Protective Effect of <em>Amaranthus cruentus</em> Seed Oil on the UVA Radiation-Induced Apoptosis in Human Skin Fibroblasts

Abstract

UVA radiation inducing oxidative stress is harmful for the skin cells. The most sensitive are dermal fibroblasts. Exposure of the cells to prolonged UVA radiation induces apoptosis. Although, skin cells have a number of defense mechanisms that protect them against UV-induced oxidative stress, they are insufficient during long-lasting UV exposure. Therefore, there is a need for effective skin protection compounds with cytoprotective and antioxidant properties. One of their sources is Amaranthus cruentus L. seed oil, rich in unsaturated fatty acids, squalene, vitamin E derivatives, and phytosterols. The aim of this study was to evaluate whether Amaranthus cruentus seed oil evokes protective effect on the apoptosis stimulated by UVA radiation in human skin fibroblasts. UVA radiation at an applied dose of 10 J/cm2 caused a significant reduction in the survival of human skin fibroblasts and directed them into apoptosis pathway. Increased expression of p53, caspase 3, and caspase 9 and PARP proteins in UVA-treated fibroblasts suggests the intrinsic mechanism of apoptosis. The application of Amaranthus cruentus seed oil at 0.1% and 0.15% concentrations to UVA-treated cells decreased the expression of these proteins, which was accompanied by increased cell survival. Similarly, the UVA-dependent decrease in expression of p-Akt and mTOR proteins was restored, under the effect of studied oil. The molecular mechanism of this phenomenon is related to the stimulation of antioxidant processes through activation of Nrf2. This suggests that Amaranthus cruentus seed oil stimulate the antioxidant system in fibroblast cells and prevent the effects of UVA-induced oxidative stress and may find application in pharmacy and cosmetology as a sun- protective substance.