Nootkatone, So A-peeling in Grapefruit, is Repellent to Mosquitoes and Ticks

When I profiled Allylix last summer, CEO Carolyn Fritz explained how the San Diego startup was using genetically engineered yeast and proprietary fermentation technology to produce specialized “aroma chemicals” for the $1.9 billion flavor and fragrance market. The company’s first product was a compound with a keen grapefruit taste and smell called nootkatone, a flavor enhancer previously extracted from grapefruit peels through a costly process.

Nootkatone is just one example of a huge class of molecules known as terpenes—naturally occurring compounds that Fritz said also happen to be highly prized in markets for pharmaceuticals, flavors and fragrances, and insect repellents.

Now, the Centers for Disease Control and Prevention are pushing to develop nootkatone as a completely natural insect repellent, according to a recent report from National Public Radio.

Unlike DEET, (also known as also known as N,N-Diethyl-meta-toluamide), which is the most common active ingredient in conventional insect repellents, CDC officials say nootkatone is nongreasy, dries quickly, and has a very pleasant, citrus-y grapefruit odor. Nootkatone also is so nontoxic you can actually drink it, as it’s already an approved flavor-enhancing food additive used in grapefruit-flavored drinks like Squirt. Yet nootkatone is highly toxic to mosquitoes, ticks, and other insects.

In an e-mail to me, Fritz writes, “In addition to being a flavor and fragrance, nootkatone is an effective insect repellent, and is the most effective tick repellent tested by the CDC. It has the added benefit of a natural product [officially designated as] GRAS (Generally Regarded as Safe).”

She adds, “We and another company have co-exclusive rights to the CDC’s patents on the use of nootkatone as a repellent. It’s actually quite exciting.”

One CDC official who talked with NPR said nootkatone is so nontoxic that it could someday become an ingredient in the world’s first all-natural and environmentally safe insecticidal soap. The challenge, according to the NPR report, is that nootkatone produced conventionally from grapefruit peel is expensive—about $4,000 per kilogram (about 2.2 pounds).

Producing nootkatone at lower cost, however, is one of the advantages addressed by the technology under development at Allylix—which might be why Fritz views nootkatone-based insect repellent as “exciting.”

Bruce V. Bigelow was the editor of Xconomy San Diego from 2008 to 2018. Read more about his life and work here. Follow @bvbigelow

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