Cytotoxic and renoprotective diterpenoids from Clerodendranthus spicatus.

Three new diterpenoids, spicatusenes A-C (1-3), and eleven known ones (4-14) were isolated from the aerial parts of Clerodendranthus spicatus. Their structures were identified by spectroscopic methods. The cytotoxic activities of all the compounds against human cancer cells (HL-60, SMMC-7721, A-549, MCF-7, and SW-480) were examined and found that compounds 2, 3, 6, 8, 10, and 13 were active against one or more cancer cell lines. Besides, the renoprotective effects of all the isolates in TGF-β1-induced rat kidney fibroblasts revealed that compounds 3-7, 9, 13, and 14 were beneficial for renal fibrosis. Finally, a plausible biosynthetic pathway for 1 via a Hantzsch-type reaction was proposed.