Armpit odor gets a chemical face.

Armpit odor gets a chemical face

That warm, dark and moist alcove under our arms regularly hosts bacterial feeding frenzies. No sooner do the underarm's scent glands release a sweaty brew of organic compounds than mobs of bacteria convert the compounds into volatile varieties nasally recognized as B.O.

The essence of this infamous fume apparently has succumbed to chemical sleuthing. Henceforth, the underarm compound 3-methyl-2-hexenoic acid shall join the ranks of foul-smelling chemicals, according to George Preti at the Monell Chemical Senses Center in Philadelphia. Although an individual's aroma comes from several dozen, mostly unidentified odor compounds, Preti says 3-methyl-2-hexenoic acid is the don. Prior studies by others had awarded that distinction to steroids and isovaleric acid. To push his point at the American Chemical Society meeting. Preti let people sniff vials containing filter strips soaked with the compound. "It's like having an armpit in a jar," he says.

To unmask the odoriferous compound, Preti's team harvested sweat from absorbent pads worn by male volunteers. The scientists separated and identified the perspiration's compounds using gas chromatography, and sniffed each isolated compound as it emerged from the chromatograph.

Uncovering the chemical basis of underarm oder should enable deodorant makers to formulate more effective and lasting products, Preti suggests.

Using a similar gas-chromatography/nose technique, Terry E. Acree and Edward H. Lavin of Cornell University's New York State Agricultural Experiment Station in Geneva, N.Y., and colleagues at Kyoto University of Japan identified o-amino acetophenone as the chemical basis for the "foxy" smell of many Labruscana grape cultivars. The same compound provides the primary odor component of extract from the anal sac of a Japanese weasel, they report.