A New ent-kaurane Diterpene Glycoside from Seeds of Pharbitis nil

A new ent-kaurane diterpene glycoside, pharboside H (1), and three known compounds, benzyl β-D-glucopyranoside (2), 1-(4′-O-glucopyranosyl-4′-hydroxy-3′,5′-dimethoxyphenyl)-2{2′′,6′′-dimethoxy-4′′-[1-(E) propen-3-ol]-phenoxy}-propane-l,3-diol (3), and butyl caffeate (4), were isolated from the seeds of Pharbitis nil. The structure of the new compound 1 was elucidated by 1D and 2D data analysis and enzyme hydrolysis. All the isolated compounds 1–4 were reported from this source for the first time. Compounds 1–4 were tested for cytotoxicity against four human tumor cell lines in vitro using the sulforhodamine B bioassay.