A novel oligosaccharide ester from Syringa pubescens.

Pubescenside A (1), a novel oligosaccharide ester, has been isolated from the flowers of Syringa pubescens, together with five known compounds D-mannitol (2), meso-inositol (3), hydrostytosol (4), glucose (5), and sucrose (6). The structure of 1 was elucidated as 1-O-[beta-D-glucopyranosyl-(1-6)-beta-D-galactopyranosyl-(1-1)-beta-D-galactopyranosyl-6]-4,4-dimethylpelargonicate by chemical and spectroscopic means. The water extract of the flowers and leaves of S. pubescens showed cytotoxicity against L2215 cell line (IC(50)=78 microg/ml).