Triterpene saponins from Eryngium kotschyi

Four new oleanane-type saponins 3-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucuronopyranosyl-22-O-β,β-dimethylacryloylA1-barrigenol (1), 3-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucuronopyranosyl-22-O-angeloylA1-barrigenol (2), 3-O-β-d-glucopyranosyl-(1 → 2)-[β-d-glucopyranosyl-(1 → 6)]-β-d-glucopyranosyl-21,22,28-O-triacetyl-(3β,21β,22α)-olean-12-en-16-one (3), and 3-O-β-d-glucopyranosyl-(1 → 2)-glucopyranosyl-22-O-β-d-glucopyranosylsteganogenin (4), along with the known 3-O-β-d-galactopyranosyl-(1 → 2)-[α-l-arabinopyranosyl-(1 → 3)]-β-d-glucuronopyranosyl-22-O-angeloylA1-barrigenol and 3-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucuronopyranosyloleanolic acid, were isolated from a methanol extract of the roots of Eryngium kotschyi by multiple chromatographic steps. Saponins 3 and 4 are unusual by the original structure of their aglycon. Compound 3 possessed an oleanane-type skeleton with a 21,22,28-triacetylation and a ketone function at the C-16 position. For compound 4, the 17,22-seco-oleanolic acid skeleton is rarely found in natural saponins.