Chemical and enzymatic synthesis of fructose analogues as probes for import studies by the hexose transporter in parasites

Various D-fructose analogues modified at C-l or C-6 positions were synthesi zed from D-glucose by taking advantage of the Amadori rearrangement or usin g the aldol condensation between dihydroxyacetone phosphate and appropriate aldehyde catalyzed by fructose I,6-diphosphate aldolase from rabbit muscle . Time affinities of the analogues for the glucose transporter expressed in the mammalian form of Trypanosoma brucei were determined by inhibition of radiolabelled 2-deoxy-D-glucose (2-DOG) transport using zero-trans kinetic analysis. Interestingly, the analogues bearing an aromatic group (i.e. a fl uorescence marker) at C-l or C-6 positions present comparable apparent affi nities to D-fructose for the transporter. This result could find applicatio ns for hexose transport studies and also provides criteria for the design o f glucose import inhibitors. (C) 2000 Elsevier Science Ltd. All rights rese rved.