Safer Ways to Stop Mosquito Bites

There are many products that can help keep mosquitoes from biting, but research at the University of Michigan-Flint is looking at ways to make the products safer. Jie Song, PhD, assistant professor, Department of Chemistry and Biochemistry and visiting scholar, Professor Zongde Wang from China, are examining a group of compounds that has been synthesized from α-pinene, the primary component in turpentine oil extracted from pine trees.

"Some of these compounds have shown promising capabilities to repel mosquitoes," said Song. "Because of the low toxicity of these compounds, they are human, and environment-friendly, and therefore, can be used with much less constraint (e.g. applied in lotion and perfume)".

One well-known repellent is N, N-diethyl-m-toluamide (DEET), developed in 1951 after testing 11,000 compounds for effectiveness in repelling insects. DEET-based products are currently marketed worldwide in a variety of concentrations and forms designed to protect consumers from biting insects and ticks. DEET-based products are used by an estimated 200 million people worldwide each year, approximately half of these consumers residing in America.According to Song, along with increased use of DEET, a public debate has waged over the adverse effects of DEET on humans. Although DEET's long-term effects are still unclear, precautions suggest minimization of DEET exposure and avoidance of the eyes, lips, inadvertent swallowing, and sunburned or damaged skin during application of DEET products. Further, use of DEET is riskier for children because their lower body weight and increased likelihood of accidental ingestion makes them more vulnerable to any adverse effects. As a result, the design of a less toxic alternative mosquito repellent from a safe natural source has received much attention.

Song says his research will speed the process of identifying which of thousands of similar compounds may be the most affective. "It is almost impossible to synthesize and test everyone because it requires tremendous money, time, and manpower," said Song. "In order to design the candidate with the best biological activity based on the limited number of synthesized compounds, the study of the quantitative structure-activity relationship (QSAR), which shows how the chemical structure is quantitatively correlated with the biological activity, must be done first."

In this project, the structure-activity relationship among these compounds will be investigated using experimental chemical/biological, and theoretical studies.

"This research will allow the design of more powerful candidate(s) for the further biological and clinical studies as well as possible commercial applications," said Wang.

According to a recent "Joint Statement on Mosquito Control in the United States from the U.S. Environmental Protection Agency (EPA) and the U.S. Centers for Disease Control and Prevention (CDC)," mosquito-borne illnesses pose a significant risk to many Americans. Mosquito-borne diseases are among the world's leading causes of illness and death today. The World Health Organization estimates that more than 300 million clinical cases each year are attributable to mosquito-borne illnesses. Despite great strides over the last 50 years, mosquito-borne illnesses continue to pose significant risks to parts of the population in the United States.