Triterpenoid acids from medicinal mushroom Inonotus obliquus (Chaga) alleviate hyperuricemia and inflammation in hyperuricemic mice: Possible inhibitory effects on xanthine oxidase activity.

The purpose of this study was to explore the hypouricemic effect in hyperuricemia mice of triterpenoid acids from Inonotus obliquus (TAIO), and decipher of the underlying xanthine oxidase inhibitory mechanism. Measurement of xanthine oxidase (XO) inhibitory activity was assayed. Organ indexes and serum biochemical indicators were measured in potassium oxonate-induced hyperuricemia mice. Studies showed that TAIO had the strong inhibitory effect on XO activity, and its inhibition type was mixed and reversible. In vivo, TAIO decreased efficiently uric acid level, hepatic XO, serum blood urea nitrogen activities in hyperuricemia mice. Indicating that TAIO may ameliorate kidney damage and relieve inflammation in hyperuricemic mice, and had the inhibitory effect on XO activity. Furthermore, eight triterpenoids were identified by Ultra performance liquid chromatography electrospray quadrupole time of flight mass spectrometry. These findings proved that triterpenoids from Inonotus obliquus would have potential biological characteristics and effect on controlling hyperuricemia and gout as an active supplement. PRACTICAL APPLICATIONS: There are a large amount of evidence indicating that hyperuricemia and gout are related to the hypertension and obesity. And gout and hyperuricemia are also possible connection with cardiovascular disease and metabolic syndrome. Currently, xanthine oxidase is the target of many kinds of chemical drugs at present, but the therapeutic drugs used in clinical medicine will produce more or less side effects. Therefore, the aim of this study was to explore the material basis of effective substances for reducing uric acid in Inonotus obliquus and to evaluate its effect. This study can provide a promising application of Inonotus obliquus in the fields of functional foods or medicines for gout and hyperuricemia.

Hypouricemic effects of acacetin and 4,5-o-dicaffeoylquinic acid methyl ester on serum uric acid levels in potassium oxonate-pretreated rats.

The effects of acacetin (1) and 4,5-O-dicaffeoylquinic acid methyl ester (2), compounds contained in the flowers of Chrysanthemum sinense SABINE, on the serum uric acid level were investigated using the rats pretreated with the uricase inhibitor potassium oxonate as an animal model for hyperuricemia. When administered per orally at doses of 20 and 50 mg/kg, 1 reduced the serum uric acid level by 49.9 and 63.9%, respectively and 2 reduced the level by 31.2 and 44.4%, respectively. On the other hand, when the same doses were given intraperitoneally, both of compounds also exhibited a dose-dependent and more marked reduction of the serum uric acid level (% reduction at 20 and 50 mg/kg were 63.0 and 95.1% in 1, respectively and 66.9 and 86.5% in 2, respectively). Furthermore, the compounds 1 and 2 inhibited the rat liver xanthine oxidase activity with IC(50) values of 2.22 muM and 5.27 muM, respectively. These results demonstrated the hypouricemic action of 1 and 2, which may be attributable to their xanthine oxidase inhibitory activity.

Allopurinol does not affect the anticonvulsant activity of carbamazepine and valproate in maximal electroshock-induced convulsions in mice.

Allopurinol, an inhibitor of xanthine oxidase, is indicated in the management of patients with elevated serum and urinary uric acid levels. It was also reported to be beneficial in patients with epilepsy when added to traditional antiepileptic drug. Here, we investigated the effect of allopurinol upon the electrical seizure threshold and its effect on the protective efficacy of common antiepileptic drugs, carbamazepine (CBZ) and valproate (VPA) against maximal electroshock (MES)-induced convulsions in mice. We found that allopurinol administered at doses of 5, 15 or 45 mg/kg, did not affect electrical seizure threshold. When administered acutely or for a prolonged period of time (5 times every 24 h), it did not affect anticonvulsant activity of CBZ and VPAin MES. Free plasma concentration of both anticonvulsants was not affected by allopurinol given at a dose of 45 mg/kg for 5 days. Thus, our results did not support suggestions that allopurinol can be beneficial as add-on drug in the management of epilepsy at least in patients treated with CBZ or VPA.

2-Methoxyestradiol enhances reactive oxygen species formation and increases the efficacy of oxygen radical generating tumor treatment.

In an investigation of the antitumor effects of 2-methoxyestradiol (2-ME) in combination with other reactive oxygen generating treatments, 2-ME (0.5 microM) was found to completely inhibit cell proliferation of rat DS-sarcoma cells in vitro, with 71% of cells dying after exposure to 5 microM 2-ME. Concentration-dependent increases in ROS-formation, lipid peroxidation and mitochondrial changes were also observed, and an elevation in caspase-3 activity resulted in DNA fragmentation and apoptosis. Combination of 2-ME with hypoxanthine and xanthine oxidase enhanced in vitro cytotoxicity. In vivo, 2-ME caused a slight inhibition of tumor growth, with no tumors cured. Combination of 2-ME treatment with localized 44 degrees C hyperthermia, respiratory hyperoxia and xanthine oxidase caused a tumor growth delay with 51% of tumors cured. These results suggest that amplifying the levels of reactive oxygen species within tumor tissue with substances such as 2-ME may prove to be a promising strategy for adjuvant treatment of solid tumors.

Enhancement of oxidative cell injury and antitumor effects of localized 44 degrees C hyperthermia upon combination with respiratory hyperoxia and xanthine oxidase.

The effects of respiratory hyperoxia (RH) and xanthine oxidase (XO) during localized hyperthermia (HT) were investigated by determining markers of oxidative damage to lipids and proteins and tumor growth. Anesthetized rats with s.c. DS-sarcomas underwent one of the following treatments: (a) localized saline-bath HT (60 min, 44 degrees C); (b) HT + RH (100% O2); and (c) HT + RH + XO (15 units/kg i.v.). Sham-treated animals served as controls. Tumors were investigated for: (a) thiobarbituric acid-reactive substance formation and protein-bound 4-hydroxynonenal, as indicators of lipid peroxidation; (b) reactive oxygen-mediated protein modifications; (c) apoptosis; and (d) tumor volume growth. Upon treatment, increases in thiobarbituric acid-reactive substances, protein-bound 4-hydroxynonenal, protein-associated carbonyl functions, and number of cells undergoing apoptosis were found in tumor tissue, together with an inhibition of tumor growth. When treatment groups were compared, effects in the group HT + RH + XO were generally most pronounced. These findings indicate that the antitumor effect of HT is at least partially mediated through the selective induction of lipid peroxidation and oxidative injury in tumor cells, leading to apoptosis. This effect was enhanced by adding RH or RH + XO, presumably due to enhanced tissue damage following an increased formation of reactive oxygen species, with higher levels of lipid peroxidation and protein oxidation.

Xanthine oxidase inhibits growth of Plasmodium falciparum in human erythrocytes in vitro.

Malaria parasites, unable to synthesize purine de novo, use host-derived hypoxanthine preferentially as purine source. In a previous study (1990. J. Biol. Chem. 265:6562-6568), we noted that xanthine oxidase rapidly and completely depleted hypoxanthine in human erythrocytes, not by crossing the erythrocyte membrane, but rather by creating a concentration gradient which facilitated hypoxanthine efflux. We therefore investigated the ability of xanthine oxidase to inhibit growth of FCR-3, a chloroquine-resistant strain of Plasmodium falciparum in human erythrocytes in vitro. Parasites were cultured in human group O+ erythrocytes in medium supplemented, as required, with xanthine oxidase or chloroquine. Parasite viability was assessed by uptake of radiolabeled glycine and adenosine triphosphate-derived purine into protein and nucleic acid, respectively, by nucleic acid accumulation, by L-lactate production, and by microscopic appearance. On average, a 90% inhibition of growth was observed after 72 h of incubation in 20 mU/ml xanthine oxidase. Inhibition was notably greater than that exerted by 10(-7) M chloroquine (less than 10%) over a comparable period. The IC50 for xanthine oxidase was estimated at 0.2 mU/ml, compared to 1.5 x 10(-7) M for chloroquine. Inhibition was completely reversed by excess hypoxanthine, but was unaffected by oxygen radical scavengers, including superoxide dismutase and catalase. The data confirms that a supply of host-derived hypoxanthine is critical for nucleic acid synthesis in P. falciparum, and that depletion of erythrocyte hypoxanthine pools of chloroquine-resistant malaria infection in humans. of chloroquine-resistant malaria infection in humans.