Hyaluronidase inhibitory saponins and a trypanocidal isoflavonoid from the aerial parts of Oxytropis lanata

Abstract

A chemical examination of an extract from the aerial part of Oxytropis lanata led to the isolation and identification of 36 compounds, including saponins, isoflavonoids, oxazoles, and glycosides. The three among them were previously unreported oleanane-type saponins. In trypanocidal screening, 5,7,4′-trihydroxyisoflavone showed inhibitory activity against Trypanosoma congolense (IC50 = 10.5 μM), the causative agent of African trypanosomosis in animals; this activity was similar to that of active compounds from the roots of this plant. O. lanata is known to be a traditional medicinal plant in Mongolia for the treatment of inflammatory diseases. The anti-hyaluronidase effect of saponins 3, 5, 8, and 9, (IC50 = 0.15–0.22 mM) was stronger than that of sodium cromoglicate, which was used as a reference drug (IC50 = 0.37 mM). The chemical structures of the new saponins were determined based on HRFABMS, 1H and 13C NMR, 1H–1H COSY, HMQC, HMBC, and ROESY spectroscopic data along with chemical procedures.