New furospirostane steroidal saponins from the flowers of Lilium Asiatic hybrids

Lilium Asiatic hybrids (Lilium spp.) are produced by interspecific crosses of Sinomartagon species belonging to Liliaceae. To date, no phytochemical work appears to have been conducted on Lilium Asiatic hybrids. In the current work, solvent extraction, solvent fractionation, and repeated SiO₂ and ODS column chromatography yielded three new steroidal saponins along with a known one, avenacoside A (1). The chemical structures of the new saponins were determined based on extensive spectroscopic methods as well as chemical and biological reactions to be 26-O-β-D-glucopyranosylnuatigenin 3-O-α-L-rhamnopyranosyl-(1 → 2)-O-[(4-O-methyl)-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl-(1 → 4)]-β-D-glucopyranoside (2), 26-O-β-D-glucopyranosylnuatigenin 3-O-β-D-glucopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-(6-acetoxyl)-β-D-glucopyranoside (3), and 26-O-β-D-glucopyranosylnuatigenin 3-O-β-D-glucopyranosyl-(1 → 2)-O-[β-D-glucopyranosyl-(1 → 6)]-β-D-glucopyranoside (4), named lilyasiasides A-C, respectively. The aglycone of the saponins, a nuatigenin, is an atypical spirostanol sapogenin possessing a pentacyclic F-ring, furospirostane steroid, which is very rarely occurred in Lilium species.