Non-natural, non-proteinogenic amino acids are rather novel in the cosmetic industry. They do not become incorporated into proteins during new protein biosynthesis, and thus, topical application of these actives can lead to skin benefits. We previously demonstrated that a novel proprietary non-proteinogenic amino acid ingredient has significant effect on stimulating epidermal turnover and epidermal hyaluronic acid production leading to clinically observable skin benefit. To shed more light on efficacy of this ingredient, its effect on skin dermal and basement membrane components was evaluated.
In vitro treatment of 3D tissue skin equivalents led to increase in pro-collagen I production. Additionally, gene expression analysis of the treated 3D tissues revealed increase in expression of collagen synthesis and decrease in matrix metalloproteinases genes that result in collagen degradation.
In vivo, treatments were evaluated in human volunteer forearms. After the treatment, biopsy samples were obtained and analyzed by histology for total collagen production, collagen III/I ratio, as well as collagen IV and VII. Samples were also collected non-invasively via D-squame tapes and analyzed for HSP-70 protein. HSP-70 is known to protect collagen from degradation and it was shown by us to be a good biomarker of age as well as wrinkle perception. Additional histological analysis revealed increase in dermal-epidermal junction collagens as well as increase in collagen III/I ratio in the dermis. Separately, increase in collagen protecting HSP-70 was observed in skin samples.
Taken together, we showed that the novel non-proteinogenic amino acids can increase collagen production and stability throughout the skin layers, which is critical for structural integrity and function of skin and translates to improvement in skin appearance.