Cytotoxic Oleanane‐Type Saponins from the Leaves of Albizia anthelmintica Brongn.

Two new oleanane‐type saponins: β ‐ d ‐xylopyranosyl‐(1 → 4)‐6‐deoxy‐ α ‐ l ‐mannopyranosyl‐(1 → 2)‐1‐ O ‐{(3 β )‐28‐oxo‐3‐[(2‐ O ‐ β ‐ d ‐xylopyranosyl‐ β ‐ d ‐glucopyranosyl)oxy]olean‐12‐en‐28‐yl}‐ β ‐ d ‐glucopyranose ( 1 ) and 1‐ O ‐[(3 β )‐28‐oxo‐3‐{[ β ‐ d ‐xylopyranosyl‐(1 → 2)‐ α ‐ l ‐arabinopyranosyl‐(1 → 6)‐2‐acetamido‐2‐deoxy‐ β ‐ d ‐glucopyranosyl]oxy}olean‐12‐en‐28‐yl] β ‐ d ‐glucopyranose ( 2 ), along with two known saponins: (3 β )‐3‐[( β ‐ d ‐Glucopyranosyl‐(1 → 2)‐ β ‐ d ‐glucopyranosyl)oxy]olean‐12‐en‐28‐oic acid ( 3 ) and (3 β )‐3‐{[ α ‐ l ‐arabinopyranosyl‐(1 → 6)‐[ β ‐ d ‐glucopyranosyl‐(1 → 2)]‐ β ‐ d ‐glucopyranosyl]oxy}olean‐12‐en‐28‐oic acid ( 4 ) were isolated from the acetone‐insoluble fraction obtained from the 80% aqueous MeOH extract of Albizia anthelmintica Brongn . leaves. Their structures were identified using different NMR experiments including: 1 H‐ and 13 C‐NMR, HSQC, HMBC and 1 H, 1 H‐COSY, together with HR‐ESI‐MS/MS, as well as by acid hydrolysis. The four isolated saponins and the fractions of the extract exhibited cytotoxic activity against HepG‐2 and HCT‐116 cell lines. Compound 2 showed the most potent cytotoxic activity among the other tested compounds against the HepG2 cell line with an IC 50 value of 3.60μ m . Whereas, compound 1 showed the most potent cytotoxic effect with an IC 50 value of 4.75μ m on HCT‐116 cells.