Fumonisins are a group of mycotoxins derived from species of the fungus Fusarium. Fumonisin B2 is a carcinogenic, toxic secondary metabolite that inhibits sphingosine acyltransferase. The alteration in sphingolipid metabolism leads to apoptosis, causing hepatoxicity and nephrotoxicity in animals.  Fumonisin B2 is more cytotoxic than its structural analog, fumonisin B1. FB2 is isolated from the fungi Fusarium moniliforme (aka Fusarium verticilliodies) and is often found as a contaminant in corn and other grains.

The removal of propane-1,2,3-tricarboxylic acid side chains produces hydrolyzed fumonisins, including hydrolyzed fumonisin B2. Hydrolyzed fumonisins may be found in alkaline cooked foods such as masa and tortillas. These forms have been found to more weakly inhibit sphingosine acyltransferase than their non-hydrolyzed form.