Anthracyclines

Abstract

Anthracycline aminoglycosides represent a wide class of antibiotics obtained by submerged aerobic fermentation of different microorganisms belonging to the genus Streptomyces and are called anthracyclines because the aglycone moiety is a tetracyclic system bearing an anthraquinone chromophore. The anthracyclines are microbial metabolites belonging, from the biogenetic standpoint, to the large family of the polyketide natural products, comprising a wide range of biologically active structural groups: the antibacterial antibiotics, tetracyclines, and the macrolides of the erythromycin type; immunosuppressants such as FK506; antiparasitic compounds such as monensin; and the avermectins. These molecules are synthesized by multifunctional polyketide synthase enzymes, which catalyze repeated condensation cycles between simple acylthioesters with the formation of a growing carbon chain containing β keto groups. These keto groups may undergo a number of intramolecular reactions, leading to aromatic derivatives, such as the aglycone of the anthracyclines, the anthracyclinones, and a series of reductive steps. The final products are characterized by a considerable molecular diversity.