Chemical Components in Hedera rhombea Leaves and Their Cytotoxicity

Two novel triterpene glycosides (1 and 2), 17 known triterpene glycosides (3-19), two known flavonoid glycosides (20 and 21), and two known norsesquiterpene glucosides (22 and 23) were isolated from Hedera rhombea (Araliaceae) leaves. The structures of 1 and 2 were determined by spectroscopic analysis, including two-dimensional NMR spectroscopy, and chromatographic analysis of the hydrolyzed products. The cytotoxicity of the isolated triterpene glycosides (1-19) against HL-60 human promyelocytic leukemia cells was evaluated. Compounds 9, 10, and 11 were cytotoxic to HL-60 cells with IC₅₀ values of 7.2, 21.9, and 32.8 µM, respectively. Other compounds isolated from the leaves were not cytotoxic at sample concentrations of 50 μM.