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Biological Chemistry

Sweetgrass Compounds Repel Mosquitoes

ACS Meeting News: Phytol and coumarin are as effective as commercial repellent DEET

by Elizabeth K. Wilson
August 24, 2015 | APPEARED IN VOLUME 93, ISSUE 33

Credit: Andrew Maxwell Phineas Jones, University of Guelph
North American sweetgrass contains compounds that repel mosquitoes.
Credit: Andrew Maxwell Phineas Jones, University of Guelph
North American sweetgrass contains compounds that repel mosquitoes.

Move over, N,N-diethyl-m-toluamide, otherwise known as DEET. Scientists have identified two compounds in North American sweetgrass that are as effective in repelling mosquitoes as the popular insect repellent. Charles L. Cantrell, a chemist at USDA’s Natural Products Utilization Research Unit in Mississippi, and colleagues at the University of Guelph, in Ontario, extracted the two compounds, coumarin and phytol, from the grass. To test the compounds’ effectiveness, they prepared vials of bloodlike liquid and covered them with skinlike membranes. They then soaked the membranes in coumarin, phytol, or DEET and observed that mosquitoes were as reluctant to “bite” the coumarin- and phytol-soaked membranes as the ones soaked in DEET. Although the two compounds, both relatively nontoxic, aren’t used specifically as insect repellents in commercial products, there’s been compelling evidence for their efficacy. For example, coumarin was an ingredient in Avon’s Skin So Soft products, which were later shown to have some insect repellent properties.



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Ron Buttery (August 27, 2015 1:21 PM)
The structure shown is not Phytol just a shortened version of it. Phytol is a C-20 terpenoid. The structure shown needs another isoprene unit on the right with a double bond (between positions 2 and 3) and a hydroxyl at the end (position 1). Its a well known plant component.
laurenkwolf (August 31, 2015 1:37 PM)
Hi Ron,
Thanks for writing. We've double-checked the structure we have here against the one in SciFinder (CAS # 150-86-7) and the one in ChemSpider. They seem to match. Is there something we're missing?

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