Bakır, T.K.Kastrati, H.2024-02-222024-02-22202409491775https://hdl.handle.net/20.500.12597/19070In this study, lipid oxidation kinetics were examined with in vitro methods to investigate whether the antioxidant substances in the final product formulations of four antioxidant-added skin care creams have an antioxidant effect on the skin layers. For the determination of primary and secondary products, iron (III)-thiocyanate (Fe(III)-SCN) and thiobarbituric acid reactive substance methods (TBARS) were used in Cu(II)-induced linoleic acid (LA) emulsions, respectively. It was found that THCl and THC2 coded cream samples slowed down the lipid oxidation rate, while THC3 and THC4 coded samples accelerated the oxidation. The inhibition effects of the same cream samples were confirmed using the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging method. In addition, UV-B-induced oxidation of the LA emulsion containing soy lecithin + Tween 20 emulsifier (HLB:10), prepared as a skin simulation medium for cream samples, was investigated at 35 °C and pH 5.5. The same results were supported by conjugated diene absorbance measurements. Kinetic data were explained by GC–MS analysis. Accordingly, it was observed that the degradation of fatty acids with 17 and 19 carbons into secondary products with low carbon numbers during the development of oxidation occurred at a lower rate in THCl and THC2 coded samples compared to THC3 and THC4 coded samples. The results of this study will raise consumer awareness about these high-cost cosmetic products and enable manufacturers to offer these products to the market with accurate information to users. Conducting in vivo studies supporting this study will provide resources for production suitable for human health. Graphical abstract: (Figure presented.)eninfo:eu-repo/semantics/openAccessAntioxidant activity, GC–MS analysis, Lipid oxidation kinetics, Skin care creams, UV-B-induced oxidationarticle10.1007/s00769-024-01574-12-s2.0-85184884589