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A series of sulfonamide-bearing azaheterocyclic Schiff base derivatives 3(a-j) were synthesized as carbonic anhydrase inhibitors. The substituted benzene sulfonyl chlorides 1(a-d) were reacted with N 2 H 4 to get aromatic sulfonyl hydrazides 2(a-d) . The intermediate hydrazides 2(a-d) were treated with substituted aldehydes to afford azaheterocyclic sulfonamide Schiff bases 3(a-j) . The spectral data of synthesized compounds confirmed the formation of the final products. The inhibitory effects of 3(a-j) on carbonic anhydrase activity were determined, and it was found that derivative 3c exhibited the most potent activity with IC 50 0.84 ± 0.12  μ M among all other derivatives and is also more active than standard acetazolamide (IC 50 0.91 ± 0.12). The enzyme inhibitory kinetics results determined by Lineweaver-Burk plots revealed that compound 3c inhibits the enzyme by noncompetitive mode of inhibition with K i value 8.6  μ M. The molecular docking investigations of the synthesized analogues 3(a-j) may serve as core structure to project carbonic anhydrase inhibitors with greater potency.3c may serve as core structure to project carbonic anhydrase inhibitors with greater potency., Competing Interests: The authors declare that they have no conflict of interest., (Copyright © 2020 Mujahid Abas et al.)

Selective inhibition of carbonic anhydrase (CA) enzyme is an active area of research for medicinal chemists. In the current account, a hybrid pharmacophore approach was employed to design sulfonamide, amide and amine containing new series of potent carbonic anhydrase II inhibitors. The aromatic fragment associated with pharmacophore was altered suitably in order to find effective inhibitors of CA-II. All the derivatives 4a-4m showed better inhibition compared to the standard acetazolamide. In particular, compound 4l exhibited significant inhibition with IC 50 value of 0.01796 ± 0.00036 µM. The chemo-informatics analysis justified that all the designed compounds possess <10 HBA and <5 HBD. The ligands-protein binding analyses showed that 4l confined in the active binding pocket with three hydrogen bonds observed with His63, Asn66 and Thr197 residues., (Copyright © 2019 Elsevier Inc. All rights reserved.)

A novel series of silyl-yne containing chalcone derivatives 5a-5j was synthesized by exploiting Sonogashira coupling reaction and Claisen-Schimdt condensation reaction. The synthesized derivative were characterized by spectroscopic and elemental analysis. The selective inhibition of carbonic anhydrases is considered critical in the field of medicinal chemistry because carbonic anhydrases exits in several isoforms. Synthesized compounds were subjected to carbonic anhydrase -II assay. Except 5j, the other derivatives exhibited better potential than standard acetazolamide. Compound 5e was found to be potent derivative in the series with IC 50 value 0.054 ± 0.001 µM. Binding analysis revealed that most potent derivative 5e binds in the active site of CA-II and single π-π stacking interaction was observed between ring structure of ligand and Phe129 having bond length 4.90 Å. Pharmacokinetics elicited that compounds obey Lipinski's rule and show significant drug score., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Hit, Lead & Candidate Discovery A series of 1-(6-methyl-2-substituted phenyl-4-thioxo-4H-1,3-oxazin-5-yl)ethanones (3a-n) were synthesized by the reaction of benzoyl isothiocyanates with active methylene compound acetylacetone in the presence of triethyl amine in a one-pot process. The structures of the products were elucidated by elemental analyses, FT-IR, 1 H NMR, 13 C NMR, and mass spectroscopy. These new 1,3-oxazine derivatives were evaluated for their inhibitory activity against carbonic anhydrase II. Results for in vitro assay revealed that compound 3b having 4-methoxy phenyl moiety was the most potent inhibitor with IC 50 value of 0.144 ± 0.008 μM. It exhibited higher enzyme inhibitory activity as compared to the standard acetazolamide (IC 50  = 0.997 ± 0.061 μM). The compounds 3c, 3h, and 3n also displayed superior inhibitory activities compared to the rest of the synthesized oxazine derivatives. The radical scavenging activity of oxazine derivatives was also performed and it was found that compounds showed moderate antioxidant activity. Lipinski rule confirmed the therapeutic potential of the synthesized compounds. Molecular docking studies were also performed to further understand the binding affinity of these compounds with PDBID 1V9E which confirmed that the synthesized derivatives bind in the active binding site of the target protein. Based upon our results, it is proposed that compound 3b may serve as a lead structure to design more potent carbonic anhydrase inhibitors., (© 2018 Wiley Periodicals, Inc.)

A series of Amantadine-based azo Schiff base dyes 6a-6e have been synthesized and characterized by 1 H NMR and 13 C NMR and evaluated for their in vitro carbonic anhydrase II inhibition activity and antioxidant activity. All of the synthesized showed excellent carbonic inhibition. Compound 6b was found to be the most potent derivative in the series, and the IC 50 of 6b was found to be 0.0849 ± 0.00245 μm (standard Acetazolamide IC 50  = 0.9975 ± 0.049 μm). The binding interactions of the most active analogs were confirmed through molecular docking studies. Docking studies showed 6b is interacting by making two hydrogen bonds w at His93 and Ser1 residues, respectively. All compounds showed a good drug score and followed Lipinski's rule. In summary, our studies have shown that these amantadine-derived phenolic azo Schiff base derivatives are a new class of carbonic anhydrase II inhibitors., (© 2018 John Wiley & Sons A/S.)

The present article illustrated the synthesis and characterization of a novel series of (E)-4-(substituted-benzylideneamino)-2H-chromen-2-one derivatives 4A-4J: in good to excellent yields. The target compounds were synthesized by refluxing 4-aminocoumarin with aromatic aldehydes in ethanol. The structural confirmation was achieved by spectroscopic techniques such as ( 1 H, 13 C-NMR and FT-IR) and elemental analysis. The synthesized compounds were evaluated for carbonic anhydrase II (CA-II) inhibition and free radical scavenging activity. All the compounds showed CA-II inhibition in the micro molar range. The compound 4C: exhibited higher potential in the series with IC 50 =0.0928±0.00545 µM (standard Acetazolamide IC 50 =0.997±0.0586 µM). Pharmacological investigations showed that the synthesized compounds 4A-4J: obey Lipinsk's rule. Compound 4C: elicited drug likeness and showed drug score value of 0.05. Molecular docking analysis showed that compound 4C: interacts with Asn66 and Gln91 amino acid residues. Graphical Abstract., Competing Interests: Authors declare no conflict of interest., (© Georg Thieme Verlag KG Stuttgart · New York.)

In this study, a series of 1,3,4-thiadiazole-thiazolidinone derivatives (7a–j) were synthesized as carbonic anhydrase inhibitors. The in vitro carbonic anhydrase inhibitory activity of these synthesized compounds was determined and the results revealed that compound 7i (IC50 = 0.402 ± 0.017 μM) is more potent than the standard reference acetazolamide (IC50 = 0.998 ± 0.046 μM). Moreover, kinetic analysis was also performed to see the mode of binding with the target enzyme, and it was shown that compound 7i bound with the target in a competitive manner. All compounds were screened for antioxidant activity against DPPH and anticancer activity against A549 (human lung cancer cells), and the MTT assay results indicated that compounds 7a and 7d had more inhibitory growth. Moreover, compound 7i exhibited a good conformational state with hydrogen bond interactions within the receptor binding pocket according to molecular docking studies. Therefore, the novel compound 7i might be employed as a promising pharmacophore for potent and selective carbonic anhydrase inhibitors. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase (CA II) inhibitors are very important therapeutic targets in drug design for treatment of neuropathic pain and in eradication of glaucoma, cancer, epilepsy, ulcer and obesity. In this study, some two2‐substituted benzoxazoles (3a‐j) were developed as a new family of carbonic anhydrase II inhibitors by employing acyl thiourea chemistry via a simple and expedient protocol and evaluated for CA II inhibitor activity and radical scavenging ability. Compounds 3f and 3j were found to be the most potent inhibitors, with IC50 values of 0.00564 and 0.00596 μM, respectively which are several times better than that of the standard, acetazolamide (IC50 value 0.997 ± 0.0586 μM). Docking experiments were carried out against the carbonic anhydrase II crystal structure to better rationalize the inhibitory activities of these new structures. Moreover, the results of a DPPH radical scavenging assay showed that the antioxidant profile of compound 3i is superior to those of other derivatives. The results have revealed that derivatives 3f and 3j behave as CA‐II inhibitors significantly better than standard and 3i has good anti‐oxidation potential. [ABSTRACT FROM AUTHOR]

• The sulfonamide bearing thiadiazole derivatives were synthesized as enzyme inhibitors. • Target compounds bind strongly with the target enzyme (PDBID 1V9E). • The compounds show anticancer activity through carbonic anhydrase inhibition rather than by DNA binding. A series of sulfonamide derivatives bearing 2,5-disubstituted-1,3,4-thiadiazole (5a–j) have been synthesized. Thiosemicarbazide was reacted with CS 2 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 (IC 50 0.60 ± 0.02 µM) as compared to acetazolamide (IC 50 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. [Display omitted] [ABSTRACT FROM AUTHOR]