Two new indole alkaloids from Vinca herbacea L.

Six indole alkaloids were isolated from the aerial parts of Vinca herbacea Waldst. et Kit. Structures of the isolated compounds were elucidated as two new alkaloids, 10-methoxyraucaffrinoline (1) and 11-methoxyburnamine (2), and four known alkaloids, picrinine (3), burnamine (4), caboxine A (5) and elegantine (6) by intensive 1D-and 2D-NMR spectroscopic techniques. Antioxidant and anticholinesterase activities were investigated for the methanol, alkaloidal and non-alkaloidal extracts of V. herbacea and isolated alkaloids (1-3, 6). The alkaloidal extract was found to be active in the three tested antioxidant assays and exhibited significant lipid peroxidation inhibitory and DPPH free radical scavenging activities. The alkaloidal extract also exhibited high anticholinesterase activity against AChE and BChE enzymes similar to galanthamine. However, none of the tested alkaloids 1-3, and 6 were found to be active in the tested antioxidant and anticholinesterase systems. The alkaloids 1, 2, 4, and 6 were also evaluated for cytotoxic activity against the MCF7 and HT29 cell lines, and showed no activity. (C) 2011 Phytochemical Society of Europe. Published by Elsevier B. V. All rights reserved.