New ent-kaurane-type diterpenoid with cytotoxic activity from Croton mekongensis

A new ent-kaurane-type diterpenoid, crotonmekongenin A (1) together with two known compounds, epifriedelanol (2) and sitosterol glucoside (3) from the leaves and twigs of Croton mekongensis were isolated. The structure of these compounds was determined by spectroscopic analysis. The structure of the new ent-kaurane-type diterpenoid (1) was elucidated using spectroscopic technique and X-ray crystallography analysis. Moreover, the cytotoxicity of all extract and isolated compounds was tested for cytotoxicity against KKU-M213, FaDu, HT-29, MDA-MB-231, A-549, SH-SY5Y, and CL cell lines. Compound 1 showed significant cytotoxic activity (ED₅₀) on FaDu (0.48 µg/ml), HT-29 (0.63 µg/ml), and SH-SY5Y (0.45 µg/ml).