Novel indole and quinoline alkaloids from Melodinus yunnanensis

Abstract

6/7-Seco rearranged spiro-indolone alkaloids, meloyunines A (1) and B (2) and a monoterpenoid quinoline alkaloid meloyunine C (3) together with its possible intermediate 14,15-dehydromelohenine B (4), and their precursor Δ14-vincamenine (5) were isolated from Melodinus yunnanensis. All structures were elucidated based on NMR, FTIR, UV, and MS spectroscopic data. The isolation of monoterpenoid indole, quinoline, and its immediate from the same plant chemically supported the biosynthesis of quinoline from indole. Compound 2 was cytotoxic against several human cancer cell lines. [InlineMediaObject not available: see fulltext.].