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 degrees C (dec.); UVmax 225.307 nm) possesses a strong antimicrobial activity against gram-positive 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 LC50 of maduramycin in mice was greater than 250 mg/kg on intraperitoneal administration. Fermentation, isolation, and some of the chemical and biological properties of this new antibiotic are described.