The effect of walnut thin shell extract on the growth of Penicillium species

Fungi broadly exist in the environment. Growing interest for natural and safe additives as well as concerns about synthetic fungicide have led to development of various fungicides. This study aimed to examine the effect of walnut thin shell ethanolic extract on the growth of Penicillium species. Antifungal effects were assessed at four different concentrations ranging from 5 to 350 mg/ml. The extract dilutions were exposed to the desired fungi using the broth dilution method, and minimum inhibitory concentrations (MIC) of fungi were determined and compared with the effects of nystatin and fluconazole. The MIC for Penicillium italicum was 15 mg/ml for both walnut thin shell and fluconazole whereas it was 30 mg/ml for nystatin. Moreover, the minimum fungicidal concentration (MFC) for walnut thin shell, fluconazole and nystatin were 250, 30 and 60 mg/ml, respectively. The MIC for Penicillium expansum was 30 mg/ml for both walnut thin shell and fluconazole while it was 40 mg/ml for nystatin. The results also revealed that the MFC for these inhibitors was 300, 40 and 70 mg/ml, respectively. Furthermore, the MIC for Penicillium digitatum forboth the shell walnut extract and nystatin was 40 mg/ml while it was 20 mg/ml for fluconazole. The MFC for walnut thin shell, fluconazole and nystatin were 325, 100 and 70 mg/ml, respectively. Thin walnut shell extract has significant antifungal effects on Penicillium species and could be used as a natural antifungal. More research is required to assess the use of the extract for treatment of fungal infections.