Peptides in cosmetic products are becoming increasingly popular, mainly due to their efficacy and high level of safety. Peptides are most commonly used in active skincare products to prevent or reduce signs of aging. The main effects of peptides are supporting the mechanisms and cells in the skin responsible for antioxidant processes, slowing down the aging processes, skin hydration, stimulation of collagen synthesis, and acceleration of wound healing.
The main objective of our work was to evaluate the content and stability of copper tripeptide and acetyl hexapeptide-8, two current and frequently used hydrophilic peptides in selected cosmetic products, and to verify compliance with the labelling on the packaging. An analytical method based on high-performance liquid chromatography was optimised, and validated according to ICH guidelines. Following a market research, nine cosmetic products from different manufacturers and price categories were selected, each containing at least one of the selected peptides. Products with declared peptide content were also included. We found that most products did not contain any of the specified peptides. Most notably, acetyl hexapeptide-8 was listed on eight products but was not detected in any of them. Copper tripeptide was detected in three out of five cosmetic products, with all three accurately declaring the peptide content on the packaging. For these three products, the actual copper tripeptide content closely matched the declared values, with measured concentrations being only 5–20% higher than claimed. It was found that price does not correlate with quality of the products.
The stability of the selected peptides in cosmetic products was tested using stress, accelerated and long-term tests. For the accelerated testing, selected products were exposed to elevated temperature (40 °C) and relative humidity (75%) and analysed weekly over a period of one month. We found that both copper tripeptide and acetyl hexapeptide-8 remained stable under accelerated conditions, as their contents remained within the acceptable range (100 ± 10%) throughout the study. The long-term stability of copper tripeptide was evaluated after one month of storage at room temperature in the original packaging. The results confirmed that the peptide remained stable under real-life storage conditions, suggesting that instability is not the reason for the absence of peptides in the tested products. Based on the obtained results, we conclude that greater control is necessary in the field of cosmetic products containing active ingredients.
|
