Ophiobolin C is a sesterterpenoid fungal phytoxin produced by many species of the genus Bipolaris. It has been identified as an antagonist of chemokine receptor CCR5 binding (IC50 = 40 μM) to the envelop protein gp120 and to CD4, which is known to mediate HIV-1 viral entry into cells. Ophiobolin C is also reported to be cytotoxic to chronic lymphocytic leukemia cells (LC50 = 8 nM).
