Metabolism of parathion

Hollingworth RM, Alstott RL, Litzenberg RD. 1973. Glutathione-S-aryl transferase in the metabolism of parathion and its analogs. Life Sci 13 191 -199. 

Munnecke DM, DPH Hsieh (1976) Pathways of microbial metabolism of parathion. Appl Environ Microbiol 31 63-69. 

Figure 2. Chemical mechanism for the metabolism of parathion to paraoxon by the Cytochrome P-450-containing monooxygenase system (6)...

The majority of the diethyl phosphate and -nitrophenol formed in the mammalian metabolism of parathion is undoubtedly derived by the action of esterases or phosphatases ( ) on paraoxon formed from parathion in a cytochrome P-450-catalyzed reaction. However, a significant portion of the diethyl phosphate and -nitrophenol must also be the result of the attack of water on the intermediate S-oxide of parathion ( ). 

We have also examined the metabolism of parathion by purified reconstituted monooxygenase systems isolated from the livers of... 

Figure 4. Linearity of the metabolism of parathion and benzphetamine by a reconstituted monooxygenase oxidase enzyme system from rabbit liver. The 0.5-mL reaction mixture contained 50 fig of sodium deoxycholate, 15 iig of dilauroyl l-5-phosphatidylcholine, 1.5 units of NADPH-Cytochrome c reductase, 0.5 nmol of Cytochrome P-450, 0.05M Hepes buffer (pH 7.8), 0.015M MgCh, O.lmU EDTA, and 5 X lO M [ethyl- C] parathion or / X 10 M benzphetamine.

Kamataki, T., Lee Lin, M.C.M., Belcher, D.H. and Neal, R.A., Studies of the metabolism of parathion with an apparently homogenous preparation of rabbit liver microsomal cytochrome P450, Drug Metab. Dispos.,4, 180-189, 1976. 

Halpert, J., Hammond, D., and Neal, R.A., Inactivation of purified rat liver cytochrome P-450 during metabolism of parathion (diethyl-p-nitrophenyl phosphoro-thionate), J. Biol. Chem., 255, 1080-1089, 1980. 

Appletort, H. T., and Nakatsugawa, T. (1972). Paraoxon deethyla-lion in the metabolism of parathion. Pestle. Biochem. Physiol 2,286-294. 

One in vivo Study on pigs (Qiao et al.. 1997) demonstrated that occlusion significantly enhanced pen-tachlorophcnol (PCP) absorption in a soil-based mixture from 29 to 85% of dose and changed the shape of the absorption profile in blood and plasma. The study also suggested that occlusion enhanced metabolism of PCP and resultantly the partitioning between plasma and red blood cells. Occlusion was kinctically linked to modification of cutaneous biotransformation of topical parathion (Qiao and Riviere, 1995). Occlusion enhanced cutaneous metabolism of parathion to paraoxon and to p-nitrophenol as well as the percutaneous absorption and penetration of both parathion and p-nitrophenol, This probably resulted in the... 

Carlson GP (1973) Comparison of the metabolism of parathion by lobsters and rats. Bull Environ Contam Toxicol 9 296-300... 

Flynn GL (1990) Physicochemical determinants of skin absorption. In Gerrity TR Hairy CJ (eds) Principles of route-to-route extrapolation for risk assessment. Elsevier, New York, pp 93-127 Foxenberg RJ, Knaak JB, McGarrigle BP, Kostyniak PJ, Olson JR (2007) Human hepatic cytochrome P450-specific metabolism of parathion and chlorpyrifos. Drug Metab Dispos 35 189-193... 

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