ARS | Publication request: Inhibitory effects of gossypol-related compounds on growth of Aspergillus flavus

Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 28, 2011
Publication Date: March 1, 2011
Citation: Mellon, J.E., Zelaya, C.A., Dowd, M.K. 2011. Inhibitory effects of gossypol-related compounds on growth of Aspergillus flavus. Letters in Applied Microbiology. 52:406-412.

Interpretive Summary: Aflatoxin is a very potent carcinogen and toxin that is produced by the fungus Aspergillus flavus. When this fungus infects cotton plants, 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). An investigation was undertaken to determine effects of gossypolone on fungal growth and production of aflatoxin. Gossypolone effected significant growth inhibition at the levels tested, and also significantly inhibited aflatoxin production in a different test system. Gossypolone shows promise as a fairly effective antifungal agent for use against A. flavus. 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: Gossypolone demonstrated growth inhibitory activity against Aspergillus flavus isolate AF13. Growth inhibition was concentration dependent, with a 50% effective dose of 90 µg gossypolone per mL of medium (165 µM). Growth inhibition levels of up to 95% were achieved with gossypolone concentrations of 25 to 200 µg per mL. In addition, presence of gossypolone appeared to stimulate production of fungal sclerotia. Using a liquid medium system, gossypolone demonstrated 82% inhibition of aflatoxin B1 biosynthesis when added at a concentration of 100 µg per mL of medium (183 µM).