Optimization of Antifungal Extracts from Ficus hirta Fruits Using Response Surface Methodology and Antifungal Activity Tests

The fruits of Ficus hirta (FH) display strong antifungal activity against Penicillium italicum and Penicillium digitatum. In order to optimize the extraction conditions of antifungal extracts from FH fruit, various extraction parameters, such as ethanol concentration, extraction time, solvent to solid ratio and temperature, were chosen to identify their effects on the diameters of inhibition zones (DIZs) against these two Penicillium molds. Response surface methodology (RSM) was applied to obtain the optimal combination of these parameters. Results showed that the optimal extraction parameters for maximum antifungal activity were: 90% (v/v) ethanol concentration, 65 min extraction time, 31 mL/g solvent to solid ratio and 51 °C temperature. Under the abovementioned extraction conditions, the experimental DIZs values obtained experimentally were 57.17 ± 0.75 and 39.33 ± 0.82 mm, which were very close to the values of 57.26 and 39.29 mm predicted by the model. Further, nine kinds of phytopathogens were tested in vitro to explore the antifungal activity of the FH extracts. It was found for the first time that the FH extracts showed significant inhibition on the growth of P. italicum, A. citri, P. vexans, P. cytosporella and P. digitatum.