203 - Phototoxic Mechanism of Triclosan through Involvement of Type 1 mediated apoptosis in HaCaT cell line

Abstract

Triclosan (TCS) is a widely used preservative in personal care products such as toothpaste, soaps and cosmetics. However its molecular mechanism under ambient ultraviolet radiation and sunlight is not well understood. In this study, we investigated phototoxic effects of TCS in HaCaT cell line under ambient intensity of UVB and sunlight exposure. TCS generates reactive oxygen species (ROS), superoxide anion (O2•‒) and hydroxyl radical (•OH) formation through type-I photodynamic mechanism. Photodegradation study has been done under UVB and sunlight exposures. Thereafter, cell viability parameters were measured using MTT, NRU assays and LDH leakage. TCS decreased cell viability of treated cells in a concentration-dependent manner along with increased expressions of apoptotic markers such as phosphatidylserine translocation, Acridine orange/Ethidium bromide double staining. Significant intracellular ROS generation was measured through DCF-DA and DHE staining. Further cell cycle study showed sub G1 population and lysosomal destabilization, through acridine orange and neutral red staining which advocates apoptotic cell death. Here we found TCS (5 µg/mL) showed reduction of mitochondrial membrane potential through JC-1, mitotracker/ Dapi staining and transmission electron microscopy. Photogenotoxicity assay was performed using comet assay and micronuclei formation. To explore the mechanisms we measured the activation of cleaved Caspase-3, Bax, while reduced expression of Bcl-2 through real time and western blotting which further leads to apoptosis. Thus study suggests that TCS leads to apoptosis via the involvement of lysosome and mitochondria both under ambient UVB and sunlight exposure. In conclusion, TCS exposure may be deleterious to human health at ambient environmental intensities. Therefore, TCS should be replaced by other photosafe preservatives for human beings.