Tetraethyl pyrophosphate TEPP

The purpose of this work was to determine the toxicity to mosquito larvae of insecticide spray residues. That certain insecticides are translocated in plants (4, 5) adds impetus to this study. Fresh orchard fruit sprayed or dusted with preparations containing parathion (0,0-diethyl O-p-nitrophenyl thiophosphate), tetraethyl pyrophosphate (TEPP, HEPP), DDD [2,2-bis(p-chlorophenyl)-l,l-dichloroethane], DDT [2,2-bis(p-chlorophenyl)-l,l,l-trichloroethane], chlorinated camphene, and basic lead arsenate were shipped from California to Yonkers, N. Y., by air express for bioassay. 

Toxicology. Tetraethyl pyrophosphate (TEPP) is a highly toxic anticholinesterase agent. 

The 2003 ACGIH time-weighted average-threshold limit value (TWA-TLV) for Tetraethyl pyrophosphate (TEPP) is 0.004 ppm (0.047 mg/m") with a notation for skin absorption. 

In the 1970s organophosphorus compounds became the leading type of insecticide and they still are, mainly because they are less persistent. Over 50 such compounds are registered in the U.S. today as insecticides. Gerhard Schrader synthesized the first organophosphorus insecticide in Germany in 1938, commonly called tetraethyl pyrophosphate (TEPP). 

The first suggestion of a practical form of antidotal therapy came in 1949 from Hestrin, who found that acetylcholinesterase (AChE) catalyzed the formation of acetohydroxamlc acid when incubated with sodium acetate and hydroxylamine. Critical in vitro studies in the next decade led to the development of a practical approach to therapy. The crucial concept in these studies was the recognition that the compound formed when AChE reacted with a phosphorus ester was a covalent phosphoryl-enzyme Intermediate similar to that formed in the hydrolysis of acetylcholine. 3 Wilson and colleagues, beginning in 1951, demonstrated that AChE inhibited by alkyl phosphate esters (tetraethyl pyrophosphate, TEPP) could be reactivated by water, but that free enzyme formed much more rapidly in the presence of hydroxylamine. 0 21 Similar results... 

In the 1970s, organophosphorus compounds became the leading type of insecticide. Over 40 such compounds have been registered in the United States as insecticides. The first organophosphorus insecticide was synthesized in 1938 and is known as tetraethyl pyrophosphate (TEPP). Another phosphate insecticide, Malathion is synthesized by condensing diethyl maleate with the o,o-dimethyl phosphorodithioic acid. 

Tetraethyl pyrophosphate (TEPP) discovered - first organo-phosphate pesticide... 

One of the first known examples of phosphorus ester insecticides was tetraethyl pyrophosphate (TEPP, 7). 

The cholinesterase inhibitors are divided into two categories organophosphorous compounds (such as parathion, malathion, and tetraethyl pyrophosphate [TEPP]) and the carbamates (such as naphthyl-iV-methyl carbamate [car-baryl and Sevin]). 

In addition to their indirect effects on muscarinic receptors through AChE-mediated changes in ACh levels, many OP and CM pesticides can affect their expression and function directly (Bakry et ai, 1988 Eldefrawi et ai. 1992). Paraoxon. dichlorvos, and tetraethyl pyrophosphate (TEPP) were found to be noncompetitive antagonists of muscarinic receptors in bovine caudate nuclei labeled with pHlquinudidinyl benzilatc ([ HJ-QNB) at concentrations that had no effect on AChE activity (Volpe et ai, 1985). The... 

The first organophosphorus ChE inhibitor was probably tetraethyl pyrophosphate (TEPP), synthesized by Wurtz and tasted (with no ill results) by Clermont in 1854.4 During the next 80 years, chemists (such as Michaelis, Arbusow, and Nylen) made numerous advances in organophosphorus chemistry, but generally they did not realize the toxicity of the substances with which they were working.4... 

Organophosphorus reagents that inhibit hydrolases (serine hydrolases) diethyl p-nitrophenyl phosphate (paraoxon) diisopropyl phosphofluoridate (DFP) dimethyl(dichlorovinyl) phosphate (dichlovos) O -methylphosphoramidothioate 3-hydroxy-N-methyl-cis-crotonamide dimethylphosphate tetraethyl pyrophosphate (TEPP)... 

Tenac, see Dichlorvos Tendimethalin, see Pendimethalin Tenoran SOW, see Chloroxuron TEP, see Tetraethyl pyrophosphate TEPP, see Tetraethyl pyrophosphate Terabol, see Methyl bromide Terbacil Terbufos... 

Blocking of the hydrolytic enzymes by selective hydrolase-inhibitors such as tetraethyl pyrophosphate (TEPP [1215]) or diethyl p-nitrophenylphosphate (paraoxon). However, aU of these inhibitors are highly toxic and have to be handled with extreme caution. 

The mechanism of the action of acetylcholinesterase purified from the electric organs of Electrophorus electricus involves the attraction of the positively charged nitrogen of acetylcholine to an anionic site on the enzyme and cleavage of the substrate at an esteratic site of a nucleophilic character. The irreversible inhibition by the alkyl phosphates, tetraethyl pyrophosphate (TEPP) and diisopropyl-fluorophosphate (DFP) may be due to phosphorylation of the nucleophilic esteratic site. The phosphorylation by DFP of the phenolic hydroxyl group of free tyrosine has been demonstrated by Ashbolt and Rydon. Chymotrypsin and citrus fruit acetylesterase are also inhibited by DFP and TEPP. ... 

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