Figure 1. Molecular structures of aldose reductase inhibitors

Molecular structures of sorbinil, tolrestat, epalrestat, and six novel inhibitors (HAR-1 through HAR-6) are shown below. HAR-1 is 1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano-[4,3-b][1]benzopyran-3-acetic acid, and is referred to as HAR-1 in the text. The synthesis of HAR-1 through HAR-6 is described in the text, under methods, and in [17].