Synthesis of pyrazoline–thiazolidinone hybrids with trypanocidal activity

Exploring rhodanine linked enamine-carbohydrazide derivatives as mycobacterial carbonic anhydrase inhibitors: Design, synthesis, biological evaluation, and molecular docking studies

With the rise of multidrug-resistant tuberculosis, the imperative for an alternative and superior treatment regimen, incorporating novel mechanisms of action, has become crucial. In pursuit of this goal, we have developed and synthesized a new series of rhodanine-linked enamine-carbohydrazide derivatives, exploring their potential as inhibitors of mycobacterial carbonic anhydrase. The findings reveal their efficacy, displaying notable selectivity toward the mycobacterial carbonic anhydrase 2 (mtCA 2) enzyme. While exhibiting moderate activity against human carbonic anhydrase isoforms, this series demonstrates promising selectivity, positioning these compounds as potential antitubercular agents. Compound 6d was the best one from the series with a Ki value of 9.5 µM toward mtCA 2. Most of the compounds displayed moderate to good inhibition against the Mtb H37Rv strain; compound 11k showed a minimum inhibitory concentration of 1 µg/mL. Molecular docking studies revealed that compounds 6d and 11k show metal coordination with the zinc ion, like classical CA inhibitors.

Synthesis and Antioxidant Studies of 2,4-Dioxothiazolidine-5-acetic Acid Based Organic Salts: SC-XRD and DFT Approach

In the current study, two organic salts (1 and 2) are synthesized, and then crystalline structures are characterized by FTIR, UV spectroscopy, and X-ray crystallographic studies. The organic salts 1 and 2 are optimized at the M06/6-311G(d,p)level of theory and further utilized for analysis of natural bond orbitals (NBOs), natural population, frontier molecular orbitals (FMOs), and global reactivity parameters, which confirmed the stability of the studied compounds and charge transfer phenomenon in the studied compounds. The studies further revealed that 1 and 2 are more stable than 3. The lowest energy merged monomer-coformer conformations were docked as flexible ligands with rigid fungal proteins and DNA receptors. The stagnant binding of the monomer through two H bonds with protein was observed for ligands 1 and 3 while different pattern was found with 2. The coformers formed a single H bond with the active site in 2 and 3 and a single pi-arene H interaction in 1. The two-point ligand-receptor interactions hooked the monomer between DNA base pairs for partial intercalation; pi stacking with additive hydrogen bonding with the base pair led to a strong benzimidazole interaction in 1 and 2, whereas ethylene diamine formed weak H bonding. Thus, the molecular docking predicted that the coformer exhibited DNA intercalation reinforced by its salt formation with benzimidazole 1 and methyl benzimidazole 2. Antioxidant studies depicted that 3 has a higher IC50 value than that of 2,4-D and also the largest value among the studied compounds, whereas 2 showed the lowest value among the studied compounds.

Thiazolidin-4-one-based derivatives - Efficient tools for designing antiprotozoal agents. A review of the last decade

Thiazolidin-4-one derivatives have a wide range of therapeutic implementations and clinical significance for medicinal chemistry. This heterocyclic ring has been reported to possess a variety of biological activities, including antiprotozoal activities that have inspired scientists to integrate this scaffold with different pharmacophoric fragments to design novel and effective antiprotozoal compounds. There are reviews describing thiazolidin-4-ones small molecules as good candidates with a single type of antiprotozoal activity, but none of these show collected news associated with the antiprotozoal activity of thiazolidin-4-ones and their SAR analysis from the last decade. In this review we are focusing on the antitoxoplasmic, anti-trypanosomal, antimalarial, antileishmanial, and antiamoebic activity of these derivatives, we attempt to summarize and analyze the recent developments with regard to the antiprotozoal potential of 4-TZD covering the structure-activity relationship and main molecular targets. The importance of various structural modifications at C2, N3, and C5 of the thiazolidine-4-one core has also been discussed in this review. We hope that all information concluded in this review can be useful for other researchers in constructing new effective antiprotozoal agents.

Pyrazole and pyrazoline derivatives as antimalarial agents: A key review

Malaria poses a severe public health risk and a significant economic burden in disease-endemic countries. One of the most severe issues in malaria control is the development of drug resistance in malaria parasites. The standard treatment for malaria is artemisinin-combination therapy (ACT). Nevertheless, the Plasmodium parasite's extensive resistance to prior drugs and reduced ACT efficiency necessitates novel drug discovery. The progress in discovering novel, affordable, and effective antimalarial agents is significant in combating drug resistance, and the hybrid drug concept can be used to covalently link two or more active pharmacophores that may act on multiple targets. Pyrazole and pyrazoline derivatives are considered pharmacologically necessary active heterocyclic scaffolds that possess almost all types of pharmacological activities. This review summarized recent progress in antimalarial activities of synthesized pyrazole and pyrazoline derivatives. The studies published since 2000 are included in this systematic review. This review is anticipated to be beneficial for future study and new ideas in searching for rational development strategies for more effective pyrazole and pyrazoline derivatives as antimalarial drugs.

Hybrid-Compounds Against Trypanosomiases

Neglected tropical diseases (NTDs) are a global public health problem associated with approximately 20 conditions. Among these, Chagas disease (CD), caused by Trypanosoma cruzi, and human African trypanosomiasis (HAT), caused by T. brucei gambiense or T. brucei rhodesiense, affect mainly the populations of the countries from the American continent and sub- Saharan Africa. Pharmacological therapies used for such illnesses are not yet fully effective. In this context, the search for new therapeutic alternatives against these diseases becomes necessary. A drug design tool, recently recognized for its effectiveness in obtaining ligands capable of modulating multiple targets for complex diseases, concerns molecular hybridization. Therefore, this review aims to demonstrate the importance of applying molecular hybridization in facing the challenges of developing prototypes as candidates for the treatment of parasitic diseases. Therefore, studies involving different chemical classes that investigated and used hybrid compounds in recent years were compiled in this work, such as thiazolidinones, naphthoquinones, quinolines, and others. Finally, this review covers several applications of the exploration of molecular hybridization as a potent strategy in the development of molecules potentially active against trypanosomiases, in order to provide information that can help in designing new drugs with trypanocidal activity.

Assessing different thiazolidine and thiazole based compounds as antileishmanial scaffolds

The compounds from eight different thiazolidine and thiazole series were assessed as potential antileishmanial scaffolds. They were tested for antileishmanial activity against promastigotes of Leishmania major using in vitro primary screen and dose response assays. The compounds from six thiazolidine and thiazole series were identified as the hits with antileishmanial activity against L. major. However, the analyses of structure-activity relations (SARs) showed that the interpretable SARs were obtained only for phenyl-indole hybrids (compounds C1, C2, C3 and C5) as the most effective compounds against L. major promastigotes (IC₅₀ < 10 µM) with low toxicity to human fibroblasts. For the scaffold of these compounds, the most significant SAR patterns were: free N3 position of thiazolidinone core, absence of big fragments at the C5 position of thiazolidinone core and presence of halogen atoms or nitro group in the phenyl ring of phenyl-indole fragment. As previous studies showed that these compounds also have activity against the two Trypanosoma species, Trypanosoma brucei and Trypanosoma gambiense, their scaffold could be associated with a broader antiparasitic activity.

Photochemical and Photobiological Properties of Pyridyl-pyrazol(in)e-Based Ruthenium(II) Complexes with Sub-micromolar Cytotoxicity for Phototherapy

The discovery of new light-triggered prodrugs based on ruthenium (II) complexes is a promising approach for photoactivated chemotherapy (PACT). The light-mediated activation of "strained" Ru(II) polypyridyl complexes resulted in ligand release and produced a ligand-deficient metal center capable of forming covalent adducts with biomolecules such as DNA. Based on the strategy of exploiting structural distortion to activate photochemistry, biologically active small molecules were coordinated to a Ru(II) scaffold to create light-triggered dual-action agents. Thirteen new Ru(II) complexes with pyridyl-pyrazol(in)e ligands were synthesized, and their photochemical reactivity and anticancer properties were investigated. Isomeric bidentate ligands were investigated, where "regular" ligands (where the coordinated nitrogens in the heterocycles are linked by C-C atoms) were compared to "inverse" isomers (where the coordinated nitrogens in the heterocycles are linked by C-N atoms). Coordination of the regular 3-(pyrid-2-yl)-pyrazol(in)es to a Ru(II) bis-dimethylphenanthroline scaffold yielded photoresponsive compounds with promising photochemical and biological properties, in contrast to the inverse 1-(pyrid-2-yl)-pyrazolines. The introduction of a phenyl ring to the 1N-pyrazoline cycle increased the distortion in complexes and improved ligand release upon light irradiation (470 nm) up to 5-fold in aqueous media. Compounds 1-8, containing pyridyl-pyrazol(in)e ligands, were at least 20-80-fold more potent than the parent pyridyl-pyrazol(in)es, and exhibited biological activity in the dark, with half-maximal inhibitory concentration (IC₅₀) values ranging from 0.2 to 7.6 μM in the HL60 cell line, with complete growth inhibition upon light irradiation. The diversification of coligands and introduction of a carboxylic acid into the Ru(II) complex resulted in compounds 9-12, with up to 146-fold improved phototoxicity indices compared with complexes 1-8.

Pyrazoline Hybrids as Promising Anticancer Agents: An Up-to-Date Overview

Pyrazolines are five-membered heterocycles possessing two adjacent nitrogens. They have attracted significant attention from organic and medicinal chemists due to their potent biological activities and the numerous possibilities for structural diversification. In the last decade, they have been intensively studied as targets for potential anticancer therapeutics, producing a steady yearly rise in the number of published research articles. Many pyrazoline derivatives have shown remarkable cytotoxic activities in the form of heterocyclic or non-heterocyclic based hybrids, such as with coumarins, triazoles, and steroids. The enormous amount of related literature in the last 5 years prompted us to collect all these published data from screening against cancer cell lines, or protein targets like EGFR and structure activity relationship studies. Therefore, in the present review, a comprehensive account of the compounds containing the pyrazoline nucleus will be provided. The chemical groups and the structural modifications responsible for the activity will be highlighted. Moreover, emphasis will be given on recent examples from the literature and on the work of research groups that have played a key role in the development of this field.

Recent advancements in the development of bioactive pyrazoline derivatives

Pyrazolines remain privileged heterocycles in drug discovery. 2-Pyrazoline scaffold has been proven as a ubiquitous motif which is present in a number of pharmacologically important drug molecules such as antipyrine, ramifenazone, ibipinabant, axitinib etc. They have been widely explored by the scientific community and are reported to possess wide spectrum of biological activities. For combating unprecedented diseases and worldwide increasing drug resistance, 2-pyrazoline has been tackled as a fascinating pharmacophore to generate new molecules with improved potency and lesser toxicity along with desired pharmacokinetic profile. This review aims to summarizes various recent advancements in the medicinal chemistry of pyrazoline based compounds with the following objectives: (1) To represent inclusive data on pyrazoline based marketed drugs as well as therapeutic candidates undergoing preclinical and clinical developments; (2) To discuss recent advances in the medicinal chemistry of pyrazoline derivatives with their numerous biological significances for the eradication of various diseases; (3) Summarizes structure-activity relationships (SAR) including in silico and mechanistic studies to afford ideas for the design and development of novel compounds with desired therapeutic implications.

Privileged Structures in the Design of Potential Drug Candidates for Neglected Diseases

Background:

Privileged motifs are recurring in a wide range of biologically active compounds that reach different pharmaceutical targets and pathways and could represent a suitable start point to access potential candidates in the neglected diseases field. The current therapies to treat these diseases are based in drugs that lack of the desired effectiveness, affordable methods of synthesis and allow a way to emergence of resistant strains. Due the lack of financial return, only few pharmaceutical companies have been investing in research for new therapeutics for neglected diseases (ND).

Methods:

Based on the literature search from 2002 to 2016, we discuss how six privileged motifs, focusing phthalimide, isatin, indole, thiosemicarbazone, thiazole, and thiazolidinone are particularly recurrent in compounds active against some of neglected diseases.

Results:

It was observed that attention was paid particularly for Chagas disease, malaria, tuberculosis, schistosomiasis, leishmaniasis, dengue, African sleeping sickness (Human African Trypanosomiasis - HAT) and toxoplasmosis. It was possible to verify that, among the ND, antitrypanosomal and antiplasmodial activities were between the most searched. Besides, thiosemicarbazone moiety seems to be the most versatile and frequently explored scaffold. As well, phthalimide, isatin, thiazole, and thiazolidone nucleus have been also explored in the ND field.

Conclusion:

Some described compounds, appear to be promising drug candidates, while others could represent a valuable inspiration in the research for new lead compounds.

Thiazolidinone/thiazole based hybrids - New class of antitrypanosomal agents

Different compounds have been investigated as potent drugs for trypanosomiasis treatment, but no new drug has been marketed in the past 3 decades. 4-Thiazolidinone/thiazole as privileged structures and thiosemicarbazides cyclic analogs are well known scaffolds in novel antitrypanosomal agent design. We present here the design and synthesis of new hybrid molecules bearing thiazolidinone/thiazole cores linked by the hydrazone group with various molecular fragments. Structure optimization led to compounds with phenyl-indole or phenyl-imidazo[2,1-b][1,3,4]thiadiazole moieties showing excellent antitrypanosomal activity towards Trypanosoma brucei brucei and Trypanosoma brucei gambiense. Biological study allowed identifying compounds with the submicromolar levels of IC₅₀, good selectivity indexes and relatively low cytotoxicity upon human primary fibroblasts as well as low acute toxicity.

Novel symmetric bis-benzimidazoles: Synthesis, DNA/RNA binding and antitrypanosomal activity

The novel benzimidazol-2-yl-fur-5-yl-(1,2,3)-triazolyl dimeric series with aliphatic and aromatic central linkers was successfully prepared with the aim of assessing binding affinity to DNA/RNA and antitrypanosomal activity. UV-Visible spectroscopy, thermal denaturation showed interaction of heterocyclic bis-amidines with ctDNA. Circular dichroism studies indicated uniform orientation of heterocyclic bis-amidines along the chiral double helix axis, revealing minor groove binding as the dominant binding mode. The amidino fragment and 1,4-bis(oxymethylene)phenyl spacer were the main determinants of activity against Trypanosoma brucei. The bis-benzimidazole imidazoline 15c, which had antitrypanosomal potency in the submicromolar range and DNA interacting properties, emerged as a candidate for further structural optimization to obtain more effective agents to combat trypanosome infections.

Synthesis of 5-enamine-4-thiazolidinone derivatives with trypanocidal and anticancer activity

A series of novel 2-(5-aminomethylene-4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropionic acid ethyl esters has been synthesized. Target compounds were evaluated for their trypanocidal activity towards Trypanosoma brucei brucei and Trypanosoma brucei gambiense. Several hit-compounds (8, 10, 12) inhibited growth of the parasites at sub-micromolar concentrations (IC₅₀ 0.027-1.936 µM) and showed significant selectivity indices (SI = 108-1396.2) being non-toxic towards the human primary fibroblasts. The screening of anticancer activity in vitro within NCI DTP protocol allowed to identify active 2-(5-{[5-(2,4-dichlorobenzyl)-thiazol-2-ylamino]-methylene}-4-oxo-2-thioxothiazolidin-3-yl)-3-phenylpropionic acid ethyl ester 14 that demonstrated inhibition against all 59 human tumor cell lines with the average GI₅₀ value of 2.57 μM. It was established that the activity type (antitrypanosomal or anticancer) as well as its level depends on the character of enamine fragment in the C5 position of thiazolidinone core.

Synthesis, anti-bacterial and anti-protozoal activities of amidinobenzimidazole derivatives and their interactions with DNA and RNA

Amidinobenzimidazole derivatives connected to 1-aryl-substituted 1,2,3-triazole through phenoxymethylene linkers 7a-7e, 8a-8e, and 9a-9e were designed and synthesised with the aim of evaluating their anti-bacterial and anti-trypanosomal activities and DNA/RNA binding affinity. Results from anti-bacterial evaluations of antibiotic-resistant pathogenic bacteria revealed that both o-chlorophenyl-1,2,3-triazole and N-isopropylamidine moieties in 8c led to strong inhibitory activity against resistant Gram-positive bacteria, particularly the MRSA strain. Furthermore, the non-substituted amidine and phenyl ring in 7a induced a marked anti-bacterial effect, with potency against ESBL-producing Gram-negative E. coli better than those of the antibiotics ceftazidime and ciprofloxacin. UV-Vis and CD spectroscopy, as well as thermal denaturation assays, indicated that compounds 7a and 8c showed also binding affinities towards ctDNA. Anti-trypanosomal evaluations showed that the p-methoxyphenyl-1,2,3-triazole moiety in 7b and 9b enhanced inhibitory activity against T. brucei, with 8b being more potent than nifurtimox, and having minimal toxicity towards mammalian cells.

Isothiochromenothiazoles-A Class of Fused Thiazolidinone Derivatives with Established Anticancer Activity That Inhibits Growth of Trypanosoma brucei brucei

Recently, thiazolidinone derivatives have been widely studied as antiparasitic agents. Previous investigations showed that fused 4-thiazolidinone derivatives (especially thiopyranothiazoles) retain pharmacological activity of their synthetic precursors-simple 5-ene-4-thiazolidinones. A series of isothiochromeno[4a,4-d][1,3] thiazoles was investigated in an in vitro assay towards bloodstream forms of Trypanosoma brucei brucei. All compounds inhibited parasite growth at concentrations in the micromolar range. The established low acute toxicity of this class of compounds along with a good trypanocidal profile indicates that isothiochromenothiazole derivatives may be promising for designing new antitrypanosomal drugs.

Development of Predictive QSAR Models of 4-Thiazolidinones Antitrypanosomal Activity Using Modern Machine Learning Algorithms

This paper presents novel QSAR models for the prediction of antitrypanosomal activity among thiazolidines and related heterocycles. The performance of four machine learning algorithms: Random Forest regression, Stochastic gradient boosting, Multivariate adaptive regression splines and Gaussian processes regression have been studied in order to reach better levels of predictivity. The results for Random Forest and Gaussian processes regression are comparable and outperform other studied methods. The preliminary descriptor selection with Boruta method improved the outcome of machine learning methods. The two novel QSAR-models developed with Random Forest and Gaussian processes regression algorithms have good predictive ability, which was proved by the external evaluation of the test set with corresponding Q²_ext =0.812 and Q²_ext =0.830. The obtained models can be used further for in silico screening of virtual libraries in the same chemical domain in order to find new antitrypanosomal agents. Thorough analysis of descriptors influence in the QSAR models and interpretation of their chemical meaning allows to highlight a number of structure-activity relationships. The presence of phenyl rings with electron-withdrawing atoms or groups in para-position, increased number of aromatic rings, high branching but short chains, high HOMO energy, and the introduction of 1-substituted 2-indolyl fragment into the molecular structure have been recognized as trypanocidal activity prerequisites.

5-Ene-4-thiazolidinones - An efficient tool in medicinal chemistry

The presented review is an attempt to summarize a huge volume of data on 5-ene-4-thiazolidinones being a widely studied class of small molecules used in modern organic and medicinal chemistry. The manuscript covers approaches to the synthesis of 5-ene-4-thiazolidinone derivatives: modification of the C5 position of the basic core; synthesis of the target compounds in the one-pot or multistage reactions or transformation of other related heterocycles. The most prominent pharmacological profiles of 5-ene derivatives of different 4-thiazolidinone subtypes belonging to hit-, lead-compounds, drug-candidates and drugs as well as the most studied targets have been discussed. Currently target compounds (especially 5-en-rhodanines) are assigned as frequent hitters or pan-assay interference compounds (PAINS) within high-throughput screening campaigns. Nevertheless, the crucial impact of the presence/nature of C5 substituent (namely 5-ene) on the pharmacological effects of 5-ene-4-thiazolidinones was confirmed by the numerous listed findings from the original articles. The main directions for active 5-ene-4-thiazolidinones optimization have been shown: i) complication of the fragment in the C5 position; ii) introduction of the substituents in the N3 position (especially fragments with carboxylic group or its derivatives); iii) annealing in complex heterocyclic systems; iv) combination with other pharmacologically attractive fragments within hybrid pharmacophore approach. Moreover, the utilization of 5-ene-4-thiazolidinones in the synthesis of complex compounds with potent pharmacological application is described. The chemical transformations cover mainly the reactions which involve the exocyclic double bond in C5 position of the main core and correspond to the abovementioned direction of the 5-ene-4-thiazolidinone modification.

Recent developments with rhodanine as a scaffold for drug discovery

INTRODUCTION

Rhodanines, as one of the 4-thiazolidinones subtypes, are recognized as privileged heterocycles in medicinal chemistry. The main achievements include the development of drug-like molecules with numerous biological activities as well as approved drugs. Among rhodanines, 5-ene-rhodanines are of special interest, and are often claimed as pan assay interference compounds due to Michael acceptor functionality. Areas covered: Herein, the synthetic protocols for rhodanines and their transformation are reviewed. Biological activity is briefly discussed as well as biotargets, mode of actions and optimization directions. Furthermore, the utilization of 5-ene-rhodanines in Michael additions are discussed while both pro and contra arguments have been outlined within medicinal chemistry application. Expert opinion: Rhodanines remain privileged heterocycles in drug discovery. They are accessible building blocks for optimization and transformation into related heterocycles, simplified analogues and fused heterocycles with a thiazolidine framework. Michael acceptor functionality, as well as the thesis about low selectivity towards biotargets of rhodanines, must be confirmed experimentally and it cannot be based on just the presence of conjugated α,β-unsaturated carbonyl. Moreover, the positive aspects of Michael acceptors must be considered as well as their multitarget properties. New criteria for target affinity must be found. In conclusion, rhodanines are generally not problematic per se.

Synthesis and biological evaluation of N-cyanoalkyl-, N-aminoalkyl-, and N-guanidinoalkyl-substituted 4-aminoquinoline derivatives as potent, selective, brain permeable antitrypanosomal agents

Current drugs against human African trypanosomiasis (HAT) suffer from several serious drawbacks. The search for novel, effective, brain permeable, safe, and inexpensive antitrypanosomal compounds is therefore an urgent need. We have recently reported that the 4-aminoquinoline derivative huprine Y, developed in our group as an anticholinesterasic agent, exhibits a submicromolar potency against Trypanosoma brucei and that its homo- and hetero-dimerization can result in to up to three-fold increased potency and selectivity. As an alternative strategy towards more potent smaller molecule anti-HAT agents, we have explored the introduction of ω-cyanoalkyl, ω-aminoalkyl, or ω-guanidinoalkyl chains at the primary amino group of huprine or the simplified 4-aminoquinoline analogue tacrine. Here, we describe the evaluation of a small in-house library and a second generation of newly synthesized derivatives, which has led to the identification of 13 side chain modified 4-aminoquinoline derivatives with submicromolar potencies against T. brucei. Among these compounds, the guanidinononyltacrine analogue 15e exhibits a 5-fold increased antitrypanosomal potency, 10-fold increased selectivity, and 100-fold decreased anticholinesterasic activity relative to the parent huprine Y. Its biological profile, lower molecular weight relative to dimeric compounds, reduced lipophilicity, and ease of synthesis, make it an interesting anti-HAT lead, amenable to further optimization to eliminate its remaining anticholinesterasic activity.

Design, synthesis, molecular docking and biological evaluation of thiophen-2-iminothiazolidine derivatives for use against Trypanosoma cruzi

In this study, we designed and synthesized a series of thiophen-2-iminothiazolidine derivatives from thiophen-2-thioureic with good anti-Trypanosoma cruzi activity. Several of the final compounds displayed remarkable trypanocidal activity. The ability of the new compounds to inhibit the activity of the enzyme cruzain, the major cysteine protease of T. cruzi, was also explored. The compounds 3b, 4b, 8b and 8c were the most active derivatives against amastigote form, with significant IC50 values between 9.7 and 6.03μM. The 8c derivative showed the highest potency against cruzain (IC50=2.4μM). Molecular docking study showed that this compound can interact with subsites S1 and S2 simultaneously, and the negative values for the theoretical energy binding (Eb=-7.39kcal·mol(-1)) indicates interaction (via dipole-dipole) between the hybridized sulfur sp(3) atom at the thiazolidine ring and Gly66. Finally, the results suggest that the thiophen-2-iminothiazolidines synthesized are important lead compounds for the continuing battle against Chagas disease.

Synthetic approaches, structure activity relationship and biological applications for pharmacologically attractive pyrazole/pyrazoline-thiazolidine-based hybrids

The features of the chemistry of 4-thiazolidinone and pyrazole/pyrazolines as pharmacologically attractive scaffolds were described in a number of reviews in which the main approaches to the synthesis of mentioned heterocycles and their biological activity were analyzed. However, the pyrazole/pyrazoline–thiazolidine-based hybrids as biologically active compounds is poorly discussed in the context of pharmacophore hybrid approach. Therefore, the purpose of this review is to summarize the data about the synthesis and modification of heterocyclic systems with thiazolidine and pyrazoline or pyrazole fragments in molecules as promising objects of modern bioorganic and medicinal chemistry. The description of biological activity was focused on SAR analysis and mechanistic insights of mentioned hybrids.

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Synthesis and chemistry of pyrazole/pyrazoline–thiazolidine-based hybrids.

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A diverse spectrum of pyrazole/pyrazoline–thiazolidine-based hybrids biological activities has been presented.

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Structure activity relationship of pyrazole/pyrazoline–thiazolidine-based hybrids for different activities has been discussed.

Multicomponent reaction-based synthesis and biological evaluation of tricyclic heterofused quinolines with multi-trypanosomatid activity

Human African trypanosomiasis (HAT), Chagas disease and leishmaniasis, which are caused by the trypanosomatids Trypanosoma brucei, Trypanosoma cruzi and Leishmania species, are among the most deadly neglected tropical diseases. The development of drugs that are active against several trypanosomatids is appealing from a clinical and economic viewpoint, and seems feasible, as these parasites share metabolic pathways and hence might be treatable by common drugs. From benzonapthyridine 1, an inhibitor of acetylcholinesterase (AChE) for which we have found a remarkable trypanocidal activity, we have designed and synthesized novel benzo[h][1,6]naphthyridines, pyrrolo[3,2-c]quinolines, azepino[3,2-c]quinolines, and pyrano[3,2-c]quinolines through 2–4-step sequences featuring an initial multicomponent Povarov reaction as the key step. To assess the therapeutic potential of the novel compounds, we have evaluated their in vitro activity against T. brucei, T. cruzi, and Leishmania infantum, as well as their brain permeability, which is of specific interest for the treatment of late-stage HAT. To assess their potential toxicity, we have determined their cytotoxicity against rat myoblast L6 cells and their AChE inhibitory activity. Several tricyclic heterofused quinoline derivatives were found to display an interesting multi-trypanosomatid profile, with one-digit micromolar potencies against two of these parasites and two-digit micromolar potency against the other. Pyranoquinoline 39, which displays IC₅₀ values of 1.5 μM, 6.1 μM and 29.2 μM against T. brucei, L. infantum and T. cruzi, respectively, brain permeability, better drug-like properties (lower lipophilicity and molecular weight and higher CNS MPO desirability score) than hit 1, and the lowest AChE inhibitory activity of the series (IC₅₀ > 30 μM), emerges as an interesting multi-trypanosomatid lead, amenable to further optimization particularly in terms of its selectivity index over mammalian cells.

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Novel classes of tricyclic heterofused quinolines have been synthesized.

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Their 2–4-step syntheses involve a multicomponent Povarov reaction as the key step.

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Some compounds exhibit single digit micromolar potencies against 2 trypanosomatids.

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All compounds with multi-trypanosomatid activity can cross the blood–brain barrier.

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Most compounds with multi-trypanosomatid activity have drug like properties.

Synthesis of Novel 4-Thiazolidinones Linked by an Aryl Spacer to a 1,2,4-Triazine Moiety

A series of potentially biologically active hydrazones, Schiff's base and hybrid thiazolidine-triazine derivatives have been prepared from 4-[(5,6-diphenyl-1,2,4-triazin-3-yl)thio]-benzaldehyde. The latter was prepared by reacting 5,6-diphenyl-1,2,4-triazine-3(2H)-thione with 4-fluorobenzaldehyde. The derivatives were then prepared by condensation of the aldehyde with hydrazines, aniline and various thiazolidin-4-ones. Their structures were established by C,H,N analyses, IR and NMR spectra.

EGFR/HER-2 inhibitors: synthesis, biological evaluation and 3D-QSAR analysis of dihydropyridine-containing thiazolinone derivatives

A series of dihydropyridin containing thiazolinone derivatives (4a–4r) have been designed, synthesized and their biological activities were also evaluated as potential EGFR and HER-2 kinase inhibitors and tumor cell antiproliferation.