D788-1

A daunorubicin-blocked mutant strain RPM-5 derived from a new baumycin-producing Streptomyces sp. D788 accumulated a major precursor metabolite D788-1 (10-carboxyl-13-deoxocarminomycin) and nine minor metabolites in the culture broth. Five among them were new with a substituent at C-10 or the altered side chains at C-9. Isolation, purification and identification of all anthracycline metabolites produced by strain RPM-5 are described with their antitumor activities against L1210 cells.

Two new anthracycline antibiotics, 10-epi-oxaunomycin and 10-epi-11-deoxyoxaunomycin, were photochemically obtained from anthracycline metabolites D788-1 (10-carboxy-13-deoxocarminomy-cin) and D788-3 (10-carboxy-11-deoxy-13-deoxocarminomycin) and were examined for their growth inhibitory activities on cultured L1210 leukemic cells. Effects of the S configuration of C-10 and a hydroxyl group at C-11 on the bioactivity are discussed in comparison with oxaunomycin and 11-deoxyoxaunomycin.

Biosynthetically blocked mutants were obtained from a baumycin-producing Streptomyces sp. D788 newly isolated from soil. The first mutant isolated was a baumycin-negative but daunorubicin-accumulating mutant with a loss of 4'-substitution activity, from which all other blocked mutants were successively derived. These included a known 11-deoxydaunorubicin-producing mutant and several new types of mutants which produced mainly 10-carboxy-13-deoxocarminomycin, 10-methoxycarbonyl-13-deoxocarminomycin, their 11-deoxy derivatives or a precursor aglycone, respectively. In this paper, all the anthracycline components produced by the parent strain and its two known blocked mutants, a daunorubicin producer and a 11-deoxydaunorubicin producer, are also determined by HPLC and five new components are isolated. Cytotoxicities in vitro of all the components against L1210 cell culture are also described.