Ascomycin

Ascomycin (Immunomycin; FR-900520; FK520) is an ethyl analog of Tacrolimus (FK506) with strong immunosuppressant properties. Ascomycin is also a macrocyclic polyketide antibiotic with multiple biological activities such as anti-malarial, anti-fungal and anti-spasmodic. Ascomycin prevents graft rejection and has potential for varying skin ailments research^[1][2]. In Vitro: Ascomycin (FR-900520) suppresses immune response in vitro with an IC₅₀ value of 0.55 nM for mouse mixed lymphocyte reaction^[1].
Ascomycin is a powerful calcium-dependent serine/threonine protein phosphatase (calcineurin [CaN], protein phosphatase 2B) inhibitors. Its mechanism of action involves the formation of a molecular complex with the intracellular FK506-binding protein-12 (FKBP12), thereby acquiring the ability to interact with CaN and to interfere with the dephosphorylation of various substrates^[3]. In Vivo: Ascomycin (FR-900520; i.m.; 0.32-32 mg/kg; 5 days a week; for 2 weeks) clearly prolongs skin allograft survival in rats^[1].