To identify and characterize the capacity of diverse botanically-derived polyphenols to inhibit
aflatoxin B1 (AFB1) production by Aspergillus flavus
A tea-derived polyphenol mixture and numerous individual polyphenols were tested for their
effects on A. flavus
growth and AFB1 production. Fungal spores were cultured for 60 h with polyphenols
(range 0 ‒ 1,000 μg/mL). The fungi were enumerated by hemocytometry, and AFB1 in culture
supernatants was quantified by high-performance liquid chromatography (HPLC).
Neither the tea-derived polyphenol mixture nor individual polyphenol compound, except
quercetin, inhibited A. flavus
growth. Quercetin detectably inhibited growth at 800 μg/mL; none of the
remaining polyphenols inhibited fungal proliferation, even at 1,000 μg/mL. However, catechin mixture
and all individual polyphenols differentially inhibited fungal AFB1 biosynthesis. Non-ester catechin
derivatives revealed stronger inhibitory activity than ester derivatives.
Quercetin exhibits the strongest inhibitory effect on AFB1 production and is the only test
compound that also inhibits fungal proliferation. Botanically-derived polyphenols are, therefore,
promising reagents for controlling fungal contamination and associated toxic aflatoxin deposition in
harvested crops and in food processing operations.