Triclosan Induces Oxidative Stress, Gene Expression Changes, and Cardiomyocyte Dysfunction in Magallana bilineata...

Triclosan (TCS) is an antimicrobial compound widely used in pharmaceutical and personal care products (PPCPs). It is classified as a contaminant of emerging concern (CEC) due to its environmental health implications. However, significant knowledge gaps remain regarding the toxic effects of environmentally relevant concentrations of TCS in coastal and marine species, such as bivalves. In this study, the impact of triclosan on the primary heart cell cultures derived from the euryhaline coastal bivalve, Magallana bilineata, was investigated. The heart cells were exposed to various concentrations of TCS, and the IC₅₀ value was determined to be 2.1494 mg L^-1. Following this, sub-lethal toxicity tests based on cellular and molecular parameters were conducted using environmentally relevant TCS concentrations. The results demonstrated that TCS induces ROS (reactive oxygen species) production at environmentally relevant levels and also alters gene expression, as evident from the mRNA profiling of superoxide dismutase (Cu/Zn sod), catalase (cat), glutathione peroxidase (gpx), calmodulin (calm), and heat shock protein 70 (hsp70). Furthermore, cardiomyocyte beating patterns varied (contraction impairment, arrhythmic activity, or absence of cardiomyocyte clusters) depending on the TCS concentrations. The results point to ROS-mediated disruptions in excitation-contraction coupling as a likely contributor, and further studies will strengthen mechanistic understanding. Overall, these findings provide critical insights into the cellular and molecular toxicity of environmentally relevant TCS concentrations and support the utility of M. bilineata heart cell cultures for advancing aquatic toxicology research.