October 3, 2013
Insect-Repelling Compounds Could Lead To Safe Alternative To DEET
[ Watch the Video: UC Riverside Research Team Identifies DEET Receptors ]
redOrbit Staff & Wire Reports - Your Universe Online
While experts have long known that bugs are repelled by DEET (also known as N,N-diethyl-m-toluamide), UC-Riverside associate professor of entomology Anandasankar Ray and his colleagues have discovered for the first time the biological receptors sensitive to the substance – which they describe as a major breakthrough in the field of olfaction.
In addition, their paper – which was published Wednesday in the online edition of the journal Nature - describes how Ray’s team was able to identify three safe compounds that mimic the effects of DEET. Those compounds could one day be used to help prevent the transmission of vector-borne diseases such as malaria, West Nile virus and yellow fever.
“Until now, no one had a clue about which olfactory receptor insects used to avoid DEET. Without the receptors, it is impossible to apply modern technology to design new repellents to improve upon DEET,” the professor explained.
Ray and his associates examined all of the sensory neurons in a fruit fly that had been genetically engineered so the neurons that were activated by DEET would glow fluorescent green. Using this method, they were able to locate receptors known as Ir40a receptors. Those Ir40a receptors line the inside of an area of the antenna known as the sacculus – a region which has been poorly studied in the past, according to the researchers.
DEET, which was introduced over six decades ago, has been largely unchanged during that time span because no one had been able to discover the receptors insects use to sense the substance. DEET is capable of dissolving plastics and nylon, and has also been known to inhibit acetylcholinesterase, an enzyme in mammals essential to the nervous system. It is also costly and inconvenient for use in Africa and other regions where large percentages of the population struggle with insect-transmitted diseases.
“Our three compounds, which we tested rigorously in the lab, do not dissolve plastics,” Ray said.
Those compounds are methyl N,N-dimethyl anthranilate, ethyl anthranilate and butyl anthranilate. They had already received Food and Drug Administration (FDA) approval in fragrances and as flavoring agents in some types of food, and can now be applied to bed-nets, clothes and other fabrics, he added.
As a result, those items could now help ward off potentially disease-ridden mosquitoes and other insects.
“Using novel chemical informatics strategies, Ray's lab screened half a million compounds against the DEET receptor to identify substitutes,” the university said in a statement. “A computer algorithm the team developed identified which compounds are not only predicted to be strong repellents but also found naturally in fruits, plants or animals. The algorithm predicted nearly 200 natural DEET substitutes; of which the researchers tested ten compounds.”
Of the compounds Ray and his colleagues tested, eight were described as being strong repellents of flies. Four of those had previously been tested in Aedes mosquitoes and found to be effective against those insects as well, and three of them had already been approved by the FDA. Each of those three compounds activated the same part of the antenna as DEET, and some of them could be mass produced affordably, the professor added.
“In the future, using this algorithm, we could find chemicals that activate DEET receptors but are substantially different, with far better properties than DEET. We could find truly novel repellants that have remarkable properties such as large spatial protection and long-term protection,” he added. “Our findings could lead to a new generation of cheap, affordable repellents that could protect humans, animals and, in the future, our crops as well.”