Carbonic Anhydrase Inhibitory Activity Research Articles

Exploring the diastereoselectivity for Fischer indolization of L-menthone under different conditions, spectral characterization, and biological activities of new (2R,4aS)-2,3,4,4a-tetrahydro-1H-carbazole analogs

Tetrahydrocarbazoles are important class of heterocycles that exhibit numerous biological properties. They are also found in several natural products. In the present study, Fischer indolization of L-menthone was investigated for diastereoselectivity using different reaction conditions. No appreciable diastereoselectivity was observed for the acids used except CuBr and boric acid at varying temperatures, where satisfactory results were obtained. In addition, a small library of new (2R,4aS)-2,3,4,4a-tetrahydro-1H-carbazole analogs was reported and structurally characterized using spectroscopic techniques herein. Additionally, the compounds were evaluated against different biological activities, such as carbonic anhydrase inhibitory, immunomodulatory, and anticancer activities and did not show any activity. As the synthesized library was found safe when tested against cytotoxicity in normal cell line, it will be explored for other biological activities in near future to identify its biological outcome.

Design and synthesis of some new benzoylthioureido phenyl derivatives targeting carbonic anhydrase enzymes

The present study aimed to develop potent carbonic anhydrase inhibitors (CAIs). The design of the target compounds was based on modifying the structure of the ureido-based carbonic anhydrase inhibitor SLC-0111. Six series of a substituted benzoylthioureido core were prepared featuring different zinc-binding groups; the conventional sulphamoyl group 4a–d and 12a–c, its bioisosteric carboxylic acid group 5a–d and 13a–c or the ethyl carboxylate group 6a–d and 14a–c as potential prodrugs. All compounds were assessed for their carbonic anhydrase (CA) inhibitory activity against a panel of four physiologically relevant human CA isoforms hCA I and hCA II, and hCA IX, and hCA XII. Compounds 4a, 4b, 4c, 4d, 5d, 12a, and 12c revealed significant inhibitory activity against hCA I that would highlight these compounds as promising drug candidates for the treatment of glaucoma.

Recent Advances in the Chemistry and Biological Activity of Sulfonamide Derivatives

Abstract: This review describes different synthetic methods for the preparation of sulfonamides. Generally, sulfonamides are synthesized from sulfonyl chloride derivative and amino derivative. A series of sulfonamide derivatives 7a-c, 8a,b, 9, 10, 11a,b, and 12 were synthesized in alkaline media by reacting different amino compounds with a p-toluene sulfonyl chloride. Different amino derivatives 13, 15, 17, 19, and 21 reacted with p-tolyl sulphonyl chloride to afford sulfonylamides 14, 16, 18, 20, and 22. Different reactions of sulfonamide derivatives have been summarized. Generally, the sulfonamide function group does not participate in any reactions, but other functional groups in the compound are involved in various reactions. Sulfonamides exhibit different biological activities, e.g., antibacterial activity, anticancer activity, urease inhibitory activity, radical scavenging activity, carbonic anhydrase inhibitory activity, non-competitive lactoperoxidase inhibitory activity, antifungal activity, and anti-mycobacterial activity.

Investigation of the carbonic anhydrase inhibitory activity of benzenesulfonamides incorporating substituted fused-pyrimidine tails.

Two new series of 2-thiocyclopenta[d]pyrimidine-benzenesulfonamides 12a-l and 2-thiotetrahydroquinazoline-benzenesulfonamides 13a-j were synthesized and evaluated for their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory acivity and cytotoxic activity. The derivatives 12a and 12i exerted effective inhibition against CA II with Ki = 0.11 and 0.15 µM, while 12a, 12e, 12i, and 13d (Ki = 0.083-0.087 µM) were found to be the most potent against CA XII. In addition, higher selectivity toward CA II and CA XII over CA I and CA IX was observed for the majority of the synthesized conjugates. Analysis of the effect of the synthesized compounds on NCI cancer cell lines revealed that compounds 12b and 13d showed mean growth inhibitory effects of 53.59% and 49.25%, respectively. Docking of the synthesized hybrids in the CA II and CA XII binding pockets displayed the capability of the benzenesulfonamide derivatives to form, through their SO2 NH2 moiety, the characteristic interactions of the traditional CA inhibitors, besides additional interactions achieved by the tail with isoform-specific residues in the peripheral part of the CA binding sites.

Efficient One-pot Synthesis of 3,3-di(indolyl)indolin-2-ones from Isatin and Indole Catalyzed by VOSO4 as Non-Sulfonamide Carbonic Anhydrase Inhibitors.

A high yielding green protocol has been developed and delineated for the synthesis of 3,3- di(indolyl)indolin-2-ones, potentially bioactive compounds, involving one pot aqueous medium condensation of isatin with indole in the presence of VOSO4. The synthesized compounds were screened for their carbonic anhydrase inhibitory activity against human (h) isoforms hCA I, hCA II, hCA IX, and hCA XII. These non-sulfonamide derivatives selectively inhibited hCA II in the micromolar range. To develop a high yielding green protocol to synthesize 3,3-diindolyl oxindole derivatives using water as solvent media and screening the synthesized molecules for their carbonic anhydrase inhibitory activity. The target compound is obtained by taking isatin, indole, VOSO4, and H2O in one-pot at 70oC. The designed molecules were synthesized by using the new method. The molecules were screened for their CA inhibitory activity, which shows selective inhibition toward hCA II.The result showed an excellent yield without any loss or decrease in catalytic activity, proving the catalyst's performance and recyclability. An efficient, simple, and green protocol was established that provides a facile and straightforward approach for the preparation of 3,3-diindolyl oxindole derivatives (3a-r) from Isatin and Indole by using 10 mol% VOSO4 in high yields in a short period of time by a one-pot coupling reaction. Furthermore, the catalyst can also be recovered and reused for three consecutive catalytic cycles without any loss of its efficiency, which was confirmed by performing the experiment with 3a. The newly synthesized molecules (3a-r) were screened for their carbonic anhydrase inhibition potency against four isoforms, hCA I, II, IX, and XII and most of the compounds were found potent against hCA II with potency low to submicromolar range.

Assessment of phytotoxic, genotoxic and enzyme inhibition potential of.

To evaluate Sterculia diversifolia stem bark and leaves for phytotoxic, genotoxic and enzymes inhibition potential. Phytotoxic activity of both stem bark and leaves were screened using Lemna minor. The genotoxic activity of Sterculia diversifolia stem bark and leaves extracts were tested using comet assay protocol while enzyme inhibition activity of crude extract and various fractions of both stem bark and leaves were evaluated using acetyl cholinesterase, lipoxygenase, β-glu-curonidase, urease, xanthine oxidase and carbonic anhydrase. Phytotoxic activity showed significant results in dose dependant manner in both stem bark (ethyl acetate and n-butanol) and leaves (ethyl acetate, n-butanol and n-hexane) fractions. In genotoxic activity, dichloromethane fraction showed significant activity followed by ethyl acetate fraction. Acetyl cholinesterease inhibitory activity showed significant results in both stem bark and leaves fractions, while significant lipoxygenase inhibition was shown by ethyl acetate, dichloromethane, crude extract and n-hexane fractions of both stem bark and leaves. β-glucuronidase, urease and carbonic anhydrase inhibitory activity showed highly significant results in ethyl acetate fraction of both stem bark and leaves, while xanthine oxidase inhibition was shown by dichloromethane fraction of stem bark and leaves extracts. This study emphasizes the important phytotoxic, genotoxic and enzyme inhibition effects of Sterculia diversifolia stem bark and leaves. Hence, it is clear that Sterculia diversifolia stem bark and leaves possess phytotoxic, genotoxic and enzyme inhibitory agents.

Evaluation of Diuretic and Laxative Potential of Onosma bracteata Wall.: A Species of the Controversial Drug ‘Gojihva’

Background: Gojihva or Gaozaban, an Ayurvedic cum Unani Medicinal plant described with various properties, including diuretic activity. Onosma bracteata Wall. is considered the official species of Gojihva in Ayurveda and is one of the species considered Unani Gaozaban. Materials and Methods: The plant was subjected to physicochemical evaluation, sequential extraction, HPTLC profiling, and phytochemical screening. The diuretic and laxative activity of sequential methanol and water extracts of O. bracteata Wall. at a dose of 100 mg/kg and 200 mg/kg of body weight per oral was measured in Wistar rats in two separate experiments. Results: Preliminary phytochemical investigation and TLC profiling revealed the presence of flavonoids/hydroquinone/phenolics in methanol extract. Additionally, elemental analysis of plant material detected Potassium (K) at a level of 672.12 ppm. The methanol extract at doses 100 mg/kg (1.65 mL ± 0.19) and 200 mg/kg (2.00 mL ± 0.28) and aqueous extract at dose 200 mg/kg (1.63 ± 0.12) showed highly significant diuretic activity (p<0.0001) at 6 h compared to standard (0.67 mL ± 0.21). Whereas the aqueous extract of the plant showed mild constipation action. Conclusion: The literature search revealed that the diuretic potential of the methanolic extract could be attributed majorly to carbonic anhydrase inhibitory activity of constituent compounds like caffeic acid, rosmarinic acid, p-hydroxybenzoic acid, artitrichin, salvianolic acid, and coumarins, in addition to natriuretic, Ca2+ sparing activity, and increased renal excretory function. The milder diuretic action of the aqueous extract can be due to the presence of potassium salts in aqueous extracts. Thus, the traditional use of Gojihva as a diuretic is established on a phytochemical basis. Further pharmacological and phytochemical investigations of Methanol extract may reveal novel compounds with diuretic potential

Synthesis, carbonic anhydrase inhibitory activity, anticancer activity and molecular docking studies of new imidazolyl hydrazone derivatives

A new series of imidazolyl hydrazone derivatives IA (1-12) were prepared from a condensation reaction between indoline-2,3-dione (isatin) and 2-benzylidenehydrazinecarboximidamide derivatives. The structure of compounds was elucidated using various spectral techniques including FTIR, 1H NMR, 13C NMR, and HRMS. The proposed structure of IA-2 was determined by single-crystal X-ray analysis. Synthesized compounds were evaluated for their inhibitory action against carbonic anhydrase I and II isoenzymes (hCA I and hCA II), as well as cytotoxicity activity in a cancer cell line (HT-29) and a healthy cell line (NIH 3T3). Among them, some compounds exhibited remarkable CA inhibitory activities compared to a standard inhibitor with Ki values in the range of 13.434 ± 3.278-522.549 ± 360.720 nM for hCA I (Ki value for standard inhibitor = 271.15 ± 74.620 nM) and 41.108 ± 10.180-271.171 ± 65.293 nM for hCA II (Ki value for standard inhibitor = 113.07 ± 20.980 nM) and significant antiproliferative activity with less toxicity to a health cell line. In addition, the theoretical parameters of the bioactive molecules were calculated to establish their drug-likeness qualities and ADME/T analysis was carried out to examine the drug properties of the synthesized compounds.

Development of 4-((3-oxo-3-phenylpropyl)amino)benzenesulfonamide derivatives utilizing tail/dual-tail approaches as novel carbonic anhydrase inhibitors

In the current work, we adopted the tail/dual tail approaches to design and synthesize the benzenesulfonamide derivatives 6a-b, 8, 10a-b, 12a-b, 14, and 16 as new SLC-0111 analogs endowed with carbonic anhydrase (CA) inhibitory activity. All the prepared benzenesulfonamide derivatives were tested for their inhibitory action towards hCA isoforms; hCA I, II, IX, and XII. The results revealed their ability to affect the examined isoforms in variable degrees with KI ranges: 49.3–6459 nM for CA I, 5.1–4171 nM for CA II, 9.4–945.1 nM for CA IX, and 5.2–1159 nM for CA XII. As expected, appending a second hydrophilic tail (ethanolamine) in compound 16 significantly enhanced the inhibitory activities towards hCA IX and hCA XII isoforms by about 5-fold in comparison to its single tail analogue 6c (KI = 51.5 and 28.2 nM for 6cvs. 10.2 and 5.2 nM for 16, respectively). Moreover, SAR analysis pointed out the significance of grafting the sulfamoyl functionality at para-position, as well as the incorporation of a bulky hydrophobic tail for CA inhibitory activity. The most potent hCA IX inhibitors (6f and 16) displayed efficient cell growth inhibitory activity against breast cancer cell lines; T-47D (IC50 = 19 and 10.9 μM, respectively) and MCF-7 (IC50 = 7.5 and 5.7 μM, respectively).

Synthesis, cytotoxicities, and carbonic anhydrase inhibition activities of pyrazoline–benzenesulfonamide derivatives harboring phenol/polyphenol moieties

Synthesis, cytotoxicities, and carbonic anhydrase inhibition activities of pyrazoline–benzenesulfonamide derivatives harboring phenol/polyphenol moieties

Hypoxia-induced carbonic anhydrase mediated dorsal horn neuron activation and induction of neuropathic pain.

Neuropathic pain, such as that seen in diabetes mellitus, results in part from central sensitisation in the dorsal horn. However, the mechanisms responsible for such sensitisation remain unclear. There is evidence that disturbances in the integrity of the spinal vascular network can be causative factors in the development of neuropathic pain. Here we show that reduced blood flow and vascularity of the dorsal horn leads to the onset of neuropathic pain. Using rodent models (type 1 diabetes and an inducible endothelial-specific vascular endothelial growth factor receptor 2 knockout mouse) that result in degeneration of the endothelium in the dorsal horn, we show that spinal cord vasculopathy results in nociceptive behavioural hypersensitivity. This also results in increased hypoxia in dorsal horn neurons, depicted by increased expression of hypoxia markers such as hypoxia inducible factor 1α, glucose transporter 3, and carbonic anhydrase 7. Furthermore, inducing hypoxia through intrathecal delivery of dimethyloxalylglycine leads to the activation of dorsal horn neurons as well as mechanical and thermal hypersensitivity. This shows that hypoxic signalling induced by reduced vascularity results in increased hypersensitivity and pain. Inhibition of carbonic anhydrase activity, through intraperitoneal injection of acetazolamide, inhibited hypoxia-induced pain behaviours. This investigation demonstrates that induction of a hypoxic microenvironment in the dorsal horn, as occurs in diabetes, is an integral process by which neurons are activated to initiate neuropathic pain states. This leads to the conjecture that reversing hypoxia by improving spinal cord microvascular blood flow could reverse or prevent neuropathic pain.

Synthesis, Carbonic Anhydrase II/IX/XII Inhibition, DFT, and Molecular Docking Studies of Hydrazide-Sulfonamide Hybrids of 4-Methylsalicyl- and Acyl-Substituted Hydrazide

Carbonic anhydrases (CAs and EC 4.2.1.1) are the Zn2+ containing enzymes which catalyze the reversible hydration of CO2 to carbonate and proton. If they are not functioning properly, it would lead towards many diseases including tumor. Synthesis of hydrazide-sulfonamide hybrids (19-36) was carried out by the reaction of aryl (10-11) and acyl (12-13) hydrazides with substituted sulfonyl chloride (14-18). Final product formation was confirmed by FT-IR, NMR, and EI-MS. Density functional theory (DFT) calculations were performed on all the synthesized compounds to get the ground-state geometries and compute NMR properties. NMR computations were in excellent agreement with the experimental NMR data. All the synthesized hydrazide-sulfonamide hybrids were in vitro evaluated against CA II, CA IX, and CA XII isozymes for their carbonic anhydrase inhibition activities. Among the entire series, only compounds 22, 32, and 36 were highly selective inhibitors of hCA IX and did not inhibit hCA XII. To investigate the binding affinity of these compounds, molecular docking studies of compounds 32 and 36 were carried out against both hCA IX and hCA XII. By using BioSolveIT's SeeSAR software, further studies to provide visual clues to binding affinity indicate that the structural elements that are responsible for this were also studied. The binding of these compounds with hCA IX was highly favorable (as expected) and in agreement with the experimental data.

Investigation of Euphorbia nivulia-HAM for Enzyme Inhibition Potential in Relation to the Phenolic and Flavonoid Contents and Radical Scavenging Activity.

Euphorbia nivulia-Ham (EN) is a neglected medicinal plant traditionally used for a number of pathologies, but it has not been explored scientifically. In the current study, its various fractions were assessed for their phenolic and flavonoid content, radical scavenging, as well as its enzyme inhibitory potential. The hydro-alcoholic crude extract (ENCr) was subjected to a fractionation scheme to obtain different fractions, namely n-hexane (ENHF), chloroform (ENCF), n-butanol (ENBF), and aqueous fraction (ENAF). The obtained results revealed that the highest phenolic and flavonoid content, maximum radical scavenging potential (91 ± 0.55%), urease inhibition (54.36 ± 1.47%), and α-glucosidase inhibition (97.84 ± 1.87%) were exhibited by ENCr, while the ENBF fraction exhibited the highest acetylcholinestrase inhibition (57.32 ± 0.43%). Contrary to these, hydro-alcoholic crude as well as the other fractions showed no significant butyrylcholinestrases (BChE) and carbonic anhydrase inhibition activity. Conclusively, it was found that EN possesses a significant radical scavenging and enzyme inhibitory potential. Thus, the study may be regarded a step forward towards evidence-based phyto-medicine.

Synthesis, molecular modelling and QSAR study of new N-phenylacetamide-2-oxoindole benzensulfonamide conjugates as carbonic anhydrase inhibitors with antiproliferative activity

In continuation of our previous studies to optimise potent carbonic anhydrase inhibitors, two new series of isatin N-phenylacetamide based sulphonamides were synthesised and screened for their human (h) carbonic anhydrase (EC 4.2.1.1) inhibitory activities against four isoforms hCA I, hCA II, hCA IX and hCA XII. The indole-2,3-dione derivative 2h showed the most effective inhibition profile against hCAI and hCA II (KI = 45.10, 5.87 nM) compared to acetazolamide (AAZ) as standard inhibitor. Moreover, 2h showed appreciable inhibition activity against the tumour-associated hCA XII, similar to AAZ showing KI of 7.91 and 5.70 nM, respectively. The analogs 3c and 3d showed good cytotoxicity effects, and 3c revealed promising selectivity towards lung cell line A549. Molecular docking was carried out for 2h and 3c to predict their binding conformations and affinities towards the hCA I, II, IX and XII isoforms.

Utilization of transition metal fluoride-based solid support catalysts for the synthesis of sulfonamides: carbonic anhydrase inhibitory activity and in silico study.

The applications of solid support catalysts in catalyzing organic reactions are well-evident. In the present study, we explored a transition metal fluoride (FeF3) adsorbed on molecular sieves (4 Å) as a solid support catalyst for the preparation of sulfonamides 3a–3o. The solid support catalyst was characterized via X-ray diffraction and AFM analysis. The catalyst was further explored for the synthesis of indoles 6a–h, 1H-tetrazoles and 1,4-dihydropyridines. The sulfonamides prepared herein were investigated for their potential to inhibit carbonic anhydrase (hCA II, hCA IX and hCA XII). All compounds were found to be active inhibitors with IC50 values in the low micromolar range. Some compounds were even found to be highly selective inhibitors. Compound 3i only inhibited hCA II (IC50 = 2.76 ± 1.1 μM) and had <27% inhibition against hCA IX and hCA XII. Similarly, 3e (IC50 = 0.63 ± 0.14 μM) only inhibited hCA XII and showed <31% inhibition against hCA II and hCA IX. Molecular docking studies were carried out to rationalize the ligand-binding site interactions. Given the lack of selective CA inhibitors, compounds 3e and 3i can provide significant leads for the further development of highly selective CA inhibitors.

RETRACTED: Synthesis, carbonic anhydrase enzyme inhibition evaluations, and anticancer studies of sulfonamide based thiadiazole derivatives

The sulfonamide-based thiadiazole derivatives (STDs) with different hydrophobic/hydrophilic substitutions were synthesized to investigate their potentials in carbonic anhydrase inhibition (CAI). The CAI activity of the STDs (4a-4h) and the mechanism of the inhibition kinetics were determined. STD 4f contained both methoxy and Cl groups at benzene ring in STD 4f showed the lowest IC50 value. The molecular docking study confirmed that STDs bind strongly with the active sites of the target protein PDBID 1V9E. With the help of Lineweaver-Burk plots, inhibition kinetics of PDBIR 1V9E protein with STDs were determined. Cytotoxicity was checked against human keratinocyte cell lines and the anticancer properties were determined against MCF-7 cell lines. The electrochemical method was used to investigate the binding study with DNA and CA enzymes. Anticancer studies showed that STDs have weak bonding ability to DNA and strong binding ability with CA. It is concluded that anticancer activity is through CAI rather than by DNA binding.

Carbonic anhydrase inhibition and antioxidant activity of the axially naphthoxazin group substituted silicon phthalocyanines

Silicon phthalocyanines are an interesting subclass of phthalocyanines. They are abundant and have extremely low toxicity levels. The low solubility of silicon phthalocyanine is the major obstacle to its use in many different applications. Therefore, in a previous study, two axially substituted silicon phthalocyanines were synthesized to increase their solubility. In this study, these axially substituted silicon phthalocyanines were evaluated for carbonic anhydrase inhibition and antioxidant activities. The carbonic anhydrase (CA) inhibition potential of silicon phthalocyanines was evaluated by esterase activity. The antioxidant activity was tested by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric ion (III) reducing/antioxidant power (FRAP) assays. The silicon phthalocyanines had significant CA inhibitory activity [50% inhibitory values (IC50): 495 ± 12.74 nM and 857 ± 13.03 nM for H4-Si and H3-Si, respectively]. According to the antioxidant studies, 50% scavenging concentration (SC50) values of DPPH• assay were 2.29 ± 0.06 µg/mL and 1.39 ± 0.43 µg/mL for H3-Si and H4-Si and Trolox Equivalent Antioxidant Capacity (TEAC) values of FRAP test were 259.33 ± 48.27 µM and 342.00 ± 44.40 for H3-Si µM and H4-Si, respectively. Consequently, silicon phthalocyanine compounds are considered to have great potential for their use in various fields such as food and medicine.

GC-MS Analysis of Biological Nitrate and Nitrite Using Pentafluorobenzyl Bromide in Aqueous Acetone: A Dual Role of Carbonate/Bicarbonate as an Enhancer and Inhibitor of Derivatization.

Carbon dioxide (CO2) and carbonates, which are widely distributed in nature, are constituents of inorganic and organic matter and are essential in vegetable and animal organisms. CO2 is the principal greenhouse gas in the atmosphere. In human blood, CO2/HCO3− is an important buffering system. Inorganic nitrate (ONO2−) and nitrite (ONO−) are major metabolites and abundant reservoirs of nitric oxide (NO), an endogenous multifunctional signaling molecule. Carbonic anhydrase (CA) is involved in the reabsorption of nitrite and nitrate from the primary urine. The measurement of nitrate and nitrite in biological samples is of particular importance. The derivatization of nitrate and nitrite in biological samples alongside their 15N-labeled analogs, which serve as internal standards, is a prerequisite for their analysis by gas chromatography–mass spectrometry (GC-MS). A suitable derivatization reagent is pentafluorobenzyl bromide (PFB-Br). Nitrate and nitrite are converted in aqueous acetone to PFB-ONO2 and PFB-NO2, respectively. PFB-Br is also useful for the GC-MS analysis of carbonate/bicarbonate. This is of particular importance in conditions of pharmacological CA inhibition, for instance by acetazolamide, which is accompanied by elevated concomitant excretion of nitrate, nitrite and bicarbonate, as well as by urine alkalization. We performed a series of experiments with exogenous bicarbonate (NaHCO3) added to human urine samples (range, 0 to 100 mM), as well as with endogenous bicarbonate resulting from the inhibition of CA activity in healthy subjects before and after ingestion of pharmacological acetazolamide. Our results indicate that bicarbonate enhances the derivatization of nitrate with PFB-Br. In contrast, bicarbonate decreases the derivatization of nitrite with PFB-Br. Bicarbonate is not a catalyst, but it enhances PFB-ONO2 formation and inhibits PFB-NO2 formation in a concentration-dependent manner. The effects of bicarbonate are likely to result from its reaction with PFB-Br to generate PFB-OCOOH. Nitrate reacts with concomitantly produced PFB-OCOOH to form PFB-ONO2 in addition to the direct reaction of nitrate with PFB-Br. By contrast, nitrite does not react with PFB-OCOOH to form PFB-NO2. Sample acidification by small volumes of 20 wt.% aqueous acetic acid abolishes the effects of exogenous and endogenous bicarbonate on nitrite measurement.

A Practical Method of N‐Methylpyrrole Disulfonamides Synthesis: Computational Studies, Carbonic Anhydrase Inhibition and Electrochemical DNA Binding Investigations

AbstractHeterocyclic compounds bearing sulfonamide moiety have been reported to possess carbonic anhydrase inhibitory activity. In the present study, a series of novel N‐methylpyrrole 3(a–j) derivatives bearing disulfonamide functional group have been synthesized by following a simple nucleophilic substitution reaction route to explore their carbonic anhydrase inhibitory activity. N‐methylpyrrole (1) was converted into N‐methylpyrrole disulfonyl chloride (2), which upon condensation with various aliphatic and aromatic amines, yielded the final products 3(a–j). In silico docking results predicted strong binding of synthesized compounds in an enzymatic pocket of human carbonic anhydrase isozyme II (PDB ID 4Q6D). In vitro carbonic anhydrase inhibitory assays revealed that analogues 3 e (1‐Methyl‐N3,N4‐bis(2‐(pyridin‐2‐yl)ethyl)‐1H‐pyrrole‐3,4‐disulfonamide) and 3j (N3,N4,1‐trimethyl‐1H‐pyrrole‐3,4‐disulfonamide) were most potent with IC50 0.38±0.01 μM and 0.75±0.88 μM respectively in comparison to standard acetazolamide (IC50 0.99±0.04 μM). The enzyme inhibitory kinetics exhibited 3 e a noncompetitive inhibitor with Km and Ki values as 0.34 mM and 18.2 μM respectively. The compounds 3 e and 3 j showed very little cytotoxicity against human keratinocyte (HaCaT) with 80 % cell viability and the anticancer activity performed against MCF‐7 cell line showed that the compounds 3 e and 3 j caused 80 % and 45 % cell death respectively at 125 μM concentrations. Combining the results of DNA binding analysis through the UV‐Vis spectroscopy (hypochromism), cyclic voltammetry (current decrease), and fluorescence spectroscopy (hypochromism in intercalator's peak); mixed binding mode (intercalation + groove binding) was suggested for 3 e and intercalation for 3 j with stronger DNA binding of 3 e than 3 j. Based on our results 3 e and 3 j may be proposed to serve as a lead structure for designing potentially more active CAIs.

Designing novel anticancer sulfonamide based 2,5-disubstituted-1,3,4-thiadiazole derivatives as potential carbonic anhydrase inhibitor

A series of sulfonamide derivatives bearing 2,5-disubstituted-1,3,4-thiadiazole (5a–j) have been synthesized. Thiosemicarbazide was reacted with CS2 to get 2-amino-5-mercapto-1,3,4-thiadiazole 1. The intermediate thiadiazole (1) was alkylated by reacting with different halides (2a–c) to afford the alkylated thiadiazoles (3a–c). The title sulfonamide bearing derivatives (5a–j) have been prepared by condensation of sulfonyl chlorides (4a–d) with thiadiazole derivatives (3a–c). The molecular docking studies of target molecules showed strong binding of compounds (5a–j) with target enzyme (PDBID 1V9E) particularly for compound 5f containing fluoro and methoxy groups. The carbonic anhydrase (CA) inhibitory activity showed derivative 5h to be the most potent (IC50 0.60 ± 0.02 µM) as compared to acetazolamide (IC50 0.984 ± 0.12 µM) used as standard. Free radical scavenging activity was measured using ascorbic acid as a reference. It was observed that just like CA inhibition the compound 5h showed greater free radical scavenging activity than all other target molecules. Enzyme inhibition kinetics (Lineweaver-Burk plots) showed a compound (5h) to inhibit the enzyme by mixed type of inhibition (Ki and Kiʹ values 2.91 µM and 3.88 µM, respectively). Compound 5h was further investigated that a smaller value of Ki than Ki′ showed preferred competitive binding over non-competitive manners. The anticancer activity performed against the MCF-7 cell line showed that the compound 5h inhibits 40% cell growth at 125 µM concentration. The mechanism of anticancer potential was further investigated by DNA binding studies through electrochemical methods. The UV-Vis spectroscopy and Cyclic voltammetry results suggested that 5h was weakly bound to DNA (binding constant 30–32 M−1). It is thus proposed that anticancer activity of 5h may be through carbonic anhydrase inhibition rather than by DNA binding. Our investigations suggested the derivative 5h to serve as a lead structure in designing potentially more active carbonic anhydrase inhibitors.