An investigation of human apocrine gland secretion for axillary odor precursors

Abstract

Recently completed studies from our laboratories have demonstrated that the characteristic human male axillary odors consist of C6 to C11 normal, branched, and unsaturated aliphatic acids, with (E)-3-methyl-2-hexenoic acid being the most abundant. To investigate the mechanism by which the odor is formed, it is necessary to determine the nature of the odorless precursor(s) found in the apocrine secretion which is converted by the cutaneous microorganisms to the characteristic axillary odor. Pooled apocrine secretion was obtained from several male volunteers by intracutaneous injection of epinephrine. Partitioning this secretion into aqueous and organic soluble fractions was followed by hydrolysis of each fraction with NaOH or incubation with axillary microorganisms (cutaneous lipophilic corynebacterium). Analysis by gas chromatography/mass spectrometry (GC/MS) revealed the presence of (E)- and (Z)-3-methyl-2-hexenoic acid in the aqueous phase hydrolysate and aqueous phase incubated with bacteria; however, only a trace amount was seen in the resultant organic phase mixtures. These results suggest that a water-soluble precursor(s) is converted by the axillary flora to the characteristic axillary odors.

Facts, fallacies, fears, and frustrations with human pheromones

“…The details of the chemical identification, exact structures, and synthesis (of noncommercially available compounds) have been described (Zeng et al, 1991(Zeng et al, , 1992. In terms of relative abundance, these acids, in particular (E)-3-methyl-2-hexenoic (E-3M2H), are present in far greater quantity than volatile steroids, e.g., androstenone, which were previously thought to be important axillary odors (Gower and Ruparelia, 1993).…”

“…The precursors to axillary odor reside in the apocrine glands (Labows et al, 1982;Zeng et al, 1992Zeng et al, , 1996aZeng et al, , 1996b. The characteristic axillary odor is formed from the interaction of odorless (water-soluble) precursor molecules found in apocrine secretion with the cutaneous axillary microorganisms (Labows et al, 1982;Zeng et al, 1992).…”

“…The characteristic axillary odor is formed from the interaction of odorless (water-soluble) precursor molecules found in apocrine secretion with the cutaneous axillary microorganisms (Labows et al, 1982;Zeng et al, 1992). In addition, it has been demonstrated that the 3M2H is carried to the skin surface bound to two proteins that have been designated apocrine secretion odor-binding proteins: ASOB1, apparent molecular weight 45 kDa, and ASOB2, apparent molecular weight 26 kDa (Spielman et al, 1995(Spielman et al, , 1998.…”

“…The concentration and biogenesis of these compounds in human axillae have been examined (Rennie et al, 1991;Gower and Ruparelia, 1993). Additionally, androstenone and androstenol were found to be present in the characteristic odor fraction, at levels 50 -100 times below the concentration of 3M2H and other organic acids (Zeng et al, 1992). Shinhoara et al (2000) found that androstenol (commercially obtained) could alter LH pulsing when applied to the upper lip/nares region of female recipients at concentrations 1,000ϫ above endogenous concentrations.…”

A human axillary odorant is carried by apolipoprotein D.

“…The water-soluble components of apocrine secretion were found to contain the odorless precursors of the characteristic odor (13). Furthermore, it was recently shown that 3M2H is carried to the skin surface bound to two proteins, which have been designated as apocrine secretion odor-binding proteins 1 and 2 (ASOB1 and ASOB2), with molecular masses of 45 and 26 kDa, respectively, as determined from SDS/PAGE (16).…”