SYNTHESIS AND EVALUATION OF GLUCOSE-ADP HYBRIDS AS INHIBITORS OF HEXOKINASE

Glucose-ADP hybrids, in which carboxamide (4) and linear acetylene (5) and allene (6) functional groups link the two moieties, were designed as potential multisubstrate analogue inhibitors for hexokinase. The diastereomeric aldehydes 15 and 28 were key intermediates in the synthesis of these compounds. Reduction of 15, amination, and acylation with (diethylphosphono)acetic acid provided the amide phosphonate 20. Reduction of 15, three-carbon extension to the propargylic bromide 25, and Arbuzov displacement gave the acetylenic phosphonate 26. Addition of ethynylmagnesium bromide to aldehyde 28, separation of the diastereomers, and Mark rearrangement afforded the allenic phosphonates 31R and 31S. Cleavage of the phosphonate esters (trimethylsilyl bromide) and acetal hydrolysis (90% aqueous trifluoroacetic acid) furnished the corresponding deprotected phosphonic acids, which were coupled with adenosine 5'-monophosphate through activation with carbonyl di(imidazole). Inhibition of yeast hexokinase by carboxamide 4 (K(i) = 0.2 mM) and acetylene 5 (K(i) = 2.5 mM) is competitive with glucose and noncompetitive with ATP; the R-allene 6R (IC50 = 1.7 mM) and S-allene 6S (IC50 = 10 mM) are also weak inhibitors. It was concluded that these compounds are not functioning as multisubstrate analogues. The beta,gamma-methylene-gamma-methylthio analogue of ATP (7) was also synthesized. This compound in combination with glucose, as well as gamma-thio-ATP (9) in combination with 6-deoxy-6-iodoglucose (8), were investigated for potential enzyme-induced, covalent coupling. No evidence for such coupling was observed.