Diterpenoids from the stem barks of Croton robustus.

Three compounds were isolated from the stem barks of Croton robustus. Their structures were elucidated as trachyloban-19-oic acid, trachyloban-19-ol and poilaneic acid by spectroscopic analysis. Among them, trachyloban-19-ol and methyl trachyloban-19-oate exhibited weak cytotoxic activity against gastric carcinoma and colon carcinoma with ED50 of 9.