Abstract

A new indole alkaloid N′-formylserotonin (1), along with five known indole alkaloids N′-methylserotonin (2), 5-hydroxy-1H-indole-3-carbaldehyde (3), N-acetylserotonin (4), 6-hydroxy-1-oxo-3,4-dihydro-β-carboline (5), and bufoserotoin C (6), were isolated from the water extract of traditional Chinese medicine Chansu. Their structures were elucidated on the basis of spectral analyses. The cytotoxicities of 1–6 against human lung adenocarcinoma epithelial cells A549 were tested using the MTT method. Compound 6 exhibited stronger cytotoxic effect than 5-FU, and 1–5 showed no cytotoxic effects. Bufoserotonin C is one of the cytotoxic components in water-soluble extract of Chansu.