ANALYTICAL AND BIOCHEMICAL STUDIES OF FENITROTHION

Abstract

Fenitrothion o,o-dimethyl-o-(-3 methyl-4-nitro phenyl) phosphorothioate, an organophosphopesticide is largely used against spruce bud worms and as aprotectant for stored grains. The present report describes the in vivo effects of intramuscularly administered fenitrothion in rat tissues. The accumulation and biodegradation of this pesticide in rats as well as in soil has also been investigated. The biochemical parameters of liver i.e. protein, nucleic acid and glycogen were markedly decreased as aresult of fenitrothion administration. The quantitative changes in various phospholipids composition and in triglycerides were studied by high performance liquid chromatography (HPLC) and gas liquid chromatography (GLC). respectively. Preferential accumulation of various lipids were found in different tissues of treated rats. Acetylcholinesterase inhibition in brain.was also noticed for 48h after administration of the pesticide. Haemoglobin%and total red blood cells were significantly decreased, whereas elevation in number of white blood cells and in bilirubin was noticed due to fenitrothion exposure. The alkaline phosphatase, acid phosphatase, glutamic oxaloacetate transaminase and glutamic pyruvate transaminase enzyme activities exhibited amarked increase in serum of treated rats. Most of the biochemical parameters studied show that the fenitrothion effect increased upto 12 or 24h after the administration of pesticide and thereafter the effect is substantially diluted and it appears that system starts regenerating itself. The fate of fenitrothion in different organs (liver, kidney and brain) of rat was investigated during the first 48h following intramuscular administration of pesticide in animals by HPLC. The biodegrada tion of pesticide and formation of metabolites in different tissues showed atime-dependent sequential conversion of pesticide into three major metabolites in liver and kidney and two metabolites in brain. These metabolites were separated and purified to homogeneity by HPLC and characterized by IR spectroscopy as aminofenitrothion (metabolite I), 0,0- dimethyl phosphorothioate (metabolitell) and 00 o.o-dimethyl phosphate (metabolite III). A change in metabolic pathway was found in liver of rats treated with high dose of pesticide and three major metabolites formed in liver were characterized as aminofenitrothion (metabolite I), aminofenitrooxon (metabolite II) and o.o-dimethyl phosphate (metabolite III). The persistency and biodegradation of fenitrothion in normal garden soil of western Uttar Pradesh of northern India was investigated under laboratory conditions. The analysis of pesticide and products formed at different intervals of 0-90 day by HPLC showed sequential conversion of pesticide into two or three products depending upon the laboratory conditions used. These products were separated and purified to homogeneity by HPLC and characterized by IR spectroscopy as fenitrooxon (metabolite I), o.o-dimethyl phosphate (metabolite II) and phosphoric acid (metabolite III). Thus, under the laboratory conditions used, the metabolite I (fenitrooxon) formed in the soil was different from the metabolite I(amino fenitrothion) formed in rats. In the former case, the first step in the metabolic pathway was oxidation where as in the latter, it was found to be reduction of the parent pesticide. Further unlike soil, no evidence for formation of phosphoric acid from the o.o-dimethyl phosphate (metabolite III) was observed within the 48 h of administration of pesticide in rats.