We investigated inhi
bitory activities of five-mem
bered sugar mimics toward
glycogen-degrading enzymes and a variety of glucosidases. 1,4-Dideoxy-1,4-imino-
d-ara
binitol (
d-AB1) is known to
be a potent inhi
bitor of
glycogen phosphorylase. However, the structural modification of
d-AB1, such as its enantiomerization, epimerization at C-2 and/or C-3, introduction of a su
bstituent to C-1, and replacement of the ring nitrogen
by sulfur, markedly lowered or a
bolished its inhi
bition toward the enzyme. The present work elucidated that
d-AB1 was also a good inhi
bitor of the de-
branching enzyme of
glycogen, amylo-1,6-glucosidase, with a IC
b>50b> value of 8.4
bc;M. In the present work, the de-sulfonated derivative of salacinol was isolated from the roots of
Salacia oblonga and found to
be a potent inhi
bitor of rat intestinal isomaltase with an IC
b>50b> value of 0.64
bc;M. On the other hand, salacinol showed a much more potent inhi
bitory activity toward maltase in Caco-2 cell model system than its de-sulfonated derivative, with an IC
b>50b> value of 0.5
bc;M, and was further a stronger inhi
bitor of human lysosomal
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border="0">-glucosidase than the derivative (IC
b>50b> = 0.34
bc;M). This indicates that the sulfate in the side chain plays an important role in the specificity of enzyme inhi
bition.