New steroidal saponin from Antigonon leptopus Hook. and Arn.

Antigonon leptopus Hook. and Arn., Polygonaceae (cadena de amor), is a herbal remedy for pain and gout-like symptoms in the Philippines. The methanol extract of A. leptopus have shown strong inhibitory action against xanthine oxidase. To isolate and identify the compound responsible for the xanthine oxidase inhibitory action. A bioassay-guided isolation scheme using an in vitro assay for the inhibition of xanthine oxidase was employed. The structure was established using spectroscopic analysis and chemical methods. The isolated compound was determined to be a noncompetitive inhibitor of xanthine with an IC50 of 1.79 μg/mL. The isolated compound may represent a new class of xanthine oxidase inhibitors.