Immunosuppressant

Cyclosporin A (CsA) is an immunosuppressant that has revolutionized organ transplantation through its use in the prevention of graft rejection. CsA binds to cyclophilin and suppresses its proline rotamase activity. The CsA-cyclophilin complex inhibits calcineurin, a type 2B phosphatase. It is an important diagnostic tool for the characterization of permeability transition-related phenomena. It inhibits mitochondrial permeability transition pore opening however, pore inhibition becomes less efficient at increasing Ca²⁺ loads and inhibition is transient. Inhibits staurosporin-induced apoptosis in cultured neural cells and rotenone-induced apoptosis in PC-12 cells. Inhibits cytochrome c release from mitochondria. Inhibits nitric oxide (NO) synthesis.

Isolated from Fusarium solani