Aflatoxins are toxic metabolites produced by certain Aspergillus species. They cause disease and contaminate food, so reducing and controlling these toxins is extremely important. Due to their antifungal properties, essential oils and extracts from medicinal plants are increasingly used. As part of this study, the medicinal plants Salvia mirzayanii and Mentha piperita were harvested from their original habitat in Hormozgan Province and essential oils were extracted. Subsequently, the toxin-producing fungus A. flavus was isolated and purified from maize kernels, and the effect of the essential oil of both plants on the toxigenicity of A. flavus and the expression of the aflatoxin-encoding gene was investigated using real-time PCR. The antifungal properties were assessed using the disk diffusion method and a mixed evaluation, and then the effective concentration of the essential oil in both plants was determined. The essential oils of both plants effectively inhibited the growth of A. flavus at concentrations of 1000 and 2000 ppm. However, peppermint essential oil significantly reduced toxin production and had a stronger effect on the expression of the gene encoding aflatoxin at a concentration of 2000 ppm. Considering the effectiveness of peppermint essential oil at a concentration of 2000 ppm on the expression of the gene encoding aflatoxin, this essential oil can be introduced as a biological and safe method for the biological control of aflatoxin.
