Protective Effect of Amaranthus cruentus L. Seed Oil on UVA-Radiation-Induced Apoptosis in Human Skin Fibroblasts

Since the exposure of fibroblasts to prolonged UVA radiation induces oxidative stress and apoptosis, there is a need for effective skin protection compounds with cytoprotective and antioxidant properties. One of their sources is Amaranthus cruentus L. seed oil (AmO), which is rich in unsaturated fatty acids, squalene, vitamin E derivatives and phytosterols. The aim of this study was to evaluate whether AmO evokes a protective effect on the apoptosis induced by UVA radiation in human skin fibroblasts. UVA radiation at an applied dose of 10 J/cm(2) caused a significant reduction in the survival of human skin fibroblasts and directed them into the apoptosis pathway. Increased expression of p53, caspase-3, caspase-9 and PARP proteins in UVA-treated fibroblasts suggests the intrinsic mechanism of apoptosis. Application of the 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 the expression of p-Akt and mTOR proteins was restored under the effect of the studied oil. The molecular mechanism of this phenomenon was related to the stimulation of antioxidant processes through the activation of Nrf2. This suggests that AmO stimulated the antioxidant system in fibroblasts, preventing the effects of UVA-induced oxidative stress, which may lead to pharmaceutical and cosmetological applications as a sun-protective substance.