Study on the xanthine oxidase inhibitory activity of some medicinal plants in Vietnam

Tóm tắt

Xanthine oxidase is a crucial enzyme catalyzing the hydroxylation of hypoxanthine to xanthine and then xanthine into uric acid. Uric acid undergoes no further metabolism in humans and is excreted by the kidneys and intestinal tract. Hyperuricemia, associated with gout, results from the overproduction or underexcretion of uric acid. Xanthine oxidase inhibitors that block the terminal step in uric acid biosynthesis can lower the plasma uric acid concentration and are generally employed for the treatment of gout. Moreover, superoxide anion radicals generated by xanthine oxidase are involved in various pathological states such as hepatitis, inflammation, ischemia-reperfusion, carcinogenesis and aging. Thus, the search for novel xanthine oxidase inhibitors would be beneficial not only to treat gout but also to combat various other diseases. In this paper, results on investigating of xanthine oxidase inhibitory activity of 22 methanolic extracts from 18 medicinal plants in Vietnam, belonging to Moraceae, Anacardiaceae, Fabaceae, Euphorbiaceae, Boraginaceae, Rutaceae, Taxaceae, Gnetaceae, Plantaginaceae, Musaceae and Sapotaceae family were reported. The results indicated that 21 methanol extracts showed the inhibition at the concentration of 100 µg mL-1, 12 extracts showed greater than 50% inhibition at 100 µg mL-1, 6 showed greater than 50% inhibition at 100 µg mL-1 and 4 demonstrated over 50% inhibition at 25 µg mL-1. Among them, the methanol extracts from the stem of Buchanania lucida and Swintonia floribunda, belonging to Dipterocarpaceae family, displayed the highest xanthine oxidase inhibitors activity, with the IC50 values of 14.20 µg mL-1 and 15.76 µg mL-1, respectively. To the best of our knowledge, this is the first time that these extracts possessing the xanthine oxidase inhibitors activity were reported. The results of this study suggest that these herbs have potential for the treatment of rheumatism and inflammatory in Vietnam.