Synthesis and characterization of a proton transfer salt between 2,6-pyridinedicarboxylic acid and 2-aminobenzothiazole,and its complexes and their inhibition studies on carbonic anhydrase isoenzymes

Abstract

A novel proton transfer compound (HABT)⁺(Hdipic)^? (1) obtained from ABT and H₂dipic and its metal complexes (2–5) have been prepared and characterized by spectroscopic techniques. Single crystal X-ray diffraction method has also been applied to 2 and 5. While complex 2 has a distorted octahedral conformation, 5 exhibits a distorted square pyramidal structure. The structures of 3 and 4 might be proposed as octahedral according to experimental data. All compounds were also evaluated for their in vitro inhibition effects on hCA I and II for their hydratase and esterase activities. Although there is no inhibition for hydratase activities, all compounds have inhibited the esterase activities of hCA I and II. The comparison of the inhibition studies of 1–5 to parent compounds indicates that 1–5 have superior inhibitory effects. The inhibition effects of 2–5 are also compared to inhibitory properties of the metal complexes of ABT and H₂dipic, revealing an improved transfection profile.     

Synthesis and characterization of some metal complexes of a proton transfer salt,and their inhibition studies on carbonic anhydrase isozymes and the evaluation of the results by statistical analysis

Abstract

A novel proton transfer compound (HMeOABT)?⁺?(HDPC)^? (1) and its Fe(III), Co(II), Ni(II) and Cu(II) complexes (2–5) have been prepared and characterized by spectroscopic techniques. Complex 4 has distorted octahedral conformation revealed by single crystal X-ray diffraction method. Structures of the other complexes might be proposed as octahedral according to experimental data. All compounds were also evaluated for their in vitro inhibition effects on hCA I and II for their hydratase and esterase activities. Although there is no inhibition for hydratase activities, all compounds have inhibited the esterase activities of hCA I and II. Data have been analyzed by using a one-way analysis of variance. The comparison of the inhibition studies of 1–5 to parent compounds indicates that 1–5 have superior inhibitory effects. The inhibition effects of 2–5 are also compared to inhibitory properties of the metal complexes of MeOABT and H2DPC, revealing an improved transfection profile.     

A novel proton transfer salt of 2-amino-6-sulfamoylbenzothiazole and its metal complexes: the evaluation of their inhibition effects on human cytosolic carbonic anhydrases

A novel proton transfer compound (SMHABT)⁺(HDPC)^? (1) obtained from 2-amino-6-sulfamoylbenzothiazole (SMABT) and 2,6-pyridinedicarboxylic acid (H₂DPC) and its Fe(III), Co(II), Ni(II) complexes (2–4), and Fe(II) complex of SMABT (5) have been prepared and characterized by spectroscopic techniques. Additionally, single crystal X-ray diffraction techniques were applied to complexes (2–4). All complexes (2–4) have distorted octahedral conformations and the structure of 5 might be proposed as octahedral according to spectral and analytical results. All compounds, including acetazolamide (AAZ) as the control compound, were also evaluated for their in vitro inhibition effects on human hCA I and hCA II for their hydratase and esterase activities. The synthesized compounds have remarkable inhibitory activities on hCA I and hCA II. Especially, the inhibition potentials of the salt and the metal complexes (1–5) are comparable with AAZ. Inhibition data have been analyzed by using a one-way analysis of variance for multiple comparisons (p?相似文献   

Carbonic anhydrase inhibitors: inhibition of human and bovine isoenzymes by benzenesulphonamides,cyclitols and phenolic compounds

Carbonic anhydrase inhibitors (CAIs) are a class of pharmaceuticals used as anti-glaucoma agents, diuretics and anti-epileptics. We report here the inhibitory capacities of benzenesulphonamides, cyclitols and phenolic compounds 1–11 against three human CA isozymes (hCA I, hCA II and hCA VI) and bovine skeletal muscle carbonic anhydrase III (bCA III). The four isozymes showed quite diverse inhibition profiles with K_i values ranging from low micromolar to millimolar concentrations against all isoenzymes. Compound 5 and 6 had more powerful inhibitory action against hCA I and very similar action against hCA II and hCA VI as compared with acetazolamide (AZA) and sulphapyridine (SPD), specific CAIs. Probably the inhibition mechanism of the tested compounds is distinct of the sulphonamides with RSO₂NH₂ groups and similar to that of the coumarins/lacosamide, i.e. binding to a distinct part of the active site than that where sulphonamides bind. These data may lead to drug design campaigns of effective CAIs possessing a diverse inhibition mechanism compared to other sulphonamide/sulphamate inhibitors.     

Facile synthesis and characterization of novel pyrazole-sulfonamides and their inhibition effects on human carbonic anhydrase isoenzymes

In the current study, a series of pyrazole-sulfonamide derivatives (2–14) were synthesized, characterized, and the inhibition effects of the derivatives on human carbonic anhydrases (hCA I and hCA II) were investigated as in vitro. Structures of these sulfonamides were confirmed by FT-IR, ¹H NMR, ¹³C NMR and LC–MS analysis. ¹H NMR and ¹³C NMR revealed the tautomeric structures. hCA I and hCA II isozymes were purified from human erythrocytes and inhibitory effects of newly synthesized sulfonamides on esterase activities of these isoenzymes have been studied. The K_i values of compounds were 0.062–1.278 μM for hCA I and 0.012–0.379 μM for hCA II. The inhibition effects of 7 for hCA I and 4 for hCA II isozymes were almost in nanomolar concentration range.     

Synthesis and characterization of novel substituted thiophene derivatives and discovery of their carbonic anhydrase and acetylcholinesterase inhibition effects

Novel substituted thiophene derivatives ( 1, 2a‐e, 3, and 4 ) were synthesized and their structures were characterized by infrared radiation, nuclear magnetic resonance, and mass analysis. These novel substituted thiophene derivatives were effective inhibitor compounds of the carbonic anhydrase I and II isozymes (hCA I and II), and acetylcholinesterase (AChE) enzyme with K _i values in the range of 447.28 to 1004.65 nM for hCA I, 309.44 to 935.93 nM for hCA II, and 0.28 to 4.01 nM for AChE, respectively. Novel substituted thiophene derivatives can be good candidate drugs for the treatment of some diseases like neurological disorders, epilepsy, glaucoma, gastric and duodenal ulcers, mountain sickness, or osteoporosis as carbonic anhydrase isozymes inhibitors, and for the treatment of Alzheimer’s and Parkinson’s diseases as acetylcholinesterase inhibitors.     

Purification of carbonic anhydrase from dog erythrocytes and investigation of in vitro inhibition by various compounds

The enzyme carbonic anhydrase (E.C. 4.2.1.1) has a stimulatory effect on glaucoma, an eye disease that has a risk to dogs, which are models for the human eye disease, that is similar to that in humans.

In this study, some sulfonamide derivatives, 2-(3-cyclohexene-1-carbamido)-1,3,4-thiadiazole-5-sulfonamide (CCTS), 4-(3-cyclohexene-1-carbamido) methyl-benzenesulfonamide (CCBS), 2-(9-octadecenoylamido)-1,3,4-thiadiazole-5-sulfonamide (ODTS), 2-(4,7,10-trioxa-tetradecanoylamido)-1,3,4-thiadiazole-5-sulfonamide (TDTS), and 2-(8-methoxycoumarine-3-carbamido)-1,3,4-thiadiazole-5-sulfonamide (MCTS), as well as some anionic compounds (perchlorate and chloride) and existing medicines (dorzolamide-HCl, gentamicine sulphate, tropicamide, and procaine-HCl) were assayed for their inhibition of dog carbonic anhydrase (dCA), which was purified from erythrocytes on an affinity gel of L-tyrosine-sulfonamide-Sepharose 4B. ODTS showed the highest potency amongst the synthetic compounds with IC₅₀ value 1.18 × 10^{? 5} M. Amongst the medicines tested, only dorzolamide showed inhibition with IC₅₀ value 5.05 × 10^{? 4} M. Procaine and tropicamide actually showed an activatory effect, whereas gentamicine sulfate had no significant effect. The inhibitory effects of anionic compounds such as perchlorate and chloride were also investigated; whereas perchlorate showed inhibition, chloride did not.     

Synthesis of 2‐amino‐3‐cyanopyridine derivatives and investigation of their carbonic anhydrase inhibition effects

The conversion of carbon dioxide (CO₂) and bicarbonate (HCO₃⁻) to each other is very important for living metabolism. Carbonic anhydrase (CA, E.C.4.2.1.1), a metalloenzyme familly, catalyzes the interconversion of these ions (CO₂ and HCO₃⁻) and are very common in living organisms. In this study, a series of novel 2‐amino‐3‐cyanopyridines supported with some functional groups was synthesized and tested as potential inhibition effects against both cytosolic human CA I and II isoenzymes (hCA I and II) using by Sepharose‐4B‐l ‐tyrosine‐sulfanilamide affinity chromatography. The structural elucidations of novel 2‐amino‐3‐cyanopyridines were achieved by NMR, IR, and elemental analyses. K _i values of the novel synthesized compounds were found in range of 2.84–112.44 μM against hCA I and 2.56–31.17 μM against hCA II isoenzyme. While compound 7d showed the best inhibition activity against hCA I (K _i: 2.84 μM), the compound 7b demonstrated the best inhibition profile against hCA II isoenzyme (K _i: 2.56 μM).     

Oxidation of cyanobenzocycloheptatrienes: Synthesis,photooxygenation reaction and carbonic anhydrase isoenzymes inhibition properties of some new benzotropone derivatives

The oxidation of some cyanocycloheptatrienes with CrO₃ and pyridine was investigated and a few new nitrile functionalised benzotropone derivatives were obtained. Photooxygenation reaction of these products was also studied. The structures of the formed products were determined on the basis of NMR spectroscopy and the formation mechanism of unusual products was discussed. Human carbonic anhydrase isoenzymes I, and II (hCA I and hCA II) inhibition properties of nitrile functionalized new benzotropone derivatives were also studied. Both CA isozymes were inhibited in the low micromolar range by these nitrile functionalized benzotropone analogues. The newly synthesized benzotropone derivatives showed inhibition constants in the sub-micromolar range (2.51–4.06 μM). The best hCA I inhibition was observed in 5H-benzocycloheptene-7-carbonitrile (K_i: 2.88 ± 0.86 μM). On the other hand, 5-oxo-5H-benzocycloheptatriene-7-carbonitrile showed the powerful inhibitory effect against hCA II (K_i: 2.51 ± 0.34 μM).     

Synthesis of novel sulfonamides under mild conditions with effective inhibitory activity against the carbonic anhydrase isoforms I and II

Novel sulfonamide derivatives 6a–i, as new carbonic anhydrase inhibitors which candidate for glaucoma treatment, were synthesized from the reactions of 4-amino-N-(4-sulfamoylphenyl) benzamide 4 and sulfonyl chloride derivatives 5a–i with high yield (71–90%). The structures of these compounds were confirmed by using spectral analysis (FT-IR, ¹H NMR, ¹³C NMR, LC/MS and HRMS). The inhibition effects of 6a–i on the hydratase and esterase activities of human carbonic anhydrase isoenzymes, hCA I and II, which were purified from human erythrocytes with Sepharose®4B-l-tyrosine-p-aminobenzene sulfonamide affinity chromatography, were studied as in vitro, and IC₅₀ and K_i values were determined. The results show that newly synthesized compounds have quite powerful inhibitory properties.     

Synthesis of 4-(2-substituted hydrazinyl)benzenesulfonamides and their carbonic anhydrase inhibitory effects

In this study, 4-(2-substituted hydrazinyl)benzenesulfonamides were synthesized by microwave irradiation and their chemical structures were confirmed by ¹H NMR, ¹³CNMR, and HRMS. Ketones used were: Acetophenone (S1), 4-methylacetophenone (S2), 4-chloroacetophenone (S3), 4-fluoroacetophenone (S4), 4-bromoacetophenone (S5), 4-methoxyacetophenone (S6), 4-nitroacetophenone (S7), 2-acetylthiophene (S8), 2-acetylfuran (S9), 1-indanone (S10), 2-indanone (S11). The compounds S9, S10 and S11 were reported for the first time, while S1–S8 was synthesized by different method than literature reported using microwave irradiation method instead of conventional heating in this study. The inhibitory effects of 4-(2-substituted hydrazinyl)benzenesulfonamide derivatives (S1–S11) against hCA I and II were studied. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized sulphonamide derivatives with K_is in the range of 1.79?±?0.22–2.73?±?0.08?nM against hCA I and in the range of 1.72?±?0.58–11.64?±?5.21?nM against hCA II, respectively.     

Synthesis of novel bisindolylmethanes: New carbonic anhydrase II inhibitors,docking, and 3D pharmacophore studies

In this study, 45 bisindolylmethanes having sulfonamide moiety had been synthesized through 3 steps. In vitro assay for inhibition of carbonic anhydrase showed that some of the compounds having sulfonamide moiety are capable of inhibiting carbonic anhydrase II. Bisindoles having halogens at fifth position showed better inhibitory activity as compared to unsubstituted bisindoles. The results obtained from in vitro inhibitory activity were subjected through 3D QSAR and docking studies to identify important features contributing to the activity and further improve the structure. Pharmacophore studies suggest that bisindolylmethane moiety is contributing significantly towards the inhibition activity. Docking studies showed that compounds having nitro substituent (5g and 5i) were found to be able interact with Zn²⁺ ion, Thr199, His94, His96, and His119, which interferes with the ZnOHThr199Glu106 hydrogen bond network. Bulky nitro substituent at ortho position for compound 5g prevents the compound from interacting with other residues like Thr199 and Thr200. Methyl substituent at ortho position for Compound 5i induces less steric hindrance effect, thus allowing second oxygen atom of sulfonamide to interact with Thr199 (2.51 Å). Hydrogen bonding between NH on indole ring with Glu69 might have increased stability of ligand-receptor complex.     

Synthesis,biological evaluation and computational studies of novel iminothiazolidinone benzenesulfonamides as potent carbonic anhydrase II and IX inhibitors

A series of iminothiazolidinone-sulfonamide hybrids (2a-k) was synthesized by heterocyclization of sulfanilamide thioureas with methyl bromoacetate and characterized by spectroscopic techniques, mass and elemental analysis. The synthesized derivatives were screened against four relevant human (h) isoforms of carbonic anydrases (CAs, EC 4.2.1.1) I, II, IV and IX. These enzymes are involved in a variety of diseases, including glaucoma, retinitis pigmentosa, epilepsy, arthritis, and tumors. Derivatives 2a-2k exhibited the best inhibitory activity against the cytosolyc hCA II (K_Is are reaching the sub-nanomolar range, 0.41–37.8 nM) and against the tumor-associated isoform hCA IX (K_Is are spanning between 24.3 and 368.3 nM). The binding mode of the reported iminothiazolidinone benzenesulfonamides within hCA II and IX catalytic clefts was investigated by docking studies.     

Synthesis,biological evaluation,and docking studies of novel thiourea derivatives of bisindolylmethane as carbonic anhydrase II inhibitor

This article describes discovery of 29 novel bisindolylmethanes consisting of thiourea moiety, which had been synthesized through three steps. These novel bisindolylmethane derivatives evaluated for their potential inhibitory activity against carbonic anhydrase (CA) II. The results for in vitro assay of carbonic anhydrase II inhibition activity showed that some of the compounds are capable of suppressing the activity of carbonic anhydrase II. Bisindoles having halogen at fifth position showed better inhibitory activity as compared to unsubstituted bisindoles. Derivatives showing inhibition activity docked to further, understand the binding behavior of these compounds with carbonic anhydrase II. Docking studies for the active compound 3j showed that nitro substituent at para position fits into the core of the active site. The nitro substituent of compound 3j is capable of interacting with Zn ion. This interaction believed to be the main factor causing inhibition activity to take place.     

Synthesis of novel 5-amino-1,3,4-thiadiazole-2-sulfonamide containing acridine sulfonamide/carboxamide compounds and investigation of their inhibition effects on human carbonic anhydrase I,II, IV and VII

Herein, we report that acridine intermediates 5 were obtained from the reduction of nitro acridine derivatives 4, which were synthesized via condensation of dimedone, p-nitrobenzaldehyde with 4-amino-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)benzamide, respectively. Then acridine sulfonamide/carboxamide (7a–i) compounds were synthesized by reaction of amino acridine 5 with sulfonyl chlorides and carbamoyl chlorides. The new compounds were characterized by melting points, FT-IR, ¹H NMR, ¹³C NMR and HRMS analyzes. The evaluation of in vitro test of the synthesized compounds against hCA I, II, IV and VII showed that some of them are potent inhibitors. Among them, compound 7e showed the most potent activity against hCA II with a K_I of 7.9 nM.     

The synthesis of (Z)-4-oxo-4-(arylamino)but-2-enoic acids derivatives and determination of their inhibition properties against human carbonic anhydrase I and II isoenzymes

The synthesis of (Z)-4-oxo-4-(arylamino)but-2-enoic acid (4) derivatives containing structural characteristics that can be used for the synthesis of several active molecules, is presented. Some of the butenoic acid derivatives (4a, 4c, 4e, 4i, 4j, 4k) are synthesized following literature procedures and at the end of the reaction. In addition, structures of all synthesized derivatives (4a–4m) were determined by ¹H-NMR, ¹³C-NMR and IR spectroscopy. Carbonic anhydrase is a metalloenzyme involved in many crucial physiologic processes as it catalyzes a simple but fundamental reaction, the reversible hydration of carbon dioxide to bicarbonate and protons. Significant results were obtained by evaluating the enzyme inhibitory activities of these derivatives against human carbonic anhydrase hCA I and II isoenzymes (hCA I and II). Butenoic acid derivatives (4a–4m) strongly inhibited hCA I and II with K_is in the low nanomolar range of 1.85?±?0.58 to 5.04?±?1.46?nM against hCA I and in the range of 2.01?±?0.52 to 2.94?±?1.31?nM against hCA II.     

Synthesis of some novel pyridine compounds containing bis‐1,2,4‐triazole/thiosemicarbazide moiety and investigation of their antioxidant properties,carbonic anhydrase,and acetylcholinesterase enzymes inhibition profiles

Some novel derivatives of thiosemicarbazide and 1,2,4‐triazole‐3‐thiol were synthesized and evaluated for their biological activities. The title compounds were prepared starting from readily available pyridine‐2,5‐dicarboxylic acid. The reaction carboxylic acid with absolute ethanol afforded the corresponding dimethyl pyridine‐2,5‐dicarboxylate ( 1 ). The reaction of dimethyl‐2,5‐pyridinedicarboxylate ( 1 ) with hydrazine hydrate good yielded pyridine‐2,5‐dicarbohydrazide ( 2 ). Refluxing compound 2 with alkyl/aryl isothiocyanate derivatives for 3–8 h afforded 1,4‐disubstituted thiosemicarbazides ( 3a–e ). Base‐catalyzed intra‐molecular dehydrative cyclization of these intermediates furnished the 4,5‐disubstituted bis‐mercaptotriazoles ( 4a–e ) in good yield (85%–95%). Among the target compounds, 2,2′‐(pyridine‐2,5‐diyldicarbonyl)bis[N‐(p‐methoxyphenyl)hydrazinecarbothioamide] ( 3c ) showed very high activity with value of 72.93% against 1,1‐diphenyl‐2‐picrylhydrazyl free radical at the concentration of 25 μg/mL. The inhibitory effects of the target compounds against acetylcholinesterase (AChE), hCA I, and II were studied. AChE, cytosolic hCA I and II isoforms were potently inhibited by synthesized these derivatives with K_is in the range of 3.07 ± 0.76–87.26 ± 29.25 nM against AChE, in the range of 1.47 ± 0.37–10.06 ± 2.96 nM against hCA I, and in the range of 3.55 ± 0.57–7.66 ± 2.06 nM against hCA II, respectively.     

Synthesis and characterisation of novel chromogenic substrates for human pancreatic alpha-amylase

Derivatives of maltose and maltotriose were chemically synthesised as substrates for human pancreatic alpha-amylases and subjected to kinetic analysis. Rates measured were shown to reflect both hydrolysis and transglycosylation reactions. 4-O-Methylated derivatives of these substrates underwent only hydrolysis, thereby simplifying kinetic analyses. These modified substrates may be used for the detection and kinetic analysis of alpha-amylases, and are useful in rapidly screening for novel alpha-amylase inhibitors and for subsequent kinetic characterisation.     

Synthesis,biological evaluation and in silico studies of novel N-substituted phthalazine sulfonamide compounds as potent carbonic anhydrase and acetylcholinesterase inhibitors

The synthesis, characterization and biological evaluation of a series of novel N-substituted phthalazine sulfonamide (5a-l) are disclosed. Phthalazines which are nitrogen-containing heterocyclic compounds are biologically preferential scaffolds, endowed with versatile pharmacological activity, such as anti-inflammatory, cardiotonic vasorelaxant, anticonvulsant, antihypertensive, antibacterial, anti-cancer action. The compounds were investigated for the inhibition against the cytosolic hCA I, II and AChE. Most screened sulfonamides showed high potency in inhibiting hCA II, widely involved in glaucoma, epilepsy, edema, and other pathologies (K_is in the ranging from 6.32 ± 0.06 to 128.93 ± 23.11 nM). hCA I was inhibited with K_is in the range of 6.80 ± 0.10–85.91 ± 7.57 nM, whereas AChE in the range of 60.79 ± 3.51–249.55 ± 7.89 nM. ADME prediction study of the designed N-substituted phthalazine sulfonamides showed that they are not only with carbonic anhydrase and acetylcholinesterase inhibitory activities but also with appropriate pharmacokinetic, physicochemical parameters and drug-likeness properties. Also, in silico docking studies were investigated the binding modes of selected compounds, to hCA I, II, and AChE.     

Synthesis of novel bis‐sulfone derivatives and their inhibition properties on some metabolic enzymes including carbonic anhydrase,acetylcholinesterase, and butyrylcholinesterase

In this study, a series of novel bis‐sulfone compounds ( 2a‐2j ) were synthesized by oxidation of the bis‐sulfides under mild reaction conditions. The bis‐sulfone derivatives were characterized by ¹H‐NMR, ¹³C‐NMR, Fourier‐transform infrared spectroscopy, and elemental analysis techniques. Nuclear Overhauser effect experiments were performed to determine the orientation of the sulfonyl groups in bis‐sulfone derivatives. Here, we report the synthesis and testing of novel bis‐sulfone compound–based hybrid scaffold of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors for the development of novel molecules toward the therapy of Alzheimer's disease. The novel synthesized bis‐sulfone compounds demonstrated K_i values between 11.4 ± 3.4 and 70.7 ± 23.2 nM on human carbonic anhydrase I isozyme (hCA I), 28.7 ± 6.6 to 77.6 ± 5.6 nM on human carbonic anhydrase II isozyme (hCA II), 18.7 ± 2.61 to 95.4 ± 25.52 nM on AChE, and 9.5 ± 2.1 to 95.5 ± 1.2 nM on BChE enzymes. The results showed that novel bis‐sulfone derivatives can have promising drug potential for glaucoma, leukemia, epilepsy, and Alzheimer's disease, which are associated with the high enzymatic activity of hCA I, hCA II, AChE, and BChE enzymes.