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Toxins 2017, 9(3), 87;

Identification of the Anti-Aflatoxinogenic Activity of Micromeria graeca and Elucidation of Its Molecular Mechanism in Aspergillus flavus

Toxalim, Université de Toulouse, INRA, ENVT, INP Purpan, UPS, Toulouse F-31027, France
Laboratoire de Mycologie et Sécurité des Aliments (LMSA), Département des sciences de la vie et de la terres - Biochimie, Faculté des Sciences, Université Saint-Joseph, P.O. Box 17-5208, Mar Mikhael Beirut 1104 2020 Lebanon
Laboratory of Microbiology, Department of Natural Sciences and Earth, Faculty of Sciences I, Lebanese University, Hadath Campus, P.O. Box 5, Beirut, Lebanon
Author to whom correspondence should be addressed.
Academic Editor: Ting Zhou
Received: 18 January 2017 / Revised: 22 February 2017 / Accepted: 24 February 2017 / Published: 1 March 2017
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Of all the food-contaminating mycotoxins, aflatoxins, and most notably aflatoxin B1 (AFB1), are found to be the most toxic and economically costly. Green farming is striving to replace fungicides and develop natural preventive strategies to minimize crop contamination by these toxic fungal metabolites. In this study, we demonstrated that an aqueous extract of the medicinal plant Micromeria graeca—known as hyssop—completely inhibits aflatoxin production by Aspergillus flavus without reducing fungal growth. The molecular inhibitory mechanism was explored by analyzing the expression of 61 genes, including 27 aflatoxin biosynthesis cluster genes and 34 secondary metabolism regulatory genes. This analysis revealed a three-fold down-regulation of aflR and aflS encoding the two internal cluster co-activators, resulting in a drastic repression of all aflatoxin biosynthesis genes. Hyssop also targeted fifteen regulatory genes, including veA and mtfA, two major global-regulating transcription factors. The effect of this extract is also linked to a transcriptomic variation of several genes required for the response to oxidative stress such as msnA, srrA, catA, cat2, sod1, mnsod, and stuA. In conclusion, hyssop inhibits AFB1 synthesis at the transcriptomic level. This aqueous extract is a promising natural-based solution to control AFB1 contamination. View Full-Text
Keywords: Aflatoxin B1; Aspergillus flavus; hyssop; inhibition; oxidative stress Aflatoxin B1; Aspergillus flavus; hyssop; inhibition; oxidative stress

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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El Khoury, R.; Caceres, I.; Puel, O.; Bailly, S.; Atoui, A.; Oswald, I.P.; El Khoury, A.; Bailly, J.-D. Identification of the Anti-Aflatoxinogenic Activity of Micromeria graeca and Elucidation of Its Molecular Mechanism in Aspergillus flavus. Toxins 2017, 9, 87.

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