Tigogenin Hexasaccharides from Camassia cusickii.Structural Elucidation by Modern NMR Techniques

Two steroidal saponins containing six carbohydrate residues have been isolated from the bulbs of Camassia cusickii. Their structures were determined by modern NMR techniques, 1H–1H COSY, HOHAHA, 1H–13C COSY, and HMBC spectra to be (25 R)-5α-spirostan-3β-yl 4-O-[2-O-[3-O-(α-l-rhamnopyranosyl)-β-d-glucopyranosyl]-3-O-[4-O-(α-l-rhamnopyranosyl)-β-d-glucopyranosyl]-β-d-glucopyranosyl]-β-d-galactopyranoside (1) and (25R)-5α-spirostan-3β-yl 4-O-[2-O-[3-O-(β-d-glucopyranosyl)-β-d-glucopyranosyl]-3-O-[4-O-(α-l-rhamnopyranosyl)-β-d-glucopyranosyl]-β-d-glucopyranosyl]-β-d-galactopyranoside (2), respectively. Compound 1 showed inhibitory activity on cyclic AMP phosphodiesterase.