Cytotoxic Alangium alkaloids from Alangium longiflorum

Abstract: 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 ED50 values of 0.013 and 0.062μM, 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. [Copyright &y& Elsevier]