Odour receptors

Dryer L. and Berghard A. (1999). Odourant receptors a plethora of G-protein-coupled receptors. Trends Pharmacol Sci 20, 413-419. 

The goal of chemical analysis of odorous compounds in air is to determine all substances, which interact with odour perception cells in our nose, both qualitatively and quantitatively. However, with a few exceptions all compounds with certain vapor pressure have an odour, meaning that their volatilized molecules react with the membrane of odour receptor cells. As will be shown, always hundreds of compounds are present in air this means that the analysis would be very complex. However as was said before, our sense of smell is selective for some products it is very sensitive for other compounds it is much less sensitive. 

Menco B. P. Cunningham A. M., Qasba P., Levy N. and Reed R. R. (1997) Putative odour receptors localize in cilia of olfactory receptor cells in rat and mouse a freeze-substitution ultrastructural. J. Neuxocytol. 26, 691-706. 

Compound (details) Plant source (family) / plant parti Odour receptor (OD-R) binding (other targets) 1 in vivo effects/... 

Flavouring substances that cause only taste impressions are defined as substances that are usually non-volatile at room temperature. Therefore, they are only perceived by the taste receptors [7]. Examples are sucrose (sweet) or caffeine (bitter). Flavouring substances causing odour impressions are volatiles that are perceived by the odour receptors [7]. Examples are ethyl butyrate or dimethyl sulfide. Some flavouring substances are perceived by taste and odour receptors (e.g. acetic acid, butyric acid). 

All eight isomers possess characteristic minty odours. The reason for the importance of /-menthol is its ability to interact, not only with odour receptors, but also with the receptors which sense cold. The presence of menthol will induce cold receptors to respond as if they had sensed a drop in temperature. This physiologically induced sensation of cold is used in many products from foodstuffs, such as confectionery, chewing gum, through oral care products such as toothpaste to cosmetic preparations such as shaving products. There is therefore a large market for menthol and, since not all of it can be met from natural mint oils, a demand for synthetic material. Consequently, there has been a lot of work on the synthesis of menthol and all of the synthetic routes considered must take stereochemistry into account as /-menthol is always the preferred target. 

ANDERS0N, P., LARSS0N, M., L0FQVIST, J., HANSS0N, B. S., Plant odour receptor neurones on the antennae of the two moths Spodoptera littoralis and Agrotis segetum, EntomoL Exp. Appl., 1996, 80, 32-34. 

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