Some SAR studies on the sense of taste

Abstract

Using the Shallenberger-Kier model as a molecular requirement for the sweet taste, adsorption and spectroscopic measurements on sweet and nonsweel analogs are described. Additional exploratory experiments were made in search of a set of parameters which could be used to predict the taste (sweet or nonsweet) oftrisubstituted benzenes. INTRODUCTIONScientists of diverse disciplines are studying the sense of taste, essentially from three different perspectives. There are those, primarily organic chemists, who seek structure-taste relationships (SAR). A sub-group, "flavor chemists", analyze foods and examine the effects of flavor-enhancers, flavor-inhibitors, and flavor modifiers. A second category of interest is the mechanism of taste stimulation, being explored by biochemists, biophysicists and others. They are probing the mechanism of stimulus-receptor interaction, cell structure of the taste buds, and the triggering process of nerve transmission up to the brain. Thirdly, there are those interested in taste perception, especially psychologists. This includes the measurements of taste quality and intensity, taste preferences, and food flavors.Recent work has shown that for a clearer elucidation of the mechanism of taste stimulation by sweet or bitter substances, studies must be made of (1) structure-activity relationships of the stimulus,'{2) the rate of development (reaction time), intensity, and longevity of response to the stimulus Cpersistance'), (3) the nature of the stimulus-receptor interaction. (4) The influence of biosphere environment, i.e. ionic strength, viscosity, temperature, concentration of stimulus, etc., (5) biochemical factors affecting transduction of the nerve impulses to the brain, e.g. presence of critical enzymes, etc. As organic chemists, we have been particulary interested in the first and third factors above.With respect to the sweet taste, a widely used working hypothesis has been that sweet molecules have a triangular region, A-H, B, y, in which A-H is a proton-donor group, B a proton-acceptor function and y is a lipophilic moiety (46,70).

Structural theories applied to taste chemistry

“…It has been mentioned above that the Me group of trifluoroacetyl-a-L-aspartyl-o-methyl-p-nitroanilide (27) hindered the cross conjugation of the nitro group with the amide group in coplanar conformation, which resulted in a loss of sweet taste and is a case in point of secondary steric effects (17). The same is true for nitroanilines (32): 28 sweet, 29 slightly sweet, 30 bitter and 31 tasteless.…”