H. K. Abbas, W. C. A. Gelderblom, M. E. Cawood and W. T. Shier. Biological activities of fumonisins, mycotoxins from Fusarium moniliforme, in jimsonweed ( Datura stramonium L.) and mammalian cell cultures. Toxicon 31, 345–353, 1993.—Fumonisins A 1, A 2, B 1, B 2 and B 3 are a series of mycotoxins produced by strains of Fusarium moniliforme. Fumonisins are hydroxylated long-chain alkylamines esterified with propanetricarboxylic acid moieties that represent approximately half the mol. wt of the toxins. The A-series fumonisins are N-acetylated, whereas the B series contains free amino groups. Hydrolytic removal of the propanetricarboxylic acid moieties from fumonisins B 1 and B 2 yields the corresponding aminopentols, AP 1 and AP 2, respectively. These compounds were tested for toxicity on widely differing bioassay systems, representing plant and animal systems. The plant bioassay system employed jimsonweed ( Datura stramonium L.) leaves and leaf discs in which toxicity was detected as electrolyte leakage, photobleaching and quantitation of chlorophyll reduction. The animal bioassay system employed cultured mammalian cell lines in which toxicity was detected as inhibition of cell proliferation. Fumonisins B 1, B 2 and B 3 at 50 μg/ml or less were effective toxins after exposure periods greater than 24 hr in all plant and animal bioassay systems examined, except 3T3 mouse fibroblasts, whereas fumonisins A 1 and A 2 exhibited little or no activity. However, the hydrolytic degradation products AP 1 and AP 2 exhibited toxicity similar to or greater than B-series fumonisins in all test systems, including substantial toxicity to 3T3 mouse fibroblasts.