New lipopeptide analogues of C16–KTTKS, containing tyrosine (C16–KTTKY) and glutamic acid (C16–KTTKE) residues, were characterized by physicochemical and biological assays to understand their collagen stimulation and ability to control skin commensal microorganism growth. The presence of nanotapes based on stacked lipopeptide lamellae was confirmed by cryogenic transmission electron microscopy and small-angle X-ray scattering. Variations in zeta potential as a function of lipopeptide concentration indicated the electrostatic stability of C16–KTTKE, while C16–KTTKY was stable at a lower concentration, with a similar aggregation state. Circular dichroism spectra revealed a transition from random coil to β-sheet for both peptides with increasing temperature (up to 50 °C). Significant statistical reductions in cell viability below 70% were observed at concentrations above 0.00625 wt % for C16–KTTKE and 0.00156 wt % for C16–KTTKY, respectively. At higher lipopeptide concentrations, C16–KTTKE promotes a decrease in total collagen production by human dermal fibroblasts; however, it has antioxidant properties. In contrast, C16–KTTKY stimulates a considerable increase in the level of total collagen production. The lipopeptides were found to stimulate S. epidermidis growth, a microorganism very important for skin microbiota health. Therefore, both lipopeptides have interesting characteristics as active ingredients in antiaging cosmetic products.
Pelin et al. (Fri,) studied this question.