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At least 685 records · Page 38Linked to original sources
PubMed2005

Chirality index, molecular overlay and biological activity of diastereoisomeric mosquito repellents.

Both 1-methylisopropyl 2-(2-hydroxyethyl)piperidine-1-carboxylate, (Picaridin((R))) and cyclohex-3-enyl 2-methylpiperidin-1-yl ketone (AI3-37220; 220) have two asymmetric centers, and the four diastereoisomers of each compound are known to have differing degrees of mosquito-repellent activity according to quantitative behavioral assays conducted at the United States Department of Agriculture. Computational chemistry was used to identify the structural and configurational basis for repellent activity. Molecular overlay of the optimized geometries of the lowest energy conformers of the diastereoisomers was investigated to elucidate the role of chiral centers in 220 and Picaridin. It was found that the presence of a chiral carbon alpha to the nitrogen with the S configuration in the piperidine ring is essential to the three-dimensional arrangement of the atoms of the pharmacophore for effective repellent activity.

Animals↗
PubMed2000

Repellent and antifeedant activity of salicylic acid and related compounds against the biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae).

An artificial membrane, blood-feeding method was used to assess the repellent and antifeedant effects of derivatives of salicylic acid on the biting midge Culicoides impunctatus Goetghebeur. Trans-2-hydroxycyclohexanecarboxylic acid, 6-methylsalicylic acid, 2,6-dihydroxy-4-methylbenzoic acid, and salicyluric acid caused highly significant inhibition of feeding, with salicyluric acid performing significantly greater than the other compounds. Investigating the effects of alkyl substitution of salicylic acid, o-thymotic and o-cresotic acids were also effective. A pilot clinical trial using salicyluric acid indicated that it provided a protective effect and it was hypothesized that this may have resulted primarily from contact, because no significant repellent effects were shown for this compound in a microscope slide test, designed to demonstrate repellency with volatile compounds.

Animals↗
PubMed2003

Repellent efficacy of DEET and KBR 3023 against Amblyomma hebraeum (Acari: Ixodidae).

The bont tick, Amblyomma hebraeum Koch, is the principal vector of Rickettsia africae, the agent of African tick bite fever, in southern Africa. In contrast to most other hard ticks, members of the genus Amblyomma exhibit a characteristic attack host-seeking behavior. The efficacy of topically applied 20% lotions of DEET (diethyl-3-methylbenzamide), the currently considered reference repellent substance, and KBR 3023, a recently developed piperidine compound, was evaluated against laboratory-reared A. hebraeum nymphs on treated fingers. Both substances repelled >85% of nymph attacks at 0 and 1 h postapplication. At 2, 3, and 4 h, the repellent efficacies of DEET were 84%, 68% and 71%, whereas those of KBR 3023 were 56, 55, and 54%. The observed differences between the two test substances were statistically significant only at 2 h postapplication. This first study of topical repellents against A. hebraeum suggests that 20% lotions of DEET and KBR 3023 are effective for 2 and 1 h, respectively, but that the repellent efficacies decrease thereafter.

Administration, Topical↗
PubMed1989

Laboratory evaluation of controlled-release repellent formulations on human volunteers under three climatic regimens.

Six controlled-release personal-use topical insect/arthropod repellent formulations of diethylmethylbenzamide (deet) were evaluated in an environmental chamber on volunteers for repellency against the mosquitoes Aedes aegypti and Ae. taeniorhynchus under three climatic regimens: basic variable high humidity (tropical environment), basic constant high humidity (forested and wet environment) and basic hot (hot-dry environment). The best protection under all the climatic regimens was provided by the Biotek formulation. In a tropical environment, some formulations induced more biting from mosquitoes than the concurrent untreated control in the late hours of the testing. Repellency was not directly related to the deet concentration in the various controlled-release repellent formulations.

Aedes↗
PubMed1988

Field bioassays of permethrin-treated uniforms and a new extended duration repellent against mosquitoes in Pakistan.

Field bioassays were conducted to evaluate the effectiveness of different treatment combinations of permethrin-impregnated clothing and a new extended duration repellent formulation of deet against natural populations of mosquitoes in Islamabad, Pakistan. Tests were initiated 2-2 1/2 hours prior to sunset and volunteers who wore the topical repellent applied it 8 hours earlier. The most effective treatment was a combination of wearing both the permethrin-impregnated clothing and the repellent on exposed skin. This combination provided 100% protection from bites whereas volunteers wearing only treated clothing received 57% protection. Those wearing only repellent received 89% protection, but, under the biting pressure observed, this was not significantly different from the treated clothing-repellent combination.

Animals↗
PubMed1991

[The effectiveness of the repellents diethyltoluamide and phenylpropandiol in grazing primiparous cows].

In practical farming conditions of an agricultural enterprise situated in South-East Moravia, the repellents N,N'-diethyl-m-toluamide and 2-phenyl propanediol 1,3 were tested after their application to grazing first-calves of the Bohemian Pied breed. The experiment was conducted in July and August 1986 and it took 40 days. In the first experimental group, 2-phenyl propanediol 1,3 was applied and in the other group a 1:1 mixture of the repellents N,N'-diethyl-m-toluamide and 2-phenyl propanediol 1,3 in form of a 10% water emulsion in the interval of 48 hours. No flights and bites of annoying insects (gad-flies, black-flies, gnats, midges, symbovine flies) were observed in treated first-calves in the two experimental groups. The economic efficiency of 2-phenyl propanediol 1,3 application in the first experimental group was manifested by the higher milk yield by 1.20% and by the higher milk fat yield by 0.13%; when the mixture of N,N'-diethyl-m-toluamide and 2-phenyl propanediol 1,3 was used, the milk yield increased by 2.27% and the milk fat yield by 0.17%, in comparison with the control group. Considering that some meteorological factors had worse values in the test year, after their mathematico-statistical evaluation they had significantly different values from those recorded in the two preceding years, the differences in milk production and fat percentage were not statistically significant.

Animals↗