Isolation and biological activity of frankiamide.

An antibiotic produced by the symbiotic actinomycete Frankia strain AiPs1 was isolated from culture broth using optimized thin-layer chromatography and high-performance liquid chromatography (HPLC) methods. The novel compound that was isolated, dubbed frankiamide, displayed antimicrobial activity against all 14 Gram-positive bacterial strains and six pathogenic fungal strains tested. The pathogenic actinomycete Clavibacter michiganensis and the oomycete Phytophthora were especially susceptible. In addition to displaying antimicrobial activity, frankiamide also strongly inhibited 45Ca(2+) fluxes in clonal rat pituitary GH4C1 tumor cells and was comparable to a frequently used calcium antagonist, verapamil hydrochloride. The results of HPLC analysis, supported by both nuclear magnetic resonance and mass spectroscopy studies, showed that frankiamide has a high affinity for Na(+) ions.

Phenolics and betacyanins in red beetroot (Beta vulgaris) root: distribution and effect of cold storage on the content of total phenolics and three individual compounds.

The distribution of total phenolics and main betacyanins in red beetroot (Beta vulgaris) root was determined. Also, the subsequent effects of cold storage on the content of total phenolics, main betacyanins (betanin and isobetanin), and the main known ferulic acid ester (beta-D-fructofuranosyl-alpha-D-(6-O-(E)-feruloylglucopyranoside) were determined in the peel, which is the root part containing the largest amount of total phenolics. The content of total phenolics in the red beetroot water extracts was determined according to a modification of the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE). The compounds of interest were identified by HPLC-ESI-MS and NMR techniques, and the contents of compounds were determined by HLPC analyses. The total phenolic contents in various root parts were found to decrease in the order peel, crown, flesh. Significant differences in the contents of total phenolics and individual compounds were found when the effect of cold storage (5 degrees C, 0-196 days) on the constituents of the peel from intact roots was examined. In addition to the betacyanins of red beetroot peel found in our earlier study, tentative identifications of betanidin and feruloylamaranthin were made.

Hybrid anthracyclines from a genetically engineered Streptomyces galilaeus mutant.

The genetic engineering of antibiotic-producing Streptomyces strains is an approach that is emerging and ready to become established as a successful methodology in developing analogues of the original, pharmaceutically important, natural products obtained from the organisms. The current report highlights this succes by demonstrating the high-level production of novel anthracyclines. The biosynthetic pathways of the nogalamycin-producing Streptomyces nogalater and the aclacinomycin-producing S. galilaeus were combined by transferring the genes of S. nogalater polyketide synthetase into a nonproducing S. galilaeus mutant. The resulting anthracycline antibiotics that were produced possessed structural features characteristic of compounds from both of the undoctored Streptomycesstrains.

Incorrectly folded aromatic polyketides from polyketide reductase deficient mutants.

Compounds produced by the polyketide ketoreductase deficient Streptomyces mutants HO61 and P67 are described. The structures of the compounds indicate that ketoreductase activity is required for correct condensation of the polyketide chain in the biosynthesis of aromatic polyketides.