Biochemical changes induced by phenthoate, an organophosphate compound to sublethal concentrations in freshwater fish Labeo Rohita (hamilton)

The present study was carried out to investigate the toxicity of commercial grade Phenthoate effects on biochemical parameters in an Indian major carp Labeo rohita under the controlled laboratory conditions. The median lethal concentration value (96 h LC50) of Phenthoate was found to be 2.1 mgl- 1 by using Finney’s Probit Method. Fish were exposed to sublethal concentration of 1/10th 96 h LC50 (0.21 mgl-1) for the period of 1 and 10 days respectively and the changes were assessed by using various methods. A significant increase in aminotransferase (AST), activity was observed in muscle (83.77% - highest), kidney (47.53% - lowest), ALT activity was noticed in muscle (61.65% - highest) and in kidney (1.84% - lowest), the ACP activity level elevated was observed in intestine (21.36% - highest) and in gill (0.78% - lowest). The acetyl cholinesterase (AChE) enzyme decreased was observed in gill (53.33% - highest) and in kidney (1.20% - lowest) for 1day. Similarly, during 10 days sublethal exposure, AST activity elevated in kidney (69.10% - highest) and muscle (18.82% - lowest), ALT activity also increased in muscle (36.77% - lowest) and (131.74% - highest) in intestine tissues. The ACP percent change was noticed in brain (36.44% - highest) and in muscle (20.20% - lowest). The AChE activity decreased in muscle (70.04% - highest) and (47.68 % - lowest) in brain compared to the control group fish (P < 0.05) during the experimentation. Hence, the percent change of biochemical constituent’s has gradually increased or decreased due to disruption of internal organ in all tissues. This might be due to enhanced enzyme turnover under pesticide stress. The decreased levels of AChE enzyme possibly due to the activity of the organophosphorus compound with the active site of AChE followed by phosphorylation of the phosphorus of the organophosphate to the oxygen of the hydroxyl group of serine at the active site.