Antimicrobial Synergistic Effects of Linezolid and Vancomycin with a Small Synthesized 2-Mercaptobenzothiazole Derivative: A Challenge for MRSA Solving

Methicillin-resistant Staphylococcus aureus (MRSA) emerged as one of the leading causes of persistent human infections and makes it difficult to treat bacteremia, especially with biofilm formation. In this work, we investigated the in vitro synergism between Linezolid (LNZ) and Vancomycin (VAN) with a 2-mercaptobenzothiazole derivative, resulting in a new small-molecule antibacterial compound that we named BTZ2e, on several clinical MRSA, MRSE (methicillin-resistant Staphylococcus epidermidis) and control (ATCC Collection) strains in their planktonic and biofilms cultures. The broth microdilution method evaluated the susceptibility of planktonic cells to each investigated antibiotic combined with BTZ2e. The biofilm's metabolic activity was studied with the XTT reduction assay. As a result, in this study, biofilm formation was significantly suppressed by the BTZ2e treatment. In terms of minimal biofilm inhibitory concentration (MBIC), BTZ2e revealed an MBIC50 value of 32 μg/mL against methicillin-susceptible S. aureus (MSSA) and 16 μg/mL against methicillin-resistant S. aureus ATCC 43300 biofilms. An inhibition range of 32 μg/mL and 256 μg/mL was registered for the clinical isolates. Interestingly, a synergistic effect (FICI ≤ 0.5) was encountered for the combination of BTZ2e with LNZ and VAN on several planktonic and sessile strains. In particular, the best result against planktonic cells emerged as a result of the synergistic association between LNZ and BTZ2e, while against sessile cells, the best synergistic association resulted from VAN and BTZ2e. The consistent results indicate BTZ2e as a promising adjuvant against multi-resistant strains such as MRSA and MRSE.

Characterization of a Bacillus subtilis S-16 Thiazole-Synthesis-Related Gene thiS Knockout and Antimicrobial Activity Analysis

Bacillus subtilis S-16 isolated from sunflower-rhizosphere soil is an effective biocontrol agent for preventing soilborne diseases in plants. Previous research revealed that the volatile organic compounds (VOCs) produced by the S-16 strain have strong inhibitory effects on Sclerotinia sclerotiorum. The identification of the VOCs of S-16 using gas chromatography-tandem mass spectrometry (GC-MS/MS) revealed 35 compounds. Technical-grade formulations of four of these compounds were chosen for further study: 2-pentadecanone, 6,10,14-trimethyl-2-octanone, 2-methyl benzothiazole (2-MBTH), and heptadecane. The major constituent, 2-MBTH, plays an important role in the antifungal activity of the VOCs of S-16 against the growth of Sclerotinia sclerotiorum. The purpose of this study was to determine the impact of the thiS gene's deletion on the 2-MBTH production and to conduct an antimicrobial activity analysis of the Bacillus subtilis S-16. The thiazole-biosynthesis gene was deleted via homologous recombination, after which the contents of 2-MBTH in the wild-type and mutant S-16 strains were analyzed using GC-MS. The antifungal effects of the VOCs were determined using a dual-culture technique. The morphological characteristics of the Sclerotinia sclerotiorum mycelia were examined via scanning-electron microscopy (SEM). Additionally, the lesion areas on the sunflower leaves with and without treatment with the VOCs from the wild-type and mutant strains were measured to explore the effects of the VOCs on the virulence of the Sclerotinia sclerotiorum. Moreover, the effects of the VOCs on the sclerotial production were assessed. We showed that the mutant strain produced less 2-MBTH. The ability of the VOCs produced by the mutant strain to inhibit the growth of the mycelia was also reduced. The SEM observation showed that the VOCs released by the mutant strain also caused more flaccid and gapped hyphae in the Sclerotinia sclerotiorum. The Sclerotinia sclerotiorum treated by the VOCs produced by the mutant strains caused more damage to the leaves than that treated by the VOCs produced by the wild type and the mutant-strain-produced VOCs inhibited sclerotia formation less. The production of 2-MBTH and its antimicrobial activities were adversely affected to varying degrees by the deletion of thiS.

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.

Network Analysis Guided Designing of Multi-Targeted Anti-Fungal Agents: Synthesis and Biological Evaluation

During the ongoing pandemic, there have been increasing reports of invasive fungal disease (IFD), particularly among immunocompromised populations. Candida albicans is one of the most common clinical pathogenic microorganisms which have become a serious health threat to population either infected with Covid-19 or on treatment with immunosuppressant's/broad-range antibiotics. Currently, benzothiazole is a well explored scaffold for anti-fungal activity, especially mercapto substituted benzothiazoles. It is reported that exploring the 2nd position of benzothiazoles yield improved anti-fungal molecules. Therefore, in the current study, lead optimization approach using bioisosteric replacement protocol was followed to improve the anti-fungal activity of an already reported benzothiazole derivative, N-(1,3-benzothiazole-2-yl)-2-(pyridine-3-ylformohydrazido) acetamide. To rationally identify the putative anti-candida targets of this derivative, network analysis was carried out. Complexes of designed compounds and identified putative targets were further analyzed for the docking interactions and their consequent retention after the completion of exhaustive MD simulations. Top seven designed compounds were synthesized and evaluated for in-vitro anti-fungal property against Candida, which indicated that compounds 1.2c and 1.2f possess improved and comparable anti-fungal activity to N-(1,3-benzothiazole-2-yl)-2-(pyridine-3-ylformohydrazido) acetamide and Nystatin, respectively.

Metal-Free Temperature-Controlled Intermolecular [3 + 2] Annulation to Access Benzo[d]thiazole-2(3H)-thiones and Benzo[d]thiazol-2(3H)-ones

A facile access to benzo[d]thiazole-2(3H)-thiones and benzo[d]thiazol-2(3H)-ones has been developed through a temperature-controlled intermolecular [3 + 2] annulation of N,N-disubstituted arylhydrazines with CS₂ in the presence of DMSO. This protocol can obviate the prefunctionalization of the starting materials. This direct C-S/C-N bond formation reaction was performed in the absence of any external catalysts, transition metals, bases, ligands, and oxidants with high step economy.

New Heterocyclic Combretastatin A-4 Analogs: Synthesis and Biological Activity of Styryl-2(3H)-benzothiazolones

Here, we describe the synthesis, characterization, and biological activities of a series of 26 new styryl-2(3H)-benzothiazolone analogs of combretastatin-A4 (CA-4). The cytotoxic activities of these compounds were tested in several cell lines (EA.hy926, A549, BEAS-2B, MDA-MB-231, HT-29, MCF-7, and MCF-10A), and the relations between structure and cytotoxicity are discussed. From the series, compound (Z)-3-methyl-6-(3,4,5-trimethoxystyryl)-2(3H)-benzothiazolone (26Z) exhibits the most potent cytotoxic activity (IC50 0.13 ± 0.01 µM) against EA.hy926 cells. 26Z not only inhibits vasculogenesis but also disrupts pre-existing vasculature. 26Z is a microtubule-modulating agent and inhibits a spectrum of angiogenic events in EA.hy926 cells by interfering with endothelial cell invasion, migration, and proliferation. 26Z also shows anti-proliferative activity in CA-4 resistant cells with the following IC50 values: HT-29 (0.008 ± 0.001 µM), MDA-MB-231 (1.35 ± 0.42 µM), and MCF-7 (2.42 ± 0.48 µM). Cell-cycle phase-specific experiments show that 26Z treatment results in G2/M arrest and mitotic spindle multipolarity, suggesting that drug-induced centrosome amplification could promote cell death. Some 26Z-treated adherent cells undergo aberrant cytokinesis, resulting in aneuploidy that perhaps contributes to drug-induced cell death. These data indicate that spindle multipolarity induction by 26Z has an exciting chemotherapeutic potential that merits further investigation.

Heteroaryl-Ethylenes as New Lead Compounds in the Fight against High Priority Bacterial Strains

The widespread use of antibiotics has led to a gradual increase in drug-resistant bacterial infections, which severely weakens the clinical efficacy of antibacterial therapies. In recent decades, stilbenes aroused great interest because of their high bioavailability, as well as their manifold biological activity. Our research efforts are focused on synthetic heteroaromatic stilbene derivatives as they represent a potentially new type of antibiotic with a wide antibacterial spectrum. Herein, a preliminary molecular modeling study and a versatile synthetic scheme allowed us to define eight heteroaromatic stilbene derivatives with potential antimicrobial activity. In order to evaluate our compound’s activity spectrum and antibacterial ability, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests have been performed on Gram-positive and Gram-negative ATCC strains. Compounds PB4, PB5, PB7, and PB8 showed the best values in terms of MIC and were also evaluated for MBC, which was found to be greater than MIC, confirming a bacteriostatic activity. For all compounds, we evaluated toxicity on colon-rectal adenocarcinoma cells tumor cells (CaCo2), once it was established that the whole selected set was more active than 5-Fluorouracil in reducing CaCo-2 cells viability. To the best of our knowledge, the biological assays have shown for these derivatives an excellent bacteriostatic activity, compared to similar molecular structures previously reported, thus paving the way for a new class of antibiotic compounds.

The Efficiency of Biocidal Silica Nanosystems for the Conservation of Stone Monuments: Comparative In Vitro Tests against Epilithic Green Algae

In the last decade, worldwide research has focused on innovative natural biocides and the development of organic and inorganic nanomaterials for long-lasting reliability. In this work, the biocide effects of two different biocides encapsulated in two different silica nanosystems for a multifunctional coating have been performed through in vitro tests, by using Chlorococcum sp. as a common stone biodeteriogen. Zosteric sodium salt (ZS), a green biocide, was compared with the commercial biocide, 2-mercaptobenzothiazole (MBT), widely used in the treatment of cultural heritage. The analyzed systems are the following: silica nanocapsules (NC) and silica nanoparticles (MNP) not loaded with biocides, two nanosystems loaded with ZS and MBT, and free biocides. The qualitative and quantitative evaluations of biocide efficiency were performed periodically, analyzing pigment autofluorescence to discriminate between active and inactive/dead cells. The analyses showed multiple differences. All the nanocontainers presented an initial reduction in chlorophyll’s autofluorescence. For the free biocide, the results highlighted higher efficiency for MBT than ZS. Finally, the nanosystems loaded with the different biocides highlighted a higher activity for nanocontainers loaded with the commercial biocide than the green product, and better efficiency for MNP in comparison with NC.

Advancement in Pharmacological Activities of Benzothiazole and its Derivatives: An Up to Date Review

Benzothiazole is a heterocyclic aromatic and bicyclic compound in which, benzene ring is attached with thiazole ring. This nucleus is established in marine as well as terrestrial natural compounds. The benzothiazole skeleton is established in a broad variety of bioactive heterocycles and natural products. The benzothiazole nucleus is considered as the principle moiety in several biologically active compounds. Over the decade, chemists are paying more attention towards the revision of the biological and therapeutic activities such as antimicrobial, analgesic, antiinflammatory, antitubercular, antiviral and antioxidant of benzothiazole containing compounds. The molecular structures of a number of potent drugs including Frentizole, Pramipexole, Thioflavin T and Riluzole etc., are based on benzothiazole skeleton. The present work is the compilation and presentation of all available information in a systematic manner with an aim to present the findings in a way, which may be beneficial for future research.

Selective C-H chalcogenation of thiazoles via thiazol-2-yl-phosphonium salts

Thiazoles and benzothiazoles undergo regioselective C2-H chalcogenation via the sequence of thiazole C2-functionalization with phosphines to produce phosphonium salts which in turn react with S- and Se-centered nucleophiles to give products of C2-H chalcogenation and allow for recovery of the starting phosphine. The atom economical sequence proceeds under mild conditions and features broad scope for both the nucleophiles (electron-rich, electron-poor, sterically hindered thiols) and the various substituted benzothiazoles. The access to the substituted medicinally relevant C2-thio benzothiazoles also enables stereoselectivity improvements in the modified Julia olefinations.

Thiazoles, Their Benzofused Systems, and Thiazolidinone Derivatives: Versatile and Promising Tools to Combat Antibiotic Resistance

Thiazoles, their benzofused systems, and thiazolidinone derivatives are widely recognized as nuclei of great value for obtaining molecules with various biological activities, including analgesic, anti-inflammatory, anti-HIV, antidiabetic, antitumor, and antimicrobial. In particular, in the past decade, many compounds bearing these heterocycles have been studied for their promising antibacterial properties due to their action on different microbial targets. Here we assess the recent development of this class of compounds to address mechanisms underlying antibiotic resistance at both bacterial-cell and community levels (biofilms). We also explore the SAR and the prospective clinical application of thiazole and its benzofused derivatives, which act as inhibitors of mechanisms underlying antibiotic resistance in the treatment of severe drug-resistant infections. In addition, we examined all bacterial targets involved in their antimicrobial activity reporting, when described, their spontaneous frequencies of resistance.

Effect of Methyl-β-Cyclodextrin on the antimicrobial activity of a new series of poorly water-soluble benzothiazoles

The antibacterial activity of the S-unsubstituted- and S-benzyl-substituted-2-mercapto-benzothiazoles 1-4 has been evaluated after complexation with Methyl-β-Cyclodextrin (Me-β-CD) or incorporation in solid dispersions based on Pluronic® F-127 and compared with that of the pure compounds. This with the aim to gain further insights on the possible mechanism(s) involved in the CD-mediated enhancement of antimicrobial effectiveness, a promising methodology to overcome the microbial resistance issue. Together with Differential Scanning Calorimetry, FT-IR spectroscopy and X-ray Powder Diffraction investigations, a molecular modeling study focused on compounds 2 and 4 showed that the S-unsubstituted compound 2/Me-β-CD complex should be more stable than S-benzyl-substituted 4/Me-β-CD. Only for 1/Me-β-CD or, particularly, 2/Me-β-CD complexes, the antibacterial effectiveness was enhanced in the presence of selected bacterial strains. The results herein presented support the mechanisms focusing on the interactions of the bacterial membrane with CD complexes more than those focusing on the improvement of dissolution properties consequent to CD complexation.

Synthesis, characterization, and antitumor activity of some novel S-functionalized benzo[d]thiazole-2-thiol derivatives; regioselective coupling to the –SH group

Several 2-substituted sulfanyl benzo[d]thiazoles were regioselectively synthesized by the reaction of benzo[d]thiazole-2-thiol (1a) with a variety of reagents under different basic conditions. Some 2-(2,3-disubstituted propyl sulfanyl)benzo[d]thiazoles were obtained from 2-(allylthio)benzo[d]thiazole, which was prepared by the allylation of 1a with allyl bromide in the presence of sodium hydride in dry N,N-dimethylformamide. Reaction of 1a with various pyrazolyl-quinoxaline derivatives was also investigated. Better yields and shorter reaction time were achieved for the synthesis of some derivatives by using ultrasound irradiation. The structural elucidation of all compounds was based on both analytical and spectroscopic data. The newly synthesized compounds were tested in vitro for their antitumor activity against Ehrlich ascites carcinoma (EAC) cells grown in albino mice. Doxorubicin was used as a standard antitumor antibiotic, and some compounds showed half maximal inhibitory concentration (IC50) in the range 40–68 μg mL−1.

Antimicrobial activity of 2-mercaptobenzothiazole released from environmentally friendly nanostructured layered double hydroxides

AIMS

The objective of this work was to assess the antibacterial effect of 2-mercaptobenzothiazole (MBT), used as model-biocide, immobilized in a layered double hydroxide (LDH) structure, under different conditions of pH and salinity, envisaging possible applications of the system in active antifouling and anticorrosion coatings.

METHODS AND RESULTS

Biological effects of MBT immobilized in LDH were assessed by monitoring bacterial bioluminescence of cell suspensions of either Allivibrio fischeri or a recombinant strain of Escherichia coli, as a proxy for bacterial activity. Salinity (1, 2 and 3% NaCl) and pH (4, 5, 6 and 7) of the suspension media were experimentally manipulated and biocide release tests were performed in parallel. The release profiles obtained by UV-visible spectrophotometry indicated a fast release of biocide from MBT@LDH, slightly enhanced in 3% NaCl and under alkaline conditions. However, biological effects were more pronounced at 1% NaCl and at neutral pH.

CONCLUSIONS

The release and toxic effect of MBT immobilized in LDH is dependent on the concentration of solutes in the suspension medium.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results confirm LDH as a biologically compatible material with potential to be used for biocide delivery.

A novel platinum(ii) anticancer complex of danysl bis(2-benzothiazolylmethyl)amine with dimethyl sulfoxide as a leaving group: synthesis, cytotoxicity, interaction with DNA and human serum albumin

A novel mononuclear platinum(ii) anticancer complex of danysl bis(2-benzothiazolylmethyl)amine with a dimethyl sulfoxide as a leaving group was reported.

Synthesis, Characterization, Antimicrobial and Antioxidant Activities of The Homocyclotrimer Of 4-Oxo-4h-Thieno[3,4-C]Chromene-3-Diazonium Sulfate

The in situ formed 4-oxo-4H-thieno[3,4-c]chromene-3-diazonium sulfate (5) in the coupling reactions involving the parent 2-aminothiophene (4) and various phenolic and arylamines’ couplers, readily undergoes homocyclotrimerization at low temperature to afford in fairly good yield the first ever reported eighteen member ring heteroaromatic holigomer 6. Compound 6 was fully characterized by its elemental analysis, IR, UV-Vis, ¹H-NMR, ¹³C-NMR and HRMS spectral data. The HMBC and HSQC techniques were used to ascertain the structural assignments. A comparative study on the antimicrobial and antioxidant activities of compounds 3, 4 and 6 was carried out to assess the SAR due to the transformations (from 3 to 6 via 4) on the tested compounds. It was found that compounds 6 and 4 were respectively the most active compounds against bacteria (MIC = 32-64 μg/ml) and yeasts (MIC = 16–64 μg/ml). Compound 6 also showed high radical-scavenging activities and ferric reducing power when compared with vitamin C and BHT used as reference antioxidants.

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.

Design, synthesis and mode of action of some benzothiazole derivatives bearing an amide moiety as antibacterial agents

Schematic outline of the most potent compound, benzothiazole bearing amide moiety A07, showing antibacterial activity and its mode of action.

Synthesis of new N-substituted 5-arylidene-2,4-thiazolidinediones as anti-inflammatory and antimicrobial agents

A novel series of 5-arylidene-2,4-thiazolidinediones (TZDs) 2a-p was synthesized from the condensation of 3-((2-phenylthiazol-4-yl)methyl)thiazolidine-2,4-dione with different benzaldehyde derivatives. All the structures were confirmed by their spectral (IR, ¹H NMR, ¹³C NMR and mass) and elemental analytical data. The new molecules were evaluated in vivo as anti-inflammatory agents in an acute experimental inflammation, evaluating the acute phase bone marrow response and phagocyte activity. All compounds, excepting one, reduced the absolute leukocytes count due to the lower neutrophil percentage. Phagocytary index was decreased by the same molecules, while only half of them reduced the phagocytary activity. The effect was superior to meloxicam, the reference anti-inflammatory drug, for the majority of the TZD derivatives. The new molecules were also investigated for their antimicrobial properties on Gram-positive and Gram-negative bacteria and one fungal strain. Two compounds (2e and 2n) manifested growth inhibition capacity on all the tested strains.

2-Aminobenzothiazole derivatives: search for new antifungal agents

A new series of 6-substituted 2-aminobenzothiazole derivatives were synthesized and screened in vitro as potential antimicrobials. Almost all the compounds showed antifungal activity. In particular, compounds 1n,o, designed on the basis of molecular modeling studies, were the best of the series, showing MIC values of 4-8 μg/mL against Candida albicans, Candida parapsilosis and Candida tropicalis. None of the two compounds did show any cytotoxicity effect on human THP-1 cells.

Synthesis and Antimicrobial Evaluation of a New Series ofN-1,3-Benzothiazol-2-ylbenzamides

Enterococcus faecalisis a Gram-positive commensal inhabitant of the intestinal tract of humans, animals, and insects. However, it is also an opportunistic pathogen and has emerged as a leading cause of hospital-acquired extraintestinal infections. Fluoroquinolones have been frequently used to treatE. faecalisinfections, and the emergence of fluoroquinolone-resistantE. faecalisstrains has recently been reported in several countries. Thus, the identifications of new antibiotics specifically directed toE. faecalismay be envisaged. In this paper, a new series ofN-1,3-benzothiazol-2-ylbenzamides have been designed, synthesized, and evaluated for theirin vitroantimicrobial activities. Among the tested compounds,3iwas active againstE. faecalis.

Medicinal significance of benzothiazole scaffold: an insight view

Heterocycles bearing nitrogen, sulphur and thiazole moieties constitute the core structure of a number of biologically interesting compounds. Benzothiazole, a group of xenobiotic compounds containing a benzene ring fused with a thiazole ring, are used worldwide for a variety of therapeutic applications. Benzothiazole and their heterocyclic derivatives represent an important class of compounds possessing a wide spectrum of biological activities. The myriad spectrum of medicinal properties associated with benzothiazole related drugs has encouraged the medicinal chemists to synthesize a large number of novel therapeutic agents. Several analogues containing benzothiazole ring system exhibit significant antitumour, antimicrobial, antidiabetic, anti-inflammatory, anticonvulsant, antiviral, antioxidant, antitubercular, antimalarial, antiasthmatic, anthelmintic, photosensitizing, diuretic, analgesic and other activities. This article is an attempt to present the research work reported in recent scientific literature on different pharmacological activities of benzothiazole compounds.

Recent advances on structural modifications of benzothiazoles and their conjugate systems as potential chemotherapeutics

INTRODUCTION

Benzothiazole scaffold comprises a bicyclic ring system and is known to exhibit a wide range of biological properties including antimicrobial and anticancer activities. Benzothiazole derivatives have long been therapeutically used for the treatment of various diseases. However, in recent years, 2-arylbenzothiazoles have emerged as an important pharmacophore in the development of antitumor agents. The promising biological profile and synthetic accessibility have been attractive in the design and development of new benzothiazoles and their conjugate systems as potential chemotherapeutics.

AREAS COVERED

This review mainly focuses on the structural modifications of benzothiazole scaffold, development of various series of benzothiazoles and their conjugates as new antitumor agents. Furthermore, heterocyclic derivatives bearing benzothiazole moiety and their in vitro as well as in vivo screening, structure-activity relationships (SAR), mechanism, pharmacokinetics, clinical use and their future therapeutic applications are discussed here.

EXPERT OPINION

A large number of benzothiazole derivatives discussed here possess potent anticancer activity and can be further developed as drug candidates. Benzothiazole conjugates could also display synergistic effect and still there is a need to use the drug combinations permitting lower dose and development of new generation of drugs. Despite encouraging results that have been observed for their response to tumor in clinical studies, full characterization of their toxicity is further required for their clinical usage as safe drugs for the treatment of cancer. We believe that this review gives a better understanding and scope for future drug design and development of benzothiazole-based compounds to implicate their use in cancer chemotherapy.

Biological activities of 2-mercaptobenzothiazole derivatives: a review

2-Mercaptobenzothiazoles are an important class of bioactive and industrially important organic compounds. These compounds are reported for their antimicrobial and antifungal activities, and are subsequently highlighted as a potent mechanism-based inhibitor of several enzymes like acyl coenzyme A cholesterol acyltransferase, monoamine oxidase, heat shock protein 90, cathepsin D, and c-Jun N-terminal kinases. These derivatives are also known to possess antitubercular, anti-inflammatory, antitumor, amoebic, antiparkinsonian, anthelmintic, antihypertensive, antihyperlipidemic, antiulcer, chemoprotective, and selective CCR3 receptor antagonist activity. This present review article focuses on the pharmacological profile of 2-mercaptobenzothiazoles with their potential activities.

Synthesis and antibacterial activity of novel fused 1,3-thiazoles and 1,3-thiazines incorporating a 2,4-dihydroxyphenyl residue

In an attempt to find a new class of antimicrobial agents, a series of benzothiazoles, 1,3-thiazolo[5,4-b]pyridines, 4H-3,1-benzothiazines, naphtho[2,3-d][1,3]thiazole-4,9-diones and other related compounds containing a 2,4-dihydroxyphenyl moiety were prepared. They were obtained via the reaction of aryl-modified sulfinyl[bis(2,4-dihydroxyphenylmethanethione)]s with appropriate commercial chemical reagents in the endocyclization processes. The MIC values of the compounds towards eight reference bacterial strains were assessed by the two-fold serial micro-dilution broth method. They exhibited inhibitory effects against the Gram-positive strains tested opposite to Gram-negative ones. Some compounds were more effective than the reference drug. 4-(6-Chloro-4H-3,1-benzothiazin-2-yl)-6-methylbenzene-1,3-diol (5b) due to its very good activity (MIC from 1.56 to 3.13 µg/mL) and low cytotoxicity (IC(50) > 50 µg/mL) may be regarded as a promising precursor for the development of novel antibacterial agents.