Antifungal and anti-aflatoxigenic activity of roots and affinin/spilanthol against by downregulating the expression of D and R genes of the aflatoxins biosynthetic pathway.

In the present study, ethanolic extract from roots and affinin/spilanthol against growth and aflatoxins production were studied in relation to the expression of D and R, two key genes of aflatoxins biosynthetic pathway. Phytochemical analysis of the ethanolic extract by GC-EIMS identified affinin/spilanthol (7.84 ± 0.27 mg g) as the most abundant compounds in roots. The antifungal and anti-aflatoxigenic assays showed that affinin/spilanthol at 300 µg mL produced the higher inhibition of radial growth (95%), as well as, the higher aflatoxins production inhibition (61%) in comparison to roots (87% and 48%, respectively). qRT-PCR revealed that the expression of D and R genes showed a higher downregulation in affinin/spilanthol at 300 µg mL. The expression ratio of D was suppressed by affinin/spilanthol in 79% and R in 84%, while, a lower expression ratio suppressed by was obtained, D (55%) and R (59%). Affinin/spilanthol possesses higher antifungal and anti-aflatoxigenic activity against rather than roots, and this anti-aflaxotigenic activity occurring via downregulation of the D and R genes. Thus, roots and affinin/spilanthol can be considered potent antifungal agents against aflatoxigenic fungus, especially, affinin/spilanthol.