Synthesis of Azoloquinazolines and Substituted Benzothiazepine as Antimicrobial Agents

BACKGROUND & OBJECTIVE

Quinazolines and their fused systems are noteworthy in pharmaceutical chemistry due to their wide range of biological activities.

METHODS

A direct and efficient approach for the synthesis of new series of fused quinazolines with triazole, thiazole, benzimidazole and tetrazole has been preceded via the reaction of quinazoline thione derivative with halogenated compounds or cyclocondensation of arylidene of quinazoline derivative with heterocyclic amines. Also, dibenzo[b,e][1,4]thiazepine derivatives was synthesized through the reaction of 2,6-bis-(2-chloro-benzylidene)-cyclohexanone with o-aminothiophenol.

RESULTS

The structures of all new synthesized heterocyclic compounds were confirmed and discussed on the bases of spectral data. The utility of the preparation and design of the above mentioned compounds has been shown to be clear in the results of their antimicrobial activity which revealed that some derivatives have potent activity exceeding or similar to the activity of the reference drugs.

CONCLUSION

The insertion of triazole or thiazole moieties to be fused with quinazoline ring helps to enhance its antimicrobial activity.

Synthesis, Characterization and Bioassay of Novel Substituted 1-(3-(1,3-Thiazol-2-yl)phenyl)-5-oxopyrrolidines

Thiazole derivatives attract the attention of scientists both in the field of organic synthesis and bioactivity research due to their high biological activity. In the present study, thiazole ring was obtained by the interaction of 1-(4-(bromoacetyl)phenyl)-5-oxopyrrolidine-3-carboxylic acid with thiocarbamide or benzenecarbothioamide, as well as tioureido acid. A series of substituted 1-(3-(1,3-thiazol-2-yl)phenyl)-5-oxopyrrolidines with pyrrolidinone, thiazole, pyrrole, 1,2,4-triazole, oxadiazole and benzimidazole heterocyclic fragments were synthesized and their antibacterial properties were evaluated against Gram-positive strains of Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Gram-negative Pseudomonas aeruginosa, Escherichia coli and Salmonella enterica enteritidis. The vast majority of compounds exhibited between twofold and 16-fold increased antibacterial effect against the test-cultures when compared with Oxytetracycline.

Efficient Methods for the Synthesis of Novel Arylazothiazoles Based on Acetylferrocene or Adamantane

BACKGROUND

Hydrazonoyl halides are convenient for the synthesis of arylazothiazoles.

MATERIALS AND METHODS

A series of novel arylazothiazoles were efficiently synthesized from the reaction of hydrazonoyl chlorides with 2-(adamantan-2-ylidene)hydrazinecarbothioamide or 2-(ferrocenyl-1-ylidene)hydrazinecarbo-- thioamide in dioxane used as an aprotic solvent because of its lower toxicity and higher boiling point (101 °C) and triethylamine at reflux. The reaction mechanistic pathway proceeded by the nucleophilic substitution reaction by the elimination of hydrogen chloride to give thiohydrazonates as intermediate, which in situ undergo intramolecular cyclization and loss of water molecule to afford the final product of novel arylazothiazoles. This method is simple with good yield and excellent purities.

RESULTS AND DISCUSSION

The synthetic schemes for the final products are proposed and discussed. The chemical structures of the final products were identified by different techniques, such as elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS).

CONCLUSION

In this article, we prepared arylazothiazoles from the reaction of 2-(adamantan-2-ylidene)hydrazinecarbothioamide or 2-(ferrocenyl-1-ylidene)hydrazinecarbothioamide with hydrazonoyl halides.

Synthesis of new 1,3-thiazol derivatives of maleopimaric acid as anticancer, antibacterial and antifungal agents

A series of new 1,3-thiazole derivatives of maleopimaric acid 6a-f, 7a-f were synthesized and evaluated for anticancer, antibacterial and antifungal activities. Evaluation of cytotoxic activity against human embryonic kidney 293 cells (HEK293), human neuroblastoma cell line (SH-SY5Y), hepatocellular carcinoma cell line (HepG2) and human T-cell lymphoblast-like line (Jurkat), showed that introduction of the aminothiazole fragment at position 6 of the diterpenoid molecule leads to decrease of cell viability. Substance 3 was found to be the most active against all tested cell lines, inhibiting cell viability with IC₅₀ values in the range of 2-24 μM. The structure-activity relationship of these compounds was studied and the results show that the compounds 6c and 7e exhibited in vitro antifungal activity against Candida albicans and also possessed antibacterial profile against Enterobacter aerogenes, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Proteus vulgaris.

One-Pot Three-Component Synthesis and Molecular Docking of Some Novel 2-Thiazolyl Pyridines as Potent Antimicrobial Agents

BACKGROUND

Thiazoles and pyridines are versatile synthetic scaffolds possessing wide spectrum of biological effects including potential antimicrobial activity.

OBJECTIVE

In the efforts to develop suitable antimicrobia drugs, medicinal chemists have focused on thiazole derivatives. A novel series of 2-thiazolyl pyridines was prepared in a one-pot three-component reaction using 2-bromoacetyl pyridine as a starting precursor.

METHOD

Structure of the synthesized compounds was elucidated by spectral data (FT-IR, 1H NMR, 13C NMR, and mass) and elemental analyses. The prepared compounds were screened for their in vitro antimicrobial activity.

RESULTS

The results revealed that compounds 4a,b,e-g and 12 showed promising activity. Molecular docking studies using MOE software were carried out for compounds 4a and 4b which exhibited potent activities indicated by the diameter zones (4a; 3.6, 4.0, 1.2 mm) (4b; 4.2, 3.5, 1.5 mm) and the binding affinities (4a; -5.7731, -5.3576, -4.6844 kcal mol-1) (4b; -5.9356, -2.8250, -5.3628 kcal mol-1) against Candida albicans, Bacillus subtilis and Escherichia coli, respectively.

CONCLUSION

This paper describes a facile and efficient MCR for synthesis of 2-thiazolyl pyridines from reaction of 2-bromoacetyl pyridine with different reagents. There was an agreement between the values of binding affinities and interactions and the data obtained from the practical antimicrobial screening of the tested compounds.

Synthesis and Biological Evaluation of Some Novel Thiazole-Based Heterocycles as Potential Anticancer and Antimicrobial Agents

A novel series of thiazole-based heterocycles was synthesized using 1,3-dipolar cycloaddition reactions in the presence of chitosan-grafted-poly(vinylpyridine) as an eco-friendly biopolymeric basic catalyst. The molecular structure of the synthesized compounds was illustrated by spectroscopic and elemental analysis. Various in vitro biological assays were performed to explore the potential antitumor, antimicrobial and hepatoprotective activities of the newly synthesized compounds. The cytotoxic activities were assessed against human hepatocellular carcinoma (HepG-2), colorectal carcinoma (HCT-116) and breast cancer (MCF-7) cell lines and results revealed that all compounds displayed antitumor activities with the chlorine-containing derivatives, 11c and 6g, being the most potent. The majority of the tested thiazole derivatives exhibited satisfactory antibacterial activity towards the used gram positive and gram-negative bacterial species. Moreover, many derivatives showed weak hepatoprotective activity against CCl₄-induced hepatotoxicity.

Eco-Friendly Synthesis, Characterization and Biological Evaluation of Some Novel Pyrazolines Containing Thiazole Moiety as Potential Anticancer and Antimicrobial Agents

The one-pot synthesis of a series of pyrazoline derivatives containing the bioactive thiazole ring has been performed through a 1,3-dipolar cycloaddition reaction of N-thiocarbamoylpyrazoline and different hydrazonoyl halides or α-haloketones in the presence of DABCO (1,4-diazabicyclo[2.2.2] octane) as an eco-friendly catalyst using the solvent-drop grinding method. The structure of the synthesized compounds was elucidated using elemental and spectroscopic analyses (IR, NMR, and Mass). The activity of these compounds against human hepatocellular carcinoma cell line (HepG2) was tested and the results showed that the pyrazoline 11f, which has a fluorine substituent, is the most active. The antimicrobial activities of the newly synthesized compounds were determined against two fungi and four bacterial strains, and the results indicated that some of the newly synthesized pyrazolines are more potent than the standard drugs against test organisms.

Chitosan-MgO Nanocomposite: One Pot Preparation and Its Utility as an Ecofriendly Biocatalyst in the Synthesis of Thiazoles and [1,3,4]thiadiazoles

A chitosan-MgO hybrid nanocomposite was prepared using a simple chemical precipitation method and characterized using Fourier transform spectroscopy (FTIR), elemental analysis (EDX), and scanning electron microscopy (SEM). The nanocomposite was served as a powerful ecofriendly basic catalyst under microwave irradiation in the synthesis of two novel series of 5-arylazo-2-hydrazonothiazoles 4a–j and 2-hydrazono[1,3,4]thiadiazoles 8a–d, incorporating a sulfonamide group. The structures of the synthesized products were elucidated by spectral data and elemental analyses. Also, their yield percentages were calculated using triethylamine (as a traditional catalyst) and chitosan-MgO nanocomposite (as a green recyclable catalyst) in a comparative study.

Application of Docking Analysis in the Prediction and Biological Evaluation of the Lipoxygenase Inhibitory Action of Thiazolyl Derivatives of Mycophenolic Acid

5-LOX inhibition is among the desired characteristics of anti-inflammatory drugs, while 15-LOX has also been considered as a drug target. Similarity in inhibition behavior between soybean LOX-1 and human 5-LOX has been observed and soybean LOX (sLOX) type 1b has been used for the evaluation of LOX inhibition in drug screening for years. After prediction of LOX inhibition by PASS and docking as well as toxicity by PROTOX and ToxPredict sixteen (E)-N-(thiazol-2-yl)-6-(4-hydroxy-6-methoxy-7-methyl-3-oxo-1,3-dihydroisobenzofuran-5-yl)-4-methylhex-4-enamide derivatives with lengths varying from about 15⁻20 Å were evaluated in vitro for LOX inhibitory action using the soybean lipoxygenase sLOX 1b. Docking analysis was performed using soybean LOX L-1 (1YGE), soybean LOX-3 (1JNQ), human 5-LOX (3O8Y and 3V99) and mammalian 15-LOX (1LOX) structures. Different dimensions of target center and docking boxes and a cavity prediction algorithm were used. The compounds exhibited inhibitory action between 2.5 μΜ and 165 μΜ. Substituents with an electronegative atom at two-bond proximity to position 4 of the thiazole led to enhanced activity. Docking results indicated that the LOX structures 1JNQ, 3V99 and 1LOX can effectively be used for estimation of LOX inhibition and amino acid interactions of these compounds.

Synthesis and Biological Evaluation of Bisthiazoles and Polythiazoles

Small heterocyclic compounds containing nitrogen and sulfur atoms, such as thiazole derivatives, represent a significant class of organic azoles that exhibit promising bioactivities and have a great potential in medicinal and agricultural fields. A convenient and high-yielding synthetic approach for a range of organic molecules is presented. The nuclease-like activities of compounds were studied with the aid of E. coli AB1157 DNA and agarose gel electrophoresis. The antioxidant evaluation of the compounds was carried out with different antioxidant techniques, such as ABTS and NO scavenging efficiency. The antibacterial behavior was evaluated against various bacterial strains, both Gram-positive and -negative, and the minimum inhibitory concentration (MIC) values of these compounds were determined. The antiproliferative activities and IC50 values of the synthesized organic molecules compounds against HEPG-2, MCF-7, and HCT-116 cell lines were evaluated.

Docking analysis targeted to the whole enzyme: an application to the prediction of inhibition of PTP1B by thiomorpholine and thiazolyl derivatives

PTP1b is a protein tyrosine phosphatase involved in the inactivation of insulin receptor. Since inhibition of PTP1b may prolong the action of the receptor, PTP1b has become a drug target for the treatment of type II diabetes. In the present study, prediction of inhibition using docking analysis targeted specifically to the active or allosteric site was performed on 87 compounds structurally belonging to 10 different groups. Two groups, consisting of 15 thiomorpholine and 10 thiazolyl derivatives exhibiting the best prediction results, were selected for in vitro evaluation. All thiomorpholines showed inhibitory action (with IC₅₀ = 4-45 μΜ, Ki = 2-23 μM), while only three thiazolyl derivatives showed low inhibition (best IC₅₀ = 18 μΜ, Ki = 9 μΜ). However, free binding energy (E) was in accordance with the IC₅₀ values only for some compounds. Docking analysis targeted to the whole enzyme revealed that the compounds exhibiting IC₅₀ values higher than expected could bind to other peripheral sites with lower free energy, E_o, than when bound to the active/allosteric site. A prediction factor, E- (Σ_Eo × 0.16), which takes into account lower energy binding to peripheral sites, was proposed and was found to correlate well with the IC₅₀ values following an asymmetrical sigmoidal equation with r² = 0.9692.

Thiazole Containing Heterocycles with Antimalarial Activity

BACKGROUND

Heterocyclic compounds are the main class of medicinally important compounds. Many heterocyclic compounds bearing a five-membered ring in their structure have a good spectrum of biological activities. Thiazole is an important class of five-membered heterocyclic compounds. Thiazole and its derivatives exhibited a broad range of biological activities due to the presence of various reaction posseses. Thiazole, heterocyclic nucleus is present in several potent pharmacologically active molecules such as Sulfathiazole (antimicrobial drug), Ritonavir (antiretroviral drug), Tiazofurin (antineoplastic drug) and Abafungin (antifungal drug) etc. The search for some novel biologically active thiazoles is to be continued in the field of medicinal chemistry for investigators. An aim of this review is to identify and try making a SAR (Structure Activity Relationship) of substituted thiazole nucleus as possible new antimalarials.

METHOD

Author undertook a structured search of bibliographic databases for peerreviewed research literature using a focused review question and inclusion/exclusion criteria. The quality of retrieved papers was appraised using standard tools. The characteristics of screened papers were described, and a deductive qualitative content analysis methodology was applied to analyse the interventions and findings of included studies using a conceptual framework.

RESULT

Fifteen papers were included in the review; the majority were described about many biological activity of thiazole nucleus. Seven papers were find that had impacted upon the thaizoles as antimalarials. Some papers focused on the design, synthesis and antimalarial activity evaluation of thiazole derivatives. This review identified and made a SAR (Structure Activity Relationship) of substituted thiazole nucleus as possible new antimalarials.

CONCLUSION

This review describes ongoing research in the search for novel thiazoles as targets and new antimalarial drug molecules.

On the Control of Chromophore Orientation, Supramolecular Structure, and Thermodynamic Stability of an Amphiphilic Pyridyl-Thiazol upon Lateral Compression and Spacer Length Variation

The supramolecular structure essentially determines the properties of organic thin films. Therefore, it is of utmost importance to understand the influence of molecular structure modifications on supramolecular structure formation. In this article, we demonstrate how to tune molecular orientations of amphiphilic 4-hydroxy thiazole derivatives by means of the Langmuir-Blodgett (LB) technique and how this depends on the length of an alkylic spacer between the thiazole chromophore and the polar anchor group. Therefore, we characterize their corresponding supramolecular structures, thermodynamic, absorption, and fluorescence properties. Particularly, the polarization-dependence of the fluorescence is analyzed to deduce molecular orientations and their possible changes after annealing, i.e., to characterize the thermodynamic stability of the individual solid state phases. Because the investigated thiazoles are amphiphilic, the different solid state phases can be formed and be controlled by means of the Langmuir-Blodgett (LB) technique. This technique also allows to deduce atomistic supramolecular structure motives of the individual solid phases and to characterize their thermodynamic stabilities. Utilizing the LB technique, we demonstrate that subtle molecular changes, like the variation in spacer length, can yield entirely different solid state phases with distinct supramolecular structures and properties.

Modulation of periodontitis progression using pH-responsive nanosphere encapsulating metronidazole or N-phenacylthialzolium bromide

BACKGROUND AND OBJECTIVE

This study aimed to develop pH-responsive polylactide-glycolic acid co-polymer and chitosan (PLGA/chitosan) nanosphere as an inflammation-responsive vehicle and evaluate the potential of the nanosphere encapsulating metronidazole, an antibiotic, and N-phenacylthiazolium bromide (PTB), a host modulator, for treating periodontitis.

MATERIAL AND METHODS

PLGA/chitosan nanospheres were fabricated using oil-in-water emulsion method. Experimental periodontitis was induced on the rat maxillae, and the sites were randomly allocated to four treatment categories, including periodontitis alone (PR), periodontitis with nanospheres alone, nanospheres encapsulating metronidazole (MT) and nanospheres encapsulating PTB (PB). The ligature was retained until the animals were killed, and the treatment outcome was evaluated by the progression of periodontal bone loss (PPBL), inflammatory cell infiltration and collagen deposition.

RESULTS

The encapsulated drug was released rapidly from the nanospheres without significant initial burst release at pH 5.5. Compared with group PR, PPBL was significantly reduced in groups MT and PB on day 4 (P<.05). On day 21, PPBL was significantly lower in group PB (P<.05). In groups MT and PB, inflammation was significantly reduced in groups MT and PB relative to groups PR and periodontitis with nanospheres alone (P<.05), and collagen deposition was significantly greater relative to group PR (P<.05).

CONCLUSION

PLGA/chitosan nanospheres encapsulating metronidazole or PTB showed potential for modulating periodontitis progression.

Heterocycle Thiazole Compounds Exhibit Antifungal Activity through Increase in the Production of Reactive Oxygen Species in the Cryptococcus neoformans-Cryptococcus gattii Species Complex

Human cryptococcosis can occur as a primary or opportunistic infection and develops as an acute, subacute, or chronic systemic infection involving different organs of the host. Given the limited therapeutic options and the occasional resistance to fluconazole, there is a need to develop novel drugs for the treatment of cryptococcosis. In this report, we describe promising thiazole compounds 1, 2, 3, and 4 and explore their possible modes of action against Cryptococcus To this end, we show evidence of interference in the Cryptococcus antioxidant system. The tested compounds exhibited MICs ranging from 0.25 to 2 μg/ml against Cryptococcus neoformans strains H99 and KN99α. Interestingly, the knockout strains for Cu oxidase and sarcosine oxidase were resistant to thiazoles. MIC values of thiazole compounds 1, 2, and 4 against these mutants were higher than for the parental strain. After the treatment of C. neoformans ATCC 24067 (or C. deneoformans) and C. gattii strain L27/01 (or C. deuterogattii) with thiazoles, we verified an increase in intracellular reactive oxygen species (ROS). Also, we verified the synergistic interactions among thiazoles and menadione, which generates superoxides, with fractional inhibitory concentrations (FICs) equal to 0.1874, 0.3024, 0.25, and 0.25 for the thiazole compounds 1, 2, 3, and 4, respectively. In addition, thiazoles exhibited antagonistic interactions with parasulphonatephenyl porphyrinato ferrate III (FeTPPS). Thus, in this work, we showed that the action of these thiazoles is related to an interference with the antioxidant system. These findings suggest that oxidative stress may be primarily related to the accumulation of superoxide radicals.

Thiazole-Based σ1 Receptor Ligands: Diversity by Late-Stage C-H Arylation of Thiazoles, Structure-Affinity and Selectivity Relationships, and Molecular Interactions

Spirocyclic thiophene derivatives represent promising σ1 ligands with high σ1 affinity and selectivity over the σ2 subtype. To increase ligand efficiency, the thiophene ring was replaced bioisosterically by a thiazole ring, and the pyran ring was opened. Late-stage diversification by regioselective C-H arylation of thiazoles 9 a-c resulted in a set of 53 compounds with high diversity. This set of compounds was analyzed with respect to σ1 affinity, σ1 /σ2 selectivity, lipophilicity (logD7.4 ), lipophilicity-corrected ligand efficiency (LELP), and molecular target interactions. The most promising candidates were pyridyl-substituted thiazole derivatives 33 c (2-(1-benzyl-4-ethoxypiperidin-4-yl)-5-(pyridin-3-yl)thiazole) and 34 c (2-(1-benzyl-4-ethoxypiperidin-4-yl)-5-(pyridin-4-yl)thiazole), possessing low-nanomolar σ1 affinity (Ki =1.3 and 1.9 nm), high σ1 /σ2 selectivity (>1500-fold), low lipophilicity (logD7.4 =1.8) and very good ligand efficiency (LELP=5.5), indicating promising pharmacodynamics and pharmacokinetics. Molecular simulation studies, including docking and deconvolution of the free binding energy into its major components, led to decreased hydrophobic stabilization of pyridyl derivatives 33 c and 34 c, which was compensated by lower desolvation energy.

Synthesisand Biological Evaluationof New Substituted Hantzsch Thiazole Derivatives from Environmentally Benign One-Pot Synthesis Using Silica Supported Tungstosilisic Acid as Reusable Catalyst

An efficient and green method has been developed for the synthesis of new substituted Hantzsch thiazole derivatives in 79%-90% yield, via the one-pot multi-component procedure, by the reaction of 3-(bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, thiourea and substituted benzaldehydes in the presence of silica supported tungstosilisic acid, as a reusable catalyst, under conventional heating or under ultrasonic irradiation. The catalyst is recoverable by a simple filtration and can be reused in the subsequent reactions. Most of the thiazoles exhibited significant antibacterial activity compared toamoxicillin and ciprofloxacin as positive controls. In addition, the new compounds showed moderate to good antioxidant (DPPH) radical scavenging activity.

N-Propargylamines: versatile building blocks in the construction of thiazole cores

Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines. This review will be helpful in the development of improved methods for the synthesis of natural and biologically important compounds.

Clozapine combined with different antipsychotic drugs for treatment-resistant schizophrenia

BACKGROUND

Between 40% and 70% of people with treatment-resistant schizophrenia do not respond to clozapine, despite adequate blood levels. For these people, a number of treatment strategies have emerged, including the prescription of a second anti-psychotic drug in combination with clozapine.

OBJECTIVES

To determine the clinical effects of various clozapine combination strategies with antipsychotic drugs in people with treatment-resistant schizophrenia both in terms of efficacy and tolerability.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Study-Based Register of Trials (to 28 August 2015) and MEDLINE (November 2008). We checked the reference lists of all identified randomised controlled trials (RCT). For the first version of the review, we also contacted pharmaceutical companies to identify further trials.

SELECTION CRITERIA

We included only RCTs recruiting people of both sexes, aged 18 years or more, with a diagnosis of treatment-resistant schizophrenia (or related disorders) and comparing clozapine plus another antipsychotic drug with clozapine plus a different antipsychotic drug.

DATA COLLECTION AND ANALYSIS

We extracted data independently. For dichotomous data, we calculated risk ratios (RRs) and 95% confidence intervals (CI) on an intention-to-treat basis using a random-effects meta-analysis. For continuous data, we calculated mean differences (MD) and 95% CIs. We used GRADE to create 'Summary of findings' tables and assessed risk of bias for included studies.

MAIN RESULTS

We identified two further studies with 169 participants that met our inclusion criteria. This review now includes five studies with 309 participants. The quality of evidence was low, and, due to the high degree of heterogeneity between studies, we were unable to undertake a formal meta-analysis to increase the statistical power.For this update, we specified seven main outcomes of interest: clinical response in mental state (clinically significant response, mean score/change in mental state), clinical response in global state (mean score/change in global state), weight gain, leaving the study early (acceptability of treatment), service utilisation outcomes (hospital days or admissions to hospital) and quality of life.We found some significant differences between clozapine combination strategies for global and mental state (clinically significant response and change), and there were data for leaving the study early and weight gain. We found no data for service utilisation and quality of life. Clozapine plus aripiprazole versus clozapine plus haloperidolThere was no long-term significant difference between aripiprazole and haloperidol combination strategies in change of mental state (1 RCT, n = 105, MD 0.90, 95% CI -4.38 to 6.18, low quality evidence). There were no adverse effect data for weight gain but there was a benefit of aripiprazole for adverse effects measured by the LUNSERS at 12 weeks (1 RCT, n = 105, MD -4.90, 95% CI -8.48 to -1.32) and 24 weeks (1 RCT, n = 105, MD -4.90, 95% CI -8.25 to -1.55), but not 52 weeks (1 RCT, n = 105, MD -4.80, 95% CI -9.79 to 0.19). Similar numbers of participants from each group left the study early (1 RCT, n = 106, RR 1.27, 95% CI 0.72 to 2.22, very low quality evidence). Clozapine plus amisulpride versus clozapine plus quetiapine One study showed a significant benefit of amisulpride over quetiapine in the short term, for both change in global state (Clinical Global Impression (CGI): 1 RCT, n = 50, MD -0.90, 95% CI -1.38 to -0.42, very low quality evidence) and mental state (Brief Psychiatric Rating Scale (BPRS): 1 RCT, n = 50, MD -4.00, 95% CI -5.86 to -2.14, low quality evidence). Similar numbers of participants from each group left the study early (1 RCT, n = 56, RR 0.20, 95% CI 0.02 to 1.60, very low quality evidence) Clozapine plus risperidone versus clozapine plus sulpirideThere was no difference between risperidone and sulpiride for clinically significant response, defined by the study as 20% to 50% reduction in Positive and Negative Syndrome Scale (PANSS) (1 RCT, n = 60, RR 0.82, 95% CI 0.40 to 1.68, very low quality evidence). There were similar equivocal results for weight gain (1 RCT, n = 60, RR 0.40, 95% CI 0.08 to 1.90, very low quality evidence) and mental state (PANSS total: 1 RCT, n = 60, MD -2.28, 95% CI -7.41 to 2.85, very low quality evidence). No-one left the study early. Clozapine plus risperidone versus clozapine plus ziprasidoneThere was no difference between risperidone and ziprasidone for clinically significant response (1 RCT, n = 24, RR 0.80, 95% CI 0.28 to 2.27, very low quality evidence), change in global state CGI-II score (1 RCT, n = 22, MD -0.30, 95% CI -0.82 to 0.22, very low quality evidence), change in PANSS total score (1 RCT, n = 16, MD 1.00, 95% CI -7.91 to 9.91, very low quality evidence) or leaving the study early (1 RCT, n = 24, RR 1.60, 95% CI 0.73 to 3.49, very low quality evidence). Clozapine plus ziprasidone versus clozapine plus quetiapineOne study found, in the medium term, a superior effect for ziprasidone combination compared with quetiapine combination for clinically significant response in mental state (> 50% reduction PANSS: 1 RCT, n = 63, RR 0.54, 95% CI 0.35 to 0.81, low quality evidence), global state (CGI - Severity score: 1 RCT, n = 60, MD -0.70, 95% CI -1.18 to -0.22, low quality evidence) and mental state (PANSS total score: 1 RCT, n = 60, MD -12.30, 95% CI -22.43 to -2.17, low quality evidence). There was no effect for leaving the study early (1 RCT, n = 63, RR 0.52, CI 0.05 to 5.41, very low quality evidence).

AUTHORS' CONCLUSIONS

The reliability of results from this review is limited, evidence is of low or very low quality. Furthermore, due to the limited number of included studies, we were unable to undertake formal meta-analyses. As a consequence, any conclusions drawn from these findings are based on single, small-sized RCTs with high risk of type II error. Properly conducted and adequately powered RCTs are required. Future trialists should seek to measure patient-important outcomes such as quality of life, as well as clinical response and adverse effects.

Microwave-Assisted Synthesis of some Novel Azoles and Azolopyrimidines as Antimicrobial Agents

In this study, new derivatives of pyrazole, isoxazole, pyrazolylthiazole, and azolopyrimidine having a thiophene ring were synthesized under microwave irradiation. Their pharmacological activity toward bacteria and fungi inhibition was screened and compared to the references Chloramphenicol and Trimethoprim/sulphamethoxazole. The antimicrobial results of the investigated compounds revealed promising results and some derivatives have activities similar to the references used.

Synthesis and Cytotoxic Activity of Triterpenoid Thiazoles Derived from Allobetulin, Methyl Betulonate, Methyl Oleanonate, and Oleanonic Acid

A total of 41 new triterpenoids were prepared from allobetulone, methyl betulonate, methyl oleanonate, and oleanonic acid to study their influence on cancer cells. Each 3-oxotriterpene was brominated at C2 and substituted with thiocyanate; subsequent cyclization with the appropriate ammonium salts gave N-substituted thiazoles. All compounds were tested for their in vitro cytotoxic activity on eight cancer cell lines and two non-cancer fibroblasts. 2-Bromoallobetulone (2 b) methyl 2-bromobetulonate (3 b), 2-bromooleanonic acid (5 b), and 2-thiocyanooleanonic acid (5 c) were best, with IC₅₀ values less than 10 μm against CCRF-CEM cells (e.g., 3 b: IC₅₀ =2.9 μm) as well as 2'-(diethylamino)olean-12(13)-eno[2,3-d]thiazole-28-oic acid (5 f, IC₅₀ =9.7 μm) and 2'-(N-methylpiperazino)olean-12(13)-eno[2,3-d]thiazole-28-oic acid (5 k, IC₅₀ =11.4 μm). Compound 5 c leads to the accumulation of cells in the G₂ phase of the cell cycle and inhibits RNA and DNA synthesis significantly at 1×IC₅₀ . The G₂ /M cell-cycle arrest probably corresponds to the inhibition of DNA/RNA synthesis, similar to the mechanism of action of actinomycin D. Compound 5 c is new, active, and nontoxic; it is therefore the most promising compound in this series for future drug development. Methyl 2-bromobetulonate (3 b) and methyl 2-thiocyanometulonate (3 c) were found to inhibit nucleic acid synthesis only at 5×IC₅₀ . We assume that in 3 b and 3 c (unlike in 5 c), DNA/RNA inhibition is a nonspecific event, and an unknown primary cytotoxic target is activated at 1×IC₅₀ or lower concentration.

Synthesis and Antimicrobial Activity of Some New Thiadiazoles, Thioamides, 5-Arylazothiazoles and Pyrimido[4,5-d][1,2,4]triazolo[4,3-a]pyrimidines

A novel series of 1,3,4-thiadiazoles, 5-arylazothiazoles and hexahydropyrimido-[4,5-d][1,2,4]triazolo[4,3-a]pyrimidines were synthesized via reaction of hydrazonoyl halides with each of alkyl carbothioates, carbothioamides and 7-thioxo-5,6,7,8-tetrahydropyrimido-[4,5-d]pyrimidine-2,4(1H,3H)-diones in the presence of triethylamine. The structures of the newly synthesized compounds were established based on their spectral data, elemental analyses and alternative synthetic routes whenever possible. Also, the newly synthesized compounds were screened for their antimicrobial activity against various microorganisms.

Synthesis of New 3-Heteroarylindoles as Potential Anticancer Agents

2-(3-(1H-Indol-3-yl)-5-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-4-substituted-5-(substituted diazenyl)thiazoles and 2-(1H-indol-3-yl)-9-substituted-4,7-disubstituted pyrido[3,2-e][1,2,4]triazolo[4,3-a]pyrimidin-5(7H)-ones were synthesized via reaction of hydrazonoyl halides with each of 3-(1H-indol-2-yl)-5-(p-tolyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide and 7-(1H-indol-3-yl)-2- thioxo-5-substituted-2,3-dihydropyrido[2,3-d]pyrimidin-4(1H)-ones, respectively. Also, hydrazonoyl halides were reacted with N’-(1-(1H-indol-3-yl)ethylidene)-2-cyanoacetohydrazide to afford 1,3,4-thiadiazole derivatives. Structures of the new synthesis were elucidated on the basis of elemental analysis, spectral data, and alternative synthetic routes whenever possible. Fifteen of the new compounds have been evaluated for their antitumor activity against the MCF-7 human breast carcinoma cell line. The results indicated that many of the tested compounds showed moderate to high anticancer activity when compared with doxorubicin as a reference drug.

Synthesis and anticonvulsant activities of novel 2-(cyclopentylmethylene)hydrazinyl-1,3-thiazoles in mouse models of seizures

Synthesis, characterization and investigation of in vivo anticonvulsant activities of 13 novel cyclopentanecarbaldehyde-based 2,4-disubstituted 1,3-thiazoles are presented. Their structures were determined using (1)H and (13)C NMR, FAB(+)-MS, HRMS and elemental analyses. The results of anticonvulsant screening reveal that seven intraperitoneally administered compounds: 3a, 3b, 3d, 3e, 3f, 3k and 3m containing F-, Cl-, Br-, CF3-, CH3- and adamantyl substituents demonstrated significant anticonvulsant activity in the pentylenetetrazole model with median effective doses (ED50) ≤ 20 mg/kg, respectively, which was approximately seven-fold lower than that reported for the reference drug, ethosuximide. Noteworthy, none of these compounds impaired animals' motor skills in the rotarod test.

Utility of 3-Acetyl-6-bromo-2H-chromen-2-one for the Synthesis of New Heterocycles as Potential Antiproliferative Agents

Coumarin derivatives containing pyrazolo[1,5-a]pyrimidine, tetrazolo[1,5-a]pyrimidine, imidazo[1,2-a]pyrimidine, pyrazolo[3,4-d]pyrimidine, 1,3,4-thiadiazoles and thiazoles were synthesized from 6-bromo-3-(3-(dimethylamino)acryloyl)-2H-chromen-2-one, methyl 2-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene)hydrazine carbodithioate, 2-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene) hydrazine carbothioamide and each of heterocyclic amine, hydrazonoyl chlorides and hydroximoyl chlorides. The structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthetic routes whenever possible. Moreover, selected newly synthesized products were evaluated for their antitumor activity against a liver carcinoma cancer cell line (HEPG2-1). The results revealed that pyrazolo[1,5-a]pyrimidine 7c, thiazole 23g and 1,3,4-thiadiazole 18a (IC50 = 2.70 ± 0.28, 3.50 ± 0.23 and 4.90 ± 0.69 µM, respectively) have promising antitumor activity against liver carcinoma (HEPG2-1) while most of the tested compounds showed moderate activity.