Effects of Paprika Extract and Its Components on Cell Death and Expression of p53 and GADD45 Genes in Ultraviolet B- Exposed HaCaT Cells

Abstract

In the present study, the effects of paprika extract and its components including vitamin C, lycopene and beta-carotene on cell death in ultraviolet B (UVB)-exposed HaCaT cells were investigated. The cell viability upon treatment for 24 hr with either paprika extract or vitamin C alone was similar to or greater than that of the untreated control. However, the viability of the cells treated with lycopene or beta-carotene decreased to about 20% of that in the untreated control. When UVB-exposed cells were post-incubated for 24 hr in medium containing paprika extract or vitamin C, cell viability increased in a concentration dependent manner as compared to those post-incubated in a normal growth medium. In contrast, post-incubation of UVB-exposed cells with lycopene or beta-carotene decreased cell viability in a concentration dependent manner as compared to those post-incubated in a normal growth medium. The nuclear fragmentation analysis showed that paprika extract or vitamin C decreases UVB-induced apoptosis. The apoptotic nuclear fragmentation resulting from UVB exposure was also protected by the paprika extract or vitamin C post-incubation. However, the UVB-induced apoptotic nuclear fragmentation of the cells treated with lycopene or beta-carotene increased in a concentration dependent manner. Western blot analysis showed that either paprika extract or vitamin C treatment alone did not significantly change the level of p53 and GADD45 protein.Interestingly, post-incubation of UVB-exposed cells with paprika extract or vitamin C decreased the p53 and GADD45 protein level as compared to those post-incubated in a normal growth medium. In contrast, incubation of UVB-exposed or non-irradiated cells with lycopene or beta-carotene increased the p53 and GADD45 protein levels in a concentration dependent manner as compared to those incubated in a normal growth medium. All these results suggest that paprika extract and vitamin C help the survival of the UVB-exposed cells, while lycopene and beta-carotene potentiate the apoptotic death of UVB-exposed cells, in accordance with the respective changes in p53 and GADD45 protein levels.