Cytotoxic ent-kaurane diterpenoids from Salvia cavaleriei

Fifteen new ent-kaurane diterpenoids, compounds 1-15, and two known analogues, 4-epi-henryine A (16) and leukamenin E (17), were isolated from the whole plants of Salvia cavaleriei. The structures of the new compounds were established by spectroscopic methods, and their absolute configurations were determined by electronic circular dichroism and single-crystal X-ray diffraction analyses with Cu Kα radiation. Compounds 1-15 were evaluated for their cytotoxicity against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7, and SW480, as well as the noncancerous Beas-2B cell line. Compounds 1-10, 12, 14, and 15 showed broad-spectrum cytotoxicity, with compounds 1, 3, 6-10, 12, and 15 exhibiting more potent cytotoxicity than the positive control, cis-platin, with IC50 values ranging from 0.65 to 6.4 μM.