A puppy pal that gets sprayed by a skunk is no friend to human noses. The nasty odor can linger for weeks or more.
But at least one kind of Tolypocladium fungi makes a chemical that can snuff out the stink. Called pericosine, it reacts with skunk spray’s sulfur-containing compounds, forming residues that aren’t offensive to the nose and can be more easily washed away, researchers report in the July 26 Journal of Natural Products.
Researchers think that the fungus uses pericosine to neutralize noxious chemicals encountered in the wild. “We’ve never seen … a form of chemical defense like this,” says Robert Cichewicz, a natural products and drug discovery researcher at the University of Oklahoma in Norman.
The scientists were clued into the compound when they grew the fungus together with a different fungal species. The Tolypocladium fungus produced pericosine that reacted with chemicals, including possibly harmful ones, made by the second fungus. What if pericosine could tackle other compounds? To find out, the team ordered skunk spray essence: the “nasal equivalent of staring at the sun” as Cichewicz puts it. Mixing the spray with pericosine made the smell go away.
The reeking molecules produced by skunks’ anal glands are hard to wash away. Typical products used to deskunk people and animals are not that effective, like soap, or harsh, like bleach. But tests of pericosine with tissues meant to stand in for eyes and skin suggest that the compound may be gentler, not causing irritation.
Adding several common cosmetic ingredients also sped up pericosine’s ability to cut the skunk spray smell, the team found. That “was really thrilling,” Cichewicz says. “This now looks a lot more like a personal-care product than it does an organic chemistry reaction.”