Abstract: Penicillium expansum is an important pathogen causing decay and deterioration of postharvest fruits. Effective control of P. expansum is important for reducing postharvest fruit losses. “Repurposing drugs” may provide a fast and effective way of finding antifungal agents. In this study, spore germination method was used to determine antifungal activity and 26 clinical drugs targeted to cell membrane functions and energy metabolism were evaluated for their inhibition on P. expansum. The results showed that miconazole, clotrimazole, bifonazole, ketoconazole, 5-fluorocytosine, natamycin, and ebselen had significant inhibitory effects on P. expansum, with median effective concentration (EC50) below 2 μg/mL, and the EC50 of inexpensive bifonazole was 0.04 μg/mL. Further it was found that bifonazole could significantly inhibit the growth of P. expansum mycelium. The antifungal activity of bifonazole was not significantly affected by temperature (25, 50 and 75 ℃), neutral and weakly alkaline environment, or metal ions such as K+, Mg2+, Na+ and Ca2+, but significantly reduced by UV irradiation. The effect of bifonazole on blue mold inoculated onto pear fruit was also investigated, and the results showed that bifonazole treatment significantly reduced the lesion diameter (P < 0.05) and effectively inhibited postharvest blue mold of pear fruit. Thus, it is feasible to develop antifungal agents from clinical drugs for postharvest preservation of fresh fruits, and bifonazole has potential application in postharvest disease control of pear fruit.

Key words: Penicillium expansum, antifungal agents, screening, “repurposing drugs”, bifonazole