Studies on the constituents of asparagi radix. I. On the structures of furostanol oligosides of Asparagus cochinchinensis (Loureio) Merrill.

Asp-IV, V, VI and VII, the major furostanol oligosides, have been isolated from the methanol extract of Asparagus cochinchinensis (LOUREIO) MERRILL (Liliaceae). The structures of Asp-IV, V, VI and VII have been established as 26-O-β-D-glucopyranosyl-22-methoxyfurostane-3β, 26-diol 3-O-β-D-xylopyranosyl (1→4)-β-D-glucopyranoside (1), 26-O-β-D-glucopyranosyl-22-methoxyfurostane-3β, 26-diol 3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside (2), 26-O-β-D-glucopyranosyl-22-methoxyfurostane-3β, 26-diol 3-O-β-D-xylopyranosyl (1→4)-[α-L-rhamnopyranosyl (1→6)]-β-D-glucopyranoside (3) and 26-O-β-D-glucopyranosyl-22-methoxyfurostane-3β, 26-diol 3-O-[β-D-glucopyranosyl (1→2)] [β-D-xylopyranosyl (1→4)] [α-L-rhamnopyranosyl (1→6)]-β-D-glucopyranoside (4), respectively. Amethoxyl group at C-22 of each furostanol oligoside is converted to a hydroxyl group by boiling in aqueous acetone. The interconversions between methoxyl and hydroxyl groups at C-22 of the furostanol oligosides were investigated and the genuine furostanol oligosides of Asparagi radix appear to be of the hydroxyl type, based on comparative studies of the methanol and pyridine extracts.