New anthracycline antibiotics produced by interspecific recombinants of streptomycetes. IV. Antimicrobial activity of iremycin

Abstract

The in vitro antimicrobial activity of iremycin (10-(alpha-L-rhodosaminyl)-gamma-rhodomycinone) was determined in comparison to that of doxorubicin, a 14-hydroxy-derivative of daunorubicin, which exhibited a strong antitumor activity and is useful in chemotherapy of human tumors. The MIC values determined by means of a standardized agar diffusion plate test indicated a lower antimicrobial activity of iremycin in vitro in comparison to that of doxorubicin. In contrast to doxorubicin, iremycin was highly active against Mycobacterium smegmatis, but five-fold less active than doxorubicin against Staphylococcus aureus, seven-fold less active against Bacillus subtilis, and twenty five-fold less active against Commamonas terrigena. Furthermore, iremycin was hundred-fold less active against a highly sensitive permeation mutant of Pseudomonas aeruginosa. No inducing activity on prophages in lysogenic E. coli cells was demonstrable for iremycin and no growth inhibition in the repair test was observable. In contrast, iremycin inhibited the multiplication of gamma-phages in the BIP test, but the MIC values of violamycin BI, doxorubicin and iremycin in this test system indicated that iremycin is two hundred fifty-fold less active than violamycin BI and ten-fold less active than doxorubicin. No serum binding was demonstrable for iremycin.