Isogarcinol is a natural polyisoprenylated benzophenone first isolated from plant species in the genus Garcinia. It has immunosuppressant actions, inhibiting the protein phosphatasecalcineurin (IC50 = 36 μM) and suppressing the proliferation of T cells. Oral administration of isogarcinol in mice decreases delayed type hypersensitivity, prolongs graft survival in allogeneic skin transplants, suppresses inflammation in collagen-induced arthritis, and reduces clinical symptoms in experimental autoimmune encephalomyelitis. Isogarcinol inhibits the proliferation of HL-60 and PC-3 cancer cells (IC50s = 4 and 8 μg ml, respectively) through cell cycle arrest and apoptosis.
Dibefurin is a metabolite that inhibits the activity of calcineurin, a calcium calmodulin-dependent protein phosphatase involved in the activation of T lymphocytes.
Cyclosporin D is a metabolite of cyclosporin A, an immunosuppressant drug that binds cyclophilin D, inhibiting the phosphatase activity of calcineurin in T cells.
Selective inhibitor of Ca2+-calmodulin-dependent protein phosphatase (calcineurin) (IC50 ~ 10 μM). Does not inhibit PP1, PP2A or CaM kinase II (IC50 > 100 mM).