Mircea D. Banciu

Carbonic anhydrase inhibitors - Part 53?. Synthesis of substituted-pyridinium derivatives of aromatic sulfonamides: The first non-polymeric membrane-impermeable inhibitors with selectivity for isozyme IV

Abstract Reaction of three aromatic sulfonamides containing a free amino group, i.e., sulfanilamide, homosulfanilamide and 4-(2-aminoethyl)-benzenesulfonamide with di-, tri- or tetra-substituted pyrylium salts afforded three series of cationic sulfonamides, containing a large variety of moieties substituting the pyridinium ring. The new derivatives were assayed as inhibitors of three carbonic anhydrase (CA) isozymes, CA I, II (cytosolic forms) and IV (membrane-bound form). Efficient inhibition was observed against all three isozymes, but due to the cationic nature of these inhibitors, in vivo and ex vivo experiments showed that only CA IV is selectively inhibited to a high degree, without affecting the cytosolic isozymes, present in appreciable concentrations in the experimental model used. This is the first example of selective in vivo inhibition of only one physiologically relevant CA isozyme with non-polymeric inhibitors and might lead to more selective drugs from this class of pharmacological agents.

Carbonic anhydrase inhibitors: sulfonamides incorporating furan-, thiophene- and pyrrole-carboxamido groups possess strong topical intraocular pressure lowering properties as aqueous suspensions

Important physiological and physio-pathological functions are played by several carbonic anhydrase (CA, EC 4.2.1.1) isozymes, which are strongly inhibited by aromatic and heterocyclic sulfonamides. Here we report several new types of such sulfonamides, incorporating furan-, thiophene- and pyrrole-carboxamide moieties in their molecules. Some of these compounds showed very good CA II and CA IV inhibitory properties. with affinities for the enzymes in the low nanomolar range. Due to their relatively low water solubility, some of the most active CA II inhibitors reported here have been formulated as aqueous suspension for topical administration as antiglaucoma agents. in normotensive and glaucomatous rabbits. The derivatives incorporating furan- and pyrrole-carboxamide moieties (but not the corresponding thiophene-substituted derivatives), showed effective and long-lasting intraocular pressure (IOP) lowering both in normotensive as well as glaucomatous animals, with potencies superior to dorzolamide and brinzolamide, the two available topically acting sulfonamide drugs. This is the first example of non-water soluble sulfonamides that significantly lower IOP, being thus similar with the recently introduced drug brinzolamide, which belongs to a completely different chemical family of antiglaucoma sulfonamides.

Carbonic anhydrase inhibitors: inhibition of isozymes I, II and IV by sulfamide and sulfamic acid derivatives.

Abstract Sulfamide and sulfamic acid are the simplest compounds containing the SO2NH2 moiety, responsible for binding to the Zn(II) ion within carbonic anhydrase (CA, EC 4.2.1.1) active site, and thus acting as inhibitors of the many CA isozymes presently known. Here we describe two novel classes of CA inhibitors obtained by derivatizations of the lead molecules mentioned above. The new compounds, possessing the general formula RSO2NH-SO2X (X = OH, NH2), were obtained by reaction of sulfamide or sulfamic acid with alkyl/arylsulfonyl halides or aryl-sulfonyl isocyanates. A smaller series of derivatives has been obtained by reaction of aromatic aldehydes with sulfamide, leading to Schiff bases of the type ArCH=NSO2NH2. All the new compounds act as strong inhibitors of isozymes I, II and IV of carbonic anhydrase. Their mechanism of CA inhibition is also discussed based on electronic spectroscopic measurements on adducts with the Co(II)-substituted enzyme. These experiments led to the conclusion that the new inhibitors are directly coordinated (in a monodentate manner) to the metal ion within the enzyme active site, similarly to the classical inhibitors, the aromatic/heterocyclic sulfonamides.

Carbonic Anhydrase Inhibitors: Inhibition of Isozymes I, II And IV with Heterocyclic Mercaptans, Sulfenamides, Sulfonamides and their Metal Complexes

A series of sulfenamides, sulfonamides and sulfonamide metal complexes have been prepared starting from 4,5-disubstituted-3-mercapto-1,2,4-triazole derivatives. The heterocyclic mercaptans were oxidized to the corresponding sulfenamides by hypochlorite in the presence of ammonia. The sulfonamides were obtained by oxidation of sulfenamides with potassium permanganate. The Zn(II) and Cu(II) complexes of the new heterocyclic sulfonamides have been prepared via the sodium salt of the ligand. Inhibition of three carbonic anhydrase (CA) isozymes, hCA I, hCA II and bCA IV (h = human, b = bovine) with the prepared compounds has been investigated. Mercaptans were generally less inhibitory than sulfenamides, which in turn behaved as weaker inhibitors than the sulfonamides. The strongest inhibitors were the Zn(II) and Cu(II) complexes of the heterocyclic sulfonamides. Susceptibility to inhibition was generally: hCA II > bCA IV > hCA I. Although none of the obtained simple inhibitors (mercaptans, sulfenamides, sulfonamides) possessed antiglaucoma action when administered directly into the eye in experimental animals, the Zn(II) and Cu(II) complexes of some sulfonamides acted as more efficient intraocular pressure lowering agents as compared to the clinical drug dorzolamide. This constitutes an encouraging result for obtaining novel antiglaucoma drugs from this class of CA inhibitors.

Carbonic anhydrase inhibitors: synthesis of Schiff bases of hydroxybenzaldehydes with aromatic sulfonamides and their reactions with arylsulfonyl isocyanates.

Abstract Reaction of o- or p-hydroxybenzaldehydes with sulfanilamide, homosulfanilamide and p-(2-aminoethyl)- benzene-sulfonamide afforded several new Schiff bases which were subsequently derivatized at the phenolic hydroxy moiety by reaction with arylsulfonylisocyanates. The new arylsulfonylcarbamates obtained in this way possessed interesting inhibitory properties against three carbonic anhydrase (CA) isozymes, hCA I, hCA II and bCA IV (h = human, b = bovine isozyme). All these new derivatives, the simple Schiff bases and the arylsulfonylcarbamates obtained as outlined above, were more inhibitory against all isozymes as compared to the corresponding parent sulfonamide from which they were obtained. Generally, the p-hydroxybenzaldehyde derivatives were more active than the corresponding ortho isomers. An interesting behavior was evidenced for some of the ortho-substituted arylsulfonylcarbamato-sulfonamides, which showed higher affinities for the isozyme hCA I, as compared to hCA II and bCA IV (generally hCA I is 10–1000 less sensitive to “normal” sulfonamide inhibitors, such as acetazolamide, methazolamide or dorzolamide, as compared to hCA II). This make the new derivatives attractive leads for designing isozyme I-specific inhibitors.

Protease inhibitors: synthesis of bacterial collagenase and matrix metalloproteinase inhibitors incorporating arylsulfonylureido and 5-dibenzo-suberenyl/suberyl moieties.

Novel matrix metalloproteinase (MMP)/bacterial collagenase inhibitors are reported, considering the sulfonylated amino acid hydroxamates as lead molecules. A series of compounds was prepared by reaction of arylsulfonyl isocyanates with N-(5H-dibenzo[a,d]cyclohepten-5-yl)- and N-(10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-yl) methyl glycocolate, respectively, followed by the conversion of the COOMe to the carboxylate/hydroxamate moieties. The corresponding derivatives with methylene and ethylene spacers between the polycyclic moiety and the amino acid functionality were also obtained by related synthetic strategies. These new compounds were assayed as inhibitors of MMP-1, MMP-2, MMP-8 and MMP-9, and of the collagenase isolated from Clostridium histolyticum (ChC). Some of the new derivatives reported here proved to be powerful inhibitors of the four MMPs mentioned above and of ChC, with activities in the low nanomolar range for some of the target enzymes, depending on the substitution pattern at the sulfonylureido moiety and on the length of the spacer through which the dibenzosuberenyl/suberyl group is connected with the rest of the molecule. Several of these inhibitors also showed selectivity for the deep pocket enzymes (MMP-2, MMP-8 and MMP-9) over the shallow pocket ones MMP-1 and ChC.

The enthalpies of formation of two dibenzocyclooctadienones

The standard molar enthalpies of formation (� f H 0 m (s)/kJ mol −1 ) for 2,3:6,7-dibenzocycloocta-2,6-dien-1-one and 2,3:7,8dibenzocycloocta-2,7-dien-1-one [6H-11,12-dihydro-dibenzo[a,e]cycloocten-5-one (ketone 1) and 10H-11,12-dihydrodibenzo[a,d]-cycloocten-5-one (ketone 2), respectively] were derived from enthalpies of combustion, measured by means of a microbomb calorimeter. The fusion and vaporization enthalpies of these compounds were obtained from DSC and correlation gas chromatography measurements. The standard molar enthalpies of formation in the gas phase were calculated by combining the condensed phase standard molar enthalpies of formation with the fusion and vaporization enthalpies adjusted to 298.15 K.

Flow vacuum pyrolysis of tetrazoles with annelated dibenzocycloalkane skeletons

Abstract Three new dibenzoannelated tetrazoloazocines 1 – 3 were synthesized from the corresponding ketones 6 – 8 and in situ generated triazidochlorosilane. The new compounds were characterized by IR, 1 H-, 13 C-NMR and MS data. The flow-vacuum pyrolyses of the tetrazoles 1 – 3 , of a recently described tetrazoloazonine 4 and of 1,5-diphenyltetrazole ( 5 ) at 1.33 mbar and temperatures between 400–550°C were studied by GC/MS. The main reaction product of 1 was 6 H -quinindoline whereas the principal products of 2 , 3 and 4 were the corresponding ring contracted N -cyanoderivatives 11 , 12 and 15 , respectively. Diphenyltetrazole 5 afforded diphenylcarbodiimide and 2-phenyl-benzoimidazole. The comparative reaction mechanisms for 1 – 5 are discussed. The N -cyano-derivatives 11 , 12 and 15 structurally are strongly related to recent anti-amnesia drugs.

Structural factors influencing the reaction rates of 4-aryloxy-7-nitrobenzofurazans with amino acids

An interesting observation was made when studying the SNAr reaction between several 4-aryloxy-7-nitrobenzofurazans (2) and several amino acids leading to the apparition of detectable fluorescence from the substitution products3. Acidic amino acids reacted very slowly=while basic amino acids react fastest with2 having an unsubstituted phenyl or a 4-formyl-phenyl Ar group. Amongst neutral amino acids, proline reacts fastest at room temperature after 100 min. With2 having a methoxy-subtituted Ar group.

The standard enthalpies of formation of some dibenzocycloheptane ketones

The heats of combustion of 10,11-dihydro-5 H-dibenzo[a,d]-cycloheptene-5-one (ketone 1), 5 H-dibenzo[a,d]cyclohepten-5-one (ketone 2) and 5,7-dihydro-6H-dibenzo[a,c]cyclohepten-6-one (ketone 4) were measured by means of a Gallenkamp adiabatic bomb calorimeter. Uncertainties in the determination of the heats of combustion ranged between 0.25% and 2%. The enthalpies of formation and of atomization for the three compounds were derived. The experimental values of the heats of atomization in the solid state were compared with those calculated using the Allen-Skinner bond energy scheme (for the liquid state). Conclusions concerning the resonance energies of the three compounds are drawn.