The Inhibitory Activity of Salicylaldehyde Compounds on <i>Aspergillus</i> Species and Their Effects on Aflatoxin Production and Crop Seed Germination
2024
Jong H. Kim | Kathleen L. Chan | William M. Hart-Cooper | DeAngela Ford | Kaydren Orcutt | Siov Bouy L. Sarreal | Jeffrey D. Palumbo | William J. Orts
Crops such as tree nuts, corn and peanut are highly susceptible to infestation by the aspergilli <i>Aspergillus flavus</i> or <i>Aspergillus parasiticus</i> and subsequent aflatoxin (AF) contamination, a serious threat to public food safety. Conventional control of the aspergilli has been through the application of fungicides; however, certain fungicides at sub-optimal doses have been correlated with increased production of mycotoxins including AF. Natural products (NP) have been a potential source of antifungal agents. In this study, we performed risk assessment testing, for which thirteen NP/derivatives (generally recognized as safe) were examined at sub-inhibitory concentrations to determine the enhancement of AF production in aspergilli. We found that benzaldehyde derivatives or thymol (THY) enhanced AF production in aspergilli, while 4-isopropyl-3-methylphenol (4I3M), a synthetic analog of the NP THY and carvacrol, or salicylaldehyde (SLD) exerted a potent antifungal or mycotoxin-inhibitory effect. In seed testing (corn, pistachio kernels), SLD effectively prevented fungal growth as a fumigant, while 4I3M completely inhibited AF production at ≥1.0 mM. Therefore, we concluded that NP/derivatives that do not have any significant environmental impact can be a potent source of antifungal or anti-mycotoxigenic agents, either in their nascent form or as leads for more effective derivatives; however, NP should be applied at optimum concentrations to prevent the abnormal enhancement of mycotoxin production by fungi.
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