Lactoperoxidase and Xanthine Oxidase Inhibition Potential of Endemic Taraxacum mirabile Wagenitz Plant Extract: A Comparative Analysis In Vitro

Xanthine oxidase-lactoperoxidase system and innate immunity: Biochemical actions and physiological roles

The fruits of andaliman (Zanthoxylum acanthopodium DC.) are well known in North Sumatera and commonly used as seasoning for Batak traditional cuisine. Aims of this study were to determine the scavenging activity of free radicals and xanthine oxidase inhibitory activity from the andaliman fruit extracts after macerated garually in petroleum ether, dichloromethane, ethyl acetate, n-butanol, and methanol. Activity assay were evaluated in vitro by using DPPH and enzyme xanthine oxidase. The result showed that n-butanol extract has medium antioxidant activity with IC 50 values of 53.51 I¼g/mL and methanol extract has strong antioxidant activity with IC 50 values of 26.39 mg/mL. Xanthine oxidase inhibitory activity of the extract given by n-butanol and methanol are very strong with IC 50 values of 3.69 I¼g/mL and 4.03 I¼g/mL. Keywords : antioxidant, free radical, xanthine oxidase, Zanthoxylum acanthopodium DC. Â

Euphorbia heterophylla Linn (Euphorbiaceae) is a medicinal plant used by traditional herbal practitioners in Nigeria and some parts of West Africa for the treatment of constipation, bacterial and inflammatory disease conditions (arthritis and rheumatism). Powdered plant material was subjected to phytochemical screening using standard experimental procedures. The crude powdered sample of Euphorbia heterophylla leaves was extracted with n-hexane, chloroform, ethylacetate and methanol. The precipitates from the fractions were subjected to chromatographic and re-crystallization procedures. The structures of isolated compounds were characterized and elucidated with chemical and spectroscopic techniques such as IR, NMR and MS experiments. The in vitro biological activity of the isolated and characterized compounds were evaluated by superoxide scavenging assay using xanthine – xanthine oxidase system to generate superoxides. The result of the study showed that the crude plant material contained some secondary metabolites such as saponins, flavonoids and tannins. The phytochemical investigation led to the isolation of four known compounds stigmasterol, β-stigmasterol glucoside, benzoic acid and 4 – hydroxyl benzoic acid. The four compounds exhibited good activity against the xanthine oxidase enzymes while the 4-hydroxybenzoic acid showed a marked activity. The isolation of the compounds from the leaves of E. heterophylla, which inhibited the xanthine oxidase enzyme, has justified the claims for which the plant is known and used. Key words: Euphorbia heterophylla, euphorbiaceae, xanthine oxidase activity, superoxide scavenging, steriods.

Although there have been many studies on this topic, the molecular mechanism of the toxic effects of hyperammonemia on cells has not yet been fully explained. Recent studies have held oxidative stress mechanisms responsible for hyperammonemia-induced cell damage. Kidney functions are affected in diseases associated with an increase in ammonia in the blood. Our study tries to determine whether oxidative stress mechanisms are responsible for kidney damage in chronic hyperammonemia. We also investigated whether kidney damage is dependent on possible reactive oxygen products associated with the xanthine oxidase (XO) enzyme and whether the possible association can be inhibited with allopurinol, an XO enzyme inhibitor. The study took into consideration the enzyme activities of XO, xanthine dehydrogenase (XDH), superoxide dismutase (SOD), glutathione-S-transferase (GST), as well as protein thiol (P–SH) and malondialdehyde (MDA) levels. The data found demonstrated that chronic hyperammonemia had oxidative stress effects on the kidney, and that kidney XO and XDH activity changed. However, it was not possible to inhibit this oxidative stress in the kidney using allopurinol. Thus, we could not conclude that oxidative stress is an XO‐dependent mechanism. The outcomes of the study suggested that this oxidative situation arising in hyperammonemia occurred through a mechanism other than the XO enzyme.

To assess the activity of xanthine oxidase (XO) enzyme in keratoconic corneal epithelium and to evaluate its relationship with the keratoconus (KC) severity. This prospective and randomized study included 66 eyes of 54 KC patients who received corneal collagen cross-linking treatment and 43 eyes of 32 patients who underwent photorefractive keratectomy due to their refractive error. During surgical procedures, the corneal epithelium was mechanically scraped and gathered to analyze the XO enzyme activity spectrophotometrically. The KC group was subdivided into three groups (stages 1, 2, and 3) according to the Amsler-Krumeich classification. The results were compared between the KC and the control group and in between KC subgroups. No significant differences in age and gender were found between the KC and control groups (p = 0.064 and p = 0.296, respectively). The mean XO activity levels of the KC and control groups were 173.57 ± 87.61 and 223.70 ± 99.52mIU/mg, respectively (p < 0.001). In KC group, 33 eyes were at stage 1, 19 were at stage 2, and 14 were at stage 3. No significant difference was observed between KC subgroups regarding XO activity levels (p = 0.681). In this study, our findings revealed that ultraviolet-related pro-oxidant XO enzyme may have a role in the etiopathogenesis of KC. Further studies are needed to support our result. When we started this study in 2018, we did not have a "Clinical Trials Registration." However, we have ethics committee approval (date: 21. 02. 2018/No: 22).

Luteolin, naringenin, myricetin, and ampelopsin are abundant flavonoids in nature, and several dietary supplements also contain them at very high doses. After the peroral intake, flavonoids go through extensive presystemic biotransformation; therefore, typically their sulfate/glucuronic acid conjugates reach high concentrations in the circulation. Xanthine oxidase (XO) enzyme is involved in uric acid production, and it also takes part in the elimination of certain drugs (e.g., 6-mercaptopurine). The inhibitory effects of flavonoid aglycones on XO have been widely studied; however, only limited data are available regarding their sulfate and glucuronic acid conjugates. In this study, we examined the impacts of luteolin, naringenin, myricetin, ampelopsin, and their sulfate/glucuronide derivatives on XO-catalyzed xanthine and 6-mercaptopurine oxidations employing in vitro enzyme incubation assays and molecular modeling studies. Our major results/conclusions are the following: (1) Sulfate metabolites were stronger while glucuronic acid derivatives were weaker inhibitors of XO compared to the parent flavonoids. (2) Naringenin, ampelopsin, and their metabolites were weak inhibitors of the enzyme. (3) Luteolin, myricetin, and their sulfates were highly potent inhibitors of XO, and the glucuronides of luteolin showed moderate inhibitory impacts. (4) Conjugated metabolites of luteolin and myricetin can be involved in the inhibitory effects of these flavonoids on XO enzyme.

S-allyl cysteine as potent anti-gout drug: Insight into the xanthine oxidase inhibition and anti-inflammatory activity

Objective: The aim of the present study was to examine the inhibiting effects of quercetin contained in Sonchusarvensis leaf extract on the activity of xanthine oxidase, an essential enzyme for uric acid synthesis.Methods: Activity test was conducted in vitro by measuring the activity of xanthine oxidase using UV spectrophotometry and in silico by determining the interaction of quercetin and allopurinol (as comparation drug) with xanthine oxidase enzyme in terms of hydrogen bonds and binding free energy. Docking simulations were performed by Autodock4.2 package.Results: The active fraction, using the solvent n-hexane, ethyl acetate and water, tested the inhibitory activity of the xanthine oxidase enzyme in vitro obtained respectively IC50 of 263.19, 16.20 and 141.80 μg/ml. Isolates with highest activity identified as quercetin. The xanthine oxidase enzyme inhibitory activity insilico by molecular docking showed quercetin has free energy binding ˗7.71 kcal/mol, more negative than that of allopurinol ˗5.63 kcal/mol.Conclusion: This shows the affinity of quercetin stronger than that of allopurinol; so that it can be predicted that quercetin was more potential to inhibit xanthine oxidase enzyme activity. Thus the extract of the S. arvensis leaves containing the active compound quercetin was a potential use as antihyperuricemia.

Exposure of human keratinocytes to ischemia, hyperglycemia and their combination induces oxidative stress via the enzymes inducible nitric oxide synthase and xanthine oxidase

BackgroundThe disorder of uric acid metabolism is closely associated with gut microbiota and short-chain fatty acids (SCFAs) dysregulation, but the biological mechanism is unclear, limiting the development of uric acid-lowering active polysaccharides. Konjac glucomannan (KGM) could attenuate metabolic disturbance of uric acid and modulate the gut microbiota. However, the relationship between uric acid metabolism and gut microbiota is still unknown.MethodsIn this study, The fecal samples were provided by healthy volunteers and hyperuricemia (HUA) patients. Fecal samples from healthy volunteers was regarded as the NOR group. Similarly, 10% HUA fecal suspension was named as the HUA group. Then, fecal supernatant was inoculated into a growth basal medium containing glucose or KGM, and healthy fecal samples were designated as the NOR-GLU and NOR-KGM groups, while HUA fecal samples were designated as the HUA-GLU and HUA-KGM groups. All samples were cultured in an anaerobic bag system. After fermentation for 24 h, the samples were collected for further analysis of composition of intestinal microbiota, SCFAs concentration and XOD enzyme activity.ResultsThe results showed that KGM could be utilized and degraded by the gut microbiota from HUA subjects, and it could modulate the composition and structure of their HUA gut microbiota to more closely resemble that of a healthy group. In addition, KGM showed a superior modulated effect on HUA gut microbiota by increasing Megasphaera, Faecalibacterium, Lachnoclostridium, Lachnospiraceae, Anaerostipes, and Ruminococcus levels and decreasing Butyricicoccus, Eisenbergiella, and Enterococcus levels. Furthermore, the fermentation solution of KGM showed an inhibitory effect on xanthine oxidase (XOD) enzyme activity, which might be due to metabolites such as SCFAs.ConclusionIn conclusion, the effect of KGM on hyperuricemia subjects was investigated based on the gut microbiota in vitro. In the present study. It was found that KGM could be metabolized into SCFAs by HUA gut microbiota. Furthermore, KGM could modulate the structure of HUA gut microbiota. At the genus level, KGM could decrease the relative abundances of Butyricicoccus, Eisenbergiella, and Enterococcus, while Lachnoclostridium and Lachnospiraceae in HUA gut microbiota were significantly increased by the addition of KGM. The metabolites of gut microbiota, such as SCFAs, might be responsible for the inhibition of XOD activity. Thus, KGM exhibited a superior probiotic function on the HUA gut microbiota, which is expected as a promising candidate for remodeling the HUA gut microbiota.

Xanthine oxidase is an enzyme involved in the catalysis of the oxidation reaction that converts hypoxanthine into xanthine and subsequently into uric acid. Elevated uric acid levels can pose various health risks. Gout treatment can be achieved by inhibiting the activity of the xanthine oxidase enzyme using black garlic. This study aims to identify the chemical compounds in black garlic methanol extract, assess the inhibitory effect of this extract on the xanthine oxidase enzyme using in silico methods, and determine the type of inhibition based on enzyme kinetics. The in silico analysis was conducted to evaluate the binding affinity of flavonoid compounds in black garlic extract with xanthine oxidase. The in vitro analysis tested the inhibition of the xanthine oxidase enzyme by black garlic using the UV-Vis spectrophotometry method at a wavelength of 291.7 nm, based on a decrease in uric acid concentration as an indicator of reduced enzyme activity. The type of inhibition mechanism was determined through enzyme kinetics using the Michaelis-Menten equation, which was transformed into the Lineweaver-Burk equation in a double reciprocal form. Black garlic methanol extract contains 133 chemical compounds, including 22 flavonoid compounds that are thought to inhibit xanthine oxidase. According to in silico studies, quercetin-3-O-malonylglucoside exhibits the lowest binding affinity (-9.2 kcal/mol) with the xanthine oxidase enzyme compared to the xanthine substrate (-5.2 kcal/mol) and allopurinol (-5.3 kcal/mol). Inhibition of the xanthine oxidase enzyme by black garlic demonstrated the highest inhibition of 76.352% at a concentration of 10 ppm of black garlic extract. The inhibition type of the xanthine oxidase enzyme by black garlic methanol extract showed a competitive inhibition mechanism, evidenced by an increase in the KM value from 0.014 to 0.134 without a significant change in the Vmax value. Thus, it can be concluded that black garlic extract has the potential to be a natural inhibitor of the enzyme xanthine oxidase that can be used to treat gout or hyperuricemia.

Objective: This study aimed to examine the in vitro xanthine oxidase inhibitory activity of 12 plants commonly used as gout medicines by the Indonesian people. Methods: The measurement of xanthine oxidase enzyme inhibitory activity was using UV spectrophotometry. The in vitro assessment of xanthine oxidase inhibition activity was tested on extracts from Eleutherine bulbosa (Mill.) Urb. Bulbs, Pandanus amaryllifolius Roxb. leaves, Alyxia reinwardtii Blume stem barks, Ruta angustifolia Pers aerial parts, Dioscorea hispida Dennst tubers, Plantago major L. leaves, Symphytum officinale L. roots, Euphorbia hirta L. aerial parts, Chromolaena odorata L. leaves, Solanum torvum Sw fruits, Peperomia pellucida L. Kunth. aerial parts and Strobilanthes crispa L. Blume leaves. Results: The results of this study showed that all tested plant extracts can inhibit xanthine oxidase activity with IC50 values varying from 27.80 µg/ml to 47.14 µg/ml. The IC50 value of allopurinol, used as positive control, was 1.24 µg/ml. Among all the tested plant extracts, Strobilanthes crispa L. Blume leaves extract has the best inhibitory activity against xanthine oxidase enzyme with IC50 value of 27.80 µg/ml. Conclusion: Strobilanthes crispa L. Blume leaves extract has the best inhibitory activity against xanthine oxidase, so It has the potential to be developed into herbal medicine to treat hyperuricemia. This study provides scientific support for the anti-hyperuricemia activity of these herbs, which are empirically used to treat gout.

Oxovanadium(IV) complexes with tetradentate thiosemicarbazones. Synthesis, characterization, anticancer enzyme inhibition and in vitro cytotoxicity on breast cancer cells

Synthesis, enzyme inhibition and molecular docking studies of pyrazolo[1,5-a][1,3,5] triazine derivatives as potential antioxidant agents

Tuna is one of the fish source of nutrition for humans because it contains high-quality protein and omega-3 fatty acids, which are beneficial for health. Tuna can be processed into various products, such as tuna-shredded. But it still has a drawback, i.e., the lower-fiber content. To enrich the fiber of tuna-shredded, fortification with banana blossoms can be developed as functional food such as preventing gout arthritis. The aims of this study were to develop a diversified product of tuna-shredded fortified banana blossoms and to determine the antioxidant activity in vitro and anti-arthritis gout through inhibition of the xanthine oxidase (XO) enzyme in silico. The method used was a simple, completely randomized design. The formulation of tuna-shredded used fortification and active compounds analyzed by LC-HRMS. The antioxidant activity was analyzed by the DPPH. Inhibition of the XO enzyme was analyzed by molecular docking in silico. The results showed that tuna-shredded extract contained 32 compounds, which had total phenolic was 0.00134 mg GAE/g, total flavonoid was 0.0006670 mg QE/g, and IC50 was 4.38 ppm. Ferulic acid had the potential to inhibit the XO enzyme with binding affinity was -9.70 kcal/mol through hydrogen bonds and hydrophobic interactions.