Yusuf Akbaba

Novel sulfamides as potential carbonic anhydrase isoenzymes inhibitors.

Sulfamides represent an important class of biologically active compounds. A series of novel sulfamides were synthesized from 1-aminoindanes, 1-aminotetralin, 2-aminoindanes and 2-aminotetralin via the reactions of free amines, benzyl alcohol and chlorosulfonyl isocyanate (CSI) followed by hydrogenolysis of the obtained sulfamoylcarbamates. Carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects of the new sulfamides have been investigated. The human (h) isozymes hCA I and hCA II have been investigated in this study by using an esterase assay with 4-nitrophenyl acetate as substrate. The new sulfamides showed inhibition constants in the micro-submicromolar range, with one compound (N-(indane-1-yl)sulfamide) showing a Ki of 0.45μM against hCA I and of 1.07μM against hCA II.

Carbonic anhydrase inhibitory properties of novel benzylsulfamides using molecular modeling and experimental studies

In this study, a series of sulfamoyl carbamates and sulfamide derivatives were synthesized. Six commercially available benzyl amines and BnOH were reacted with chlorosulfonyl isocyanate (CSI) to give sulfamoyl carbamates. Pd-C catalyzed hydrogenolysis reactions of carbamates afforded sulfamides. The inhibition effects of novel benzylsulfamides on the carbonic anhydrase I, and II isoenzymes (CA I, and CA II) purified from fresh human blood red cells were determined by Sepharose-4B-L-Tyrosine-sulfanilamide affinity chromatography. In vitro studies were shown that all of novel synthesized benzylsulfamide analogs inhibited, concentration dependently, both hCA isoenzyme activities. The novel benzylsulfamide compounds investigated here exhibited nanomolar inhibition constants against the two isoenzymes. Ki values were in the range of 28.48±0.01-837.09±0.19nM and 112.01±0.01-268.01±0.22nM for hCAI and hCA II isoenzymes, respectively. Molecular modeling approaches were also applied for studied compounds.

Carbonic anhydrase inhibitory properties of novel sulfonamide derivatives of aminoindanes and aminotetralins.

Abstract Six sulfonamides derived from indanes and tetralines were synthesized. The human carbonic anhydrase isozymes hCA I and hCA II inhibition effects of the synthesized sulfonamides were determined. From these compounds, while N-(5,6-dimethoxy-2,3-dihydro-1H-inden-2-yl)methane sulfonamide showed the most potent inhibitory effect against hCA I (Ki = 46 ± 5.4 µM, r2 = 0.978), N-(1,2,3,4-tetrahydronaphthalene-2-yl)methanesulfonamide was found to have the best inhibitory effect against hCA II (Ki = 94 ± 7.6 µM, r2 = 0.982).

Synthesis and Carbonic Anhydrase Inhibitory Effects of Novel Sulfamides Derived from 1-Aminoindanes and Anilines

Three 1‐aminoindanes, four anilines and BnOH or t‐BuOH were reacted with chlorosulfonyl isocyanate to give sulfamoyl carbamates. Pd‐C catalysed hydrogenolysis reactions of carbamates or deprotection of the Boc group of the carbamates with CF3CO2H afforded seven novel sulfamides. Human carbonic anhydrase (hCA) isoenzymes I and II (hCA I and hCA II) were purified from fresh human blood erythrocytes with one‐step affinity chromatography on Sepharose 4B‐tyrosine‐sulfanilamide. The inhibitory properties of the novel sulfamides on both isoenzymes were determined using the esterase activity with 4‐nitrophenyl acetate (NPA) as substrate. The tested novel sulfamides derived from 1‐aminoindanes and anilines effectively inhibited hCA I and II competitively in the nanomolar range. Among these compounds, the novel sulfamide derivative 17 showed the most potent inhibitory effect against hCA I (Ki: 153.88 nM), while sulfamide derivative 26 showed the highest inhibitory potential against hCA II (Ki: 117.80 nM).

Synthesis and Biological Evaluation of Novel Bromophenol Derivatives as Carbonic Anhydrase Inhibitors

Here, we provide an alternative synthesis of the natural bromophenol 3,4‐dibromo‐5‐(2,3‐dibromo‐4,5‐dihydroxybenzyl)‐6‐(ethoxymethyl)benzene‐1,2‐diol (3) and the first synthesis of (4,5‐dihydroxy‐2‐methylphenyl)(3,4‐dihydroxyphenyl)methanone (18) and its brominated derivatives 19–21. The compounds were characterized and tested against the two most studied members of the pH regulatory enzyme family, carbonic anhydrase (CA). The inhibitory potencies of the novel compounds and two natural bromophenols 2, 3 were analyzed at the human isoforms hCA I and hCA II as targets and the KI values were calculated. The KI values of the novel compounds were measured in the range of 13.7–32.7 µM for the hCA I isozyme and 0.65–1.26 µM for the hCA II isozyme. The structurally related compound 14 was also tested in order to understand the structure–activity relationship, and the clinically used sulfonamide acetazolamide (AZA) was tested for comparison reasons. All of the compounds exhibited competitive inhibition with 4‐nitrophenylacetate as substrate. The compounds showed strong inhibitory activity against hCA I, being more effective as compared to the clinically used AZA (KI: 36.2 µM), but rather less activity against hCA II.

Synthesis and inhibitory properties of some carbamates on carbonic anhydrase and acetylcholine esterase

Abstract A series of carbamate derivatives were synthesized and their carbonic anhydrase I and II isoenzymes and acetylcholinesterase enzyme (AChE) inhibitory effects were investigated. All carbamates were synthesized from the corresponding carboxylic acids via the Curtius reactions of the acids with diphenyl phosphoryl azide followed by addition of benzyl alcohol. The carbamates were determined to be very good inhibitors against for AChE and hCA I, and II isoenzymes. AChE inhibition was determined in the range 0.209–0.291 nM. On the other hand, tacrine, which is used in the treatment of Alzheimer’s disease possessed lower inhibition effect (Ki: 0.398 nM). Also, hCA I and II isoenzymes were effectively inhibited by the carbamates, with inhibition constants (Ki) in the range of 4.49–5.61 nM for hCA I, and 4.94–7.66 nM for hCA II, respectively. Acetazolamide, which was clinically used carbonic anhydrase (CA) inhibitor demonstrated Ki values of 281.33 nM for hCA I and 9.07 nM for hCA II. The results clearly showed that AChE and both CA isoenzymes were effectively inhibited by carbamates at the low nanomolar levels.

Synthesis and paroxonase activities of novel bromophenols

Three novel bromophenols 10–12 were synthesized. Acylation of veratrole (4) with 2,3-dimethoxy benzoic acid (5) gave a kown diarylmethanone 6. Bromination of 6 with different equivalents of molecular bromine afforded new di and tribrominated compounds 7–9 which were converted to their corresponding bromophenols 10–12 via O-demethylation with BBr3. Paraoxonase-1 (PON1) was purified from human serum with approximately 42% and 3584 U × mg−1 specific activity. The synthesized compounds 6–12 showed inhibitory effects on paraoxonase-1 (PON1) which is an organophosphate (OP) hydrolyser and an antioxidant bioscavenger enzyme. IC50 values were determined in the range of 0.123–1.212 mM. Graphical abstract