trans-3-Methyl-2-hexenoic acid (TMHA) is an unsaturated short-chain fatty acid that occurs in sweat secreted by the axillary (underarm) apocrine glands of Caucasians and some Asians.[1]
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| Names | |
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| Preferred IUPAC name
(2E)-3-Methylhex-2-enoic acid | |
| Other names | |
| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.225.656 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C7H12O2 | |
| Molar mass | 128.171 g·mol−1 |
| Density | 0.97 g/cm3 |
| Melting point | −3.4 °C (25.9 °F; 269.8 K) |
| Boiling point | 225.2 °C (437.4 °F; 498.3 K) |
| Hazards | |
| Flash point | 132 °C (270 °F; 405 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hexanoic acids such as TMHA have a hircine odor. Of the fatty acids contributing to Caucasian men's underarm odor, TMHA has the most prominent odor.[2]
Schizophrenia odor
editIt has long been claimed that schizophrenia patients exhibit a particular peculiar body odor, and it has been postulated the odor may be caused by underlying metabolic abnormalities associated with the condition, among other factors.[3][4] Initial studies identified the causal component as TMHA,[5] however, subsequent studies failed to reproduce such results,[3][6] with subsequent researchers suggesting the initial research may have had misidentified impurities in samples as TMHA due to poor methodology.[3] However, a 2007 study found schizophrenia patients to have reduced olfactory sensitivity to TMHA, possibly indicating sensory habituation; the decreased ability to smell the substance due to the presence of the substance as a constant component of subjects' own sweat and body odor. Furthermore, the researchers noted a positive association between reduced ability to smell TMHA and greater severity of disorganised and negative symptoms.[4]
An allusion to TMHA and its purported link to the smell of the mentally ill is made in the 1996 David Foster Wallace novel, Infinite Jest,[7] and in the 1988 novel The Silence of the Lambs by Thomas Harris.
References
edit- ^ Akutsu, T.; Sekiguchi, K; Ohmori, T; Sakurada, K (2006). "Individual Comparisons of the Levels of (E)-3-Methyl-2-Hexenoic Acid, an Axillary Odor–Related Compound, in Japanese". Chemical Senses. 31 (6): 557–63. doi:10.1093/chemse/bjj060. PMID 16690870.
- ^ Sun, Lixing; Williams, Wendy A.; Avalos, Corinna (2005). Human sweaty smell does not affect women's menstrual cycle. pp. 308–312. doi:10.1007/0-387-25160-X_34. ISBN 978-0-387-25159-2.
- ^ a b c Perry, Thomas L.; Melançon, Serge B.; Lesk, Donna; Hansen, Shirley (December 1970). "Failure to detect trans-3-methyl-2-hexenoic acid in the sweat of schizophrenic patients". Clinica Chimica Acta. 30 (3): 721–725. doi:10.1016/0009-8981(70)90266-4. ISSN 0009-8981. PMID 5493894.
- ^ a b Brewer, Warrick J.; Wood, Stephen J.; Pantelis, Christos; Berger, Gregor E.; Copolov, David L.; McGorry, Patrick D. (January 2007). "Olfactory sensitivity through the course of psychosis: Relationships to olfactory identification, symptomatology and the schizophrenia odour". Psychiatry Research. 149 (1–3): 97–104. doi:10.1016/j.psychres.2006.03.005. ISSN 0165-1781. PMID 17156856. S2CID 37511465.
- ^ Smith, K.; Thompson, G. F.; Koster, H. D. (1969-10-17). "Sweat in schizophrenic patients: identification of the odorous substance". Science. 166 (3903): 398–399. Bibcode:1969Sci...166..398S. doi:10.1126/science.166.3903.398. ISSN 0036-8075. PMID 5818039. S2CID 21377002.
- ^ Gordon, S. G.; Smith, K.; Rabinowitz, J. L.; Vagelos, P. R. (July 1973). "Studies of trans-3-methyl-2-hexenoic acid in normal and schizophrenic humans". Journal of Lipid Research. 14 (4): 495–503. doi:10.1016/S0022-2275(20)36883-8. ISSN 0022-2275. PMID 4715330.
- ^ Foster., Wallace David (1996). Infinite jest: a novel (1 ed.). Boston: Little, Brown and Co. pp. 748–749. ISBN 978-0-316-07385-1. OCLC 669069481.