PubMed Health⌕ Search

Biomedical subjects

Ralf Thiericke

Publications and source records attributed to Ralf Thiericke.

3 recordsLinked to original sources

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.

Isoflavones↗

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. The jenamidines have an unusual octahydro-pyrido[1,2-a]pyrimidine skeleton. Jenamidine A (1) shows antiproliferative effects against the chronic myeloid leukaemic cell line K-562. In addition, the new tricyclic sesquiterpenoid, africantriol (4) was isolated from the same strain.

Alkaloids↗