Analysis of characteristic human female axillary odors: Qualitative comparison to males

Odors produced in the human female axillae are of both biological and commercial importance. Several studies have suggested that extracts from female underarm secretions can alter the length and timing of the female menstrual cycle. In addition, more than 1.6 billion dollars are spent annually on products to eliminate or mask the axillary odors. Our recent studies have determined that the characteristic axillary odors in males consist of C₆–C₁₁, saturated, unsaturated and branched acids, with (E)-3-methyl-2-hexenoic acid (3M2H) being the major compound in this mixture. The 3M2H appears to be carried to the skin surface bound to two proteins in the axillary secretions. Data reported here show that the same mixture of odorous compounds is found in female axillary secretions, with several minor qualitative differences. Separation of the female apocrine secretions into aqueous and organic soluble fractions demonstrated that 3M2H, and several other members of the acids in the characteristic odor, are released by hydrolysis with base. Electrophoretic separation of the proteins found in the aqueous phase of female apocrine secretions revealed a pattern identical to that seen in males. The qualitative similarity of the acidic constituents making up the characteristic axillary odors of both females and males as well as the proteins present in the aqueous phase suggest a similar origin for axillary odors in both sexes.