A diverse series of substituted benzenesulfonamides as aldose reductase inhibitors with antioxidant activity: design, synthesis, and in vitro activity.

We have previously reported the successful replacement of a carboxylic acid functionality with that of a difluorophenolic group on the known aldose reductase inhibitors (ARIs) of 2-(phenylsulfonamido)acetic acid chemotype. In the present work, based on bioisosteric principles, additional 2,6-difluorophenol and tetrazole, methylsulfonylamide, and isoxazolidin-3-one phenylsulfonamide derivatives were synthesized and tested in vitro in protocols primarily related to the long-term diabetic complications. Most of the compounds were found as ARIs at IC(50) < 100 μM, while the introduction of the 4-bromo-2-fluorobenzyl group in a phenylsulfonamidodifluorophenol structure resulted in a compound (4c) presenting a submicromolar inhibitory profile. However, the derivatives of tetrazole, methylsulfonylamine, and the (R)-enantiomer of isoxazolidin-3-one did not exhibit appreciable ARI activity. The selectivity of the active ARIs is also discussed. Furthermore, the synthesized compounds exhibited potent antioxidant potential (homogeneous and heterogeneous systems).