Synthesis and biological evaluation of coumarin-1,3,4-oxadiazole hybrids as selective carbonic anhydrase IX and XII inhibitors

Chemistry of heterocycles as carbonic anhydrase inhibitors: A pathway to novel research in medicinal chemistry review

Nowadays, the scientific community has focused on dealing with different kinds of diseases by exploring the chemistry of various heterocycles as novel drugs. In this connection, medicinal chemists identified carbonic anhydrases (CA) as one of the biologically active targets for curing various diseases. The widespread distribution of these enzymes and the high degree of homology shared by the different isoforms offer substantial challenges to discovering potential drugs. Medicinal and synthetic organic chemists have been continuously involved in developing CA inhibitors. This review explored the chemistry of different heterocycles as CA inhibitors using the last 11 years of published research work. It provides a pathway for young researchers to further explore the chemistry of a variety of synthetic as well as natural heterocycles as CA inhibitors.

The dopamine D2 receptors antagonist Veralipride inhibits carbonic anhydrases: solution and crystallographic insights on human isoforms

The inhibitory effects of veralipride, a benzamide-class antipsychotic acting as dopamine D2 receptors antagonist incorporates a primary sulfonamide moiety and was investigated for its interactions with carbonic anhydrase (CA) isoforms. In vitro profiling using the stopped-flow technique revealed that veralipride exhibited potent inhibitory activity across all tested hCA isoforms, with exception of hCA III. Comparative analysis with standard inhibitors, acetazolamide (AAZ), and sulpiride, provided insights for understanding the relative efficacy of veralipride as CA inhibitor. The study reports the X-ray crystal structure analysis of the veralipride adduct with three human (h) isoforms, hCA I, II, and CA XII mimic, allowing the understanding of the molecular interactions rationalizing its inhibitory effects against each isoform. These findings contribute to our understanding of veralipride pharmacological properties and for the design of structural analogs endowed with polypharmacological properties.

Design and synthesis of novel coumarin-benzimidazole hybrids as human galectin-1 inhibitors

Aim: To develop novel non-carbohydrate inhibitors of human galectin-1 (GAL-1), we have designed a series of coumarin-benzimidazole hybrids. Methods: We synthesized and characterized the coumarin-benzimidazole hybrids and further evaluated them using an in vitro GAL-1 enzyme-linked immunosorbent assay and in silico methods. Results: Among all, the compounds 6p and 6q were found to be potent, with GAL-1 inhibition of 37.61 and 36.92%, respectively, at 10 μM in GAL-1-expressed cell culture supernatant of MCF-7 cells. These two compounds are feasible for fluorine-18 radiolabeling to develop GAL-1 selective PET radiotracers. Computational studies revealed strong binding interactions of GAL-1 with these novel coumarin-benzimidazole hybrids. Conclusion: Coumarin-benzimidazole hybrids can serve as potential leads to develop selective non-carbohydrate GAL-1 inhibitors for cancer therapy.

pH regulators and their inhibitors in tumor microenvironment

As an important characteristic of tumor, acidic tumor microenvironment (TME) is closely related to immune escape, invasion, migration and drug resistance of tumor. The acidity of the TME mainly comes from the acidic products produced by the high level of tumor metabolism, such as lactic acid and carbon dioxide. pH regulators such as monocarboxylate transporters (MCTs), carbonic anhydrase IX (CA IX), and Na+/H+ exchange 1 (NHE1) expel protons directly or indirectly from the tumor to maintain the pH balance of tumor cells and create an acidic TME. We review the functions of several pH regulators involved in the construction of acidic TME, the structure and structure-activity relationship of pH regulator inhibitors, and provide strategies for the development of small-molecule antitumor inhibitors based on these targets.

Latest developments in coumarin-based anticancer agents: mechanism of action and structure-activity relationship studies

Many researchers around the world are working on the development of novel anticancer drugs with different mechanisms of action. In this case, coumarin is a highly promising pharmacophore for the development of novel anticancer drugs. Besides, the hybridization of this moiety with other anticancer pharmacophores has emerged as a potent breakthrough in the treatment of cancer to decrease its side effects and increase its efficiency. This review aims to provide a comprehensive overview of the recent development of coumarin derivatives and their application as novel anticancer drugs. Herein, we highlight and describe the largest number of research works reported in this field from 2015 to August 2023, along with their mechanisms of action and structure-activity relationship studies, making this review different from the other review articles published on this topic to date.

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.

Discovery of 2,4-thiazolidinedione-tethered coumarins as novel selective inhibitors for carbonic anhydrase IX and XII isoforms

Different 2,4-thiazolidinedione-tethered coumarins 5a-b, 10a-n and 11a-d were synthesised and evaluated for their inhibitory action against the cancer-associated hCAs IX and XII, as well as the physiologically dominant hCAs I and II to explore their selectivity. Un-substituted phenyl-bearing coumarins 10a, 10 h, and 2-thienyl/furyl-bearing coumarins 11a-c exhibited the best hCA IX (KIs between 0.48 and 0.93 µM) and hCA XII (KIs between 0.44 and 1.1 µM) inhibitory actions. Interestingly, none of the coumarins had any inhibitory effect on the off-target hCA I and II isoforms. The sub-micromolar compounds from the biochemical assay, coumarins 10a, 10 h and 11a-c, were assessed in an in vitro antiproliferative assay, and then the most potent antiproliferative agent 11a was tested to explore its impact on the cell cycle phases and apoptosis in MCF-7 breast cancer cells to provide more insights into the anticancer activity of these compounds.

Design and synthesis of benzothiazole-based SLC-0111 analogues as new inhibitors for the cancer-associated carbonic anhydrase isoforms IX and XII

In this work, different series of benzothiazole-based sulphonamides 8a-c, 10, 12, 16a-b and carboxylic acids 14a-c were developed as novel SLC-0111 analogues with the goal of generating potent carbonic anhydrase (CA) inhibitors. The adopted strategy involved replacing the 4-fluorophenyl tail in SLC-0111 with a benzothiazole motif that attached to the ureido linker to produce compounds 8c and its regioisomers 8a-b. In addition, the ureido spacer was elongated by methylene or ethylene groups to afford the counterparts 10 and 12. In turn, the primary sulfamoyl zinc binding group (ZBG) was either substituted or replaced by carboxylic acid functionality in order to provide the secondary sulphonamide-based SLC-0111 analogues 16a-b, and the carboxylic acid derivatives 14a-c, respectively. All compounds (8a-c, 10, 12, 14a-c and 16a-b) were tested for their ability to inhibit CA isoforms CA I, II, IX and XII. Additionally, the in vitro anticancer properties of the developed CAIs were evaluated.

Design, Synthesis and Biological Evaluation of New Carbohydrate-Based Coumarin Derivatives as Selective Carbonic Anhydrase IX Inhibitors via “Click” Reaction

In this work, we designed a series of new carbohydrate-based coumarin carbonic anhydrase IX inhibitors by using 1,2,3-triazoles as linker. Next, these designed compounds were synthesized by the optimized one-pot click chemistry reaction condition. Subsequently, these target compounds were assayed for the inhibition of three carbonic anhydrase isoforms (CA I, CA II and CA IX). Intriguingly, all the compounds showed better CA IX inhibitory activity than initial coumarin fragments. Among them, compound 10a (IC₅₀: 11 nM) possessed the most potent CA IX inhibitory activity, which was more potent than the reference drug acetazolamide (IC₅₀: 30 nM). Notably, compound 10a showed 3018-fold, 1955-fold selectivity relative to CA I and CA II, respectively. Meanwhile, representative compounds could reduce tumor cell viability and the extracellular acidification in HT-29 and MDA-MB-231 cancer cell lines. Even more interestingly, our target compounds had no apparent cytotoxicity toward MCF-10A cell line. In addition, the in vitro stability assays also indicated our developed compounds possessed good liver microsomal metabolic stabilities and plasma stability. Furthermore, representative compounds revealed relatively low hERG cardiac toxicity and acute toxicity. Furthermore, docking studies were carried out to understand the interactions of our target compounds with the protein target CA IX. Collectively, our results suggest that compound 10a, as a selective CA IX inhibitor, could be an important lead compound for further optimization and development as an anticancer agent.

Carbon-11 patents (2012-2022): synthetic methodologies and novel radiotracers for PET imaging

INTRODUCTION

Carbon-11 is a short-lived radionuclide with versatile applications in synthetic methodologies to develop a variety of novel PET radiotracers. Different primary and secondary carbon-11 precursors are generated from cyclotron produced [¹¹C]CO₂ and used to insert carbon-11 radionuclide into the target specific bioactive molecules.

AREAS COVERED

In this review, the patents as well as specific research articles on carbon-11 radiotracer synthesis and PET imaging applications in various diseases are mentioned since 2012 to 2022 through SciFinder database.

EXPERT OPINION

Carbon-11 is generally easier to insert into more organic scaffolds as a greater variety of functional groups. Despite the short half-life of carbon-11 radionuclide (t_1/2 = 20.4 min), it is widely used in PET radiotracer development due to its direct insertion into bioactive compounds and less isotopic dilution unlike other positron emitters like fluorine-18. Various synthons can be easily generated using the primary and secondary carbon-11 precursors like [¹¹C]CO₂, [¹¹C]CH₄, ¹¹CH₃I, ¹¹CO, ¹¹COCl_2, ¹¹CN, ¹¹CS_2, and ¹¹CH₃OTf etc. that would be useful to develop any PET radiotracers by adapting various organic methods. The carbon-11 radiotracers provide target-oriented information associated with the pharmacology, and physiological conditions of the disease status. Various protocols and automated methods were adapted for easy and convenient synthesis of carbon-11 radiotracers. The PET advances drug development and clinical trials by revealing biological target engagement, proof of mechanism, pharmacokinetic, and pharmacodynamic profiles of new drug candidates using selective radiotracers.

Synthesis and Biological Activity of 1,3,4-Oxadiazoles Used in Medicine and Agriculture

Biologically active compounds play a key role in the fight against diseases affecting both human and animal living organisms, as well as plants. Finding out about new molecules with a potential biological effect, not yet described in the literature, is one of the most important aspects in the development of medicine and agriculture. Compounds showing desirable biological activity include heterocyclic moieties such as 1,3,4-oxadiazoles. The oxadiazole molecule is composed of two nitrogen atoms and one oxygen atom, forming a five-membered heterocyclic ring. Structures of this type have been successfully used in the treatment of various diseases in humans and animals, and play an important role in modern agriculture. It has been proven that many oxadiazole derivatives exhibit antibacterial, antiviral, blood pressure lowering, antifungal, antineoplastic, anticancer, antioxidant, anti-inflammatory and analgesic properties. In addition, compounds based on 1,3,4-oxadiazole can act as plant protection agents due to their herbicidal, insecticidal and fungicidal activity. Due to the constantly growing interest in heterocyclic systems of this nature, new methods of obtaining complex structures containing oxadiazole rings are sought. This article discusses various methods of synthesis of 1,3,4-oxadiazole derivatives exhibiting biological activity. Based on these techniques, these compounds could be used in the future in medicine and agriculture.

PET Molecular Imaging in Drug Development: The Imaging and Chemistry Perspective

Positron emission tomography with selective radioligands advances the drug discovery and development process by revealing information about target engagement, proof of mechanism, pharmacokinetic and pharmacodynamic profiles. Positron emission tomography (PET) is an essential and highly significant tool to study therapeutic drug development, dose regimen, and the drug plasma concentrations of new drug candidates. Selective radioligands bring up target-specific information in several disease states including cancer, cardiovascular, and neurological conditions by quantifying various rates of biological processes with PET, which are associated with its physiological changes in living subjects, thus it reveals disease progression and also advances the clinical investigation. This study explores the major roles, applications, and advances of PET molecular imaging in drug discovery and development process with a wide range of radiochemistry as well as clinical outcomes of positron-emitting carbon-11 and fluorine-18 radiotracers.

Recent Developments of Coumarin-based Hybrids in Drug Discovery

Coumarin scaffold is a highly significant O-heterocycle, namely benzopyran-2-ones, form an elite class of naturally occurring compounds that possess promising therapeutic perspectives. Based on its broad spectrum of biological activities, the privileged coumarin scaffold is applied to medicinal and pharmacological treatments by several rational design strategies and approaches. Structure-activity relationships of the coumarin-based hybrids with various bioactivity fragments revealed significant information toward the further development of highly potent and selective disorder therapeutic agents. The molecular docking studies between coumarins and critical therapeutic enzymes demonstrated mode of action by forming noncovalent interactions with more than one receptor, further rationally confirm information about structure-activity relationships. This review summarizes recent developments relating to coumarin-based hybrids with other pharmacophores aiming to numerous feasible therapeutic enzymatic targets to combat various therapeutic fields, including anticancer, antimicrobic, anti-Alzheimer, anti-inflammatory activities.

Pharmacological report of recently designed multifunctional coumarin and coumarin-heterocycle derivatives

Coumarin is a naturally available molecule and has been identified as a potent pharmacophore due to its pharmacological activity. Because of this, coumarin has been exploited synthetically to prepare a wide range of derivatives. In fact, most coumarin derivatives have been found to be less toxic, which is the most essential property for a drug molecule. Such molecules are being prepared for therapeutic use as broad-spectrum pharmacological agents. Microbial diseases including viral diseases have become very common and are responsible for many deaths worldwide. In particular, microbial drug resistance is a problem that needs to be tackled in an effective manner. Also, for Alzheimer's disease, which affects most elderly persons, no efficient chemotherapy exists. In addition, although diabetes, a metabolic syndrome, can be treated with many drugs, there is no complete cure. Thus, more potent antidiabetic agents are required for the management of diabetes. Likewise, for the treatment of a wide range of ailments caused by microbes, genetic factors, or lifestyle-related factors, an efficient drug regimen is needed. In view of this, coumarin derivatives are designed and evaluated. Here, coumarin derivatives that have been reported recently are compiled, classified and evaluated critically. This study briefly takes the structure-activity relationship into consideration and suggests the next suitable step. With a focus on the most potent molecules, the pharmacological activity of the evaluated molecules is described.

Synthesis, Crystal Structure, Inhibitory Activity and Molecular Docking of Coumarins/Sulfonamides Containing Triazolyl Pyridine Moiety as Potent Selective Carbonic Anhydrase IX and XII Inhibitors

In this work, two classes of Carbonic Anhydrase (CA) inhibitors, sulfonamide and coumarin derivatives linked to pyta moiety (2a-b) and their corresponding rhenium complexes (3a-b), were designed. These compounds were synthesized and fully characterized by classical analytical methods and X-ray diffraction. All the synthesized compounds were evaluated for their inhibitory activity against the hCA isoforms I, II, IX and XII. They exhibited high inhibitory activities in the range of nanomolar for both hCA IX and hCA XII isoforms. The sulfonamide compound 2a showed the strongest inhibition against the tumour-associated hCA IX isoform with a Ki of 11.7 nM. The tumour-associated isoforms hCA IX and hCA XII were selectively inhibited by all the coumarin derivatives, with inhibition constants ranging from 12.7 nM (2b) to 44.5 nM (3b), while the hCA I and II isoforms were slightly inhibited (in the micromolar range), as expected. In terms of selectivity, compared to previously published rhenium complex-based CA inhibitors, complex 3b showed one of the highest selectivities against hCA IX and hCA XII compared to the off-target isoforms hCA I and hCA II, making it a potential anti-cancer drug candidate. Molecular docking calculations were performed to investigate the inhibition profiles of the investigated compounds at the tumour-associated hCA IX active site and to rationalize our results.

Design, Synthesis, In Silico and In Vitro Studies for New Nitric Oxide-Releasing Indomethacin Derivatives with 1,3,4-oxadiazole-2-thiol Scaffold

Starting from indomethacin (IND), one of the most prescribed non-steroidal anti-inflammatory drugs (NSAIDs), new nitric oxide-releasing indomethacin derivatives with 1,3,4-oxadiazole-2-thiol scaffold (NO-IND-OXDs, 8a-p) have been developed as a safer and more efficient multitarget therapeutic strategy. The successful synthesis of designed compounds (intermediaries and finals) was proved by complete spectroscopic analyses. In order to study the in silico interaction of NO-IND-OXDs with cyclooxygenase isoenzymes, a molecular docking study, using AutoDock 4.2.6 software, was performed. Moreover, their biological characterization, based on in vitro assays, in terms of thermal denaturation of serum proteins, antioxidant effects and the NO releasing capacity, was also performed. Based on docking results, 8k, 8l and 8m proved to be the best interaction for the COX-2 (cyclooxygense-2) target site, with an improved docking score compared with celecoxib. Referring to the thermal denaturation of serum proteins and antioxidant effects, all the tested compounds were more active than IND and aspirin, used as references. In addition, the compounds 8c, 8h, 8i, 8m, 8n and 8o showed increased capacity to release NO, which means they are safer in terms of gastrointestinal side effects.

Synthesis, computational studies and assessment of in vitro inhibitory activity of umbelliferon-based compounds against tumour-associated carbonic anhydrase isoforms IX and XII

Coumarins are widely diffused secondary metabolites possessing a plethora of biological activities. It has been established that coumarins represent a peculiar class of human carbonic anhydrase (hCA) inhibitors having a distinct mechanism of action involving a non-classical binding with amino acid residues paving the entrance of hCA catalytic site. Herein, we report the synthesis of a small series of new coumarin derivatives 7-11, 15, 17 prepared via classical Pechmann condensation starting from resorcinol derivatives and suitable β-ketoesters. The evaluation of inhibitory activity revealed that these compounds possessed nanomolar affinity and high selectivity towards tumour-associated hCA IX and XII over cytosolic hCA I and hCA II isoforms. To investigate the binding mode of these new coumarin-inspired inhibitors, the most active compounds 10 and 17 were docked within hCA XII catalytic cleft.

Design, synthesis and in vitro antiproliferative activity of new thiazolidinedione-1,3,4-oxadiazole hybrids as thymidylate synthase inhibitors

Thymidylate synthase (TS) has been an attention-grabbing area of research for the treatment of cancers due to their role in DNA biosynthesis. In the present study, we have synthesised a library of thiazolidinedione-1,3,4-oxadiazole hybrids as TS inhibitors. All the synthesised hybrids followed Lipinski and Veber rules which indicated good drug likeness properties upon oral administration. Among the synthesised hybrids, compound 9 and 10 displayed 4.5 and 4.4 folds activity of 5-Fluorouracil, respectively against MCF-7 cell line whereas 3.1 and 2.5 folds cytotoxicity against HCT-116 cell line. Furthermore, compound 9 and 10 also inhibited TS enzyme with IC50 = 1.67 and 2.21 µM, respectively. Finally, the docking studies of 9 and 10 were found to be consistent with in vitro TS results. From these studies, compound 9 and 10 has the potential to be developed as TS inhibitors.

Synthesis and biological evaluation of some coumarin hybrids as selective carbonic anhydrase IX and XII inhibitors

Two series, coumarin-linked to thiazolidinone via a pyrazole linker (6a-m, Series 1) and coumarin-linked 1,2,3-triazoles (5a-j, Series 2) were synthesized and the synthesized compounds were subjected for evaluation against the four physiologically and pharmacologically relevant hCA isoforms, hCA I, II, IX and XII. The results indicated selective inhibition of tumor-associated isoforms hCA IX and XII over the off-target isoforms, hCA I and II. The compounds of series 1 exhibited better hCA IX inhibition compared to hCA XII, with compounds 6i, 6h, 6a and 6k, exhibiting notable K_i values of less than 100 nM. Among all the compounds, compound 6i showed the best inhibition with a K_i value of 61.5 nM. Among the compounds of series 2, compounds 5a, 5b, 5c, 5d, 5f and 5j exhibited notable hCA IX inhibition. Compound 5d showed the best inhibition with a K_i value of 32.7 nM. In the case of hCA XII, compound 5i showed the best inhibition with a K_i value of 84.2 nM. Hence, compound 6i from Series 1 and 5d from Series 2 could be taken as lead compounds for the further development of selective and potent hCA IX inhibitors, whereas the compound 5i from Series 2 can be explored further for the design of selective and potent hCA XII inhibitors.

Synthesis of 1,3,4-oxadiazole derivatives with anticonvulsant activity and their binding to the GABAA receptor

In this study, a series of 1,3,4-oxadiazole derivatives (5a-s, 10a-s, and 16a-d) were designed and synthesized using maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) models, to test the anticonvulsant activity of the target compounds in vivo. The neurotoxicity (NT) of the target compounds was measured using the rotating rod (ROT) method. Seven compounds with potential activity were selected to test the 50% effective dose (ED₅₀) and 50% toxic dose (TD₅₀). Pharmacological experiments revealed that 6-((5-(pentylthio)-1,3,4-oxadiazol-2-yl)methoxy)-3,4-dihydroquinolin-2(1H)-one (5b) showed the best anticonvulsant activity (MES, ED₅₀ = 8.9 mg/kg; scPTZ, ED₅₀ = 10.2 mg/kg), which was greater than the activities of carbamazepine and ethosuximide. Compound 5b exhibited the most potent binding affinity toward the GABA_A receptor (IC₅₀ = 0.11 μM) in the in vitro binding experiments. Compound 5b displayed significant anxiolytic activity at a low dose (1 mg/kg) in the elevated plus maze (EPM) test. The GABA content in rat brains was also investigated, and the results showed that compound 5b might have affected the GABA system. In our molecular docking experiment, compound 5b showed significant interactions with residues present at the benzodiazepine binding site on the GABA_A receptor. The structure and physicochemical and pharmacokinetic properties of the target compound were predicted using Discovery Studio 2019 and ChemBioDraw Ultra 14.0. Finally we demonstrated that compound 5b mainly acted on GABA_A receptor. Thus the present study has provided potential candidates for further investigation in epilepsy.

An Overview of Coumarin as a Versatile and Readily Accessible Scaffold with Broad-Ranging Biological Activities

Privileged structures have been widely used as an effective template for the research and discovery of high value chemicals. Coumarin is a simple scaffold widespread in Nature and it can be found in a considerable number of plants as well as in some fungi and bacteria. In the last years, these natural compounds have been gaining an increasing attention from the scientific community for their wide range of biological activities, mainly due to their ability to interact with diverse enzymes and receptors in living organisms. In addition, coumarin nucleus has proved to be easily synthetized and decorated, giving the possibility of designing new coumarin-based compounds and investigating their potential in the treatment of various diseases. The versatility of coumarin scaffold finds applications not only in medicinal chemistry but also in the agrochemical field as well as in the cosmetic and fragrances industry. This review is intended to be a critical overview on coumarins, comprehensive of natural sources, metabolites, biological evaluations and synthetic approaches.

Overview on developed synthesis procedures of coumarin heterocycles

Considering highly valuable biological and pharmaceutical properties of coumarins, the synthesis of these heterocycles has been considered for many organic and pharmaceutical chemists. This review includes the recent research in synthesis methods of coumarin systems, investigating their biological properties and describing the literature reports for the period of 2016 to the middle of 2020. In this review, we have classified the contents based on co-groups of coumarin ring. These reported methods are carried out in the classical and non-classical conditions particularly under green condition such as using green solvent, catalyst and other procedures.

New coumarin/sulfocoumarin linked phenylacrylamides as selective transmembrane carbonic anhydrase inhibitors: Synthesis and in-vitro biological evaluation

Two novel series of phenylacrylamide linked coumarins and sulfocoumarins (6a-p, 8a-i, and 14a-g) were synthesized and evaluated against four physiologically relevant human carbonic anhydrases (hCAs, EC 4.2.1.1), isoforms hCA I, hCA II, hCA IX and hCA XII for their inhibitory action. All new compounds when screened for carbonic anhydrase inhibitory activity have shown selective inhibition towards the tumor associated isoforms hCA IX and XII over CA I and II, with inhibition constants in the submicromolar to low nanomolar range. Compound 6b and 14g exhibited significant inhibition with low nanomolar potency against hCA IX, whereas 6k was effective against hCA XII. Compounds 6b, 14g and 6k may be considered as lead molecules for future development of cancer therapeutics based on a novel mechanism of action.

Synthesis, pharmacological evaluation and structure-activity relationship of recently discovered enzyme antagonist azoles

Global people are suffering from the legion of diseases. Cytotoxic property of the chemical compound would not solely influence effective drug properties and reduce unnecessary side effects. Proteins/enzymes responsible for microbe proliferation or survival are specifically targeted and inhibited successfully making the cells to undergo apoptosis. Furthermore, isoforms of essential enzymes have distinct physiological functions; thereby inhibition of essential enzyme isoforms is an apt way to the clinical approach of disease neutralization. Drugs are designed so as to play significant roles such as signaling pathways in the oncogenic process including cell proliferation, invasion, and angiogenesis. The present review comprises collective information of the recent synthesis of various organic drug compounds in brief, which could inhibit particular enzyme. The review also covers the correlation of the structure of a drug molecule designed and its inhibitory activity. Also, the most significant enzyme inhibitors are highlighted and structural moieties/core units responsible for remarkable inhibitory values are emphasized.

Synthesis of 1,3,4-oxadiazoles derivatives with antidepressant activity and their binding to the 5-HT1A receptor

In this study, two series of 1,3,4-oxadiazole derivatives were designed and synthesized using the forced swimming test (FST) model to test the antidepressant activity of the target compound in vivo. Five compounds with potential activity were selected from the FST model to test affinity with 5-HT_1A receptor in vitro. The results of the FST experiment showed that compound N-(3-((5-((4-chlorobenzyl)thio)-1,3,4-oxadiazol-2-yl)methoxy)phenyl)acetamide (10g) showed the best antidepressant activity (DID = 58.93, percentage decrease in immobility duration in FST), similar to the activity of positive drug fluoxetine. Compound 10g also exhibited the most potent binding affinity to 5-HT_1A receptors (K_i = 1.52 nM). The results of the in vivo 5-HT concentration estimation in mice showed that compound 10g may have an effect on the brain. The experimental results of exploratory activity in mice showed that compound 10g did not affect spontaneous activity in the open-field test model. Molecular docking was used to study the binding mode of compound 10g and the 5-HT_1A receptor. Compound 10g showed significant interactions with residues at the active site on the 5-HT_1A receptor. The physicochemical and pharmacokinetic properties of the target compounds were predicted using Discovery Studio 2019 and ChemBioDraw Ultra 14.

Compound 10g (R = –CH₂Ph (p-Cl)) showed the best antidepressant activity in vivo and in vitro.

Polymorphism of 3-(5-phenyl-1,3,4-oxadiazol-2-yl)- and 3-[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]-2H-chromen-2-ones

This study of 3-(5-phenyl-1,3,4-oxadiazol-2-yl)-2H-chromen-2-one, C₁₇H₁₀N₂O₃, 1, and 3-[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]-2H-chromen-2-one, C₁₆H₉N₃O₃, 2, was performed on the assumption of the potential anticancer activity of the compounds. Three polymorphic structures for 1 and two polymorphic structures for 2 have been studied thoroughly. The strongest intermolecular interaction is stacking of the `head-to-head' type in all the studied crystals. The polymorphic structures of 1 differ with respect to the intermolecular interactions between stacked columns. Two of the polymorphs have a columnar or double columnar type of crystal organization, while the third polymorphic structure can be classified as columnar-layered. The difference between the two structures of 2 is less pronounced. Both crystals can be considered as having very similar arrangements of neighbouring columns. The formation of polymorphic modifications is caused by a subtle balance of very weak intermolecular interactions and packing differences can be identified only using an analysis based on a study of the pairwise interaction energies.

Coumarin-containing hybrids and their anticancer activities

Cancer is the second leading cause of death worldwide, and it results in around 9 million deaths annually. The anticancer agents play an intriguing role in the treatment of cancers, while the severe anticancer scenario and the emergence of drug-resistant especially multidrug-resistant cancers create a huge demand for novel anticancer drugs with different mechanisms of action. The coumarin scaffold is ubiquitous in nature and is a highly privileged motif for the development of novel drugs due to its biodiversity and versatility. Coumarin derivatives can exert diverse antiproliferative mechanisms, and some of them such as Irosustat are under clinical trials for the treatment of various cancers, revealing their potential as putative anticancer drugs. Hybridization of coumarin moiety with other anticancer pharmacophores is a promising strategy to reduce side effects, overcome the drug resistance, and may provide valuable therapeutic intervention for the treatment of cancers. Thus, coumarin-containing hybrids occupy an important position in the development of novel anticancer agents. This review aims to summarize the recent advances made towards the development of coumarin-containing hybrids as potential anticancer agents, covering articles published between 2015 and 2019, and the structure-activity relationship together with mechanisms of action are also discussed.