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Compounds Related to Active Ingredient in Peppers May Lead to Longer-Lasting Mosquito Repellents

By Kelli Miller Stacy
WebMD Health News

Reviewed By Louise Chang, MD

May 27, 2008 — Imagine dousing yourself with mosquito repellent at the start of summer and remaining bite-free nearly all season long.

Researchers in Gainesville, Fla., have identified several potent mosquito repellents that keep bugs from biting for up to 73 days — more than three times longer than the current gold standard, N,N-diethyl-m-toluamide, better known as DEET. DEET is the world's most widely used bug repellent.

Alan Katritzky of the University of Florida and colleagues used artificial neural networking software to predict how certain compounds called N-acylpiperidines would keep mosquitoes from feeding on human flesh. N-acylpiperidines are related to the active ingredient in pepper. The researchers identified 23 strong candidates, which they expected to be as effective as DEET.

Two volunteers wore cloth arm patches containing standard amounts of each compound and placed their gloved arms into a cage swarming with 500 mosquitoes. A lot of clock watching ensued. Researchers measured the repellent's duration by simply watching and waiting to see how soon the mosquitoes started feeding on each arm patch worn by the volunteers.

The experiment showed that "most of these novel acylpiperidines were equivalent to or better than DEET in duration of protection," Katritzky writes in the journal article. His team reports that DEET repelled the mosquitoes for 17.5 days. Some of the pepper-based compounds lasted up to 73 days.

The team published their findings in the May 27 issue of Proceedings of the National Academy of Sciences.

But because bug sprays wear off with water and washings, it's unlikely you'd be able to spray once and keep bugs off all summer — unless of course you never shower, sweat, or swim. You should always reapply insect repellents after such activities. However, longer-lasting mosquito repellents are favorable, because many of us forget to reapply and don't use protection when we need it — and chances are mosquitoes are around even when you don't see them. Using insect repellent helps protect you against dangerous mosquito-borne diseases such as West Nile virus and malaria.

SOURCES: News release, National Academy of Sciences. Katritzky, A. Proceedings of the National Academy of Sciences, May 27, 2008; vol 105: pp 7359-7364.

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