Nature's Answer to Insect Repellent

By: Katie Schaefer, Cosmetics & Toiletries magazine

Posted: May 29, 2009, from the June 2009 issue of Cosmetics & Toiletries.

Researchers have sourced fragrance ingredients that could provide a natural alternative to N,N-diethyl-m-toluamide (DEET), one of the most frequently used actives in insect repellents. Although DEET effectively repels mosquitoes and ticks, some agencies have questioned its effects on the environment and its skin irritation potential.

In May 2008, the US Centers for Disease Control recommended the use of DEET, picardin, lemon eucalyptus and IR3535 to repel mosquitoes from human skin.1 However, both the US Environmental Protection Agency (EPA)2 and the Pesticide Information Project of Cooperative Extension offices at Cornell University3 have found DEET to produce dermal and neurological reactions in humans. With ongoing debate regarding the safety of DEET, an equally effective but safer alternative would prove beneficial (and lucrative).

While searching for a compound to repel insects from coffee beans, Aijun Zhang, PhD, and his team at the US Department of Agriculture (USDA) stumbled upon what they believe to be a safe, cost-effective active for insect repellents.“We discovered a fungus that repelled insects from the coffee bean,” explained Zhang, who added that a volatile or some other chemical from the fungus was providing this effect. After comparisons with a control, the team isolated the compound: isolongifolenone.

Zhang then explored sources from which the compound could economically be obtained. “I did some research to see if it existed naturally,” said Zhang, who found the compound present in the leaves of Humiria balsamifera (tauroniro), a tree from South America. However, according to Zhang, isolating the compound from the tauroniro tree can be expensive, so he sought other sources.

An Evergreen Answer
“When I [searched the] literature, I found that isolongifolenone is not used in the pharmaceutical or cosmetic industry,” said Zhang “but its derivative, isolongifolene, was discovered by the USDA 50 or 60 years ago, and has been used by the perfumery industry for a long time.” In perfumery, isolongifolene is incorporated into products for its woody scent. Zhang adds, “We [also] discovered that ... isolongifolene can be synthesized from pine oil.”