Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/12/2012
Publication Date: 2/13/2012
Citation: Mellon, J.E., Zelaya, C.A., Dowd, M.K., Beltz, S.B., Klich, M.A. 2012. Inhibitory effects of gossypol, gossypolone, and apogossypolone on a collection of economically important filamentous fungi. Journal of Agricultural and Food Chemistry. 60:2740-2745. Interpretive Summary: Aflatoxin is a very potent carcinogen and toxin that is produced by the fungus Aspergillus flavus. When this fungus infects oilseed crops, the developing seed can become contaminated with this toxin, rendering the product unusable for food or feed. Cotton plants contain high levels of gossypol that provides protection against insect predation and possibly additional defense functions. Gossypolone is an oxidative derivative of gossypol formed in animal systems (e.g. liver detoxification); apogossypolone is another oxidative derivative of gossypol. An investigation was undertaken to determine effects of these gossypol related compounds on fungal growth in a collection of agriculturally important filamentous fungi that included both plant and human pathogens. These terpenoid compounds were also tested for their effects on aflatoxin biosynthesis in A. flavus and A. parasiticus. Gossypolone and apogossypolone were more effective fungal growth inhibitors than gossypol, with the former producing 100% inhibition in all fungi tested except A. flavus. Apogossypolone displayed the most potent antiaflatoxigenic activity of the tested compounds, yielding greater than 94% inhibition in A. flavus and greater than 65% inhibition in A. parasiticus. This research will benefit oilseed breeders, producers and pathologists, and will aid in the formulation of methods to prevent aflatoxin contamination of food and feedstuffs.
Technical Abstract: Racemic gossypol and derivatives gossypolone and apogossypolone demonstrated significant growth inhibition against a diverse collection of filamentous fungi that included Aspergillus flavus, A. parasiticus, A. alliaceus, A. fumigatus, Fusarium graminearum, F. moniliforme, Penicillium chrysogenum, P. corylophilum and Stachybotrys atra. The compounds were tested at a concentration of 100 µg per mL. Racemic gossypol and apogossypolone induced growth inhibition values of up to 95%, whereas gossypolone effected 100% growth inhibition in all fungal isolates except A. flavus. Gossypolone demonstrated significant aflatoxin biosynthesis inhibition in A. flavus AF13 (B1, 76% inhibition). Apogossypolone was the most potent aflatoxin inhibitor, showing greater than 90% inhibition against A. flavus and greater than 65% inhibition against A. parasiticus (B1, 67%; G1, 68%). Gossypol was an ineffectual inhibitor of aflatoxin biosynthesis in both A. flavus and A. parasiticus.