Abstract
Aflatoxin biosynthesis has established a connection with oxidative stress, suggesting a prevention strategy for aflatoxin contamination via reactive oxygen species (ROS) removal. Epigallocatechin gallate (EGCG) is one of the most active and the richest molecules in green tea with well-known antioxidant effects. Here, we found EGCG could inhibit aflatoxin B1 (AFB1) biosynthesis without affecting mycelial growth in Aspergillus flavus, and the arrest occurred before the synthesis of toxin intermediate metabolites. Further RNA-seq analysis indicated that multiple genes involved in AFB1 biosynthesis were down-regulated. In addition, EGCG exposure facilitated the significantly decreased expression of AtfA which is a bZIP (basic leucine zipper) transcription factor mediating oxidative stress. Notably, KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis indicated that the MAPK signaling pathway target transcription factor was down-regulated by 1 mg/mL EGCG. Further Western blot analysis showed 1 mg/mL EGCG could decrease the levels of phosphorylated SakA in both the cytoplasm and nucleus. Taken together, these data evidently supported that EGCG inhibited AFB1 biosynthesis and alleviated oxidative stress via MAPK signaling pathway. Finally, we evaluated AFB1 contamination in soy sauce fermentation and found that EGCG could completely control AFB1 contamination at 8 mg/mL. Conclusively, our results supported the potential use of EGCG as a natural agent to prevent AFB1 contamination in fermentation industry.
Highlights
Aflatoxins (AFs), the most carcinogenic and toxic naturally occurring metabolites, are primarily produced by Aspergillus parasiticus and Aspergillus flavus [1,2,3]
Inhibition rate of norsolorinic acid (NOR) synthesis was only 0.45% of that in contro for 5 d. These results indicated that the aflatoxin B1 (AFB1) biosynthesis pathway was blocked prior to epigallocatechin gallate (EGCG) for 5 d. These results indicated that the AFB1 biosynthesis p the production of NOR by EGCG
These results indicated that the AFB1 biosynthesis pathway was prior to the production of NOR by EGCG
Summary
Aflatoxins (AFs), the most carcinogenic and toxic naturally occurring metabolites, are primarily produced by Aspergillus parasiticus and Aspergillus flavus [1,2,3]. They were widely distributed in food and feed crops, which caused huge losses in crop quality and posed a global threat to animal and human health through the food chains [4,5,6]. Oxidative stress occurs when ROS (reactive oxygen species) accumulation surpasses the intracellular antioxidant ability [11,12] It has been implicated as a prerequisite for AFs formation [13,14].
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