-Q-TOF-MS/MS. Ethyl acetate (EtOAc) fraction exhibited the highest XO inhibition among the fractions. It was further fractionated into 15 sub-fractions. F10 exhibited high XO inhibitory activity, cellular pro-proliferative effect, and intracellular antioxidant activity among the sub-fractions tested. This sub-fraction was non-cytotoxic at 0.1–10 µg/mL, and very effective in lowering serum and urine uric acid level in rat models upon oral consumption. A total of 26 known compounds were identified and seven unknown compounds were detected via HPLC-Q-TOF–MS/MS analysis. The possible mechanisms contributing to the anti-hyperuricemic effect were suggested to be the non-competitive inhibition of XO enzyme, XO gene expression down-regulation, and the enhancement of uric acid excretion.

Improving bioactivities of Momordica charantia broth through fermentation using mixed cultures of Lactobacillus plantarum, Gluconacetobacter sp. and Saccharomyces cerevisiae

Momordica charantia [MC] is consumed as a vegetable and traditional medicine due to the presence of various bioactive compounds including charantin and coumarin which have anti-diabetic and anti-gout effects respectively. In this study, we investigated the effect of MC fermentation on its bioactivities. Anaerobic fermentation of Lactobacillus plantarum using MC extract with 10% soymilk at 30 °C increased charantin content to 13.46 ppm. Furthermore, α-amylase inhibition activity was increased to 64.75% and DPPH free radical scavenging ability to 47.14%, a 13.02%, and 11.68% increase, respectively. MC broth fermentation by Gluconacetobacter increased xanthine oxidase inhibition (XOI) activity by 30.77% on the 18th day of fermentation. Co-culture of Gluconacetobacter and S. cerevisiae increased XOI activity by 34.28% on the 12th day of fermentation. When compared to pure cultures, the multi-strain fermentation involving Gluconacetobacter, S. cerevisiae and L. plantarum increased XOI activity by 44.72% on the 6th day of fermentation and reduced fermentation time by 12 days. The results show that L. plantarum has an additive effect on XOI activity, whereas, S. cerevisiae works indirectly by producing alcohol which serves as a nutrient for Gluconacetobacter.

Vanillic Acid as a Promising Xanthine Oxidase Inhibitor: Extraction from Amomum villosum Lour and Biocompatibility Improvement via Extract Nanoemulsion.

Gout is an oxidative stress-related disease. Food-derived vanillic acid, a promising xanthine oxidase inhibitor, could potentially be used as a safe, supportive, and therapeutic product for gout. The extraction of vanillic acid from a classic Chinese herbal plant Amomum villosum with ethanol was investigated in the study. The optimum conditions were determined as extraction time of 74 min, extraction temperature of 48.36 °C, and a solid-to-liquid ratio of 1:35 g·mL−1 using the Box–Behnken design (BBD) of response surface methodology (RSM). The experimental extraction yield of 9.276 mg·g−1 matched with the theoretical value of 9.272 ± 0.011 mg·g−1 predicted by the model. The vanillic acid in Amomum villosum was determined to be 0.5450 mg·g−1 by high-performance liquid chromatography–diode array detection (HPLC–DAD) under the optimum extraction conditions and exhibited xanthine oxidase (XO) inhibitory activity, with the half-maximal inhibitory concentration (IC50) of 1.762 mg·mL−1. The nanoemulsion of Amomum villosum extract consists of 49.97% distilled water, 35.09% Smix (mixture of tween 80 and 95% ethanol with 2:1 ratio), and 14.94% n-octanol, with a particle size of 110.3 ± 1.9 nm. The nanoemulsion of Amomum villosum extract exhibited markable XO inhibitory activity, with an inhibition rate of 58.71%. The result demonstrated the potential benefit of Amomum villosum as an important dietary source of xanthine oxidase inhibitors for gout.

In silico xanthine oxidase inhibitory activities of alkaloids isolated from Alphonsea sp.

Xanthine oxidase is an enzyme responsible for the build-up of excess uric acid that causes gout, one of the most common inflammatory arthritis found in Malaysia. The present study investigate in silico xanthine oxidase inhibitory activities of alkaloids isolated from Alphonsea cylindrica and Alphonsea elliptica. Serial column chromatography led to the isolation of compounds which were characterized as kinabaline, atherospermidine, cyathocaline, and N-methylouregidione on the basis of various spectroscopic techniques. Binding orientation and binding energy of all compounds were predicted via docking studies. Docking simulations revealed that kinabaline has the lowest binding energy at 6.9040 kcal/mol. All compounds revealed at least one hydrogen bond to key amino acids. Docking study showed that atherospermidine and cyathocaline bind to active sites which suggest they are competitive inhibitors while the other two compounds are non-competitive inhibitors. The findings of this study reveal the potential of Alphonsea sp. as remedy for gout.

ANTIOXIDANT AND ANTIGOUT ACTIVITY OF ULTRASONIC EXTRACT OF UNRIPE MUSA BALBISIANA COLLA PULP

Ultrasonic-Assisted Extraction (UAE) technology is an effective method for the extraction of chemical constituents from plant materials. The antioxidant activity found in Musa balbisiana Colla may be related to antigout activity, where there is a role for antioxidants in the inhibition of xanthine oxidase activity. The extraction of secondary metabolites from Musa balbisiana Colla using the UAE method has never been reported; in addition, antioxidant testing using the FRAP method and uric acid test have never been carried out. This research aims to gain ultrasonic extract from the unripe Musa balbisiana Colla pulp using the UAE method and obtain information about secondary metabolites and their bioactivity as antioxidant and antigout agents. Ethanolic extract was obtained by the UAE method, total phenolic content was determined by the Folin–Ciocalteu method, antioxidant activity was measured using DPPH and FRAP method, then the uric acid level was measured using uric acid test kit. The results showed that the antioxidant activity test using the DPPH and FRAP methods gave IC50 values of 411.59 ± 0.1336 mg/L and 98.03 ± 0.2926 mg/L, respectively. The total phenolic content value of 823.95 ± 3.9806 mg GAE/g ultrasonic extract is thought to have a role in high antioxidant activity. Furthermore, ultrasonic extract with a concentration of 50 mg/L has activity in reducing uric acid levels by around 10%. It can be concluded that the ultrasonic extract produced by the UAE has potential as a source of antioxidant and antigout agents.

Phytochemical and Xanthine Oxidase Inhibitory Activity in Nypa fruticans Wurmb. Fruit Extracts

Thai wisdom knows the benefits of mangrove palm fruits to be boiled in water and drink as herbal medicines for healing gout. However, there is no scientific paper to confirm the relief of gout symptoms by mangrove palm, this is the first report. The mangrove palm: exocarp/mesocarp, endocarp, endosperm, and the whole of fruit in the ripe stage were extracted with water and ethanol. The crude extracts were studied for the phytochemical and inhibitory activity of xanthine oxidase, one of the causes of gout. Most of the crude extracts showed similar phytochemicals as, phenolic compounds, flavonoids, terpenoids, and steroids, but there was no alkaloid, anthraquinone, and iridoid glycoside. The endocarp extracted with ethanol showed the highest phenolic content (102.85±5.73 mg GAE/g), flavonoid content (531.02±10.46 mg QUE/g), and strongest antioxidant activity (26.79±0.57 mg VCE/g). The ethanolic and water extract (heating at 60 °C) of endocarp showed the strongly inhibited xanthine oxidase activity with IC50 of 0.029±0.001 mg/mL and 0.14±0.04 mg/mL, respectively. Therefore, this research has already confirmed that the fruit of mangrove palm could inhibit xanthine oxidase enzyme. It would be useful for further development as an herbal medicine or supplementary food for gout likely in the form of hot brewed teas or products that are safe for consumers. Moreover, it also adds value to the peel of the leftovers from consumption.
 HIGHLIGHTS
 
 This is the first report to use Nypa fruticans fruit for healing gout
 The ethanolic and water extract of endocarp gave the strongly inhibition of xanthine oxidase enzyme
 The endocarp of Nypa fruticans fruit can be developed for supplementary food or treatment for gout
 
 GRAPHICAL ABSTRACT

Biological activities and in vitro digestion characteristics of glycosylated α-lactalbumin prepared by microwave heating: Impacts of ultrasonication

The research focuses on application of ultrasonic-assisted glycosylation in food protein modification. Biological activities and in vitro digestion characteristics of the glycosylated α-lactalbumin (UMGLA) and α-lactalbumin (UMLA) prepared by ultrasonic pretreatment and microwave heating at 85 °C for 2 h were investigated mainly through the browning degree, free amino group, reducing sugar and surface hydrophobicity, in vitro digestibility and degree of hydrolysis, total antioxidant capacity, α-glucosidase inhibitory activity, xanthine oxidase inhibitory activity determination methods. The results showed that ultrasonic pretreatment could effectively promote the occurrence of glycosylation reaction, reduce in vitro digestibility and degree of hydrolysis of glycosylated α-lactalbumin and enhance biological activities of glycosylated α-lactalbumin digestive products. Furthermore, after 60 min of ultrasound treatment, the total antioxidant capacity and α-glucosidase inhibitory activity of glycosylated α-lactalbumin digested products were increased by 76.52 ± 0.02% and 12.42 ± 0.04%, respectively, compared with α-lactalbumin without ultrasound treatment. In conclusion, ultrasonic-assisted glycosylation had positive effects on improving the biological activities of in vitro digestion product of α-lactalbumin. It provides a theoretical basis for ultrasonic-assisted glycosylation in the modification field of food proteins.

Anti-gout potential of selected edible flowers

Gout is a form of inflammatory arthritis triggered by the interaction between monosodium urate crystals and tissues during the purine metabolism by xanthine oxidase. This study aimed to determine the xanthine oxidase inhibitory activity, total phenolic content, total flavonoid content and total anthocyanin content of 10 selected edible flowers, namely Rosa sp., Malus sp., Lavandula sp., Lilium sp., Hibiscus sabdariffa L., Chrysanthemum sp., Matricaria sp., Gomphrena sp., Myosotis sp. and Jasminum sp. extracted using hot water infusion method. Phytochemical contents and the anti-gout activity of the flower extracts using the xanthine oxidase inhibition assay were determined spectrophotometrically. The results revealed that three aqueous flower extracts (Rosa sp., Hibiscus sabdariffa L. and Malus sp.) exhibited potent xanthine oxidase inhibitory activity (IC50 values, 0.10±0.15 µg/mL, 0.12±0.11 µg/mL and 2.59±3.8 µg/mL, respectively), which were comparable to the positive control, allopurinol (IC50 value, 4.9±0.00 µg/mL). The highest phenolic and flavonoid contents were found in Lavandula sp. (4.39±0.13 mg GAE/g and 63.46±1.07 mg RE/g) while Rosa sp. showed the highest content of anthocyanin (70.14±4.82 mg c-3-gE/g). Positive correlations were observed between the phytochemicals and xanthine oxidase inhibitory activity of the flower extracts. Hence, this study suggests that Rosa sp., Hibiscus sabdariffa L. and Malus sp. possess anti-gout potential, which is associated with the presence of possible anti-gout phytochemicals. The isolation of the bioactive compounds that exhibit significant anti-gout activity among the selected flowers is recommended for future research.

Discovery of 4-(phenoxymethyl)-1H-1,2,3-triazole derivatives as novel xanthine oxidase inhibitors

A series of 4-(phenoxymethyl)-1H-1,2,3-triazole derivatives were designed, synthesized, and evaluated for their xanthine oxidase (XO) inhibitory activities. Among these compounds, 9m emerged as the most effective XO inhibitor with an IC50 value of 0.70 μM, which was approximately 14-fold more potent than allopurinol. Additionally, compound 9m displayed favorable drug-like properties with ligand efficiency (LE) and lipophilic ligand efficiency (LLE) values of 0.33 and 3.41, respectively. We further explored the binding mode of 9m in complex with XO by molecular docking and molecular dynamics studies. In vivo hypouricemic studies also suggested that 9m could effectively lower the serum uric acid levels of rat. In summary, compound 9m could be a promising lead for further development of XO inhibitors.

Anti-Gout Effects of the Medicinal Fungus Phellinus igniarius in Hyperuricaemia and Acute Gouty Arthritis Rat Models.

Background: Phellinus igniarius (P. igniarius) is an important medicinal and edible fungus in China and other Southeast Asian countries and has diverse biological activities. This study was performed to comparatively investigate the therapeutic effects of wild and cultivated P. igniarius on hyperuricaemia and gouty arthritis in rat models. Methods: UPLC-ESI-qTOF-MS was used to identify the chemical constituents of polyphenols from wild P. igniarius (WPP) and cultivated P. igniarius (CPP). Furthermore, WPP and CPP were evaluated in an improved hyperuricaemia rat model induced by yeast extract, adenine and potassium oxonate, which was used to examine xanthine oxidase (XO) activity inhibition and anti-hyperuricemia activity. WPP and CPP therapies for acute gouty arthritis were also investigated in a monosodium urate (MSU)-induced ankle swelling model. UHPLC-QE-MS was used to explore the underlying metabolic mechanisms of P. igniarius in the treatment of gout. Results: The main active components of WPP and CPP included protocatechuic aldehyde, hispidin, davallialactone, phelligridimer A, hypholomine B and inoscavin A as identified by UPLC-ESI-qTOF-MS. Wild P. igniarius and cultivated P. igniarius showed similar activities in reducing uric acid levels through inhibiting XO activity and down-regulating the levels of UA, Cr and UN, and they had anti-inflammatory activities through down-regulating the secretions of ICAM-1, IL-1β and IL-6 in the hyperuricaemia rat model. The pathological progression of kidney damage was also reversed. The polyphenols from wild and cultivated P. igniarius also showed significant anti-inflammatory activity by suppressing the expression of ICAM-1, IL-1β and IL-6 and by reducing the ankle joint swelling degree in an MSU-induced acute gouty arthritis rat model. The results of metabolic pathway enrichment indicated that the anti-hyperuricemia effect of WPP was mainly related to the metabolic pathways of valine, leucine and isoleucine biosynthesis and histidine metabolism. Additionally, the anti-hyperuricemia effect of CPP was mainly related to nicotinate and nicotinamide metabolism and beta-alanine metabolism. Conclusions: Wild P. igniarius and cultivated P. igniarius both significantly affected the treatment of hyperuricaemia and acute gouty arthritis models in vivo and therefore may be used as potential active agents for the treatment of hyperuricaemia and acute gouty arthritis.