Synthesis and antileishmanial activity of (1,3-benzothiazol-2-yl) amino-9-(10H)-acridinone derivatives

Benzothiazole derivatives in the design of antitumor agents

Benzothiazoles are a class of heterocycles with multiple applications as anticancer, antibiotic, antiviral, and anti-inflammatory agents. Benzothiazole is a privileged scaffold in drug discovery programs for modulating a variety of biological functions. This review focuses on the design and synthesis of new benzothiazole derivatives targeting hypoxic tumors. Cancer is a major health problem, being among the leading causes of death. Tumor-hypoxic areas promote proliferation, malignancy, and resistance to drug treatment, leading to the dysregulation of key signaling pathways that involve drug targets such as vascular endothelial growth factor, epidermal growth factor receptor, hepatocyte growth factor receptor, dual-specificity protein kinase, cyclin-dependent protein kinases, casein kinase 2, Rho-related coil formation protein kinase, tunica interna endothelial cell kinase, cyclooxygenase-2, adenosine kinase, lysophosphatidic acid acyltransferases, stearoyl-CoA desaturase, peroxisome proliferator-activated receptors, thioredoxin, heat shock proteins, and carbonic anhydrase IX/XII. In turn, they regulate angiogenesis, proliferation, differentiation, and cell survival, controlling the cell cycle, inflammation, the immune system, and metabolic alterations. A wide diversity of benzothiazoles were reported over the last years to interfere with various proteins involved in tumorigenesis and, more specifically, in hypoxic tumors. Many hypoxic targets are overexpressed as a result of the hypoxia-inducible factor activation cascade and may not be present in normal tissues, providing a potential strategy for selectively targeting hypoxic cancers.

Synthesis and Characterization of Zn(II) Complex of 4-chloro-2-(((2-phenoxyphenyl)imino)methyl)phenol and its Biological Efficacies: DNA Interaction, ADMET, DFT and Molecular Docking Study

Condensing 2-phenoxyaniline with 5-chlorosalicyldehyde under reflux conditions, a 4-chloro-2-(((2-phenoxyphenyl)imino)methyl)phenol Schiff base has been Synthesized. A zinc complex was synthesized by combining the ligand in a 1:1 molar ratio with zinc sulphateheptahydrate. Mass spectroscopy, NMR, infrared, and elemental analysis were used to characterize the ligand and zinc complex. By measuring the molar conductance, the non-electrolytic character of the complex was confirmed. The zinc ion is coordinated in a pentadentate manner, according to an IR and NMR investigation. Viscosity measurements, absorption and fluorescence spectroscopy were utilized to examine the complex's interaction with CT (calf thymus) DNA. Furthermore, the ligand and complex's ADMET characteristics were ascertained through the use of ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) study. Calculation of the different electronic parameters of the optimized structure through Density Functional Theory (DFT) indicated the stability of the Zn(II) complex. Molecular docking study reflected the future opportunity for the consideration of Zn(II) complex to fight against Alzheimer and Glaucoma diseases.

Novel 2-Aminobenzothiazole Derivatives: Docking, Synthesis, and Biological Evaluation as Anticancer Agents

Sixteen novel 2-aminobenzothiazole compounds with different amines or substituted piperazine moieties were designed, synthesized, and tested using various methods. Potential interactions were assessed by docking new compounds in the adenosine triphosphate (ATP) binding domain of the PI3Kγ enzyme (PDB code: 7JWE) by nucleophilic substitution or solvent-free/neat fusion for docked compound synthesis. Final 2-aminobenzothiazole compounds were characterized by direct probe gas chromatography-mass spectrometry (GC-MS), proton (1H-NMR), carbon-13 (13C-NMR), and attenuated total reflectance-infrared Fourier transform infrared (ATR FT-IR). The synthesized compounds were investigated for anticancer activities on lung cancer (A549) and breast cancer (MCF-7) cell lines. The compounds' PI3Kγ inhibition was evaluated at a 100 μM concentration. 4-Nitroaniline and piperazine-4-nitroaniline combination in OMS5 and OMS14 reduced lung and breast cancer cell line growth. IC50 values for OMS5 and OMS14, the strongest compounds, ranged from 22.13 to 61.03 μM. OMS1 and OMS2 inhibited PI3Kγ at the highest rates (47 and 48%, respectively) at a 100 μM concentration. Results show that the PI3Kγ enzyme suppression is not the main mechanism behind these OMS5 and OMS14 anticancer effects. CDK2, Akt, mTOR, and p42/44 MAPK are affected. EGF receptor suppression matters. AKT1, AKT3, CDK1/cyclin B, PDK1 direct, PIK3CA E542 K/PIK3R1 (p110 α/p85 α), PIK3CD/PIK3R1 (p110 δ/p85 α), and PKN inhibition were measured to evaluate the possible mechanism of compound OMS14. PIK3CD/PIK3R1 (p110 δ/p85 α) is the most, with 65% inhibition, suggesting a possible mechanism of anticancer properties. Furthermore, the NCI 60-cell line inhibition demonstrates promising broad anticancer inhibition against numerous cancer cell lines of OMS5 and OMS14, which could be good lead compounds for future development.

Recent advances in the synthesis of new benzothiazole based anti-tubercular compounds

This review highlights the recent synthetic developments of benzothiazole based anti-tubercular compounds and their in vitro and in vivo activity. The inhibitory concentrations of the newly synthesized molecules were compared with the standard reference drugs. The better inhibition potency was found in new benzothiazole derivatives against M. tuberculosis. Synthesis of benzothiazole derivatives was achieved through various synthetic pathways including diazo-coupling, Knoevenagel condensation, Biginelli reaction, molecular hybridization techniques, microwave irradiation, one-pot multicomponent reactions etc. Other than recent synthetic developments, mechanism of resistance of anti-TB drugs is also incorporated in this review. Structure activity relationships of the new benzothiazole derivatives along with the molecular docking studies of selected compounds have been discussed against the target DprE1 in search of a potent inhibitor with enhanced anti-tubercular activity.

Syntheses and evaluation of acridone derivatives as anticancer agents targeting Kras promoter i-motif structure

Two series of novel acridone derivatives were designed and synthesized, with their anticancer activity evaluated. Most of these compounds showed potent antiproliferative activity against cancer cell lines. Among them, compound C4 with dual 1,2,3-triazol moieties exhibited the most potent activity against Hep-G2 cells with IC₅₀ value determined to be 6.29 ± 0.93 μM. Subsequent experiments showed that C4 could bind to and destabilize Kras gene promoter i-motif structure without significant interaction with its corresponding G-quadruplex. C4 could down-regulate Kras expression in Hep-G2 cells, possibly due to its interaction with the Kras i-motif. Further cellular studies indicated that C4 could induce apoptosis of Hep-G2 cells, possibly related to its effect on mitochondrial dysfunction. These results indicated that C4 could be further developed as a promising anticancer agent.

Antibacterial Potential of Novel Acetamide Derivatives of 2-Mercaptobenzothiazole: Synthesis and Docking Studies

2-Mercaptobenzothiazole and its derivatives are widely known for their diverse biological activities, particularly antimicrobial and anticancer potential. In the present study, a series of new hybrid compounds consisting of 2-mercaptobenzothiazole and different aryl amines 2(a-j) were synthesized and characterized by Fourier transform infrared (FTIR), ¹H NMR, and ¹³C NMR spectral data. The synthesized compounds were screened for in vitro antibacterial activities through agar well diffusion assay. Among the series, 2b, 2c, and 2i exhibited significant antibacterial activity comparable to the standard drug levofloxacin. Based on their antibacterial potential, these compounds were further tested for their antibiofilm activity. All of the three compounds showed promising antibiofilm potential, even better than the standard drug cefadroxil at 100 μg/100 μL concentration. Molecular docking studies were performed to explore the antibacterial mechanism of these compounds. Strikingly, the molecule 2i shared the same hydrophobic pockets as those of levofloxacin in case of bacterial kinases and DNA gyrases. In addition, 2i exhibited satisfactory antibiofilm activity in comparison to the standard. Our study therefore suggested that the synthetic compound 2i possesses remarkable antibacterial activity and may serve as a lead molecule for the discovery of potent antibacterial agents.

Anti-amoebic effects of synthetic acridine-9(10H)-one against brain-eating amoebae

Pathogenic A. castellanii and N. fowleri are opportunistic free-living amoebae. Acanthamoeba spp. are the causative agents of granulomatous amebic encephalitis (GAE) and amebic keratitis (AK), whereas Naegleria fowleri causes a very rare but severe brain infection called primary amebic meningoencephalitis (PAM). Acridinone is an important heterocyclic scaffold and both synthetic and naturally occurring derivatives have shown various valuable biological properties. In the present study, ten synthetic Acridinone derivatives (I-X) were synthesized and assessed against both amoebae for anti-amoebic and cysticidal activities in vitro. In addition, excystation, encystation, cytotoxicity, host cell pathogenicity was also performed in-vitro. Furthermore, molecular docking studies of these compounds with three cathepsin B paralogous enzymes of N. fowleri were performed in order to predict the possible docking mode with pathogen. Compound VII showed potent anti-amoebic activity against A. castellanii with IC₅₀ 53.46 µg/mL, while compound IX showed strong activity against N. fowleri in vitro with IC₅₀ 72.41 µg/mL. Compounds II and VII showed a significant inhibition of phenotypic alteration of A. castellanii, while compound VIII significantly inhibited N. fowleri cysts. Cytotoxicity assessment showed that these compounds caused minimum damage to human keratinocyte cells (HaCaT cells) at 100 µg/mL, while also effectively reduced the cytopathogenicity of Acanthamoeba to HaCaT cells. Moreover, Cathepsin B protease was investigated in-silico as a new molecular therapeutic target for these compounds. All compounds showed potential interactions with the catalytic residues. These results showed that acridine-9(10H)-one derivatives, in particular compounds II, VII, VIII and IX hold promise in the development of therapeutic agents against these free-living amoebae.

Control of selectivity in the preparation of 2-substituted benzoazoles by adjusting the surface hydrophobicity in two solid-based sulfonic acid catalysts

A series of metal-free tandem reactions for the synthesis of pharmaceutically important 2-substituted benzoazoles from isothiocyanates and 2-aminothiophenol under catalyst-free conditions in the presence of Et-PMO-Me-PrSO₃H (1a) and SBA-15-PrSO₃H (1b) as solid acids were carried out in a highly selective way under solvent free conditions. A significant selectivity changeover toward either 2-mercaptobenzoxazole or 2-aminobenzoazole derivatives could be achieved by changing the employed catalyst from the relatively hydrophobic material 1a to the more hydrophilic catalyst 1b. This simple experimental procedure with a novel selective approach toward benzoazoles accompanied by green and reusable catalysts could be considered as an alternative to the existing methods for the synthesis of 2-substituted benzoazole derivatives.

First-in-class pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones against leishmaniasis and tuberculosis: Rationale, in vitro, ex vivo studies and mechanistic insights

Pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones were synthesized, for the first time, from indole chalcones and 6-aminouracil, and their ability to inhibit leishmaniasis and tuberculosis (Tb) infections was evaluated. The in vitro antileishmanial activity against promastigotes of Leishmania donovani revealed exceptional activities of compounds 3, 12 and 13, with IC₅₀ values ranging from 10.23 ± 1.50 to 15.58 ± 1.67 µg/ml, which is better than the IC₅₀ value of the standard drug pentostam of 500 μg/ml. The selectivity of the compounds towards Leishmania parasites was evaluated via ex vivo studies in Swiss albino mice. The efficiency of these compounds against Tb infection was then evaluated using the in vitro anti-Tb microplate Alamar Blue assay. Five compounds, 3, 7, 8, 9 and 12, showed MIC₁₀₀ values against the Mycobacterium tuberculosis H₃₇ Rv strain at 25 µg/ml, and compound 20 yielded an MIC₁₀₀ value of 50 µg/ml. Molecular modelling of these compounds highlighted interactions with binding sites of dihydrofolate reductase, pteridine reductase and thymidylate kinase, thus establishing the rationale of their pharmacological activity against both pathogens, which is consistent with the in vitro results. From the above results, it is clear that compounds 3 and 12 are promising lead candidates for Leishmania and Mycobacterium infections and may be promising for coinfections.

Evolution of Acridines and Xanthenes as a Core Structure for the Development of Antileishmanial Agents

Nowadays, leishmaniasis constitutes a public health issue in more than 88 countries, affecting mainly people from the tropics, subtropics, and the Mediterranean area. Every year, the prevalence of this infectious disease increases, with the appearance of 1.5–2 million new cases of cutaneous leishmaniasis and 500,000 cases of visceral leishmaniasis, endangering approximately 350 million people worldwide. Therefore, the absence of a vaccine or effective treatment makes the discovery and development of new antileishmanial therapies one of the focuses for the scientific community that, in association with WHO, hopes to eradicate this disease shortly. This paper is intended to highlight the relevance of nitrogen- and oxygen-containing tricyclic heterocycles, particularly acridine and xanthene derivatives, for the development of treatments against leishmaniasis. Thus, in this review, a thorough compilation of the most promising antileishmanial acridine and xanthene derivatives is performed from both natural and synthetic origins. Additionally, some structure–activity relationship studies are also depicted and discussed to provide insight into the optimal structural features responsible for these compounds’ antileishmanial activity.

Synthesis of acridinones via palladium-catalyzed reductive annulation of 2-nitrobenzaldehydes and resorcinols

Through a palladium-catalyzed reductive annulation reaction of resorcinols and 2-nitrobenzaldehydes, reported is a new synthesis of acridinones with the features of operational simplicity, broad substrate scope, and readily available feedstocks.

Access to acridones by tandem copper(I)-catalyzed electrophilic amination/Ag(I)-mediated oxidative annulation of anthranils with arylboronic acids

An efficient and practical approach for the synthesis of medicinally important acridones was developed from anthranils and commercially available arylboronic acids by a tandem copper(I)-catalyzed electrophilic amination/Ag(I)-mediated oxidative annulation strategy. This new and straightforward protocol displayed a broad substrate scope (25 examples) and high functional group tolerance. What's more, a possible mechanistic proposal was also presented.

In vitro anti-Leishmania activity and molecular docking of spiro-acridine compounds as potential multitarget agents against Leishmania infantum

Leishmaniasis is an infectious disease with several limitations regarding treatment schemes. This work reports the anti-Leishmania activity of spiroacridine compounds against the promastigote (IC₅₀ = 1.1 to 6.0 µg / mL) and amastigote forms of the best compounds (EC₅₀ = 4.9 and 0.9 µg / mL) inLeishmania (L.) infantumand proposes an in-silico study with possible selective therapeutic targets for L. infantum. The substituted dimethyl-amine compound (AMTAC 11) showed the best leishmanicidal activity in vitro, and was found to interact with TryRandLdTopoI. comparisons with standard inhibitors were performed, and its main interactions were elucidated. Based on the biological assessment and the structure-activity relationship study, the spiroacridine compounds appear to be promisinganti-leishmaniachemotherapeutic agents to be explored.

Benzothiazole derivatives as anticancer agents

Benzothiazole (BTA) belongs to the heterocyclic class of bicyclic compounds. BTA derivatives possesses broad spectrum biological activities such as anticancer, antioxidant, anti-inflammatory, anti-tumour, antiviral, antibacterial, anti-proliferative, anti-diabetic, anti-convulsant, analgesic, anti-tubercular, antimalarial, anti-leishmanial, anti-histaminic and anti-fungal among others. The BTA scaffolds showed a crucial role in the inhibition of the metalloenzyme carbonic anhydrase (CA). In this review an extensive literature survey over the last decade discloses the role of BTA derivatives mainly as anticancer agents. Such compounds are effective against various types of cancer cell lines through a multitude of mechanisms, some of which are poorly studied or understood. The inhibition of tumour associated CAs by BTA derivatives is on the other hand better investigated and such compounds may serve as anticancer leads for the development of agents effective against hypoxic tumours.

In silico ADME predictions and in vitro antibacterial evaluation of 2-hydroxy benzothiazole-based 1,3,4-oxadiazole derivatives

In the present work, a library of fifteen 2-hydroxy benzothiazole-linked 1,3,4 -oxadiazole derivatives have been synthesized and confirmed using different analytical techniques. All of the synthesized compounds have been tested for antibacterial and in silico pharmacokinetic studies for the first time. From the ADME predictions, compound 4 showed the highest in silico absorption percentage (86.77%), while most of the compounds showed more than 70% absorption. All of the compounds comply with the Lipinski rule of 5, suggesting that the compounds possess good drug likeness properties upon administration. Furthermore, all of the compounds follow the Veber rule, indicating good bioavailability and good intestinal absorption. The antibacterial results exhibited excellent to moderate activity. Compounds 5 , 9 , 12 , 14 , 15 , 16 , and 17 were the most active compounds against the tested bacterial strains. Compound 14 showed comparable MIC 6.25 ±0.2 μg/disc to the standard drug amoxicillin against the tested Gram-positive bacterial strains. Compounds 5 , 14 , 17 exhibited MIC 12.5 ±0.8 μg/disc, which was comparable to the standard drug against E. faecalis . It can be concluded that the synthesized compound could be used as a lead molecule in the development of new antibacterial agents with high efficacy.

Structural Activity Relationship and Importance of Benzothiazole Derivatives in Medicinal Chemistry: A Comprehensive Review

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Benzothiazole (1, 3-benzothiazole) is one of the heterocyclic compounds, which is a weak base having varied biological activities. The unique methine center present in the thiazole ring makes benzothiazole as the most important heterocyclic compound. It is a common and integral structure of many natural and synthetic bioactive molecules. Benzothiazole derivatives show a variety of activities, with less toxic effects and their derivatives showed enhanced activities, which has proven Benzothiazole scaffold as one of the important moieties in medicinal chemistry. Benzothiazole ring containing compounds possess various pharmacological activities such as anti-viral, anti-microbial, antiallergic, anti-diabetic, anti-tumor, anti-inflammatory, anthelmitic and anti-cancer, which makes benzothiazole a rapidly developing and interesting compound in the medicinal chemistry. This review briefly explains the importance, common methods of synthesis of the benzothiazole scaffold and also explains the popular benzothiazole molecules which have applications in various fields of chemistry. A review has been carried out based on various pharmacological activities containing benzothiazole moieties and rationalize the activities based on the structural variations. Literature on benzothiazole derivatives reveals that substitution on the C-2 carbon atom and C-6 are the reasons for a variety of biological activities.

Crystal structure, Hirshfeld surface analysis and inter-action energy and DFT studies of 1-(1,3-benzo-thia-zol-2-yl)-3-(2-hy-droxy-eth-yl)imidazolidin-2-one

In the title mol-ecule, C12H13N3O2S, the benzo-thia-zine moiety is slightly non-planar, with the imidazolidine portion twisted only a few degrees out of the mean plane of the former. In the crystal, a layer structure parallel to the bc plane is formed by a combination of O-HHydethy⋯NThz hydrogen bonds and weak C-HImdz⋯OImdz and C-HBnz⋯OImdz (Hydethy = hy-droxy-ethyl, Thz = thia-zole, Imdz = imidazolidine and Bnz = benzene) inter-actions, together with C-HImdz⋯π(ring) and head-to-tail slipped π-stacking [centroid-to-centroid distances = 3.6507 (7) and 3.6866 (7) Å] inter-actions between thia-zole rings. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (47.0%), H⋯O/O⋯H (16.9%), H⋯C/C⋯H (8.0%) and H⋯S/S⋯H (7.6%) inter-actions. Hydrogen bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing. Computational chemistry indicates that in the crystal, C-H⋯N and C-H⋯O hydrogen-bond energies are 68.5 (for O-HHydethy⋯NThz), 60.1 (for C-HBnz⋯OImdz) and 41.8 kJ mol-1 (for C-HImdz⋯OImdz). Density functional theory (DFT) optimized structures at the B3LYP/6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state.

A Fluorinated Phenylbenzothiazole Arrests the Trypanosoma cruzi Cell Cycle and Diminishes the Infection of Mammalian Host Cells

Chagas disease (CD) is a human infection caused by Trypanosoma cruzi CD was traditionally endemic to the Americas; however, due to migration it has spread to countries where it is not endemic. The current chemotherapy to treat CD induces several side effects, and its effectiveness in the chronic phase of the disease is controversial. In this contribution, substituted phenylbenzothiazole derivatives were synthesized and biologically evaluated as trypanocidal agents against Trypanosoma cruzi The trypanocidal activities of the most promising compounds were determined through systematic in vitro screening, and their modes of action were determined as well. The physicochemical-structural characteristics responsible for the trypanocidal effects were identified, and their possible therapeutic application in Chagas disease is discussed. Our results show that the fluorinated compound 2-methoxy-4-[5-(trifluoromethyl)-1,3-benzothiazol-2-yl] phenol (BT10) has the ability to inhibit the proliferation of epimastigotes [IC_50(Epi) = 23.1 ± 1.75 μM] and intracellular forms of trypomastigotes [IC_50(Tryp) = 8.5 ± 2.9 μM] and diminishes the infection index by more than 80%. In addition, BT10 has the ability to selectively fragment 68% of the kinetoplastid DNA compared with 5% of nucleus DNA. The mode of action for BT10 on T. cruzi suggests that the development of fluorinated phenylbenzothiazole with electron-withdrawing substituent is a promising strategy for the design of trypanocidal drugs.

Benzothiazole analogs as potential anti-TB agents: computational input and molecular dynamics

Biotin is very important for the survival of Mycobacterium tuberculosis. 7,8-Diamino pelargonic acid aminotransaminase (DAPA) is a transaminase enzyme involved in the biosynthesis of biotin. The benzothiazole title compounds were investigated for their in vitro anti-tubercular activity against two tubercular strains: H37Rv (ATCC 25,177) and MDR-MTB (multidrug-resistant M. tuberculosis, resistant to isoniazid, rifampicin, and ethambutol) by an agar incorporation method. The possible binding mode and predicted affinity were computed using a molecular docking study. Among the synthesized compounds in the series, the title compound {2-(benzo[d]thiazol-2-yl-methoxy)-5-fluorophenyl}-(4-chlorophenyl)-methanone was found to exhibit significant activity with minimum inhibitory concentrations of 1 μg/mL and 2 μg/mL against H37Rv and MDR-MTB, respectively; this compound showed the highest binding affinity (-24.75 kcal/mol) as well.

Acridone suppresses the proliferation of human breast cancer cells in vitro via ATP-binding cassette subfamily G member 2

In the past decades, the tricyclic acridone ring system has become a focus of major research by medicinal chemists due to the biological significance of this moiety in drug design and discovery. Acridone has substantial bio-potential since it performs crucial functions, including antibacterial, antimalarial, antiviral and anti-neoplastic activities. However, the anticancer effect and the underlying mechanisms of acridone on breast cancer cells remains unclear. In the present study, the anti-tumor function and the underlying mechanisms of acridone were evaluated in vitro. Firstly, an MTT assay was used to evaluate the inhibitory effect of acridone. Subsequently, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to investigate whether ATP binding cassette subfamily G member 2 (ABCG2) was associated with the function of acridone. Finally, western blotting was used to confirm the results of RT-qPCR. The present study demonstrated that acridone may decrease the proliferation of MDA-MB-231 cells dose-dependently. Further experiments revealed that acridone may downregulate the mRNA and protein expression levels of ABCG2, supporting the potential application of acridone in breast cancer treatment. These findings suggested that acridone is a potential agent in the treatment of human breast cancer.

Ethyl 2-[9-(5-bromo-2-hydroxyphenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8,9,10-decahydroacridin-10-yl]acetate

In the title compound, C27H32BrNO5, the central 1,4-dihydropyridine ring adopts a shallow sofa conformation (with the C atom bearing the bromophenol ring as the flap), whereas the pendant cyclohexene rings both have twisted-boat conformations. The molecule features an intramolecular O—H...O hydrogen bond, which closes anS(8) ring. In the crystal, molecules are linked by C—H...O interactions, formingC(12) chains along thec-axis direction. The ethyl acetate grouping is disordered over two sets of sites in a 0.719 (11):0.281 (11) ratio.

One-Pot Synthesis and Evaluation of Antileishmanial Activities of Functionalized S-Alkyl/Aryl Benzothiazole-2-carbothioate Scaffold

The synthesis of hitherto unreported S-alkyl/aryl benzothiazole-2-carbothioate is reported from thiols, oxalyl chloride, and 2-aminothiophenols using 10 mol % n-tetrabutylammonium iodide (TBAI) as catalyst in acetonitrile through multicomponent reaction (MCR) strategy. The present protocol favored formation of benzothiazoles and thioesters via simultaneous formation of C-N and C-S bonds in good yields with a wide range of substrates. A few of the synthesized derivatives were evaluated for their antimicrobial activity against the protozoan parasite Leishmania donovani, a causative agent of visceral leishmaniasis (VL). Further, these compounds displayed no toxicity toward macrophage RAW 264.7 cells and are therefore nontoxic and effective antileishmanial leads. In silico docking studies were performed to understand the possible binding site interaction with trypanothione reductase (TryR).

Study on molecular structure, spectroscopic behavior, NBO, and NLO analysis of 3-methylbezothiazole-2-thione

Experimentally observed spectral data (FT-TR and FT-Raman) of 3-methylbezothiazole-2-thione (3MBT2T) were compared with the spectral data obtained by DFT/B3LYP method using 6-311++G(d,p) basis set. UV-Vis spectrum of the title compound was recorded and the electronic properties, such as frontier molecular orbitals and band gap energies were calculated by TD-DFT approach. The molecular properties like dipole moment, polarizability, first static hyperpolarizability, molecular electrostatic potential surface (MEPs), and contour map were calculated to get a better comprehension of the properties of the title molecule. Natural bond orbital (NBO) analysis was applied to investigate the stability of the molecule arising from charge delocalization. Global and local reactivity descriptors were also computed to predict reactivity and reactive sites on the molecule.

Asymmetric synthesis of amino-benzothiazol derivatives by additions of 2-lithiated benzothiazoles to (S)-N-t-butylsulfinyl-ketimines

We reported the asymmetric Mannich reactions between lithium-benzothiazoles and (S)-N-tert-butanesulfinylketimines, which gave unknown type of amino-benzothiazol derivatives of high pharmaceutical potential with up to 96% yields and 99 : 1 diastereoselectivities.

Design, facile synthesis and anthelmintic activity of new O-substituted 6-methoxybenzothiazole-2-carbamates

Hypothesis for designing 6-substituted benzothiazolecarbamate prototype anthelmintics having diversities in flexibility and rigidity of substituents with different polar nature and hydrophilic–lipophilic properties.

Antileishmanial drug discovery: comprehensive review of the last 10 years

This review covers the current aspects of leishmaniasis including marketed drugs, new antileishmanial agents, and possible drug targets of antileishmanial agents.

A comprehensive review in current developments of benzothiazole-based molecules in medicinal chemistry

Benzothiazole (BTA) and its derivatives are the most important heterocyclic compounds, which are common and integral feature of a variety of natural products and pharmaceutical agents. BTA shows a variety of pharmacological properties, and its analogs offer a high degree of structural diversity that has proven useful for the search of new therapeutic agents. The broad spectrum of pharmacological activity in individual BTA derivative indicates that, this series of compounds is of an undoubted interest. The related research and developments in BTA-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous BTA-based compounds as clinical drugs have been extensively used in practice to treat various types of diseases with high therapeutic potency. This work systematically gives a comprehensive review in current developments of BTA-based compounds in the whole range of medicinal chemistry as anticancer, antibacterial, antifungal, antiinflammatory, analgesic, anti-HIV, antioxidant, anticonvulsant, antitubercular, antidiabetic, antileishmanial, antihistaminic, antimalarial and other medicinal agents. It is believed that, this review article is helpful for new thoughts in the quest for rational designs of more active and less toxic BTA-based drugs, as well as more effective diagnostic agents and pathologic probes.

Quantum chemical exploration of the intramolecular hydrogen bond interaction in 2-thiazol-2-yl-phenol and 2-benzothiazol-2-yl-phenol in the context of excited-state intramolecular proton transfer: a focus on the covalency in hydrogen bond

The present work demonstrates a computational exploration of the intramolecular H-bond (IMHB) interaction in two model heterocyclic compounds - 2-thiazol-2-yl-phenol (2T2YP) and 2-benzothiazol-2-yl-phenol (2B2YP) by meticulous application of various quantum chemical tools. Major emphasis is rendered on the analysis of IMHB interaction by calculation of electron density ρ(r) and Laplacian ∇(2)ρ(r) at the bond critical point using the Atoms-In-Molecule methodology. Topological features based on ρ(r) suggest that at equilibrium geometry the IMHB interaction develops certain characteristics typical of a covalent interaction. The interplay between aromaticity and Resonance-Assisted H-Bond (RAHB) has also been discussed using both geometrical and magnetic criteria. The occurrence of IMHB interaction in 2T2YP and 2B2YP has also been criticized under the provision of the Natural Bond Orbital (NBO) analysis. The ESIPT phenomenon in the molecular systems is also critically addressed on the lexicon of potential energy surface (PES) analysis.

In vitro DNA binding, pBR322 plasmid cleavage and molecular modeling study of chiral benzothiazole Schiff-base-valine Cu(II) and Zn(II) complexes to evaluate their enantiomeric biological disposition for molecular target DNA

Bicyclic heterocyclic compounds viz. benzothiazoles are key components of deoxyribonucleic acid (DNA) molecules and participate directly in the encoding of genetic information. Benzothiazoles, therefore, represent a potent and selective class of antitumor compounds. The design and synthesis of chiral antitumor chemotherapeutic agents of Cu(II) and Zn(II), L- and -D benzothiazole Schiff base-valine complexes 1a &b and 2a &b, respectively were carried out and thoroughly characterized by spectroscopic and analytical techniques. Interaction of 1a and b and 2a and b with CT DNA by employing UV-vis, florescence, circular dichroic methods and cleavage studies of 1a with pBR322 plasmid, molecular docking were done in order to demonstrate their enantiomeric disposition toward the molecular drug target DNA. Interestingly, these studies unambiguously demonstrated the greater potency of L-enantiomer in comparison to D-enantiomer.