Preliminary results on antifungal activity of donkey milk

Donkey milk is being increasingly studied for its use in the human medicine and its antimicrobial activity has been reported in the literature. However, there have been only few studies on milk’s inhibiting activity against fungi. Donkey milk is currently used in the personal healthcare industry, thus evaluating its antifungal activity against some dermatophytes is of interest in relation to the natural prevention or control of dermatophyte infections. This preliminary study evaluated the in vitro antifungal activity of donkey milk. Four fresh pasteurized bulk milk samples were collected from a donkey farm. Pasteurized donkey bulk milk samples were analysed in relation to gross composition, individual mineral content (Ca, P, Mg, K, Na, and Zn mg/L), fatty acid profile, and lysozyme activity. The milk samples were tested against isolates of Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes. Sensitivity testing was assessed by a microdilution test, starting by a milk concentration of 90%. To calculate minimal inhibitory concentration values, 80%, 70%, 60% 50%, 40%, 30%, 20%, and 10% dilutions were tested. Donkey milk was proven to inhibit mycotic growth. In particular, M. canis and T. mentagrophytes failed to grow in 60% donkey milk and M. gypseum appeared to be sensitive to 70%. The antidermatophyte effect could be related to the milk content of some fatty acids with reported antifungal activities. In the analysed donkey milk, C10:0 on average constituted 70% of the short chain fatty acids and the milk fat showed a relatively high content of linoleic and alpha linolenic acid (15.34 and 4.87 g/100 g of the total fatty acids respectively). We also found a high lysozyme activity (1402.50 U/mL of milk). In conclusion, donkey milk showed an overall in vitro antidermatophytic effect. On the basis of the promising results obtained in this preliminary report, further studies are needed to evaluate the in vivo use of donkey milk against dermatophytosis.