| Abstract
| - Two new bisindole alkaloids, vingramine (1) and methylvingramine (2), were isolated from theseeds of Catharanthus roseus, Apocynaceae. The structures were determined by HRFABMS aswell as one- and two-dimensional NMR experiments. They possess a new bisindole skeletoninvolving 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 areconnected via an 11,10‘-biphenyl linkage. The relative configuration was determined by NMRanalysis. 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 absoluteconfiguration of 10 stereocenters: 2S, 7R, 15R, 16R, 3‘R, 14‘S, 15‘S, 16‘R, 19‘S, and 20‘R. Thealkaloids 1 and 2 display, in vitro, cytotoxic activity against nasopharynx carcinoma KB cells, IC505 and 6 μM (4 and 5 μg/mL).
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