Purpose: To identify and characterize the capacity of diverse botanically-derived polyphenols to inhibit
aflatoxin B1 (AFB1) production by
Aspergillus flavus
.
Methods: 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).
Results: 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.
Conclusion: 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.
