Profenofos is an

organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered a ...

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

. It is a

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...

with a pale yellow to amber color and a

garlic Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Allium fistulosum, Welsh onion and Allium chinense, Chinese onion. It is native to South A ...

-like

odor An odor (American English) or odour (English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is caused by one or more volatilized chemical compounds ...

. It was first registered in the United States in 1982. As of 2015, it was not approved in the European Union.

Uses

Profenofos can be used on a variety of crops including cotton and vegetables such as maize, potato, soybean, and

sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose and which is grown commercially for sugar production. In plant breeding, it is known as the Altissima cultivar group of the common beet (''Beta vulgaris''). Together wi ...

. In the United States it is used exclusively on cotton and is primarily used against lepidopteran insects. Mixed with phoxim, cypermethrin, beta-cypermethrin imidacloprid and deltamethrin, profenofos can be used against Cotton MealyBug, cabbage caterpillar, '' Plutella xylostella'' and asparagus caterpillars, as well as against wheat and cabbage aphids.

Mechanism of action

Like other organophosphates, the profenofos mechanism of action is via the inhibition of the

acetylcholinesterase Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme Enzymes () are proteins that a ...

enzyme. Although it is used in the form of a racemate, the S(-)

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

is a more potent inhibitor.

Synthesis

Profenofos can be synthesized by reacting phosphorus oxychloride with sodium ethoxide and sodium 1- propanethiolate, followed by treatment with 4-bromo-2-chloro phenol.

Toxicity

A 2007 World Health Organization report found no adverse effects to workers of routine exposure to profenofos and no teratogenicity or carcinogenicity. Based on a study of patients poisoned with profenofos and its close chemical relative prothiofos, the compound has been described as "of moderately severe toxicity", causing respiratory failure. Differences in chemical structure that distinguish these two compounds from more common organophosphate pesticides - namely, the presence of the ''S''- alkyl group on the phosphorus atom where most OP compounds possess a methoxy or ethoxy group - underlie differences in their behavior as

enzyme inhibitors compared to the rest of the OP class. In one study of a patient who died of profenofos poisoning, the major

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s of profenofos were identified as des-''S''- propylated profenofos, two

s of despropylated propenofos, and des

ethyl Ethyl may refer to: Arts and entertainment * Cold Ethyl, a Swedish rock band *Ethyl Sinclair, a character in the ''Dinosaurs'' television show Science and technology * Ethyl group, an organic chemistry moiety * Ethyl alcohol (or ethanol) * E ...

ated propenofos. A downstream, nontoxic metabolite, 4-bromo-2-chlorophenol, has been proposed as biomarker for exposure.

Environmental effects

A United States

Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...

report identified profenofos as toxic to birds, small

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyly, monophyletic lineage within the ...

s, fish, and aquatic invertebrates, noting several

fish kill The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (2005) ''Plant Management in Fl ...

incidents in which profenofos exposure, primarily due to runoff, was implicated as a probable cause.

References

{{Acetylcholine metabolism and transport modulators Acetylcholinesterase inhibitors Organophosphate insecticides Chlorobenzenes Bromoarenes Phenol esters Ethyl esters