Vitis vinifera seeds extract for the modulation of cytosolic factors Bax-α and NF-kB involved in UVB-induced oxidative stress and apoptosis of human skin cells

Abstract

Background and aims. The depletion of the ozone layer allows overexposure of the skin to UV radiation, which is prolonged due to the increasing life expectancy, together with inappropriate life habits contribute to the increasing incidence of cutaneous malignancies. Plant extracts with antioxidant capacities are frequently employed as a means to protect skin against ultraviolet (UV) radiations, thus preventing skin cancers. In the present study we assessed a red grape seed extract (GSE) potential capacities to reduce ultraviolet B (UVB) radiation-induced reactive oxygen species (ROS) and subsequent apoptosis in a human keratinocytes cell line (HaCaT). We identified molecules and pathways modulated by the GSE through which this may exert its photoprotective effect.

Methods. The GSE was standardized according to its polyphenolic content and the most important biologically active compounds, such as epigallocatechin and epicatechin, catechin hydrate, procyanidin B and gallic acid were evidenced by high-performance liquid chromatography. According to the plant extract cytotoxicity on the HaCaT cell line, two concentrations were selected for testing from the non-toxic range: GSE₁ (37.5 μgEqGA/ml) and GSE₂ (75 μgEqGA/ml). The level of ROS was evaluated with CM-H₂DCFDA assay, while apoptosis, Bax-α and NF-kβ p65 proteins with ELISA and confirmed by western-blot.

Results. Both concentrations of the extract decreased the level of ROS in UVB-irradiated keratinocytes (p<0.001), whereas apoptosis and Bax-α pro-apoptotic protein were only reduced by the higher concentration (GSE₂). The NF-kB p65 protein level registered increasing values in time after UVB exposure of the cells, while the tested plant extract re-established its level when its smaller concentration was used (GSE₁).

Conclusion These results encourage further studies on this extract in order to identify other molecules and pathways through which this extract might exert its beneficial effects and also recommend its use as a potential photoprotective agent.