Answer to Question #150645 in Analytical Chemistry for roben

Question

Describe the mechanism of action of dactinomycin, mention the types of interactions,
structural features.
(drug chemistry)

Answer 1

Dactinomycin is an antineoplastic antibiotic. The drug has bacteriostatic activity, particularly against gram-positive organisms, but its cytotoxicity precludes its use as an anti-infective agent. Although the exact mechanism(s) of action has not been fully elucidated, the drug appears to inhibit DNA-dependent RNA synthesis by forming a complex with DNA by intercalating with guanine residues and impairing the template activity of DNA. Protein and DNA synthesis are also inhibited but less extensively and at higher concentrations of dactinomycin than are needed to inhibit RNA synthesis. Dactinomycin is immunosuppressive and also possesses some hypocalcemic activity similar to plicamycin.

Dactinomycin is a clear, yellowish liquid administered intravenously and most commonly used in treatment of a variety of cancers, it binds strongly, but reversibly, to DNA, interfering with synthesis of RNA (prevention of RNA polymerase elongation) and, consequently, with protein synthesis.

structural features

Dactinomycin (actinomycin D) is a crystalline antibiotic composed of a phenoxazone chromophore and two cyclic peptide chains obtained as a product of fermentation by Streptomyces parvulus. The drug intercalates into DNA between adjacent guanine–cytosine base pairs and inhibits DNA-directed RNA synthesis. Dactinomycin is rapidly distributed into tissues and has a prolonged terminal half-life.