Piperonyl butoxide pyrethroids

Gas ehromatography mass-mass aequisition was used for the pyrethroid determination. Pyrethroids investigated were Allethrin, Prallethrin, Tetramethrin, Bifenthrin, Phenothrin, X-Cyhalothrin, Permethrin, Cyfluthrin, Cypermethrin, Flueythrinate, Fsfenvalerate, Fluvalinate and Deltamethrin. Piperonyl butoxide, main synergist eompound for pyrethroid eompounds, was also studied. 

Examples of these include sesamin and sesamolin, both active principles of sesame oil, and piperonyl butoxide (PBO) and sesamex, both synthetic products. Although initially developed for use with pyrethrins, they have since been observed to synergize some, but not all, carbamates, organophosphates, pyrethroids, and organochlorines. In addition to the MDP compounds, another type of synergist called MGK 264 was developed to synergize the toxicity of pyrethroids and rotenone. The structure of piperonyl butoxide and MGK 264 are as follows ... 

Piperonyl butoxide exerts toxicity by inhibiting mixed function oxidases. These enzymes are responsible for detoxifying pyrethrins and pyrethroids their toxicity is therefore increased by piperonyl butoxide. 

Piperonyl butoxide is a synergist for carbamates, pyrethrins, pyrethroids, and rotenone. 

Pyrethrins and synthetic pyrethroids are among the safest of the topically applied ectoparasiticides, because of their selective toxicity for insects (mam-malian-to-insect toxic dose ratio is greater than 1000, compared with 33 for organophosphates and 16 for carbamate insecticides). In contrast to the very wide margin of safety for mammalian species, pyrethroids are toxic to fish. The synergistic action of pyrethrins and piperonyl butoxide (in combination preparations) is due to the inhibition by piperonyl butoxide of the microsomal enzyme system of some arthropods. Preparations of synthetic pyrethroids (permethrin, cypermethrin) often contain a mixture of drug isomers in varying proportions. 

Synthetic pyrethroids (cypermethrin, permethrin) and natural pyrethrins (pyrethrum extract) combined with piperonyl butoxide constitute the most important class of insecticide applied topically to horses (Table 5.7). The liquid concentrate containing cypermethrin which, after dilution, is applied to horses by spray contains a mixture of the isomers in equal proportion (cis trans 50 50). 

Piperonyl butoxide (PBO) in combination wiih pyre thrum and pyrethroids is used to control insect pests on a wide variety of food crops. Defining the nature and magnitude of the residues in crops resulting from such uses is an important part of the evaluation of the safety of the product to humans and to the environment. 

Lcvot, G.W. (1994). Pyrethroid synergism by piperonyl butoxide in Bmicofa uvti (Schrank) (Phthirapterat Trichodectidae), J. Ao-sir. Entomai. Sac. 33, 123-126. 

The oxidation, which is the bioactivation reaction, is inhibited by piperonyl butoxide, whereas the demethylation reaction catalyzed by glutathione transferase is not inhibited. Piperonyl butoxide is therefore an antagonist to methyl-parathion, but a synergist to most other pesticides, including carbamates and pyrethroids. Pyrethrins are very quickly detoxified by oxidation of one of the methyl groups, catalyzed by the CYP enzymes. 

In the indoor environment, many types of products such as crystals, sprays and liquids are used for active and preventative protection from insects. Insect sprays are very popular because they are easy to handle and can be combined with air fresheners. Commonly, the amount of active agents is well below 2 %. For example, a commercially available product for indoor use contained 0.25 % tetramethrin, 0.05 % c -phenothrin and 1 % of the synergist piperonyl butoxide. Volatile ingredients were mainly aliphatic hydrocarbons (C4-C12), cycloalkanes and branched alkanes. Pyrethroids are also used as active agents in liquid products against furniture beetle. A commercially available insecticide contained 0.1% cyfluthrin and a variety of volatile components such as acetone, aliphatic hydrocarbons (C10-C14), branched alkanes, cycloalkanes, C3 benzenes and dipropylene glycol monomethyl ether. It should also be mentioned that materials containing natural fibers are often equipped with synthetic pyrethroids as a precaution. 

Pyrethrins are naturally occurring insecticides derived from the chrysanthemum plant. Pyrethroids (Table 11-48) are synthetically derived compounds. Acute human poisoning from exposure to these insecticides is rare however, they can cause skin and upper-airway irritation and hypersensitivity reactions. Piperonyl butoxide is added to these compounds to prolong their activity by inhibiting mixed oxidase enzymes in the liver that metabolize the pyrethrins. Common pyrethrin-oontaining pedi-culicides include A-200, Triple-X, and RID. 

Pyrethroids available today include allethrin, phenothrin, tetramethrin and cyphenothrin, usually for household insects control, and cypermethrin, deltamethrin, permethrin, y-cyhalothrin and cyfluthrin, mainly for agricultural insects. Pyrethroids are often commercially combined with synergist compounds like piperonyl butoxide, which enhance their insecticidal activity, or mixed with fungicides such as 2-phenylphenol or other pesticides like propoxur (a carbamate pesticide). 

Toxicology LD50 (oral, rat) 2800 mg/kg, (skin, rabbit) 470 mg/kg mod. toxic by ing., skin contact, and IP routes large doses may cause CNS effects (excitation and depression) toxic by skin absorption causing CNS effects experimental reproductive effector Hazardous Decomp. Prods. CO2, CO, NOx Uses Synergist in insecticides to increase insecticidal effect of pyrethrins, pyrethroids (esp. allethrin), and rotenones usually used with piperonyl butoxide stabilizer in repellents for personal use... 

Since pyrethrins are highly photolytic, antioxidants are often added to preparations to stabilize formulations antioxidants adjoin include pyrocatechol, pyrogal-lol, hydroquinone, and l-benzene-azo-2-naphthol. Practically, all pyrethrins and many pyrethroids are commonly combined to additives (including synergists), some formulations include additional insecticides, insect repellents, or both, and many contain hydrocarbon solvents [3] to enhance their insecticidal activity. Pyrethrin and pyrethroid sprays may also be water based or be alcohol or petroleum based, which increases the overall toxicity. It is known that concomitant use of pyrethrins and pyrethroids with synergists such as piperonyl butoxide, A -octyl bicycloheptene dicarboximide, sulfoxide, sesamin, sesame oil, sesamolin, isosafrole, and organophosphorus compounds or carbamates may increase toxicity by mechanisms involving inhibition of microsomal oxidation [4]. 

The mechanisms by which pyrethroids alone are toxic are complex and become more complicated when they are co-formulated with piperonyl butoxide, an organ-ophosphorus insecticide, or both, as these compounds inhibit pyrethroid metabolism. The main effects of p3rethroids are on sodium and chloride channels. As a result, excitable (nerve and muscle) cells are the principal targets of pyrethroid toxicity, which is manifested as disordered function rather than structural damage. In that way, the major toxic effect of dermal exposure is paresthesia, supposable also due to hyperactivity of cutaneous sensory nerve fibers [12]. 

Wester RC, Bucks DAW, Maibach HI (1994) Human in vivo percutaneous absorption of pyrethrin and piperonyl butoxide. Food Chem Toxicol 32 51-53 Wheelock CE, Wheelock AM, Zhang R, Stok JE, Morisseau C, Le Valley SE (2003) Evaluation of alpha-cyanoesters as fluorescent substrates for examining intraindividual variation in general and pyrethroid-selective esterases in human liver microsomes. Anal Bioehran 315 208—222 Wheelock CR, Miller JL, Miller MJ, Phillips BM, Huntley SA, Gee SJ, Tjeerdem RS, Hammock BD (2006) Use of carboxylesterase activity to remove pyrethroid-associated toxicity to Ceiiodaphnia dubia and Hyalella azteca toxicity in identification evaluations. Environ Toxicol Chem 25 973-984... 

Here R, R2, and R3 have a multiplicity of organic functions, and these materials synergize many insecticides. In piperonyl butoxide, an important pyrethroid synergist, the Ri group is butoxyethoxyethyl. In addition there also is a propyl group in the 6-position in piperonyl butoxide. Certain alkyne, hetero-... 

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