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-β-d-glucopyranosyl-(1–6)-β-d-galactopyranosyl-(1–1)-β-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 (IC₅₀ = 78 μg/ml).