Melodinines A-G, monoterpenoid indole alkaloids from Melodinus henryi.

Nineteen monoterpenoid indole alkaloids including seven new ones, melodinines A-G (1-7), were isolated from Melodinus henryi. The structures of the new compounds were elucidated using spectroscopic methods, and the structure of compound 4 was confirmed by single-crystal X-ray diffraction analysis. The known compounds were identified by comparing their spectroscopic data with those reported in the literature. All of the compounds were evaluated for cytotoxic activity against five human cancer cell lines, and compound 11 exhibited cytotoxicity against HL-60, SMMC-7721, A-549, and SK-BR-3 cells with IC50 values of 2.0, 16.8, 25.9, and 24.7 microM, respectively.