A series of xanthone-2-carboxylic acids substituted in the 7 position with sulfamoyl and other groups was synthesized and assayed in vitro for inhibition of aldose reductase isolated from rabbit lenses. At a concentration of lo4 M, the N-methyl-N-(2-hydroxyethyl) sulfamoyl derivative 14 produced an 83% inhibition of aldose reductase. The structural requirements for this type of activity are discussed.
