Carbonic Anhydrase Inhibitors: Perfluoroalkyl/Aryl-Substituted Derivatives of Aromatic/Heterocyclic Sulfonamides as Topical Intraocular Pressure-Lowering Agents with Prolonged Duration of Action Andrea Scozzafava, † Luca Menabuoni, ‡ Francesco Mincione, # Fabrizio Briganti, † Giovanna Mincione, † and Claudiu T. Supuran* ,† Laboratorio di Chimica Inorganica e Bioinorganica, Universita ` degli Studi di Firenze, Via Gino Capponi 7, I-50121 Florence, Italy, Ospedale San Giovanni di Dio, S. A. Oculistica, Via Torregalli 3, I-50123 Florence, Italy, and Istituto Oculistico, Universita ` degli Studi di Firenze, Viale Morgagni 85, I-50134 Florence, Italy Received July 13, 2000 Reaction of perfluoroalkyl/arylsulfonyl chlorides or perfluoroalkyl/arylcarbonyl chlorides with aromatic/heterocyclic sulfonamides possessing a free amino/imino/hydrazino/hydroxy group afforded compounds with the general formula C x F y Z-A-SO 2 NH 2 , where Z ) SO 2 NH, SO 3 , CONH, or CO 2 and A ) aromatic/heterocyclic moiety. The sulfonyl chlorides used in synthesis included: CF 3 SO 2 Cl, n-C 4 F 9 SO 2 Cl, n-C 8 F 17 SO 2 Cl, and C 6 F 5 SO 2 Cl, whereas the acyl chlorides were C 8 F 17 COCl and C 6 F 5 COCl. A total of 25 different sulfonamides have been derivatized by means of the above-mentioned perfluorosulfonyl/acyl halides. These new series of sulfonamides showed strong affinities toward isozymes I, II, and IV of carbonic anhydrase (CA). For a given sulfonamide derivatized by the above procedures, inhibitory power was greater for the alkyl/ arylsulfonylated compounds, as compared to the corresponding perfluoroalkyl/arylcarbonylated ones. In vitro inhibitory activity generally increased with the number of carbon atoms in the molecule of the acylating/sulfonylating agent, with a maximum for the perfluorophenylsulfon- ylated and perfluorobenzoylated derivatives. Some of the prepared CA inhibitors displayed very good water solubility (in the range of 2%) and strongly lowered intraocular pressure (IOP) when applied topically, directly into the normotensive/glaucomatous rabbit eye, as 2% water solutions. The good water solubility of these new classes of CA inhibitors, correlated with the neutral pH of their solutions used in the ophthalmologic applications, makes them attractive candidates for developing novel types of antiglaucoma drugs devoid of unpleasant ocular side effects. Introduction Sulfonamides possessing carbonic anhydrase (CA; EC 4.2.1.1) inhibitory properties 1,2 such as acetazolamide (AAZ), methazolamide (MZA), ethoxzolamide (EZA), and dichlorophenamide (DCP) have been used for more than 45 years as pressure-lowering systemic drugs in the treatment of open-angle glaucoma as well as other diseases associated with acid base/secretory disequilib- ria. 3,4 Recently, they started to show increasing interest as potential agents for the treatment of macular edema, a condition for which no effective therapy was known up to now. 1 The ocular effects of such sulfonamides are due to inhibition of at least two CA isozymes present within cilliary processes of the eye, i.e., CA II and CA IV, which is followed by a diminished secretion of bicarbonate and reduction of aqueous humor secretion. 5-7 Their main drawback is constituted by systemic side effects such as fatigue, augmented diuresis, or pares- thesias, due to CA inhibition in other tissues/organs than the target one, i.e., the eye. 8 The above-mentioned side effects are absent in the case in which the inhibitor has topical activity and is applied directly into the eye. This route, discovered in 1983 by Maren’s group, 9 was shortly followed by the development of the first clinical agents of this type, dorzolamide (DZA) 10 as well as the structurally related brinzolamide (BRZ), several years later. 11 The clinical success of topical antiglaucoma CA inhibitors fostered much research in the synthesis and evaluation of other types of such compounds. 12-16 These two drugs men- tioned above are effective in reducing intraocular pres- * To whom correspondence should be addressed. Tel: +39-055- 2757551. Fax: +39-055-2757555. E-mail: cts@bio.chim.unifi.it. † Laboratorio di Chimica Inorganica e Bioinorganica, Universita ` degli Studi di Firenze. ‡ Ospedale San Giovanni di Dio. # Istituto Oculistico, Universita ` degli Studi di Firenze. 4542 J. Med. Chem. 2000, 43, 4542-4551 10.1021/jm000296j CCC: $19.00 © 2000 American Chemical Society Published on Web 10/28/2000