Isopimarane-type diterpenoids from the rhizomes of Kaempferia galanga L. and their biological activities

Fourteen isopimarane diterpenoids (1-14) were isolated from the rhizomes of Kaempferia galanga, including four new compounds (1-4). The isolated secondary metabolites were identified through analysis of spectroscopic (1 D and 2 D NMR) and mass spectrometric data, together with X-ray diffraction studies. Compounds 4-5, 7-11, and 13 showed strong antimalarial activities, with IC50 values in the range of 1.46-3.99 μg/mL. Moreover, compounds 4, 5, 8, and 12 showed cytotoxicity against KB cell line with IC50 values in the range of 6.13-38.2 μg/mL, while compounds 4, 5, and 12 showed cytotoxicity against MCF-7 cell line with IC50 values in the range of 11.75-47.4 μg/mL. Eventually, the isolated compounds were screened against six bacterial strains and Mycobacterium tuberculosis, demonstrating weak to moderate activities.