Cytotoxic Indole Alkaloids from Melodinus fusiformis and M. morsei

AimTo investigate antitumor indole alkaloids from the leaves and twigs of Melodinus fusiformis and M. morsei.MethodsThe indole alkaloids were isolated by column chromatography and preparative HPLC. Their structures were elucidated by 1D and 2D-NMR spectroscopic methods in combination with MS experiments. Their cytotoxicity were evaluated using the MTT method in 96-well microplates.ResultsTwo new bisindole alkaloids, melofusine I (1) and melomorsine I (2), together with 22 known indole alkaloids 3–24, were isolated from M. fusiformis and M. morsei. All isolated compounds were tested against five human tumor cell lines, SW480, SMMC-7721, HL-60, MCF-7 and A-549.ConclusionCompounds 1 and 2 are new bisindole alkaloids, whereas, compounds tabersonine (3) and 19S-vindolinine (14) showed significant cytotoxicity against the above-mentioned five human tumor cell lines.