Confronting Tuberculosis: A Synthetic Quinoline-Isonicotinic Acid Hydrazide Hybrid Compound as a Potent Lead Molecule Against Mycobacterium tuberculosis.

The current tuberculosis (TB) treatment is challenged by a complex first-line treatment for drug-sensitive (DS) TB. Additionally, the prevalence of multidrug (MDR)- and extensively drug (XDR)-resistant TB necessitates the search for new drug prototypes. We synthesized and screened 30 hybrid compounds containing aminopyridine and 2-chloro-3-formyl quinoline to arrive at a compound with potent antimycobacterial activity, UH-NIP-16. Subsequently, antimycobacterial activity against DS and MDR Mycobacterium tuberculosis (M.tb) strains were performed. It demonstrated an MIC50 value of 1.86 ± 0.21 µM for laboratory pathogenic M.tb strain H37Rv and 3.045 ± 0.813 µM for a clinical M.tb strain CDC1551. UH-NIP-16 also decreased the MIC50 values of streptomycin, isoniazid, ethambutol, and bedaquiline to about 45, 55, 68, and 76%, respectively, when used in combination, potentiating their activities. The molecule was active against a clinical MDR M.tb strain. Cytotoxicity on PBMCs from healthy donors and on human cell lines was found to be negligible. Further, blind docking of UH-NIP-16 using Auto Dock Vina and MGL tools onto diverse M.tb proteins showed high binding affinities with multiple M.tb proteins, the top five targets being metabolically critical proteins CelA1, DevS, MmaA4, lysine acetyltransferase, and immunity factor for tuberculosis necrotizing toxin. These bindings were confirmed by fluorescence spectroscopy using a representative protein, MmaA4. Envisaging that a pathogen will have a lower probability of developing resistance to a hybrid molecule with multiple targets, we propose that UH-NIP-16 can be further developed as a lead molecule with the bacteriostatic potential against M.tb, both alone and in combination with first-line drugs.

Design, synthesis and in vitro evaluation of novel thiazole-coumarin hybrids as selective and potent human carbonic anhydrase IX and XII inhibitors.

The coumarin is one of the most promising classes of non-classical carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. In continuation of our ongoing work on search of coumarin based selective carbonic anhydrase inhibitors, a new series of 6-aminocoumarin based 16 novel analogues of coumarin incorporating thiazole (4a-p) have been synthesized and studied for their hCA inhibitory activity against a panel of human carbonic anhydrases (hCAs). Most of these newly synthesized compounds exhibited interesting inhibition constants in the nanomolar range. Among the tested compounds, the compounds 4f having 4-methoxy substitution exhibited activity at 90.9 nM against hCA XII isoform. It is noteworthy to see that all compounds were specifically and selectively active against isoforms hCA IX and hCA XII, with Ki under 1000 nM range. It is anticipated that these newly synthesized coumarin-thiazole hybrids (4a-p) may emerge as potential leads candidates against hCA IX and hCA XII as selective inhibitors compared to hCA I and hCA II.

Design, synthesis, and biological evaluation of 3-benzenesulfonamide-linked 3-hydrazinoisatin derivatives as carbonic anhydrase inhibitors.

A new series of isatin-linked benzenesulfonamide derivatives (9a-w) were synthesized using the tail approach and assayed for their inhibitory potency against four different human carbonic anhydrase (hCA) isoforms, hCA I, II, IX, and XII. Most of these synthesized compounds exhibited interesting inhibition potency against isoforms hCA I, IX, and XII in the nanomolar range and by taking the standard drug acetazolamide. The most potent compounds in the case of hCA I were 9c (435.8 nM) and 9s (956.4 nM), for hCA IX, 9a (60.5 nM), 9d (95.6 nM), 9g (92.1 nM), and 9k (75.4 nM), and for hCA XII, 9p (84.5 nM). However, these compounds showed more selectivity toward hCA IX over hCA I, II, and XII. Thus, these compounds can be further developed as potential lead molecules for the development of isoform-selective hCA IX inhibitors with further structural modifications.

Recent Developments in Colorimetric and Fluorometric Detection Methods of Trivalent Metal Cations (Al3+, Fe3+ and Cr3+) Using Schiff Base Probes: At a Glance.

This review basically concerned with the application of different Schiff bases (SB) based fluorimetric (turn-off and turn-on) and colorimetric chemosensors for the detection of heavy metal cations particularly Al(III), Fe(III), and Cr(III) ions. Chemosensors based on Schiff bases have exhibited outstanding performance in the detection of different metal cations due to their facile and in-expensive synthesis, and their excellent coordination ability with almost all metal cations and stabilize them in different oxidation states. Moreover, Schiff bases have also been used as antifungal, anticancer, analgesic, anti-inflammatory, antibacterial, antiviral, antioxidant, and antimalarial etc. The Schiff base also can be used as an intermediate for the formation of various heterocyclic compounds. In this review, we have focused on the research work performed on the development of chemosensors (colorimetric and fluorometric) for rapid detection of trivalent metal cations particularly Al(III), Fe(III), and Cr(III) ions using Schiff base as a ligand during 2020-2022.

Design, synthesis, and structure-activity studies of new rhodanine derivatives as carbonic anhydrase II, IX inhibitors.

Rhodanine and its derivatives are an important class of heterocycles with diverse biological properties, including anticancer, antibacterial, and anti-mycobacterial activities. In the present work, four series of new Rhodanine derivatives were synthesized and evaluated for their inhibitory activity against carbonic anhydrase I, II, IX, and XII isoforms. Interestingly, the tested compounds exhibited good inhibitory activity against the cytosolic isoform human carbonic anhydrase (hCA) II and tumor-associated hCA IX. While the Rhodanine-benzylidene derivatives (3a-l) and Rhodanine-hydrazine derivatives (6a-e) are found to be selective against hCA II, the Rhodanine-N-carboxylate derivatives (8a-d) are found to be highly selective toward hCA IX. The Rhodanine-linked isoxazole and 1,2,4-oxadiazole derivatives (8ba, 8da, and 8db) exhibited inhibitory activity against hCA II and hCA IX. Among the tested compounds, 3b, 3j, 6d, and 8db were found to inhibit hCA II with Ki values of 9.8, 46.4, 7.7, and 4.7 µM, respectively. Furthermore, their mechanism of action is supported by molecular docking studies. Notably, the synthesized Rhodanine derivatives belong to a nonsulfonamide class of carbonic anhydrase inhibitors.

Development of 2-chloroquinoline based heterocyclic frameworks as dual inhibitors of SARS-CoV-2 MPro and PLPro.

Evolution of new variants of SARS-CoV-2 warrant the need for the continued efforts in identifying target-oriented new drugs. Dual targeting agents against MPro and PLPro not only overcome the incomplete efficacy but also the drug resistance, which is common problem. Since both these are cysteine proteases, we designed 2-chloroquinoline based molecules with additional imine moiety in the middle as possible nucleophilic warheads. In the first round of design and synthesis, three molecules (C3, C4 and C5) inhibited (Ki < 2 µM) only MPro by binding covalently to C145 and one molecule (C10) inhibited both the proteases non-covalently (Ki < 2 µM) with negligible cytotoxicity. Further conversion of the imine in C10 to azetidinone (C11) improved the potency against both the enzymes in the nanomolar range (820 nM against MPro and 350 nM against PLPro) with no cytotoxicity. Conversion of imine to thiazolidinone (C12), reduced the inhibition by 3-5 folds against both the enzymes. Biochemical and computational studies suggest that C10-C12 bind in the substrate binding pocket of MPro and in the BL2 loop of the PLPro. Since these dual inhibitors have least cytotoxicity, they could be further explored as therapeutics against the SARS-CoV-2 and other analogous viruses.

Exploration of seryl tRNA synthetase to identify potent inhibitors against leishmanial parasites.

Aminoacyl-tRNA synthetases are crucial enzymes for cellular protein metabolism and have been considered as an attractive target for development of new antimicrobials. In the current study, seryl tRNA synthetase of Leishmania donovani (LdSerRS) and its mutants were purified and characterized through biochemical and structural methods. Purified LdSerRS was found to be enzymatically active and exhibited more alpha helices in secondary structure. The enzymatic activity of purified protein was observed as highest near physiological temperature and pH. Mutation in ATP binding residues (R295 and E297) demonstrated reduction in the affinity for cofactor with no significant deviation in secondary structure. In vitro inhibition studies with ureidosulfocoumarin derivatives helped to identify Comp 5l as a specific inhibitor for leishmanial SerRS that showed lesser potency towards purified HsSerRS. The identified compound presented competitive mode of inhibition for LdSerRS and also revealed druglikeness along with very low toxicity for human macrophages. Structural analysis of protein and ligand complex depicted the binding of Comp 5l into the cofactor binding site of LdSerRS with high affinity succeeded by validation employing molecular dynamics simulations. Altogether, our study presents a promising scaffold to explore small molecules to target the enzymatic activity of leishmanial SerRS to develop the specific therapeutics.

PET radiotracers and fluorescent probes for imaging human carbonic anhydrase IX and XII in hypoxic tumors.

Positron emission tomography (PET) and fluorescent imaging play a pivotal role in medical diagnosis, biomedical oncologic research, and drug development process, which include identification of target location, target engagement, but also prove on mechanism of action or pharmacokinetics of new drug candidates. PET estimates physiological changes at the molecular level using specific radiotracers containing a short-lived positron emitting radionuclide such as fluorine-18 or carbon-11, whereas fluorescent imaging techniques use fluorescent probes labeled with suitable drug candidates for detection at the molecular level. The human carbonic anhydrase (hCA) isoforms IX and XII are overexpressed in hypoxic cancer cells, promoting tumor growth by regulating extra/intracellular pH, ferroptosis, and metabolism, being recognized as promising targets for anticancer theranostic agents. In this review, we have focused on PET radiotracers as well as fluorescent probes for diagnosis and treatment of tumors expressing hCA IX and hCA XII.

Coumarin and Piperazine Conjugates as Selective Inhibitors of the Tumor-associated Carbonic Anhydrase IX and XII Isoforms.

BACKGROUND: Carbonic Anhydrases (CAs) are a family of metalloenzymes that catalyze the reversible interconversion of CO2 and water to bicarbonate and proton. CA isoforms I, II, IX, and XII are considered physiologically and pharmacologically relevant. OBJECTIVE: The objective of this study is to synthesize potent and selective tumor-associated CA IX and XII inhibitors. METHODS: A library of 17 coumarin derivatives clubbed with piperazine and benzyl moiety was designed, synthesized and evaluated for its inhibitory effects and selectivity profile towards physiologically and pharmacologically relevant CA isoforms I, II, IX, and XII. RESULTS: All the derivatives were found to be active against the tumor-associated isoforms IX and XII. The most active compound against hCA (human Carbonic Anhydrase) IX was found to possess a Ki of 229 nM, while the one against hCA XII had a Ki of 294.2 nM. Additionally, two of the compounds were found to have exquisite selectivity towards the off-target hCA I and II isoforms. Moreover, they were found to be approximately 20-fold more selective towards hCA IX than XII. The selectivity of the compounds was further investigated via molecular modeling techniques. CONCLUSION: Coumarin-piperazine hybrids were identified as potent and selective CA IX and XII inhibitors. Molecular modeling techniques provided interesting cues pertaining to observed selectivity.

Development of Novel Indole-3-sulfonamide-heteroaryl Hybrids as Carbonic Anhydrase Inhibitors: Design, Synthesis and in-vitro Screening.

BACKGROUND: Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the reversible hydration of carbon dioxide to bicarbonate and a proton. Inhibition of isoforms IX and XII has induced potent anticancer effects. OBJECTIVE: A series of indole-3-sulfonamide-heteroaryl hybrid (6a-y) was synthesized and screened for the inhibition of human (h) hCA isoforms I, II, IX, and XII. METHODS: The synthesis of target compounds (6a-y) was carried out in multistep starting from 5-nitro indole as starting material by using classical reported reaction conditions. The steps involved are N-Alkylation Chlorosulfonation, amination, reduction, and finally amidation reaction. RESULTS: Amongst all the compounds (6a-y) synthesized and screened, 6l was found to be active against all the screened hCA isoforms, with Ki ranging 8.03 µM, 4.15 µM, 7.09 µM, and 4.06 µM respectively. On the other hand, 6i, 6j, 6q, 6s, and 6t were highly selective against tumor-associated hCA IX, and 6u was selective against both hCA II and hCA IX with moderate inhibitory activities under the range of 100 µM. These compounds showed good activity against the tumor-associated hCA IX and might be developed as future drug leads for anticancer drug discovery. CONCLUSION: These compounds may be useful as starting points for the design and development of more selective and potent hCA IX and XII inhibitors.

Design, Synthesis and Biological Assessment of Rhodanine-Linked Benzenesulfonamide Derivatives as Selective and Potent Human Carbonic Anhydrase Inhibitors.

A novel series of twenty-five rhodamine-linked benzenesulfonamide derivatives (7a-u and 9a-d) were synthesized and screened for their inhibitory action against four physiologically relevant human (h) carbonic anhydrase (CA) isoforms, namely hCA I, hCA II, hCA IX, and hCA XII. All the synthesized molecules showed good to excellent inhibition against all the tested isoforms in the nanomolar range due to the presence of the sulfonamide as a zinc binding group. The target compounds were developed from indol-3-ylchalcone-linked benzenesulfonamide where the indol-3-ylchalcone moiety was replaced with rhodanine-linked aldehydes or isatins to improve the inhibition. Interestingly, the molecules were slightly more selective towards hCA IX and XII compared to hCA I and II. The most potent and efficient ones against hCA I were 7h (KI 22.4 nM) and 9d (KI 35.8 nM) compared to the standard drug AAZ (KI 250.0 nM), whereas in case of hCA II inhibition, the derivatives containing the isatin nucleus as a tail were preferred. Collectively, all compounds were endowed with better inhibition against hCA IX compared to AAZ (KI 25.8 nM) as well as strong potency against hCA XII. Finally, these newly synthesized molecules could be taken as potential leads for the development of isoform selective hCA IX and XII inhibitors.

Synthesis and biological evaluation of coumarin-thiazole hybrids as selective carbonic anhydrase IX and XII inhibitors.

A series of coumarin-linked thiazoles (6a-p) was synthesized and the synthesized compounds were evaluated against human carbonic anhydrases (hCAs) IX and XII, which have been implicated in cancer. All the compounds exhibited selective inhibition of both isoforms. The designed compounds inhibited hCA IX in a moderate nanomolar to submicromolar range. The hCA XII was inhibited in a low to moderate nanomolar range. Compound 6o exhibited the best inhibition of hCA XII with a Ki value of 91.1 nM. The hydrolyzed form of compound 6o also exhibited favorable interactions as well as good docking scores with both the isoforms. Hence, this compound can be taken as a template for the design of selective and potent hCA XII inhibitors.

Synthesis of a new series of quinoline/pyridine indole-3-sulfonamide hybrids as selective carbonic anhydrase IX inhibitors.

In this manuscript, design, rational, synthesisand carbonic anhydrases (CAs) inhibitory profile of the quinoline/pyridine linked indole-3-sulfonamide derivatives were reported. The library of 29newly quinoline/pyridine indole-3-sulfonamide derivatives have been generated and examined against the panel of four physiological relevant human CA isoforms, namely, the cytosolic isoforms hCA I and hCA II and the transmembrane tumor associated isoforms hCA IX and hCA XII. Pyridine indole-3-sulfonamide hybrids are selective inhibit transmembrane tumor associated isoforms hCA IX and hCA XII. However, all synthesized quinoline indole-3-sulfonamide hybrids have inhibitory effect on hCA IX isoforms, whereas few have shown inhibitory activity against hCA II and hCA XII as well. However, among all synthesized compound 6q and6p having good inhibitory activity against hCA IX with Ki 1.47 µM and 1.57 µM respectively.These quinoline/pyridine indole-3-sulfonamide conjugatesmay be regarded as potential leads for hCA IXselective inhibitors as anti-cancer agents.

Anticancer carbonic anhydrase inhibitors: a patent and literature update 2018-2022.

INTRODUCTION: Cancer affects an increasing number of patients each year with an unacceptable death toll worldwide. A new therapeutic approach to combat tumors consists in targeting human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms IX and XII, which are tumor-associated, overexpressed enzymes in hypoxic tumors, being involved in metabolism, pH regulation, ferroptosis, and overall tumor progression. AREAS COVERED: Small molecule hCA IX/XII and antibody drug conjugate inhibitors targeting the two enzymes and their applications in the management of cancer are discussed. EXPERT OPINION: The available 3D crystal structures of hCA IX, XII as well as the off target isoforms hCA I and II, afforded structure-based drug design opportunities, which led to the development of various isoform-selective small molecule inhibitors belonging to diverse classes (sulfonamides, sulfamates, benzoxaboroles, selenols, coumarins, sulfocoumarins, and isocoumarins). Many patents focused on small inhibitors containing sulfonamide/sulfamide/sulfamide derivatives as well as hybrids incorporating sulfonamides and different antitumor chemotypes, such as cytotoxic drugs, kinase/telomerase inhibitors, P-gp and thioredoxin inhibitors. The most investigated candidate belonging to the class is the sulfonamide SLC-0111, in Phase Ib/II clinical trials for the management of advanced, metastatic solid tumors.

Design, synthesis, SAR, and biological evaluation of saccharin-based hybrids as carbonic anhydrase inhibitors.

Saccharin is a cyclic secondary sulfonamide, which is a selective inhibitor of the tumor-associated carbonic anhydrase (CA; EC 4.2.1.1) enzymes CA IX and CA XII compared to many primary sulfonamides. In this study, new saccharin-1,2,3-triazole and saccharin-1,2,4-oxadiazole hybrids were synthesized. All the newly synthesized molecules were screened for their CA-inhibitory activity against four important human CA (hCA) isoforms: hCA I, hCA II, hCA IX, and hCA XII. Compounds 8a and 8f emerged as potent hCA II inhibitors (Ki = 3 µM). Compounds 6d, 6e and 7a, 7b were highly selective against hCA IX (6d, 6e) and hCA II (7a, 7b), with moderate inhibitory activity. The activity of these compounds was further confirmed by performing in silico docking studies against hCA II and hCA IX.

Exploration of 2-phenylquinoline-4-carboxamide linked benzene sulfonamide derivatives as isoform selective inhibitors of transmembrane human carbonic anhydrases.

A novel series of 32 sulfonamide containing quinolines (5a-j, 7a-k and 9a-k) were synthesized using tail approach and assayed for their carbonic anhydrase inhibitory potency against four human (h) carbonic anhydrase (CA) isoforms hCA I, II, IX and XII. Most of these newly synthesized compounds exhibited interesting inhibition potency against hCA I, II, IX and XII, in the nanomolar range with some derivatives being more potent than the standard drug acetazolamide (AAZ). The most effective ones on hCA I were 9b (91.8 nM), on hCA II: 5b (7.1 nM), 9c (9.6 nM) and on hCA IX: 5b (6.5 nM), 5g (21.4 nM), 5i (9.1 nM), 9a (22.8 nM), 9b (9.7 nM). Compounds 5h (8.8 nM), 7a (9.6 nM), 9d (6.9 nM), 9e (6.7 nM) were found highly effective against hCA XII. These 4-functionalized benzenesulfonamides (5a-5j, 9a-9k) were found to be more potent than the corresponding 3-functionalized derivatives (7a-k). These compounds may emerge as potential leads for the development of isoform selective hCA IX and XII inhibitors.

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.

BACKGROUND: 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. OBJECTIVE: 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. METHODS: The target compound is obtained by taking isatin, indole, VOSO4, and H2O in one-pot at 70oC. RESULTS: 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. CONCLUSION: 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.

Design and development of novel series of indole-3-sulfonamide ureido derivatives as selective carbonic anhydrase II inhibitors.

Indole is a privileged moiety with a wide range of bioactivities, making it a popular scaffold in drug design and development studies as well as in synthetic chemistry. Here, novel urea derivatives of indole, containing sulfonamide at position-3 of indole, were synthesized using a well-known tail approach, as carbonic anhydrases (CAs; EC 4.2.1.1) inhibitors. All the newly synthesized molecules were screened for their CA-inhibitory activity against four clinically relevant isoforms of human-origin carbonic anhydrase (hCA), that is, hCA I, hCA II, hCA IX, and hCA XII. These compounds were specifically active against hCA II, more than against hCA I, hCA IX, and hCA XII. Derivative 6l was found to be most active, with a Ki value of 7.7 µM against hCA II.

Ureidosulfocoumarin Derivatives As Selective and Potent Carbonic Anhydrase IX and XII Inhibitors.

Owing to severe allergic reactions (anaphylaxis) and resistance exhibited by sulfonamide-based carbonic anhydrase (CA) inhibitors, non-classical or non-sulfonamide CA inhibitors are gaining increased attention by medicinal chemists. In this context, we report the design and synthesis of 30 new non-sulfonamide sulfocoumarin derivatives as CA inhibitors. They were investigated against hCA I and II (cytosolic isozymes) as well as hCA IX and XII (transmembrane, tumor-associated enzymes). All compounds showed prominent selectivity for the tumor-associated isoenzymes hCA IX and XII over the cytosolic isoenzymes hCA I and II. Among all synthesized compounds, 1-(2,2-dioxidobenzo[e][1,2]oxathiin-6-yl)-3-(o-tolyl)urea(5 j)and1-(3-fluorophenyl)-3-(8-methoxy-2,2-dioxidobenzo[e][1,2]oxathiin-6-yl)urea(5 q)were found to be more potent and to have better inhibition constant values against hCA IX than the standard acetazolamide (AAZ), with Ki values of 23.6 and 23.3 nM, respectively. All other compounds were found to be active under Ki =920 nM against hCA IX and XII.This study provides a new perspective for the future development of non-sulfonamide derivatives as selective CA inhibitors.

Synthesis and Biological Evaluation of Coumarin-Linked 4-Anilinomethyl-1,2,3-Triazoles as Potent Inhibitors of Carbonic Anhydrases IX and XIII Involved in Tumorigenesis.

A series of coumarin-linked 4-anilinomethyl-1,2,3-triazoles (6a-t) was synthesized via a molecular hybridization approach, through carbon C-6 of the coumarin moiety. The synthesized compounds were evaluated for their inhibition of carbonic anhydrase (CA) isoforms I, II, IX and XIII. CAs IX and XIII were selectively inhibited over the off-target isoforms I and II. The best inhibitory profiles against CA IX were shown by compounds 6a, 6e and 6f (Ki < 50 nM), with compound 6e displaying the best inhibition with a Ki value of 36.3 nM. Compounds 6a, 6b, 6j, 6o and 6q exhibited the best inhibitory profiles against CA XIII (Ki < 100 nM). These compounds can be further explored for the discovery of potent and effective CA IX and CA XIII inhibitors.