The preferable structural feature for sweetness is a lipophilic moiety, e.g., a fiveor six-membered ring with a polar substituent containing an A-H/B system outside the ring. In ketoses, this unit is probably the 1,2-glycol. If a third feature (the lipophilic, 7, site) is required for the attainment of optimum sweetness and if it is C-6 in ketoses, then this site can accommodate quite a large constituent, both above and below the plane of the ring. The removal of the hydroxyl group from the C-6 hydroxymethyl substituent to yield the 7-deoxy derivatives causes bitterness, thus implicating the primary hydroxymethyl group with bitterness. Therefore, the creation of lipophilic site(s) in the sugar ring causes the realignment of the sugar molecule on the taste receptor surface. The disturbance of the proposed A-H/B system, e.g., the removal of the C-2 hydroxyl group, causes the ring a-glycol unit (most likely the ring C-3 and C-4 hydroxyl groups) to function as the A-H/B system.
Keyphrases 0 Structure-activity relationships-sweetness of ketoses related to structural functions Ketoses-structural functions related to sweetness Sweetness-related to structural functions of ketoses Taste physiolom-structural functions of ketoses related to sweetness