Cytotoxic triterpenoids and steroids from the bark of Melia azedarach.

Two new triterpenoids (1, 2) and two new steroids (3, 4) along with twelve related known compounds (5-16) were isolated from the bark of Melia azedarach. The new structures were elucidated by means of spectroscopic methods and molecular modeling studies and found to be 21,24-cycloeupha- 7-ene-3 beta,16 beta,21 alpha,25-tetrol (1), 3 beta-acetoxy-12 beta-hydroxy-eupha-7,24-dien-21,16 beta-olide (2), 29-hydroperoxy-stigmasta-7,24(28)E-dien-3 beta-ol (3), and 24 xi-hydroperoxy-24-vinyl-lathosterol (4). All isolated compounds were tested for their cytotoxic activity against three human cancer cell lines (A549, H460, HGC27) using the Cell-Titer Glo (TM) luminescent cell viability assay. Among them, compounds 2-4, 24 xi-hydroperoxy-24-vinyl-cholesterol (6), kulinone (7), meliastatin 3 (8), 3-oxo-olean-12-en-28-oic acid (10), and (22E,24S)-5 alpha,8 alpha-epidioxy-24-methyl-cholesta-6,22-dien-3 beta-ol (12) were found to have cytotoxic effects, with IC50 values of 5.6-21.2 mu g/mL.