- A group of peptide antibiotic agents, isolated from several species of Streptomyces (originally Actinomyces), that are active against Gram-positive bacteria, fungi, and neoplasms. Actinomycins are chromopeptides, most containing the chromophore actinocin, and are derivatives of phenoxazine that differ in their amino acid s and their sequence in the peptide chains; they form complexes with DNA and therefore inhibit RNA synthesis, primarily the ribosomal type.- a. C SYN: cactinomycin.- a. D SYN: dactinomycin.- a. F1 KS4; produced by a. C-elaborating strains of Streptomyces chrysomallus; used as an antineoplastic agent.
* * *ac·ti·no·my·cin -'mīs-ən n any of various red or yellow-red mostly toxic polypeptide antibiotics isolated from soil bacteria (esp. Streptomyces antibioticus) specif one used to inhibit DNA or RNA synthesis
* * *ac·ti·no·my·cin (ak″tĭ-no-miґsin) a large, complex family of antibiotics obtained from cultures of various species of Streptomyces, which have antibacterial, antifungal, and cytotoxic properties. Actinomycin D (see dactinomycin) is an antineoplastic agent.
Medical dictionary. 2011.