Investigation of the inhibitory, fungicidal and interactive effects of the aqueous extract of Calotropis procera on Alternaria alternata, Alternaria solani, Saccharomyces cerevisiae, and Fusarium solani “in vitro”

Calotropis procera from the Apocynaceae family is called Stabregh in Iran. This plant is found in tropical areas and southern coasts in Iran and North Africa, Middle East Asia, and Southeast Asia on coastal sand dunes. In this study, the C. procera extract was separated using water solvent. The antifungal effect of C. procera aqueous extract on Alternaria alternata, Alternaria solani, Saccharomyces cerevisiae, and Fusarium solani was investigated. The antifungal activity was evaluated through, disk diffusion agar (Kirby-Bauer), well diffusion agar, minimum inhibitory concentration (MIC), and minimum fungicidal concentration (MFC). In the combined mode (interaction) of C. procera aqueous extract with nystatin antibiotic was investigated. In general, Saccharomyces cerevisiae and Alternaria solani were the most sensitive and resistant fungal strains with the highest and the lowest diameter of inhibition zone, respectively. So that the diameter of the inhibition zone for Saccharomyces cerevisiae and Alternaria solani in the presence of 80 mg/ml extract concentration was equal to 13.20 and 8.20 mm, respectively. In the interaction of C. procera aqueous extract with nystatin antibiotic, synergistic mode was observed for all fungal strains. The MIC and MFC values for S. cerevisiae were 32 and 128 mg/mL, respectively. The MIC and MFC results for Alternaria solani were found to 256 and > 512 mg/mL, respectively.