title: A New Structural Class of Bisindole Alkaloids from the Seeds of Catharanthus roseus: Vingramine and Methylvingramine.
abstract: Two new bisindole alkaloids, vingramine (1) and methylvingramine (2), were isolated from the seeds of Catharanthus roseus, Apocynaceae. The structures were determined by HRFABMS as well as one- and two-dimensional NMR experiments. They possess a new bisindole skeleton involving an indole alkaloid part B with loss of 5',6'-ethylene, a C7'-C16' linkage, a 14'-O-19'-tetrahydrofuran, and a N-4'-isobutyramide group. The 12-methyl vincorine part A and part B are connected via an 11,10'-biphenyl linkage. The relative configuration was determined by NMR analysis. Biogenetic considerations suggested a rearrangement and a double fragmentation at C6'/C7' and N4'/C5' for the formation of 1 from strictamine, further allowing deduction of the absolute configuration of 10 stereocenters: 2S, 7R, 15R, 16R, 3'R, 14'S, 15'S, 16'R, 19'S, and 20'R. The alkaloids 1 and 2 display, in vitro, cytotoxic activity against nasopharynx carcinoma KB cells, IC(50) 5 and 6 &mgr;M (4 and 5 &mgr;g/mL).
authors.affiliation: Laboratoire de Chimie, CNRS URA 401, Muséum National d'Histoire Naturelle, 63 Rue Buffon 75005 Paris, France, and Centre de Recherches Helena Rubinstein, 188 Rue P. Hochart, Chevilly-Larue BP 553, 94152 Rungis Cedex.
authors.forename: Akino
authors.initials: A
authors.lastname: Jossang
authors.forename: Pierre
authors.initials: P
authors.lastname: Fodor
authors.forename: Bernard
authors.initials: B
authors.lastname: Bodo