Effective Insect Repellent Formulation in both Surfactantless and Classical Microemulsions with a Long-Lasting Protection for Human Beings

摘要

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 surfactant less microemulsion (H2O/(PrOH)-Pr-i/PMD) and then in classical rnicroeniulsions. The presence of sclf-associated nanostructures is detected by dynamic light scattering (DLS). A synergetic system of surfactants (Cremophor (R) RH40 and Texapon (R) N70) is used. Additionally, 2-ethylhexane-1,3-diol and ethyl (-)-(S)-lactate are incorporated. The final product contains. as main components, 46% of H2O, 25% of (PrOH)-Pr-i, 20% of non-H2O-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 he efficient for human protection against mosquitoes.