Study of Oxidative Stress and Histo-Biochemical Biomarkers of Diethyl Phthalate Induced Toxicity in a Cultureable Fish, Labeo rohita

Diethyl phthalate (DEP) is a widely used low-molecular weight phthalate which is ubiquitously detected in almost all kind of the environmental matrices. The aim of the present study was to investigate the impact of DEP-induced toxicity on a suite of biomarker responses in Labeo rohita (rohu). The median lethal concentration of DEP was found to be 4.38 mg L-1 for 96 h. Fingerlings were exposed to a sub-lethal concentration of DEP i.e. 0.51 mg L-1(1/10th LC50) for a period of 21 day of the experiment. Oxidative stress and histo-biochemical biomarkers were studied using gills, liver, kidney and brain tissues on 7, 14 and 21 day. The results indicated that DEP-exposure has damaged the antioxidant status by inhibiting the activities of enzymatic stress markers (catalase, glutathione-s-transferase, glutathione peroxidase, reduced glutathione) in all the studied tissues of rohu throughout the study period. Moreover, a significant increase in the levels of lipid peroxidation was observed in all the studied tissues in a time-dependent manner. The levels of hepatic-nephric biomarkers (ALT, AST, ALP, Urea and Creatinine) were found to be significantly elevated for DEP-exposed rohu when compared to control (P<0.05) throughout the study period. The histopathological marker showed severe lesions in the gills (hypertrophy, fusion and curling of lamellae,), liver (pyknotic nuclei, leukocytes infiltration and vacuolization) and kidney tissues (glomerulus expansion, narrowing and elongation of renal tubules) of DEP-exposed rohu. In conclusion, the above mentioned histo-biochemical parameters could be used as biomarkers for DEP toxicity monitoring in the aquatic ecosystem. (C) 2019 PVJ. All rights reserved