Biochemical markers for prolongation of the acute stress of triclosan in the early life stages of four food fishes

Abstract

In the present study, embryos of four food fishes viz. Cyprinus carpio, Ctenopharyngodon idella, Labeo rohita and Cirrhinus mrigala were given acute (96 h) exposure to their respective LC₀, LC₁₀ and LC₃₀ (causing 0, 10 and 30% mortality, respectively) concentrations of triclosan [TCS, 5-chloro-2-(2,4-dichlorophenoxy) phenol], a broad spectrum biocide. Bioaccumulation, contents of protein, non-enzymatic antioxidants (GSH and GSSG), MDA (lipid peroxidation product) and organic acids (fumarate, succinate, malate and citrate) along with the activities of AChE (neurological enzyme), GST (detoxification enzyme) and three metabolic enzymes (LDH, AST and ALT) were estimated after 48 and 96 h exposure and 10 days post exposure. Around 1/10 of the TCS in water got accumulated in the hatchlings after 96 h, increase over 48 h values was maximum at LC₀ (+195.30, +143.23 and + 140.75%) but minimum at LC₃₀ (+89.62, +84.26 and + 126.72%) for C. idella, L. rohita and C. mrigala, respectively. In C. carpio, TCS got accumulated only at LC₃₀ after 48 h but at all the concentrations after 96 h exposure. Contents of protein, GSH, GSSG and activity of AChE decreased but activities of GSH, LDH, AST and ALT and contents of MDA and organic acids increased concentration dependently in all the fishes. TCS declined by 85-90% but its toxic effects on biomolecules prolonged till the end of the recovery period. Such acute exposures are accidental but there is a need to evaluate biomarkers for prolongation of the stress of small concentrations especially LC₀ and LC₁₀ (causing negligible mortality) of lipophilic pollutants like TCS.

Keywords: Early life stages; Enzymes; Food fishes; Organic acids; Triclosan accumulation.