Studies on the synthesis and structure-activity relationships of 5-(3'-indolal)-2-thiohydantoin derivatives as aldose reductase enzyme inhibitors.

A new series of 5-(3'-indolal)-2-thiohydantoin derivatives was synthesized and tested for the ability to inhibit bovine lens aldose reductase (AR) enzyme. The compounds were prepared by condensation of substituted indole-3-aldehyde derivatives with 2-thiohydantoin. The capacity of inhibiting the semi-purified bovine lens enzyme in vitro was observed for several of the compounds tested. One of them was found to be effective in reducing the enzyme activity compared with a corresponding well-known AR inhibitor.