Jenamidines A to C: unusual alkaloids from Streptomyces sp. with specific antiproliferative properties obtained by chemical screening.

Three new naturally occurring bicyclic alkaloids, jenamidines A (1), B (2) and C (3), were discovered and isolated from the culture broth of Streptomyces sp. (strain HKI0297) via the chemical screening approach. Fermentation, isolation, structure and biological activities of these three new secondary metabolites are reported.

New 2-o-methylrhamno-isoflavones from Streptomyces sp.

Chemical screening with extracts of Actinomycetes strains resulted in the detection, isolation and structure elucidation of five new isoflavone glycosides from Streptomyces sp. (GT 51173): 5-O-alpha-L-rhamnopyranosyl genestein (genestein G1, 1), 5-O-alpha-L-rhamnopyranosyl-7-O-[2-O-(methyl)-alpha-L-rhamnopyranosyl] genestein (genestein G2, 2), 7,4'-O-di-[2-O-(methyl)-alpha-L-rhamnopyranosyl] daidzein (daidzein G1, 3), 6-O-methyl-7-O-[2-O-(methyl)-alpha-L-rhamnopyranosyl] daidzein (daidzein G2, 4) and 7-O-[2-O-(methyl)-alpha-L-rhamnopyranosyl] daidzein (daidzein G3, 5). As a striking structural feature, 2-5 bear one or two alpha-L-rhamnopyranosyl sugar moieties with methoxy groups in an axial position at C-2.