Cytotoxic diterpenes from the root tuber of Curcuma wenyujin

Bioassay-guided fractionation of ethanolic extract from the root tuber of Curcuma wenyujin afforded three new diterpenes, curcumrinols A-C (1-3), where 2 is the (14S)-epimer of 1. The structures of 1-3 were established on the basis of spectroscopic analysis, mainly NMR and MS. 1-3 were tested in vitro for their cytotoxic activity against the HL-60 and K562 cancer cells. Among the compounds tested, 1 exhibited medium cytotoxicity against K-562 and HL60 human cancer cells with IC50 values of 11.2 and 3.2 mu g/ml, respectively. However, 2 showed only weak activity against the above cancers cells, which suggested that C(14) may be an important position for cytotoxic activity.