Abstract:

The anti-aging effect of donkey milk on skin was evaluated. More and more attention has been paid to donkey milk in recent years since its nutrition composition shows higher similarity to human milk than others. Donkey milk has not only high nutritional value but also a wide range of medicinal value. Herein, the measurement of cell activity, cell proliferation, extracellular matrix （collagen, matrix metalloproteinase） content and invitro wound healing by the scratch assay were used. Donkey milk was found to be safe and nontoxic up to the concentration of 0.63- 10 mg/mL. Bromodeoxyuridine （BrdU） assay data showed the proliferation of HDFn cells and HaCaT cells after 48 h, and it was found that when the concentration of donkey milk was 5 and 10 mg/mL, the proliferation of cells was increased significantly （p<0.01）. The collagen in extracellular matrix was increased by 38% at 10 mg/mL donkey milk compared to the control group （p<0.01）. The content of MMP-1 secreted by HDFn cells induced by UVB was significantly reduced after treated with 5 and 10 mg/mL donkey milk. In addition, wound healing assay exhibited significant wound closure and cell migration compared to the control group after HDFn cells being treated with donkey milk for 24 h. In conclusion, donkey milk can promote cell proliferation, increase collagen content, inhibit MMP-1 secretion, promote damage repair, and thereby delay skin aging. It provides a necessary scientific basis for the application of donkey milk in functional cosmetics; however, the roles and specific molecular mechanism in delaying skin aging need to be further explored.

Key words: donkey milk, anti-aging, cell proliferation, collagen, matrix metalloproteinase, scratch assay