Oleanane‐type Saponins from Glochidion hirsutum and Their Cytotoxic Activities

Five new oleanane‐ type saponins, hirsutosides A – E, were isolated from the leaves of Glochidion hirsutum ( Roxb .) Voigt . Their structures were elucidated as 21 β ‐benzoyloxy‐3 β ,16 β ,23,28‐tetrahydroxyolean‐12‐ene 3 ‐O‐β ‐ d ‐glucopyranoside ( 1 ), 21 β ‐benzoyloxy‐3 β ,16 β ,23,28‐tetrahydroxyolean‐12‐ene 3 ‐O‐β ‐ d ‐glucopyranosyl‐(1 → 3) ‐β ‐ d ‐glucopyranoside ( 2 ), 21 β ‐benzoyloxy‐3 β ,16 β ,23,28‐tetrahydroxyolean‐12‐ene 3 ‐O‐ 6‐acetyl‐[ β ‐ d ‐glucopyranosyl‐(1 → 3)] ‐β ‐ d ‐glucopyranoside ( 3 ), 21 β ‐benzoyloxy‐3 β ,16 β ,23,28‐tetrahydroxyolean‐12‐ene 3 ‐O‐β ‐ d ‐glucopyranosyl‐(1 → 3) ‐〈 ‐ l ‐arabinopyranoside ( 4 ), and 21 β ‐benzoyloxy‐3 β ,16 β ,23‐trihydroxyolean‐12‐ene‐28‐al 3 ‐O‐β ‐ d ‐glucopyranosyl‐(1 → 3) ‐α ‐ l ‐arabinopyranoside ( 5 ). All isolated compounds were evaluated for cytotoxic activities on four human cancer cell lines, HepG‐2, A‐549, MCF ‐7, and SW ‐626 using the SRB assay. Compounds 1 , 2 , 4 , and 5 showed significant cytotoxic activities against all human cancer cell lines with IC 50 values ranging from 3.4 to 10.2 μ m . Compound 3 containing acetyl group at glc C(6″) exhibited weak cytotoxic activity with IC 50 values ranging from 47.0 to 54.4 μ m .