Phytochemicals from Tradescantia albiflora Kunth Extracts Reduce Serum Uric Acid Levels in Oxonate-induced Rats

BACKGROUND: Tradescantia albiflora (TA) Kunth (Commelinaceae) has been used for treating gout and hyperuricemia as folklore remedies in Taiwan. Therefore, it is worthwhile to study the effect of TA extracts on lowering uric acid activity. The hypouricemic effects of TA extracts on potassium oxonate (PO)-induced acute hyperuricemia were investigated for the first time. MATERIALS AND METHODS: All treatments at the same volume (1 ml) were orally administered to the abdominal cavity of PO-induced hyperuricemic rats. One milliliter of TA extract in n-hexane (HE), ethyl acetate (EA), n-butanol (BuOH), and water fractions has 0.28, 0.21, 0.28, and 1.03 mg TA, respectively; and the plasma uric acid (P(UA)) level was measured for a consecutive 4 h after administration. RESULTS: All four fractions' extracts derived from TA were observed to significantly reduce P(UA) compared with the PO group. The EA-soluble fraction (TA-EA) exhibited the best xanthine oxidase (XO) inhibitory activity. Following column chromatography, 12 phytochemicals were isolated and identified from the EA fraction. The IC(50) values of isolated phytochemicals indicated that bracteanolide A (AR11) showed the remarkable XO inhibitory effect (IC(50) value of 76.4 μg/ml). These findings showed that the in vivo hypouricemic effect in hyperuricemic rats was consistent with in vitro XO inhibitory activity, indicating that TA extracts and derived phytochemicals could be potential candidates as hypouricemic agents. SUMMARY: Tradescantia albiflora extracts possess in vivo hypouricemic action in hyperuricemic rats. T. albiflora extracts exhibited strong inhibitory activity against xanthine oxidase (XO). Butenolide may play an important role in XO inhibition. The extract bracteanolide A was demonstrated potent XO inhibitory activity in vitro. . Abbreviations used: TA: Tradescantia albiflora, PO: potassium oxonate, HE: n-hexane, EA: ethyl acetate, BuOH: n-butanol, P(UA): plasma uric acid, XO: xanthine oxidase, MeOH: methanol, IP: intraperitoneal