ANALYSES OF HUMAN AXILLARY ODORS AND THEIR
PRECURSORS IN NORMAL AND STRESSFUL SITUATIONS
Yabuki M.1, Takeuchi K.1, Hagura T.1, Hasegawa Y.1 1Tokyo Research
Laboratory, Kao Corporation, Tokyo, Japan
Our laboratory previously reported the 3-Hydroxy-3-methylhexanoic
acid (3H3MH) and 3-methyl-3-sulfanylhexan-1-ol (3M3SH) as key
odorants in human axillary sweat (Hasegawa, 2004). We had also
elucidated the occurrence of cysteine-linked precursor of 3M3SH on the
axillary skin and applied for a patent for the use of body odor indicator
(Yabuki, 2004). One objective of this study is to analyze amino acid
linked axillary odor precursors quantitatively. A second objective is to
evaluate the effect of mentally stressful situation on axillary odor. In
this study, we evaluated axillary odor of healthy American women (n =
26, aged 18-63) and collected their sweat samples in both normal (day
- and mentally stressful situation (day 2). During 10-minute stress
session trained moderator asked math, trivia and word questions to
subjects continuously. LC-MS/MS analyses showed there was
correlation between the precursor levels on skin surface and odor
intensity. Whereas the ratios of glutamine-linked two odor precursors,
Gln-3H3MH to Gln-3M2H (3-Methyl-2-Hexenoic acid) were
approximately 7:1 with no inter-subject variation, the ratios of Gln-
3H3MH to Cys-3M3SH were unique to subjects. This finding indicates
a presence of common synthetic pathway for the glutamine-linked
3H3MH and 3M2H. The temperature and other circumstances remained
unchanged for testing two days. However, 70% of subjects of the day 2
had higher odor and precursor levels compared to day 1. Some subjects
had more than three times higher amounts of precursors. This result
suggests mental stress induced perspiration acts as an accelerator for
strong odor formation.