Eight new bisindole alkaloids, melosuavines A C (1-3), having an aspidosperma-scandine linkage, melosuavines D F (4-6), possessing an aspidosperma-aspidosperma skeleton, and melosuavines G and H (7 and 8) of the aspidosperma-venalatonine type, tenuicausine (9), and melodinine J (10) were isolated from the twigs and leaves of Melodinus suaveolens. The structures of 1-8 were elucidated by extensive spectroscopic methods, and compounds 9 and 10 were identified by comparison with data in the literature. The relative configuration 9 was determined from the ROESY spectrum, and some NMR signals were reassigned. Compounds 1, 2, 4-6, 8, and 10 exhibited low micromolar cytotoxicity against one or more of five human cancer cell lines.
1.Chinese Acad Sci, Kunming Inst Bot, State Key Lab Phytochem & Plant Resources West Ch, Kunming, Peoples R China 2.Chinese Acad Sci, Grad Sch, Beijing, Peoples R China 3.Kunming Fengshanjian Pharmaceut Corp, Kunming, Peoples R China