Mosquito-repelling chemicals identified in traditional sweetgrass

http://www.eurekalert.org/pub_releases/2015-08/acs-mci071615.php

Public Release: 17-Aug-2015
Mosquito-repelling chemicals identified in traditional sweetgrass

American Chemical Society

Native North Americans have long adorned themselves and their homes with fragrant sweetgrass (Hierochloe odorata), a native plant used in traditional medicine, to repel biting insects, and mosquitoes in particular. Now, researchers report that they have identified the compounds in sweetgrass that keep these bugs at bay.

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Cantrell's team at the U.S. Department of Agriculture, in collaboration with researchers at the University of Guelph and the University of Mississippi, performed steam distillation on sweetgrass samples and evaluated its oil for the ability to deter mosquitoes from biting.

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Using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, the researchers identified two chemicals in these active fractions that seemed to be responsible for putting off mosquitoes: phytol and coumarin.

Coumarin is an ingredient in some commercial anti-mosquito products, he adds, while phytol is reported to have repelling activity in the scientific literature. So although Cantrell didn't find brand-new insect deterrents in this experiment, he is happy to have demonstrated that "we were able to find constituents that are known to act as insect repellents in a folk remedy, and now we understand that there's a real scientific basis to this folklore."