Steroidal saponins from Asparagus officinalis and their cytotoxic activity

Two oligofurostanosides were isolated from the seeds of Asparagus officinalis L. and their structures characterized as 3-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-{alpha-L-rhamnopyranosyl-(1 --> 4)}-beta-D-glucopyranosyl]-26-O-[beta-D-glucopyranosyl]-(25R)-22 alpha-methoxyfurost-5-ene-3 beta,26-diol (methyl protodioscin) and its corresponding 22 alpha-hydroxy analogue (protodioscin). The structural identification was performed using detailed analysis of H-1- and C-13-NMR spectra including two-dimensional NMR spectroscopy (COSY, HMQC, NOESY and HMBC), and chemical conversions. These two compounds have been shown to inhibit the growth of human leukemia HL-60 cells in culture and macromolecular synthesis in a dose-dependent manner. The inhibitory effect on DNA synthesis was found to be irreversible.