Sulfonylmethanesulfonamide inhibitors of carbonic anhydrase.

A series of sulfonylmethanesulfonamide derivatives is described, which are inhibitors of carbonic anhydrase (CA). The most potent of these is the racemic fluoro sulfone 9, which inhibits carbon dioxide hydration catalyzed by human CA II (CA-II) with an IC50 of 3 nM. Binding competition studies versus dansylamide indicate that the enantiomers of 9 have different affinities for CA-II, with equilibrium dissociation constants of 3.6 and 0.6 nM. QSAR analysis suggests that the key factors involved in achieving high affinity in this series are sulfonamide acidity, hydrophobicity, and minimization of steric demands at the carbon atom adjacent to the sulfonamide group.

4-substituted thiophene- and furan-2-sulfonamides as topical carbonic anhydrase inhibitors.

A series of 4-substituted thiophene- and furan-2-sulfonamides was prepared and was found to possess nanomolar-level potency for inhibition of human carbonic anhydrase II in vitro. Selected examples from this group were further evaluated for their potential to act as topically effective ocular hypotensive agents in the ocular normotensive albino rabbit and the ocular alpha-chymotrypsinized rabbit. Solubility studies in water and pH 7.4 buffer were carried out to estimate the ability of compounds to be formulated in solution. The sensitization potential of key representative structures was determined by in vitro glutathione reactivity studies and guinea pig maximization testing.

3-substituted thieno[2,3-b][1,4]thiazine-6-sulfonamides. A novel class of topically active carbonic anhydrase inhibitors.

3-Aminoalkyl derivatives of thieno[2,3-b][1,4]thiazine-6-sulfonamide were prepared for evaluation as topically active ocular hypotensive agents. The compounds described were found to be excellent in vitro inhibitors of carbonic anhydrase II and in vivo to lower intraocular pressure in three rabbit models of ocular hypertension. Compounds 20A, 20B, and 20C met the requirement of formulation as a 1% solution at pH 5.2, but none of the compounds described exhibited greater activity in the normotensive albino rabbit, the alpha-chymotrypsin-treated albino rabbit, or the normotensive pigmented rabbit than MK-927 or MK-507, the present clinical candidates.

New isomeric classes of topically active ocular hypotensive carbonic anhydrase inhibitors: 5-substituted thieno[2,3-b]thiophene-2-sulfonamides and 5-substituted thieno[3,2-b]thiophene-2-sulfonamides.

A series of 5-substituted thieno[2,3-b]- and thieno[3,2-b)- and thieno[3,2-b)thiophene-2-sulfonamides was prepared and evaluated for topical ocular hypotensive activity in glaucoma models. The 5-substituents were varied to maximize both inhibitory potency against carbonic anhydrase and water solubility. At the same time, these substituents were varied in order to obtain compounds with the appropriate pKa to minimize pigment binding in the iris. All of these variables were optimized in the best compound, 5-[[(methoxyethyl)[(methoxyethyl)ethyl] amino]methyl]thieno[2,3-b]thiophene-2-sulfonamide hydrochloride (55).

Topically active carbonic anhydrase inhibitors. 4. [(Hydroxyalkyl)sulfonyl]benzene and [(hydroxyalkyl)sulfonyl]thiophenesulfonamides.

For several decades a tantalizing goal for the treatment of primary open-angle glaucoma has been the development of a topically active carbonic anhydrase inhibitor. Recent results from several research groups indicate that considerable progress has been made toward this objective. In this report, we present the design and synthesis of (hydroxyalkyl)sulfonyl-substituted benzene- and thiophenesulfonamides. These compounds exhibit inhibition of carbonic anhydrase II in the nanomolar range and lower intraocular pressure in the alpha-chymotrypsinized rabbit model of ocular hypertension after topical instillation.

Thieno[2,3-b]furan-2-sulfonamides as topical carbonic anhydrase inhibitors.

Novel 5-[(alkylamino)methyl]thieno[2,3-b]furan-2-sulfonamides were prepared and evaluated in vitro for inhibition of human carbonic anhydrase II (CA II) and ex vivo for their ability to inhibit Ca II in the albino rabbit eye after topical administration. Compound 11a was found to lower intraocular pressure (IOP) in both the alpha-CT ocular hypertensive albino rabbit and the normal albino rabbit, but was ineffective at lowering IOP in a hypertensive, pigmented monkey model. Since 11a was highly bound to ocular pigment, a series of less basic analogs was prepared. Examples in this series were both less extensively bound to ocular pigment and more active at reducing IOP in pigmented rabbits after topical dosing. Key examples displayed moderate reactivity toward glutathione.

Topically active carbonic anhydrase inhibitors. 3. Benzofuran- and indole-2-sulfonamides.

Derivatives of benzofuran- and indole-2-sulfonamide were prepared for evaluation as topically active ocular hypotensive agents. These compounds were found to be excellent inhibitors of carbonic anhydrase and to lower intraocular pressure in a rabbit model of ocular hypertension. However, the development of these compounds for clinical use was precluded by the observation that they cause dermal sensitization in guinea pigs. A correlation between electrophilicity, as assessed by in vitro reactivity with reduced glutathione, and dermal sensitization potential was further documented.

Dihydrofolate reductase: the amino acid sequence of the enzyme from a methotrexate-resistant mutant of Escherichia coli.

The determination of the amino acid sequence of the enzyme dihydrofolate reductase (5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3) from a mutant of Escherichia coli B is described. The 159 residues were positioned by automatic Edman degradation of the whole protein, of the reduced and alkylated cyanogen bromide fragments, and of selected tryptic, chymotryptic, and thermolytic digestion products. An N-bromosuccinimide produced fragment of the largest cyanogen bromide peptide was also used in the sequence determination.