Antitoxin Characteristic of Licorice Extract: The Inhibitory Effect on Aflatoxin Production in Aspergillus parasiticus

Recent investigations revealed the effects of herbal extracts on both fungal growth as well as aflatoxins production. In the present study, we tried to evaluate antifungal activity as well as antitoxin activity of Glycyrrhiza glabra (licorice) extract. Strain American Type Culture Collection 15517 of Aspergillus parasiticus was used to perform antifungal susceptibility test according to Clinical and Laboratory Standards Institute document M27‐A3, and the rate of aflatoxin production was determined using high‐performance liquid chromatography technique after exposure to different concentrations of licorice extract. Quantitative changes in the expression of the aflR gene were analyzed by measuring the cognate aflR mRNA level with quantitative real‐time reverse‐transcription polymerase chain reaction assay. Our obtained results demonstrated the inhibitory effect of licorice extract on Aspergillus parasiticus growth at 500 mg/mL of licorice extract. In addition, a significant decrease in aflatoxin production was revealed at the same concentration. However, the production of aflatoxin B₁ was entirely inhibited in 10 g/mL of licorice extract. The level of aflR gene expression was significantly decreased after the exposure of fungal cells to 500 g/mL of licorice extract. Evaluation of the antifungal and antitoxin activity of licorice extract on Aspergillus parasiticus revealed its antifungal properties as well as its effective ability to decrease aflatoxin production. PRACTICAL APPLICATION: Several classes of synthetic antifungal drugs are used today to treat fungal infections in humans and crops. However, this antifungal therapy is not always effective because of emerging of drug‐resistant strains. Therefore, using effective natural antifungal agents with fewer side effects is a promising approach to combat fungal diseases either in medicine or in agriculture. In the present study, we introduced the licorice extract as a novel natural compound to inhibit the growth and production of aflatoxin in the filamentous fungi Aspergillus parasiticus and evaluated this natural herbal extract as an antifungal agent.