The aflatoxin inhibitors capsaicin and piperine from Capsicum chinense and Piper nigrum fruits modulate the antioxidant system in Aspergillus parasiticus.

Several aflatoxin inhibitors can modulate the antioxidant system in fungi. In this work, the effect of the ethanolic extract of Capsicum chinense and Piper nigrum fruits, capsaicin, and piperine on the expression of the aflE, aflG, aflH, aflI, aflK, aflL, aflO, aflP, and aflQ genes involved in the aflatoxin biosynthetic pathway in Aspergillus parasiticus were studied by qRT-PCR analysis. As well as, the effect on the expression of fungal antioxidant genes (sod1, catA, and cat2) and enzymatic activity of catalase (CAT) and superoxide dismutase (SOD). Results reveal that the highest (p < 0.05) radial growth inhibition (68 and 86%) and aflatoxins production inhibition (73 and 80%) was observed with capsaicin and piperine respectively, at 300 µg/mL, instead of the ethanolic extract at the same concentration. The qRT-PCR analysis showed that compounds and extracts at 300 µg/mL induced a down-regulation of aflatoxin genes and an up-regulation on the fungal antioxidant genes. CAT activity increased by 23.15, 36.65, 51.40, and 65.50%, in the presence of C. chinense and P. nigrum extract, capsaicin, and piperine exposure, respectively. While SOD activity was not significantly impacted (p > 0.05). In conclusion, the capsaicin and piperine, two antifungal and anti-aflatoxigenic compounds produce an up-regulation of antioxidant defense genes accompanied by an enhancement of catalase enzymatic activity in A. parasiticus.