Cytotoxic triterpenoid saponins from Aesculus glabra Willd.

Twenty-four acylated polyhydroxyoleanene saponins were isolated from the seeds of Aesculus glabra. Sixteen of them, namely aesculiosides G1–G16 (1–16), were determined as compounds by spectroscopic and chemical analysis. The structural features of all 24 saponins are: (1) arabinofuranosyl units affixed to C-3 of the glucuronopyranosyl unit in the trisaccharide chain; (2) no 24-OH substitution; (3) C-2 sugar moiety substitution of the 3-O-glucuronopyranosyl unit is either glucopyranosyl or galactopyranosyl. The features of these isolated saponin structures provide more evidence for chemical taxonomy within the genus Aesculus. The cytotoxicity of the aesculiosides (1–16) were tested against A549 and PC-3 cancer cell lines with GI₅₀ from 5.4 to >25 μM.