Casein-derived peptides from the dairy product kashk exhibit wound healing properties and antibacterial activity against Staphylococcus aureus: Structural and functional characterization.

Kashk is a fermented dairy product typical of the Middle East, traditionally produced with sour milk and/or dairy waste. The kashk water-soluble peptide fraction was characterized at the molecular level by liquid chromatography-mass spectrometry and its antibacterial and skin healing activity was evaluated. Antibacterial assays showed a significant antibacterial activity against clinical isolates of Staphylococcus aureus (S. aureus) from patients with atopic dermatitis, inhibiting bacterial growth by approximately 45% (500 μg/mL). Skin repair activity was evaluated on keratinocytes through scratch tests showing accelerated wound closure in vitro in the presence of TNF-α, by approximately 44% (500 μg/mL), compared to control cells. Furthermore, based on the MTT assay, the kashk peptide fraction did not show toxicity on keratinocytes. The results suggested that the peptide kashk extract may be useful in skin care for patients with atopic dermatitis.