Sesquiterpenoids from Bombax malabaricum.

Phytochemical investigation of the chemical constituents of the roots of Bombax malabaricum afforded nine cadinane sesquiterpenoids, including five new compounds (bombamalones A-D, 1-4; bombamaloside, 5), and four known compounds (isohemigossypol-1-methyl ester, 6; 2-O-methylisohemigossylic acid lactone, 7; bombaxquinone B, 8; and lacinilene C, 9). The structures of 1-5 were identified by spectroscopic methods and comparison with literature values. Compounds 1-9 were evaluated against the HGC-27 human gastrointestinal cancer cell line, but all were inactive (IC(50) >10 microM).