Cytotoxic Alangium alkaloids from Alangium longiflorum

Seven alkaloids ( 1 – 7 ) were isolated from the stem bark of Alangium longiflorum . Compound 1 , (−)-10- O -demethylisocephaeline, was isolated for the first time as a naturally occurring product from a plant source. All structures were elucidated by detailed spectroscopic analysis. Biological evaluation showed that 2 , 10- O -demethylcephaeline, exhibited potent cytotoxic activity against human lung carcinoma (A549) and breast adenocarcinoma (MCF-7) with ED 50 values of 0.013 and 0.062 μM, respectively. The stereoisomer 1 was less potent than 2 , and related compounds with different hydroxy/methoxy substitution patterns were also less potent or inactive. Thus, compound 2 merits attention as a cytotoxic lead for further study.