Cytotoxic carbazole alkaloid derivatives from the leaves and stems of Murraya microphylla

Abstract Four new carbazole alkaloid derivatives, including a pair of enantiomers of the heterodimers of carbazole and phenylpropanoid ( 1a / 1b ) and two rare polyprenylated carbazole alkaloids ( 2 , 3 ), together with 19 known analogues ( 4 – 22 ), were isolated from the leaves and stems of Murraya microphylla . Their structures were established by UV, IR, 1D/2D NMR, and HRESIMS data analysis, and their absolute configurations were determined by comparison of experimental and calculated ECD data and the ECD exciton coupling method. All the isolates were evaluated for their cytotoxicities against HepG2, Du145, HCT-116, and HeLa tumor cell lines. Compounds 7 and 11 exhibited obvious cytotoxic effects on four cancer cell lines in a dose-dependent manner.