Bakuchiol is increasingly recognized in the cosmetic industry as a safer and less irritating alternative to retinol, as it shows similar effects in reducing signs of skin aging and also exhibits anti-inflammatory, antioxidant and anti-hyperpigmentation effects. Despite its growing popularity and use in cosmetics, inadequate storage conditions and improper formulation may affect its stability, and consequently the quality and efficacy of the final cosmetic products. The main objective of this thesis was to evaluate the actual content and stability of bakuchiol in a selected range of cosmetic products available on the Slovenian market, to verify the accuracy of the claims and to assess possible correlations between product quality and price. For this purpose, a high-performance liquid chromatography method was used, which was appropriately validated. As part of stress testing, bakuchiol was found to be most susceptible to elevated temperatures and acidic conditions, and to a lesser extent to light, confirming the stability-indicating nature of the method.
Ten cosmetic products of various formulation types and price ranges were included in the analysis, and bakuchiol was detected in all of them. The content in most products ranged between 0.5 and 1,0 %, which is within the concentration range associated with its anti-aging efficacy. For six products with labeled bakuchiol content, we compared the stated content with the determined content. Five contained bakuchiol in amounts very close to their labeled claims (100 ± 10 %), while one product contained only 21 % of the stated content. We found no direct correlation between product price and product quality or bakuchiol content. The largest differences were observed among the lowest-priced products, which included both the product with the lowest determined bakuchiol content (0.09 %) and the product with the highest content (1.9 %).
Eight selected cosmetic products and standard bakuchiol solutions were subjected to long-term and accelerated conditions. Under long-term conditions, bakuchiol remained stable in all products, whereas accelerated testing revealed a decrease in content in seven products (between 17,8 % and 32,0 % after four weeks). Testing of standard solutions further revealed the high sensitivity of bakuchiol to the presence of water, resulting in a greater decrease in content than in cosmetic products (up to 60 % after four weeks). Overall, the quality of the analyzed cosmetic products was generally adequate, while the results also confirm the importance of proper formulation and quality control to ensure the stability of bakuchiol.
|
