title: Effective insect repellent formulation in both surfactantless and classical microemulsions with a long-lasting protection for human beings.
abstract: The aim of this work is to develop a new generation of repellent products with a long-lasting protection based on a natural component, para-menthane-3,8-diol (PMD). The active is first rendered soluble in a surfactantless microemulsion (H(2)O/(i)PrOH/PMD) and then in classical microemulsions. The presence of self-associated nanostructures is detected by dynamic light scattering (DLS). A synergetic system of surfactants (Cremophor) RH40 and Texapon N70) is used. Additionally, 2-ethylhexane-1,3-diol and ethyl (-)-(S)-lactate are incorporated. The final product contains, as main components, 46% of H(2)O, 25% of (i)PrOH, 20% of non-H(2)O-soluble PMD, and only 4% of surfactants. Investigations of lasting protection on human volunteers are carried out using a cage test bioassay protocol and Aedes aegypti mosquitoes. A complete protection of 315 min is found on the test persons using the surfactantless microemulsion. An extension is observed with the final formulation to reach a mean of complete protection of 385 min. This study demonstrates that alternative formulations using a natural active instead of synthetic chemicals like N,N-diethyl-m-methylbenzamide (DEET) can be efficient for human protection against mosquitoes.
authors: University of Regensburg, Institute of Physical and Theoretical Chemistry, Universitätstrasse 31, D-93053 Regensburg.
authors: Jeremy
authors: J
authors: Drapeau
authors: Marie
authors: M
authors: Verdier
authors: Didier
authors: D
authors: Touraud
authors: Ulla
authors: U
authors: Kröckel
authors: Martin
authors: M
authors: Geier
authors: Andreas
authors: A
authors: Rose
authors: Werner
authors: W
authors: Kunz
mesh_terms: D000330:Aedes / Q000187:drug effects; D000818:Animals; D002626:Chemistry, Pharmaceutical; D000081005:Cyclohexane Monoterpenes; D004655:Emulsions; D006801:Humans; D007302:Insect Repellents / Q000737:chemistry* / Q000494:pharmacology; D008610:Menthol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000081005:Cyclohexane Monoterpenes; D004655:Emulsions; D007302:Insect Repellents; D013501:Surface-Active Agents; D008610:Menthol; C005804:terpin