Cytotoxic Isopimarane Diterpenoids from Kaempferia koratensis Rhizomes

Two new isopimarane diterpenoids, koratanes A and B, were identified from the rhizomes of Kaempferia koratensis Picheans., Zingiberaceae, together with thirteen known isopimarane diterpenoids. Spectroscopic evidence was used to determine the structures. CD spectra were applied to determine the absolute configuration of koratanes A. The isolated compounds were evaluated for their cytotoxicity against human HL-60 and MOLT-3 leukemia cells, T-47D breast cancer cells, and MRC-5 healthy cells. Among the isolates, compounds named koratanes A, koratanes B, boesenberrol J, saraburane B, kaempulchraol A, kaempulchraol B, kaempulchraol C, and curcumrinol A showed IC₅₀ values ranging from 42.10 to 56.57 μM against MOLT-3 cancer cell line. Koratanes B and galangol D were the most active against HL-60 and T-47D with IC₅₀ values of 55.62 and 79.51 μM, respectively. Graphical Abstract: [Figure not available: see fulltext.].