Iso-rhodomycin A, ein neues Antibioticum aus Streptomyces purpurascens, Rhodomycine, III. Mitteil.1); Antibiotica aus Actinomyceten, XXXII. Mitteil2)

Rhodomycin analogues from Streptomyces purpurascens: isolation, characterization and biological activities

During a screening program for bioactive natural products, a potential Streptomyces sp was isolated from soil. On the basis of biochemical, cultural, physiological and 16S rRNA gene analysis, it was identified as Streptomyces purpurascens. The isolate was grown in liquid medium and the crude antibiotic complex was obtained by ethyl acetate extraction. Seven purified fractions were obtained by preparative Thin Layer Chromatography (TLC). Acid hydrolysis of each fraction and subsequent TLC led to the identification of aglycones and sugars indicating these compounds to be Rhodomycin and its analogues. The identity of these compounds was established on the basis of UV-visible and FT-IR spectra and comparison with published data. The compounds were active against Gram-positive bacteria. Compound E, identified as Rhodomycin B, was found to be the most potent compound with an MIC of 2 μg/ml against Bacillus subtilis. Compounds A and F identified as α2-Rhodomycin II and Obelmycin respectively, and Compound E exhibited an IC50 of 8.8 μg/ml against HeLa cell line but no cytotoxicity was found against L929.

Effect of 5-azacytidine and sinefungin on Streptomyces development

The effect of two DNA-methyltransferase inhibitors, 5-azacytidine (5azaC) and sinefungin (Sf), on the development of Streptomyces antibioticus ETH7451 (Sa) was studied. Pulse labeling experiments and SDS-PAGE analysis of proteins from cells grown in sporulation synthetic medium showed that both inhibitors affect a limited number of systems. Synthesis of the antibiotic rhodomycin was increased in the presence of 5azaC. 5azaC also stimulated the production of actinorhodin in cultures of S. coelicolor A3(2) grown in minimal medium. The analog did not affect the expression of whiB and whiG, two sporulation genes from S. coelicolor A3(2) whose homologues are present in Sa. Overall results indicated that 5azaC and Sf affect specific events associated with differentiation and secondary metabolism in Streptomyces.

Leukaemomycin, an antibiotic with antitumor activity. I. Screening, fermentation, and biological activity

A Streptomyces strain belonging to S. griseus (Krainski) Waksman et Henrici 1948 sensu Hütter (1967) was found to produce an antibiotic designated as leukaemomycin. The red-pigment antibiotic, having antimicrobial and antitumor activity in vitro and in vivo, was isolated from C-, N-, and Fe-containing cultures of the strains IMET JA 3933, IMET JA 5570, IMET JA 10086, and IMET JA 10431. Leukaemomycin has indicator properties and is produced by the classic procedures of submerged fermentation. The crude base of leukaemomycin consists of 4 main components, designated as leukaemomycin A, B, C, and D. The biological activity of the main components leukaemomycin B and C was compared. The biological activity and the physicochemical properties of leukaemomycin C are identical with known properties of the anthracycline antibiotic daunorubicin.