Fermentation, isolation, and biological activity of maduramycin: A new antibiotic from Actinomadura rubra

In a continuing search for new antibiotics, the species Actinomadura rubra (Sveshnikova et al.) J. MEYER et M. SVESHNIKOVA 1974 (strain IMET 13001) was found to produce a red pigment with indicator properties, designated maduramycin. The pigment (C28H22O10; m.w. 518 m/e−; m.p. 305‐310 °C (dec.); uvmax 225.307 nm) possesses a strong antimicrobial activity against grampositive bacteria, including strains which produce inactivating enzymes for some commercial antibiotics. Maduramycin forms a complex with serum albumin, but no complex formation with DNA was observed using absorption spectroscopic and polarographic methods. Maduramycin additionally inhibits the action of some enzymes. The LD50 of maduramycin in mice was > 250 mg/kg on intraperitoneal administration. Fermentation, isolation, and some of the chemical and biological properties of this new antibiotic are described.