Novel saponins from Nigella arvensis var. involucrata

Abstract

Four new oleanane-type triterpene glycosides namely 3-O-[β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)-α-l-arabinopyranosyl] oleanolic acid, 3-O-[β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)-α-l-arabinopyranosyl]-28-O-[α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl] oleanolic acid, 3-O-[β-d-quinovopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl]-28-O-[β-d-glucopyranosyl] oleanolic acid, 3-O-[β-d-quinovopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl]-28-O-[α-l-rhamnopyranosyl(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl] oleanolic acid, were isolated from methanol extract of the roots of Nigella arvensis var. involucrata along with five known oleanane-type triterpene glycosides and a steroid glucoside. Structures of the new compounds were established as by using 1D and 2D NMR techniques and mass spectrometry.