Reducing effect of mangiferin on serum uric acid levels in mice

Context: Mangiferin, a natural bioactive xanthone C-glycoside, is widely present in medicinal plants like the leaf of Mangifera indica L. (Anacardiaceae). It has been reported that mangiferin possesses a variety of biological activities, including antidiabetic, hepatoprotective, anti-inflammatory, antioxidant, and anticarcinogenic. Objective: The hypouricemic effect and xanthine oxidoreductase (XOR) inhibitory activity of mangiferin were investigated here for the first time. Materials and methods: The hypouricemic effect of mangiferin was investigated in normal and hyperuricemic mice induced by potassium oxonate. Mangiferin at a dose of 0.75-100.0 mg/kg was given intragastrically to mice. The serum urate levels were determined using the phosphotungstic acid method. The hepatic activities of xanthine dehydrogenase (XDH) and xanthine oxidase (XOD) in hyperuricemic mice were assayed using commercially available kits. Results: The results showed that mangiferin at a dose of 1.5, 3.0, and 6.0 mg/kg significantly reduced the serum urate levels (148.7 ± 37.8, 142.2 ± 44.5, 121.7 ± 21.7 μmmol/L) in hyperuricemic mice, compared with untreated hyperuricemic mice (201.8 ± 71.2 μmmol/L). However, mangiferin did not decrease the serum urate levels in normal mice until mangiferin was up to 100 mg/kg. In addition, the hepatic activities of XDH in hyperuricemic mice were significantly decreased by mangiferin, while no changes of XOD were observed. Acute toxicity study in mice showed that mangiferin was very safe at a dose of up to 25 g/kg. Discussion and conclusion: These findings demonstrate that mangiferin has the potential to be developed as a new therapeutic agent for the treatment of hyperuricemia and gout.     

芒果苷对氧嗪酸钾所致慢性高尿酸血症大鼠尿酸及肝肾功能的影响

目的研究芒果苷对氧嗪酸钾所致慢性高尿酸血症大鼠尿酸及肝肾功能的影响。方法连续灌胃给予SD大鼠氧嗪酸钾(2.5 g·kg-1体重)复制慢性高尿酸血症大鼠模型。以苯溴马隆和别嘌醇为阳性对照,研究芒果苷灌胃给药5周对高尿酸血症大鼠血尿酸(uric acid,UA)、肌酐(creatinine,Cr)、尿素氮(blood urea nitrogen,BUN)、谷丙转氨酶(ALT)、γ-谷氨酰转肽酶(GGT)、谷草转氨酶(AST)等水平的影响。结果芒果苷(1.55和3.13 mg·kg-1)灌胃给药能剂量依赖性地降低氧嗪酸钾所致的慢性高尿酸血症大鼠的血清尿酸水平,其效价弱于别嘌醇,但不亚于苯溴马隆;对肌酐、尿素氮和尿量的影响不明显,对血清AST、GGT水平亦无明显影响,但可改善慢性高尿酸血症大鼠的血清ALT水平。结论芒果苷可降低氧嗪酸钾所致慢性高尿酸血症大鼠的尿酸水平,对肝肾功能无明显影响。     

Comparative effects of green and black tea extracts on lowering serum uric acid in hyperuricemic mice

Context: Tea (Camellia sinensis (L.) Kuntze [Theaceae]) is used to induce urination and inducing nervous excitation. Green and black teas have multifarious physiological functions. The different effects of green and black tea aqueous extracts (GTEs and BTEs) on hyperuricemia are not definitely reported.

Objective: The different effects of GTEs and BTEs on lowering serum uric acid (UA) in hyperuricemic mice were determined.

Materials and methods: Kunming mice were divided into nine groups (n?=?6/each group). GTEs and BTEs at the doses of 0.5, 1 and 2?g/kg were orally administrated to mice for seven days, respectively. Hepatic xanthine oxidase (XOD) and adenosine deaminase (ADA) activities as mechanisms of actions were assessed.

Results: Research indicated that the LD₅₀ of tea extract is greater than 2?g/kg in mice. UA levels were suppressed significantly with dose-dependent treatment of 0.5, 1 and 2?g/kg BTEs (up to 25.5%, 28.7% and 29.8%, respectively); the serum UA levels were decreased by GTEs but not significant. The activities of XOD and ADA in high dose (2?g/kg) groups of both GTEs and BTEs were notably lower than those of the model group.

Discussion and conclusions: The results suggested that both GTEs and BTEs have hypouricaemic and renal protective effects on hyperuricemic mice and the latter one was better. Our study sheds light on the research and development of anti-hyperuricemic functional foods and drugs from tea.     

Hypouricaemic action of mangiferin results from metabolite norathyriol via inhibiting xanthine oxidase activity

Context Mangiferin has been reported to possess a potential hypouricaemic effect. However, the pharmacokinetic studies in rats showed that its oral bioavailability was only 1.2%, suggesting that mangiferin metabolites might exert the action.

Objective The hypouricaemic effect and the xanthine oxidase inhibition of mangiferin and norathyriol, a mangiferin metabolite, were investigated. Inhibition of norathyriol analogues (compounds 3–9) toward xanthine oxidase was also evaluated.

Materials and methods For a dose-dependent study, mangiferin (1.5–6.0?mg/kg) and norathyriol (0.92–3.7?mg/kg) were administered intragastrically to mice twice daily for five times. For a time-course study, mice received mangiferin and norathyriol both at a single dose of 7.1?μmol/kg. In vitro, inhibition of test compounds (2.4–2.4?mM) against xanthine oxidase activity was evaluated by the spectrophotometrical method. The inhibition type was identified from Lineweaver–Burk plots.

Results Norathyriol (0.92, 1.85 and 3.7?mg/kg) dose dependently decreased the serum urate levels by 27.0, 33.6 and 37.4%, respectively. The action was more potent than that of mangiferin at the low dose, but was equivalent at the higher doses. Additionally, the hypouricaemic action of them exhibited a time dependence. In vitro, norathyriol markedly inhibited the xanthine oxidase activities, with the IC₅₀ value of 44.6?μM, but mangiferin did not. The kinetic studies showed that norathyriol was an uncompetitive inhibitor by Lineweaver–Burk plots. The structure–activity relationships exhibited that three hydroxyl groups in norathyriol at the C-1, C-3 and C-6 positions were essential for maintaining xanthine oxidase inhibition.

Discussion and conclusion Norathyriol was responsible for the hypouricaemic effect of mangiferin via inhibiting xanthine oxidase activity.     

Hypouricemic action of selected flavonoids in mice: structure-activity relationships

Hyperuricemia and gout appear to be rapidly increasing worldwide and frequently cause symptoms of metabolic syndrome. Dietary flavonoids have their potential beneficial effects on human health. In the present study, 15 flavonoids (quercetin, morin, myricetin, kaempferol, icariin, apigenin, luteolin, baicalin, silibinin, naringenin, formonoetin, genistein, puerarin, daidzin and naringin dihydrochalcone) were selected to investigate for their hypouricemic action in mice. Oral administration of quercetin, morin, myricetin, kaempferol, apigenin and puerarin at 50 and 100 mg/kg for 3 d was able to elicit hypouricemic actions in hyperuricemic mice induced by potassium oxonate. Luteolin, formonoetin and naringenin showed the significant effects only at 100 mg/kg. Quercetin, puerarin, myricetin, morin and kaempferol significantly reduced liver uric acid level in hyperuricemic animals. In addition, quercetin, morin, myricetin, kaempferol and puerarin exhibited significant inhibition on the liver xanthine oxidase (XOD) activities. It seems to be likely that these flavonoids reduce serum urate levels by mainly inhibiting XOD activity. However, the hypouricemic effect of apigenin observed seemed not to parallel with the changes in liver uric acid level and liver XOD activity, implying that apigenin might act via other mechanisms apart from inhibiting enzyme activity simply. Analysis of the chemical structure showed that a planar structure with the hydroxyl groups played a crucial role in hypouricemic activity of flavonoids. The exact mechanism of the hypouricemic action of flavonoids in vivo should be investigated in the future.     

Pharmacological effects of Chatuphalatika in hyperuricemia of gout

Context: Chatuphalatika (CTPT), is a Thai herbal formulation mixture of Phyllanthus emblica Linn. (Euphorbiaceae), Terminalia belerica Linn. (Combretaceae), T. chebula and the fruit of T. arjuna (Roxb.) Wight &; Arn. CTPT is considered to exert anti-inflammatory and antihyperuricemic effects, but there have been no reports to demonstrate these pharmacological effects in a quantitative manner.

Objectives: To investigate the antioxidative, anti-inflammatory and antihyperuricemic effects of CTPT.

Materials and methods: Antioxidant activities of CTPT extracts were measured in vitro by DPPH, ABTS and FRAP assays, and anti-inflammatory effect by measuring inflammatory mediator production induced by lipopolysaccharide (LPS) in RAW264.7 macrophages. The mechanism of the hypouricemic effect was investigated using oxonate-induced hyperuricemic ddY mice treated with oral administrations of CTPT at 250, 500 and 1000?mg/kg.

Results: Antioxidant activities of CTPT measured by ABTS and FRAP assays were 1.35?g TEAC/g extract and 10.3?mmol/100?g extract, respectively. IC₅₀ for the inhibition of DPPH radical was 13.8?µg/mL. CTPT (10?µg/mL) significantly downregulated the mRNA expression of TNF-α and iNOS in RAW 264.7 cells. Lineweaver–Burk analysis of the enzyme kinetics showed that CTPT inhibited xanthine oxidase (XOD) activity in a noncompetitive manner with the K_i of 576.9?µg/mL. Oral administration of CTPT (1000?mg/kg) significantly suppressed uric acid production by inhibiting hepatic XOD activity, and decreased plasma uric acid levels in hyperuricemic mice by approximately 40% (p?Conclusions: This study demonstrated for the first time the antioxidative, anti-inflammatory and antihyperuricemic effects of CTPT in vivo and in vitro, suggesting a possibility of using CTPT for the treatment of hyperuricemia in gout.     

Hypouricemic effect of the methanol extract from Prunus mume fruit in mice

Context: The fruit of the Prunus mume Sieb. et Zucc (Rosaceae) is used as a health food or medicinal material in traditional herb medicine for a long time in Eastern Asian countries.

Objective: Our present study investigated the hypouricemic effect of the methanol extract from P. mume fruit (MPMF) in mice with potassium oxonate-induced hyperuremia.

Materials and methods: Effect of MPMF (35, 70 and 140 mg/kg, p.o.) administrated for 7 days on the serum, liver, urinary uric acid levels and liver xanthine oxidase (XO) activity were assessed in mice.

Results: Hyperuricemic mice induced by potassium oxonate demonstrated an elevation in serum and liver uric acid levels (11.0 mg/dL and 0.52 mg/g tissue) and a reduction in urinary uric acid levels (49.9 mg/dL). Oral administration of 140 mg/kg MPMF for 7 days reversed the abnormalities in serum, liver and urinary uric acid levels (7.1 mg/dL, 0.37 mg/g tissue and 69.7 mg/dL, respectively). In addition, 70 and 140 mg/kg MPMF (3.1 and 2.9 nmol/min per mg protein) inhibited liver XO activity compared with hyperuricemic mice (3.9 nmol/min per mg protein).

Discussion and conclusion: The results indicated that the beneficial hypouricaemic effect of MPMF may be mediated, at least in part, by inhibiting XO activity in the liver. Our study suggests that P. mume and its extracts may have a considerable potential for development as an anti-gout agent for clinical application.     

Aesculin possesses potent hypouricemic action in rodents but is devoid of xanthine oxidase/dehydrogenase inhibitory activity

The natural product aesculin was demonstrated to possess potent hypouricemic effects in in vivo models of hyperuricemia in both mice and rats pretreated with oxonate. Aesculin, when administered intraperitoneally to the oxonate-induced hyperuricemic rodents, was able to elicit dose-dependent hypouricemic effects. At doses of 150 mg/kg of aesculin or above, the serum urate levels of the oxonate-pretreated mice were not different from normal mice. Such an effect in mice was observed as quick as 1.5 h after aesculin administration and was persistent for at least 5 h after aesculin administration. In rats, similar hypouricemic effects of intraperitoneally administered aesculin could also be demonstrated at doses of 100 mg/kg of aesculin or above, the serum urate levels of the oxonate-pretreated rats were not different from normal rats. Again, the effect persisted for at least 5 h after aesculin administration. In both rodents, however, oral administration at the same doses did not produce any observable hypouricemic effects. In addition, aesculin, when tested in vitro on rat and mouse liver homogenates, did not elicit any measurable inhibitory actions on the xanthine oxidase/xanthine dehydrogenase activities.     

Antioxidant,antihyperuricemic and xanthine oxidase inhibitory activities of Hyoscyamus reticulatus

Context:?Xanthine oxidase (XO) is a key enzyme in the pathophysiological homeostasis of hyperuricemia. It catalyzes the oxidation of hypoxanthine to xanthine and then to uric acid, the reaction involves the formation of free radical intermediates and superoxide byproducts.

Objectives:?This study was undertaken to investigate the antioxidant, antihyperuricemic, and xanthine oxidase inhibitory potentials of Hyoscyamus reticulatus L. (Solanaceae) extract.

Materials and methods:?The antioxidant potency was measured using the ABTS^?+ scavenging capacity system, which includes Trolox as a standard. The xanthine oxidase inhibitory activity of the extract was quantitated in vitro by measuring the decline in the catalytic rate of xanthine oxidase following incubations with the plant extracts and using xanthine as a substrate. The hypouricemic potential of the extract was evaluated using an in vivo model for hyperuricemia. We tested three different doses of the extract and allopurinol was used as standard antihyperuricemic positive control.

Results:?H. reticulatus aqueous extract exhibited significant antioxidant scavenging properties (533.26 μmol TE/g dry extract weight) and inhibitory effect on xanthine oxidase activity (IC₅₀ 12.8 μg/mL). Furthermore, oral administration of the aqueous extract significantly reduced serum urate levels in oxonate-induced hyperuricemic mice in a dose-dependent manner.

Discussion and conclusion:?Our results suggest that the aqueous extract of H. reticulatus aerial parts might have great potential as an antioxidant and a hypouricemic agent. Our lab is currently identifying the active compounds in the extract to which the biological activities could be attributed.     

Hypouricemic action of scopoletin arising from xanthine oxidase inhibition and uricosuric activity

Scopoletin exhibited an immediate and dose-dependent hypouricemic effect after intraperitoneal administration (50, 100, 200 mg/kg) in hyperuricemic mice induced by potassium oxonate; however, it did not affect the serum uric acid level in normal mice at the tested doses. For exploring the involved mechanisms of action of scopoletin, potential inhibitory effects on xanthine oxidase and possible uricosuric effects were investigated. Scopoletin (50, 100, 200 mg/kg) significantly inhibited the activity of xanthine oxidase in liver homogenates of hyperuricemic mice although it only showed a relatively weak, albeit competitive-type, inhibition of xanthine oxidase in a commercial assay. Furthermore, a potent uricosuric effect of scopoletin (100, 200 mg/kg) was ascertained. These results demonstrated for the first time that scopoletin exhibits, hypouricemic activities through decreasing uric acid production and as well as a uricosuric mechanism.     

栀子苷对氧嗪酸钾盐致小鼠高尿酸血症的作用及其机制研究

目的探讨栀子苷对氧嗪酸钾盐致小鼠高尿酸血症的作用及其机制。方法连续7d灌胃给予氧嗪酸钾盐诱导小鼠高尿酸血症,对比各组血清尿酸水平和24h尿酸排泄量,检测肝脏黄嘌呤氧化酶（XOD）的活性和肾脏尿酸转运体（mURAT1、mGLUT9、mOAT1）的mRNA和蛋白表达水平。结果栀子苷可显著降低高尿酸血症小鼠血清尿酸水平并升高24h尿酸排泄量,同时可抑制肝脏XOD活性,调节肾脏尿酸转运体的表达。结论栀子苷对氧嗪酸钾盐致小鼠高尿酸血症具有明显的改善作用,其作用机制可能是通过抑制XOD活性和调节尿酸转运体的表达水平实现。     

短穗兔耳草提取物对高尿酸血症小鼠肾脏保护作用研究

目的 研究短穗兔耳草提取物对高尿酸血症小鼠肾脏有无保护作用。方法 以氧嗪酸钾盐诱导小鼠高尿酸血症模型为实验系统,通过检测血清尿酸和黄嘌呤氧化酶含量和肾脏病理病变等指标,评价短穗兔耳草提取物对高尿酸血症小鼠肾脏的保护作用。结果 短穗兔耳草可显著降低模型大鼠血清、尿酸和黄嘌呤氧化酶含量, 改善了小鼠肾脏结构的变化。结论 短穗兔耳草具有降尿酸活性及肾脏保护作用。     

拟黑多刺蚁乙醇提取物中降低小鼠血清尿酸水平活性部位的筛选与化学成分分析

目的研究拟黑多刺蚁乙醇提取物(EEPR)中降低高尿酸血症模型小鼠血清尿酸水平的活性部位及其主要化学成分。方法昆明小鼠分别ig给予别嘌醇0.04 g.kg-1(阳性对照),EEPR 0.128,0.256和0.512 g.kg-1,EEPR的石油醚部位0.079和0.158 g.kg-1,乙酸乙酯部位0.051和0.102 g.kg-1,正丁醇部位0.052和0.104 g.kg-1和水部位0.042和0.084 g.kg-1,每天1次,连续12 d。正常对照组和模型对照组ig给予等体积含0.3%吐温-80的水溶液。末次给药1 h后除正常对照组外,其余各组小鼠均ip给予次黄嘌呤0.6 g.kg-1。1 h后眼眶静脉丛取血,用磷钨酸比色法测定血清尿酸水平,酶比色法测定黄嘌呤氧化酶活性。对降低血清尿酸水平的活性部位进行GC-MS分析,鉴定其主要化学成分。结果高尿酸血症模型小鼠血清尿酸水平与正常对照组比较明显升高(P<0.01),别嘌醇0.04 g.kg-1,EEPR 0.256和0.512 g.kg-1可明显降低该模型小鼠血清尿酸水平(P<0.05),分别由模型组的(464±143)μmol.L-1下降到273±80,346±85和(302±72)μmo.l L-1(P<0.05)。EEPR中石油醚部位0.079和0.158 g.kg-1可显著降低该模型小鼠血清尿酸水平,分别由模型组的(446±139)μmo.lL-1下降到328±100和(314±112)μmol.L-1(P<0.05),其他部位各剂量组对血清尿酸水平均无明显影响。石油醚部位0.158 g.kg-1可明显抑制黄嘌呤氧化酶活性,由模型对照组的(18±8)U.L-1下降到(11±5)U.L-1(P<0.05)。GC-MS分析结果表明,石油醚部位的脂肪酸中,反式十八碳烯酸甲酯占60.77%,十六烷酸甲酯占18.99%,十六碳烯酸甲酯占9.31%。结论 EEPR中石油醚部位可降低高尿酸血症模型小鼠血清尿酸水平,不饱和脂肪酸为石油醚部位脂肪酸的主要成分。     

Therapeutic and cosmetic applications of mangiferin: a patent review

Introduction: Mangiferin, a natural C-glucoside xanthone [2-C-β-D-glucopyranosyl-1, 3, 6, 7-tetrahydroxyxanthone], is abundantly present in young leaves and stem bark of the mango tree. The xanthonoid structure of mangiferin with C-glycosyl linkage and polyhydroxy components contributes to its free radical-scavenging ability, leading to a potent antioxidant effect as well as multiple biological activities.

Areas covered: An extensive search was carried out to collect patent information on mangiferin and its derivatives using various patent databases spanning all priority years to date. The patents claiming therapeutic and cosmetic applications of mangiferin and its derivatives were analyzed in detail. The technology areas covered in this article include metabolic disorders, cosmeceuticals, multiple uses of the same compound, miscellaneous uses, infectious diseases, inflammation, cancer and autoimmune disorders, and neurological disorders.

Expert opinion: Mangiferin has the potential to modulate multiple molecular targets including nuclear factor-kappa B (NF-κB) signaling and cyclooxygenase-2 (COX-2) protein expression. Mangiferin exhibits antioxidant, antidiabetic, antihyperuricemic, antiviral, anticancer and antiinflammatory activities. The molecular structure of mangiferin fulfils the four Lipinski's requisites reported to favor high bioavailability by oral administration. There is no evidence of adverse side effects of mangiferin so far. Mangiferin could thus be a promising candidate for development of a multipotent drug.     

Mangiferin induces immune responses and evaluates the survival rate in WEHI‐3 cell generated mouse leukemia in vivo

Mangiferin is a naturally occurring polyphenol, widely distributed in Thymeraceae families, and presents pharmacological activity, including anti‐cancer activities in many human cancer cell lines. Mangiferin has also been reported to affect immune responses; however, no available information concerning the effects of mangiferin on immune reactions in leukemia mice in vivo. In the present study, we investigated the effects of mangiferin on leukemia WEHI‐3 cell generated leukemia BLAB/c mice. Overall, the experiments were divided into two parts, one part was immune responses experiment and the other was the survival rate experiment. The immune responses and survival rate study, 40 mice for each part, were randomly separated into five groups (N = 8): Group I was normal animals and groups II‐V WEHI‐3 cell generated leukemia mice. Group II mice were fed normal diet as a positive control; group III, IV, and V mice received mangiferin at 40, 80, and 120 mg/kg, respectively, by intraperitoneal injection every 2 days for 20 days. Leukocytes cell population, macrophage phagocytosis, and NK cell activities were analyzed by flow cytometry. Isolated splenocytes stimulated with lipopolysaccharide (LPS) and concanavalin A (Con A) were used to determine the proliferation of B and T cells, respectively, and subsequently were analyzed by flow cytometry. Results indicated that mangiferin significantly increased body weight, decreased the liver and spleen weights of leukemia mice. Mangiferin also increased CD3 T‐cell and CD19 B cell population but decreased Mac‐3 macrophage and CD11b monocyte. Furthermore, mangiferin decreased phagocytosis of macrophages from PBMC and peritoneal cavity at 40, 80, and 120 mg/kg treatment. However, it also increased NK cell activity at 40 and 120 mg/kg treatment. There were no effects on T and B cell proliferation at three examined doses. In survival rate studies, mangiferin significantly elevated survival rate at 40 and 120 mg/kg treatment of leukemia mice in vivo.     

The dual actions of Paederia scandens extract as a hypouricemic agent: xanthine oxidase inhibitory activity and uricosuric effect

Hyperuricemia is associated with a number of pathological conditions, such as gout. Lowering of elevated uric acid levels in the blood could be achieved by xanthine oxidase inhibitors and inhibitors of renal urate reabsorption. Some natural compounds isolated from herbs used in traditional Chinese medicine have been previously demonstrated to act as xanthine oxidase inhibitors. In the present investigation, Paederia scandens (Lour.) Merrill (Rubiaceae) extract (PSE; 4.5, 2.25, and 1.125 g/kg) orally for 14 days was demonstrated to possess in vivo potent hypouricemic activity in hyperuricemic rats pretreated with potassium oxonate. In addition, PSE was also demonstrated to be an inhibitor of xanthine oxidase. Lineweaver-Burk analysis of the enzyme kinetics indicated that the inhibition of PSE was of a mixed type. Using an oxonate-induced hyperuricemic rat model, PSE was indeed shown to exhibit uricosuric action in vivo, which could explain, at least in part, the observed hypouricemic effect of PSE in these rats. The potential application of this compound in the treatment of conditions associated with hyperuricemia is discussed.     

Pleurotus ostreatus,an edible mushroom,enhances glucose 6-phosphate dehydrogenase,ascorbate peroxidase and reduces xanthine dehydrogenase in major organs of aged rats

Context: Aging is now considered to be associated with an elevation in oxidative damage to macromolecules and enhanced levels of inflammation. Therefore, inhibition of age-related oxidative stress by natural supplement is an important study.

Objectives: To investigate whether the treatment with Pleurotus ostreatus (Jacq.: Fr) Kumm, (Pleurotaceae) can ameliorate oxidative damage in aged rats.

Materials and methods: Male Wistar rats were divided into three groups of six each: group 1, normal young rats; group 2, normal aged untreated rats; group 3, normal aged rats treated with P. ostreatus (200?mg/kg body wt administered intraperitoneally for 21 days). On the 22nd day, rats were sacrificed by decapitation; the liver, kidneys, heart and brain were removed from each rat for the biochemical and isozyme analyses of the antioxidant enzymes glucose 6-phosphate dehydrogenase (G6PDH), ascorbate peroxidase (Apx) and xanthine dehydrogenase (XDH).

Results: An elevated activity of XDH was observed in the liver (G2:13.72?±?4.1 versus G1: 7.57?±?1.15; p?p?p?p?P. ostreatus to aged rats resulted in decreased XDH and increased G6PDH and Apx activities in liver, kidneys, heart and brain. Interestingly, analyses of isozyme pattern of these enzymes are support the results obtained from the spectrophotometric determinations.

Conclusion: These results suggest that an extract of P. ostreatus can protect the age-related oxidative damage in major organs of Wistar rats by enhancing the antioxidant enzymes G6PDH and Apx and by reducing XDH.     

Hypouricemic effect of allopurinol and the novel xanthine oxidase inhibitor TEI-6720 in chimpanzees

The hypouricemic effect of a newly synthesized xanthine oxidase / xanthine dehydrogenase inhibitor, TEI-6720, 2-(3-cyano-4-isobutoxyphenyl)-4-methyl-5-thiazolecarboxylic acid, was investigated and compared with that of allopurinol in male chimpanzees (n = 3). When allopurinol (10 mg/kg) was administered orally once a day for three consecutive days, it cumulatively reduced serum urate levels by 29.7, 50.1 and 60.2%, 24, 48 and 72 h, respectively, after the initial dose. This effect was dose dependent at doses of 3 and 10 mg/kg. At 3 mg/kg, the mean serum urate levels were 3.1, 2.4, 2.5 and 2.3 mg/dl before and 24, 48 and 72 h, respectively, after the initial dose. Animals treated with 10 mg/kg of allopurinol showed serum urate levels of 3.3, 2.3, 1.6 and 1.3 mg/dl, respectively. The urate-lowering effect of TEI-6720 was then comapred with that of allopurinol at a daily dose of 5 mg/kg (n = 3). Both compounds caused striking reductions in serum and urinary uric acid levels accompanied by an increase in urinary xanthine levels. These effects of TEI-6720 were more potent than those of allopurinol. TEI-6720 reduced serum urate levels by 55.9, 69.6 and 73.6%, 24, 48 and 72 h, respectively, after the first dose, whereas, the corresponding values after allopurinol were 28.1, 41.6 and 45.1%. These results suggest that the hypouricemic effect of TEI-6720 may be more potent than that of allopurinol in the treatment of hyperuricemia and gout, and that TEI-6720 may become an effective alternative drug.     

Evaluating the urate-lowering effects of different microbial fermented extracts in hyperuricemic models accompanied with a safety study

Uric acid (UA) is an end product of purine metabolism by the enzyme xanthine oxidase (XOD). Hyperuricemia is characterized by the accumulation of serum UA and is an important risk factor for gout and many chronic disorders. XOD inhibitors or uricase (catalyzes UA to the more soluble end product) can prevent these chronic diseases. However, currently available hypouricemic agents induce severe side effects. Therefore, we developed new microbial fermented extracts (MFEs) with substantial XOD inhibition activity from Lactobacillus (MFE-21) and Acetobacter (MFE-25), and MFE-120 with high uricase activity from Aspergillus. The urate-lowering effects and safety of these MFEs were evaluated. Our results showed that MFE-25 exerts superior urate-lowering effects in the therapeutic model. In the preventive model, both MFE-120 and MFE-25 significantly reduced UA. The results of the safety study showed that no organ toxicity and no treatment-related adverse effects were observed in mice treated with high doses of MFEs. Taken together, the results showed the effectiveness of MFEs in reducing hyperuricemia without systemic toxicity in mice at high doses, suggesting that they are safe for use in the treatment and prevention of hyperuricemia.     

Mangiferin activates the Nrf2-ARE pathway and reduces etoposide-induced DNA damage in human umbilical cord mononuclear blood cells

Abstract

Context: Mangiferin (2-C-β-d-gluco-pyranosyl-1,3,6,7-tetrahydroxyxanthone) is a well-known natural antioxidant distributed in various plants of the Anacardiaceae and Gentianaceae families. Mangiferin can inhibit carcinogen-induced lung or colon tumor formation in experimental animals. However, the molecular mechanisms of its chemopreventive activity remain unexplored.

Objective: This study aimed to investigate the effects of mangiferin on chemical carcinogen-induced DNA damage and Nrf2-ARE signaling in hematopoietic cells.

Materials and methods: Mononuclear cells (MNCs) were isolated from human umbilical cord blood (hUCB). DNA damage was evaluated by comet and micronucleus assays. The expression of Nrf2 and NQO1 was examined by immunofluorescence and western blotting. An electrophoretic mobility shift assay (EMSA) was used to detect the binding activity of Nrf2 with NQO1-ARE sequences.

Results: We found that mangiferin treatment significantly reduced DNA damage in etoposide-treated MNCs, which was verified by decreased olive tail moment (OTM) and micronucleus (MN) frequency. Mangiferin treatment significantly promoted Nrf2 translocation into the nucleus and increased nuclear Nrf2 expression. Moreover, NQO1, an Nrf2 signaling target, was significantly upregulated by mangiferin treatment, and the binding activity of Nrf2 with NQO1-ARE sequences was elevated after mangiferin treatment.

Discussion and conclusion: Mangiferin activated Nrf2 signaling, upregulated NQO1 expression, and significantly reduced etoposide-induced DNA damage. Thus, mangiferin is a potential cytoprotective agent for hematopoietic cells.