12alpha-hydroxystigmast-4-en-3-one: a new bioactive steroid from Toona ciliata (Meliaceae).

In a bioassay guided phytochemical investigation of Toona ciliata (Fam. Meliaceae), a new hydroxy steroidal ketone, 12alpha-hydroxystigmast-4-en-3-one (1) was isolated from the petroleum ether extract of the plant together with two known steroids and three C-methyl coumarins. The structure of 1 was established by means of spectroscopic analyses. Compound 1 was found cytotoxic in a brine shrimp lethality bioassay with LC50 of 9.9 microg/ml and it also showed significant antitumor activity with Ti50 value of 14.1 microg/ml in a potato disc bioassay.