Alpneumines A–H, new anti-melanogenic indole alkaloids from Alstonia pneumatophora
摘要:
Eight new indole alkaloids, alpneumines A-H (1-8) were isolated from the Malaysian Alstonia pneumatophora (Apocynaceae) and their structures were determined by MS and 2D NMR spectroscopic methods. Alpneumines E and G (5 and 7), vincamine, and apovincamine showed anti-melanogenesis in B16 mouse melanoma cells. (C) 2010 Elsevier Ltd. All rights reserved.
The dimeric products (la-c) have been prepared by treatment of N-oxides derived from some indole alkaloids. Their structures have been elucidated by detailed NMR investigations and the structure of 1c determined by X-ray analysis. The importance of the E2-type trans-axial elimination of the N-acyloxy intermediate in the dimer formation has also been established. The iminium salts 4a-b and the derived
Eight new indole alkaloids, alpneumines A-H (1-8) were isolated from the Malaysian Alstonia pneumatophora (Apocynaceae) and their structures were determined by MS and 2D NMR spectroscopic methods. Alpneumines E and G (5 and 7), vincamine, and apovincamine showed anti-melanogenesis in B16 mouse melanoma cells. (C) 2010 Elsevier Ltd. All rights reserved.