Synthesis and inhibitory properties of (1R,2R,4R,6 R)-6-O -(2-hydroxyethyl)cyclohexane-1,2,4,6-tetraol derivatives: mechanistic probes for the inositol monophosphatase reaction1

Abstract

The phosphate derivatives 2, 3 and 4 of 6-O-(2-hydroxyethyl)cyclohexane-1,2,4,6-tetraol have been designed to inhibit inositol monophosphatase, the putative target for lithium therapy, by interacting simultaneously with both cofactor metal ions at the active site of the enzyme. The compounds have been synthesised, via the known key common intermediate cyclohexene oxide, from cyclohexane-1,4-diol in moderate yield, and have been tested for activity in standard enzyme assays. Each compound serves as a competitive inhibitor and displays the expected inhibitory properties. Indeed, compound 4 and the cyclic phosphate 3 of 6-O-(2-hydroxyethyl)cyclohexane-1,2,4,6-tetraol are, respectively, the most potent examples of a primary alkyl phosphate inhibitor and a phosphate monoanion inhibitor yet reported for the enzyme. The stereochemistry of the most potent inhibitor, (1R,2R,4R,6R)-2 as deduced from the X-ray crystal structure of a synthetic precursor, provides useful mechanistic insight into the action of the enzyme and the mode of inhibitor binding.