Biomaterial Database

[Lipoxygenase-mediated N-demethylation of pesticides in vitro]. 2002

Jianan Hu, and Arun P Kulkarni

Department of Occupational Medicine, School of Public Health, Central South University, Changsha 410078, China.

OBJECTIVE In order to explore the pathway of dealkylation of pesticides other than cytochrome P450 monocoxygenases, lipoxygenase (LOX)-mediated demethylation of aminocarb and some other pesticides were measured. METHODS Formaldehyde generated in the reaction was estimated by Nash reaction to express the rate of demethylation of pesticides mediated by soy lipoxygenase (SLO). RESULTS N-demethylation of aminocarb mediated by SLO was found to depend on the incubation time, concentration of the enzyme, concentration of aminocarb and hydrogen peroxide. Under optimal conditions, Vmax value of 18 nmol of formaldehyde.min-1.nmol-1 of lipoxygenase was observed. The reaction exhibited Km values of 3.4 mmol/L for aminocarb and 235 mumol/L for hydrogen peroxide. A strong inhibition of the reaction by nordihydroguaiaretic acid, gossypol, and phenidone clearly implicated the lipoxygenase involvement as the protein catalyst. A significant decline in the formaldehyde accumulation in the presence of either reduced glutathione or dithiothreitol suggested generation of a free radical species as an initial oxidation intermediate during the demethylation of aminocarb by SLO. The inhibition of formaldehyde generation by butylated hydroxyanisole(BHT) and butylated hydroxy toluene(BHA) further supported this contention. In addition to aminocarb, seven other pesticides were also found to undergo N-demethylation, albeit at relatively low rates. CONCLUSIONS Certain pesticides may oxidatively undergo dealkylation via the lipoxygenase pathway in animals and plants.

UI	MeSH Term	Description	Entries
D008084	Lipoxygenase	An enzyme of the oxidoreductase class primarily found in PLANTS. It catalyzes reactions between linoleate and other fatty acids and oxygen to form hydroperoxy-fatty acid derivatives.	Lipoxidase,Linoleate-Oxygen Oxidoreductase,Lipoxygenase-1,Lipoxygenase-2,Linoleate Oxygen Oxidoreductase,Lipoxygenase 1,Lipoxygenase 2,Oxidoreductase, Linoleate-Oxygen
D010575	Pesticides	Chemicals used to destroy pests of any sort. The concept includes fungicides (FUNGICIDES, INDUSTRIAL); INSECTICIDES; RODENTICIDES; etc.	Pesticide
D002083	Butylated Hydroxyanisole	Mixture of 2- and 3-tert-butyl-4-methoxyphenols that is used as an antioxidant in foods, cosmetics, and pharmaceuticals.	Butylhydroxyanisole,(1,1-Dimethylethyl)-4-methoxyphenol,AMIF-72,BHA,Butyl Methoxyphenol,Embanox,Nipantiox 1-F,Tenox BHA,AMIF 72,AMIF72,Hydroxyanisole, Butylated,Methoxyphenol, Butyl,Nipantiox 1 F,Nipantiox 1F
D002084	Butylated Hydroxytoluene	A di-tert-butyl PHENOL with antioxidant properties.	Butylhydroxytoluene,2,6-Bis(1,1-dimethylethyl)-4-methylphenol,2,6-Di-t-butyl-4-methylphenol,2,6-Di-tert-butyl-4-methylphenol,2,6-Di-tert-butyl-p-cresol,4-Methyl-2,6-ditertbutylphenol,BHT,Di-tert-butyl-methylphenol,Dibunol,Ionol,Ionol (BHT),2,6 Di t butyl 4 methylphenol,2,6 Di tert butyl 4 methylphenol,2,6 Di tert butyl p cresol,4 Methyl 2,6 ditertbutylphenol,Di tert butyl methylphenol,Hydroxytoluene, Butylated
D003640	Dealkylation	The removing of alkyl groups from a compound. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)	Dealkylations
D005609	Free Radicals	Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. Free radicals include reactive oxygen and nitrogen species (RONS). They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.	Free Radical
D013025	Glycine max	An annual legume. The SEEDS of this plant are edible and used to produce a variety of SOY FOODS.	Soy Beans,Soybeans,Bean, Soy,Beans, Soy,Soy Bean,Soybean
D048448	Phenylcarbamates	Phenyl esters of carbamic acid or of N-substituted carbamic acids. Structures are similar to PHENYLUREA COMPOUNDS with a carbamate in place of the urea.	Phenyl-Carbamates,Phenyl Carbamates