Synthesis and evaluation of anti-Toxoplasma gondii and antimicrobial activities of thiosemicarbazides, 4-thiazolidinones and 1,3,4-thiadiazoles

Identification of (E)-1-((1H-indol-3-yl)methylene)-4-substitute-thiosemicarbazones as potential anti-hepatic fibrosis agents

Liver fibrosis remains a global health challenge due to its rapidly rising prevalence and limited treatment options. The orphan nuclear receptor Nur77 has been implicated in regulation of autophagy and liver fibrosis. Targeting Nur77-mediated autophagic flux may thus be a new promising strategy against hepatic fibrosis. In this study, we synthesized four types of Nur77-based thiourea derivatives to determine their anti-hepatic fibrosis activity. Among the synthesized thiourea derivatives, 9e was the most potent inhibitor of hepatic stellate cells (HSCs) proliferation and activation. This compound could directly bind to Nur77 and inhibit TGF-β1-induced α-SMA and COLA1 expression in a Nur77-dependent manner. In vivo, 9e significantly reduced CCl4-mediated hepatic inflammation response and extracellular matrix (ECM) production, revealing that 9e is capable of blocking the progression of hepatic fibrosis. Mechanistically, 9e induced Nur77 expression and enhanced autophagic flux by inhibiting the mTORC1 signaling pathway in vitro and in vivo. Thus, the Nur77-targeted lead 9e may serve as a promising candidate for treatment of chronic liver fibrosis.

Naphthyl bearing 1,3,4-thiadiazoleacetamides targeting the parasitic folate pathway as anti-infectious agents: in silico, synthesis, and biological approach

Malaria is still a complex and lethal parasitic infectious disease, despite the availability of effective antimalarial drugs. Resistance of malaria parasites to current treatments necessitates new antimalarials targeting P. falciparum proteins. The present study reported the design and synthesis of a series of a 2-(4-substituted piperazin-1-yl)-N-(5-((naphthalen-2-yloxy)methyl)-1,3,4-thiadiazol-2-yl)acetamide hybrids for the inhibition of Plasmodium falciparum dihydrofolate reductase (PfDHFR) using computational biology tools followed by chemical synthesis, structural characterization, and functional analysis. The synthesized compounds were evaluated for their in vitro antimalarial activity against CQ-sensitive PfNF54 and CQ-resistant PfW2 strain. Compounds T5 and T6 are the most active compounds having anti-plasmodial activity against PfNF54 with IC50 values of 0.94 and 3.46 μM respectively. Compound T8 is the most active against the PfW2 strain having an IC50 of 3.91 μM. Further, these active hybrids (T5, T6, and T8) were also evaluated for enzyme inhibition assay against PfDHFR. All the tested compounds were non-toxic against the Hek293 cell line with good selectivity indices. Hemolysis assay also showed non-toxicity of these compounds on normal uninfected human RBCs. In silico molecular docking studies were carried out in the binding pocket of both the wild-type and quadruple mutant Pf-DHFR-TS to gain further insights into probable modes of action of active compounds. ADME prediction and physiochemical properties support their drug-likeness. Additionally, they were screened for antileishmanial activity against L. donovani promastigotes to explore broader applications. Thus, this study provides molecular frameworks for developing potent antimalarials and antileishmanial agents.

Vetting of New 2,5-Bis (2,2,2-trifluoroethoxy) Phenyl-Linked 1,3-Thiazolidine-4-one Derivatives as AURKA and VEGFR-2 Inhibitor Antiglioma Agents Assisted with In Vitro and In Silico Studies

The bioactivity of 1,3-thiazolidin-4-one derivatives with a 2,5-bis (2,2,2-trifluoroethoxy) phenyl moiety was computationally developed and evaluated. All of the synthesized thiazolidin-4-one derivatives have their chemical structures characterized using a variety of methods, including nuclear magnetic resonance (NMR) (1H and 13C), high-resolution mass spectrometry (HRMS), and Fourier transform infrared (FTIR) radiation. A human glioblastoma cancer cell line (LN229) was used to investigate the purified derivatives' antiglioma cancer efficacy. By using the MTT, colony formation, and tunnel tests, respectively, the in vitro cytotoxic and apoptotic effects of these compounds were assessed. Thiazolidin-4-one derivatives 5b, 5c, and 5e were discovered to have the best efficacy against glioblastoma cells out of all of these compounds. The derivatives 5b, 5c, and 5e were determined to have respective IC50 values of 9.48, 12.16, and 6.43 g/mL. Computation results showed that the bioactivity evaluations of the compounds were quite significant. The bridging -NH group forms a hydrogen bond with Glu 260 of synthesized derivatives 5b, 5c, 5d, 5e, and 5h. The vast majority of freshly developed compounds obeyed Lipinski's rule of five, which is in line with the results that the ADMET model predicted. Additionally, molecular docking evaluation and molecular dynamics simulation investigations against the proteins AURKA and VEGFR-2 were conducted for the synthesized compounds to incorporate both in silico and in vitro data. The findings revealed that almost all of the compounds had considerable binding to AURKA and VEGFR-2 residues, with binding affinities ranging from -9.8 to -7.9 kcal/mol. Consequently, the results of the biological investigations and the docking scores demonstrated that thiazolidinone molecule 5e containing 4-chlorophenyl substituent may be considered as a potential moiety for glioblastoma cancer treatments.

Evaluation of long-term immunity and protection against T. gondii after immunization with multivalent recombinant chimeric T. gondii proteins

Toxoplasmosis caused by the opportunistic, cosmopolitan protozoan Toxoplasma gondii is one of the most common parasitoses in the world. Although it may prove dangerous or even fatal for immunocompromised individuals, immunoprophylaxis for humans is still nonexistent. Thus, the aim of the current work was to assess the ability of two immunogenic recombinant chimeric T. gondii proteins, SAG2-GRA1-ROP1 (SGR) and SAG1-MIC1-MAG1-GRA2 (SMMG), selected in previous experiments to induce long-lasting immunity when administered with a safe adjuvant. Thus, the determination of immunological parameters and parasite challenge were performed both two weeks after the last boost injection and 6 months postvaccination. Both experimental vaccines triggered specific humoral and cellular responses in immunized C3H/HeOuJ male mice, characterized by the production of specific IgG (IgG1/IgG2a) antibodies in vivo and the synthesis of key Th1/Th2 cytokines by Toxoplasma lysate antigen-stimulated splenocytes in vitro. Although the levels of specific antibodies and cytokine release were in most cases lower six months postimmunization, the protection rates conferred by the vaccination were comparable regardless of the time after the administration of the last vaccine dose. The results indicate that both preparations induce long-lasting immunity, which makes them attractive candidates for further research aimed at boosting their immunogenicity and immunoprotective capacity.

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.

TZD-Based Hybrid Molecules Act as Dual Anti-Mycobacterium tuberculosis and Anti-Toxoplasma gondii Agents

Two distinct intracellular pathogens, namely Mycobacterium tuberculosis (Mtb) and Toxoplasma gondii (Tg), cause major public health problems worldwide. In addition, serious and challenging health problems of co-infections of Tg with Mtb have been recorded, especially in developing countries. Due to this fact, as well as the frequent cases of resistance to the current drugs, novel anti-infectious therapeutics, especially those with dual (anti-Tg and anti-Mtb) modes of action, are needed. To address this issue, we explored the anti-Tg potential of thiazolidinedione-based (TZD-based) hybrid molecules with proven anti-Mtb potency. Several TZD hybrids with pyridine-4-carbohydrazone (PCH) or thiosemicarbazone (TSC) structural scaffolds were more effective and more selective than sulfadiazine (SDZ) and trimethoprim (TRI). Furthermore, all of these molecules were more selective than pyrimethamine (PYR). Further studies for the most potent TZD-TSC hybrids 7, 8 and 10 and TZD-PCH hybrid molecule 2 proved that these compounds are non-cytotoxic, non-genotoxic and non-hemolytic. Moreover, they could cross the blood-brain barrier (BBB), which is a critical factor linked with ideal anti-Tg drug development. Finally, since a possible link between Tg infection and the risk of glioblastoma has recently been reported, the cytotoxic potential of TZD hybrids against human glioblastoma cells was also evaluated. TZD-PCH hybrid molecule 2 was found to be the most effective, with an IC₅₀ of 19.36 ± 1.13 µg/mL against T98G cells.

New class of fused [3,2-b][1,2,4]triazolothiazoles for targeting glioma in vitro

Glioma is aggressive malignant tumor with limited therapeutic interventions. Herein we report the synthesis of fused bicyclic 1,2,4-triazolothiazoles by a one-pot multi-component approach and their activity against C6 rat and LN18 human glioma cell lines. The target compounds 2-(6-phenylthiazolo[3,2-b][1,2,4]triazol-2-yl) isoindoline-1,3-diones and (E)-1-phenyl-N-(6-phenylthiazolo[3,2-b][1,2,4]triazol-2-yl) methanimines were obtained by the reaction of 5-amino-4H-1,2,4-triazole-3-thiol with substituted phenacyl bromide, phthalic anhydride, and different aromatic aldehydes in EtOH/HCl under reflux conditions. In C6 rat glioma cell lines, compounds 4g and 6i showed good cytotoxic activity with IC₅₀ values of 8.09 and 8.74 μM, respectively, resulting in G1 and G2-M phase arrest of the cell cycle and activation of apoptosis by modulating phosphorylation of ERK and AKT pathway.

Exploring the Antiparasitic Activity of Tris-1,3,4-Thiadiazoles against Toxoplasma gondii-Infected Mice

Nitrogen-containing atoms in their core structures have been exclusive building blocks in drug discovery and development. One of the most significant and well-known heterocycles is the 1,3,4-thidiazole nucleus, which is found in a wide range of natural products and therapeutic agents. In the present work, certain tris-1,3,4-thiadiazole derivatives (6, 7) were synthesized through a multi-step synthesis approach. All synthesized compounds were characterized using different spectroscopic tools. Previously, thiadiazole compounds as anti-Toxoplasma gondii agents have been conducted and reported in vitro. However, this is the first study to test the anti-Toxoplasma gondii activity of manufactured molecular hybrids thiadiazole in an infected mouse model with the acute RH strain of T. gondii. All the observed results demonstrated compound (7)’s powerful activity, with a considerable reduction in the parasite count reaching 82.6% in brain tissues, followed by liver and spleen tissues (65.35 and 64.81%, respectively). Inflammatory and anti-inflammatory cytokines assessments proved that Compound 7 possesses potent antiparasitic effect. Furthermore, docking tests against TgCDPK1 and ROP18 kinase (two major enzymes involved in parasite invasion and egression) demonstrated compound 7’s higher potency compared to compound 6 and megazol. According to the mentioned results, tris-1,3,4-thiadiazole derivatives under test can be employed as potent antiparasitic agents against the acute RH strain of T. gondii.

Synthesis and Antiproliferative Activity of New Thiosemicarboxamide Derivatives

To discover new anticancer agents, two series of thiosemicarboxamide derivatives were synthesized and evaluated for their antiproliferative activity against human cancer cells in vitro. Most target compounds (especially 3f, 3g, and 3h) exhibit potent antiproliferative activity against HeLa cells. Importantly, compound 3h, bearing a 4-methylphenyl substituent at N position of thiourea moiety, has significant and broad-spectrum inhibitory activities against cancer cells (HepG2, HeLa, MDA-MB231, A875, and H460 cells) with low IC₅₀ values (<5.0 μM) and shows low toxicity to normal LO2 and MRC-5 cells. Further studies show that compound 3h exerts high inhibitory activity in cancer cells by inducing the G2/M-phase arrest of cancer cells. Collectively, this study presents compound 3h as a new entity for the development of cell cycle arrest inducers for the treatment of cancer.

In vitro evaluation of new 4-thiazolidinones on invasion and growth of Toxoplasma gondii

Treatments for toxoplasmosis such as pyrimethamine have shown numerous side effects. It has been reported that the likelihood of relapse associated with pyrimethamine-based therapy in patients with HIV and toxoplasmic encephalitis (TE) can have significant implications, even for patients who often develop new lesions in areas of the brain previously free of infection. This led us to research for new agents against Toxoplasma gondii. Recent findings have shown the potent biological activity of 4-thiazolidinones. We proposed to design and synthesize a new series of 2-hydrazono-4-thiazolidinones derivatives to evaluate the in vitro growth inhibition effect on T. gondii. The growth rates of T. gondii tachyzoites in Human Foreskin Fibroblast (HFF) cell culture were identified by two in vitro methodologies. The first one was by fluorescence in which green fluorescent RH parasites and cherry-red fluorescent ME49 parasites were used. The second one was a colorimetric methodology using β-Gal parasites of the RH strain constitutively expressing the enzyme beta-galactosidase. The 4-thiazolidinone derivatives 1B, 2B and 3B showed growth inhibition at the same level of Pyrimethamine. These compounds showed IC50 values of 1B (0.468-0.952 μM), 2B (0.204-0.349 μM) and 3B (0.661-1.015 μM) against T. gondii. As a measure of cytotoxicity the compounds showed a TD50 values of: 1B (60 μM), 2B (206 μM) and 3B (125 μM). The in vitro assays and molecular modeling results suggest that these compounds could act as possible inhibitors of the Calcium-Dependent Protein Kinase 1 of T. gondii. Further, our results support the fact that of combining appropriate detection technologies, combinatorial chemistry and computational biology is a good strategy for efficient drug discovery. These compounds merit in vivo analysis for anti-parasitic drug detection.

4-Arylthiosemicarbazide derivatives as a new class of tyrosinase inhibitors and anti-Toxoplasma gondii agents

We report herein anti-proliferation effects of 4-arylthiosemicarbazides, with a cyclopentane substitution at N1 position, on highly virulent RH strain of Toxoplasma gondii. Among them, the highest in vitro anti-Toxoplasma activity was found with the meta-iodo derivative. Further experiments demonstrated inhibitory effects of thiosemicarbazides on tyrosinase (Tyr) activity, and good correlation was found between percentage of Tyr inhibition and IC_50Tg. To confirm the concept that thiosemicarbazides are able to disrupt tyrosine metabolism in Toxoplasma tachyzoites, the most potent Tyr inhibitors were tested for their efficacy of T. gondii growth inhibition. All of them significantly reduced the number of tachyzoites in the parasitophorous vacuoles (PVs) compared to untreated cells, as well as inhibited tachyzoites growth by impeding cell division. Collectively, these results indicate that compounds with the thiosemicarbazide scaffold are able to disrupt tyrosine metabolism in Toxoplasma tachyzoites by deregulation of their crucial enzyme tyrosine hydroxylase (TyrH).

1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b-12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b-12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

Antitubercular properties of thiazolidin-4-ones - A review

Thiazolidin-4-one scaffold has great potential for medicinal chemistry and is of interest to scientists in view of wide spectrum of biological activity. This scaffold is often used for designing of small molecules with various biological activity including antituberculosis activity. The presented review is an attempt to gather, analyze and systemize data about antitubercular properties of thiazolidine-4-ones from two last decades. Some of them have promising antitubercular activity which is significantly higher than that of the reference drugs. Among them compounds 82c, 82d and 84 that were active against M. tuberculosis H37Rv strain with MICs in the range of 0.05-0.2 μg/mL and compound 108 exhibited activity with MIC = 0.36 μM. Compounds 115a-115c and 116a-116c were very effective against M. tuberculosis H37Ra with MIC values in the range of 0.031-0.125 μg/mL. Acidomycin was showed activity against seven MDR M. tuberculosis strains with MICs in the range of 0.6-0.62 μM and against two XDR M. tuberculosis strains with MICs 0.096 and 1.2 μM. The structure-activity relationship (SAR) of some groups of compounds, as well as some potential molecular targets were also discussed.

Neto JDB, de Abreu FC, Figueiredo IM, Carinhanha C. Santos J, Pessoa CDÓ, da Silva-Júnior EF, de Araújo-Júnior JX, M. de Aquino T. Synthesis of hybrids thiazole–quinoline, thiazole–indole and their analogs: in vitro anti-proliferative effects on cancer cell lines, DNA binding properties and molecular modeling

A quinoline–thiazole hybrid was synthesized, which showed cytotoxicity against the HL-60 cell line. Electrochemical and spectroscopic experiments suggested DNA as the biological target.

Naphthalimide Imidazolium-Based Supramolecular Hydrogels as Bioimaging and Theranostic Soft Materials

1,8-Naphthalimide-based imidazolium salts differing for the alkyl chain length and the nature of the anion were synthesized and characterized to obtain fluorescent probes for bioimaging applications. First, their self-assembly behavior and gelling ability were investigated in water and water/dimethyl sulfoxide binary mixtures. Only salts having longer alkyl chains were able to give supramolecular hydrogels, whose properties were investigated by using a combined approach of fluorescence, resonance light scattering, and rheology measurements. Morphological information was obtained by scanning electron microscopy. In addition, conductive properties of organic salts in solution and gel state were analyzed. Imidazolium salts were successfully tested for their possible application as bioimaging and cytotoxic agents toward three cancer cell lines and a nontumoral epithelial cell line. Characterization of their behavior was performed by MTT and cell-based assays. Finally, the biological activity of hydrogels was also investigated. Collectively, our findings showed that naphthalimide-based imidazolium salts are promising theranostic agents and they were able to preserve their biological properties also in the gel phase.

2-Amino-1,3,4-thiadiazoles as prospective agents in trypanosomiasis and other parasitoses

Parasitic diseases are a serious public health problem affecting hundreds of millions of people worldwide. African trypanosomiasis, American trypanosomiasis, leishmaniasis, malaria and toxoplasmosis are the main parasitic infections caused by protozoan parasites with over one million deaths each year. Due to old medications and drug resistance worldwide, there is an urgent need for new antiparasitic drugs. 1,3,4-Thiadiazoles have been widely studied for medical applications. The chemical, physical and pharmacokinetic properties recommend 1,3,4-thiadiazole ring as a target in drug development. Many scientific papers report the antiparasitic potential of 2-amino-1,3,4-thiadiazoles. This review presents synthetic 2-amino-1,3,4-thiadiazoles exhibiting antitrypanosomal, antimalarial and antitoxoplasmal activities. Although there are insufficient results to state the quality of 2-amino-1,3,4-thiadiazoles as a new class of antiparasitic agents, many reported derivatives can be considered as lead compounds for drug synthesis and a promise for the future treatment of parasitosis and provide a valid strategy for the development of potent antiparasitic drugs.

Synthesis of a New [3-(4-Chlorophenyl)-4-oxo-1,3-thiazolidin-5-ylidene]acetic Acid Derivative

The new methyl [3-(4-chlorophenyl)-2-{[(2,4-dichloro-1,3-thiazol-5-yl)methylidene]hydrazinylidene}-4-oxo-1,3-thiazolidin-5-ylidene]acetate was synthesized from 4-(4-chlorophenyl)-1-(2,4-dichloro-1,3-thiazol-5-yl)methylidene-3-thiosemicarbazide using dimethyl acetylenedicarboxylate as thia-Michael reaction acceptor. New compounds (3 and 4) were characterized by IR, 1H and 13C NMR spectroscopy methods.

Emerging Therapeutic Targets Against Toxoplasma gondii: Update on DNA Repair Response Inhibitors and Genotoxic Drugs

Toxoplasma gondii is the causative agent of toxoplasmosis in animals and humans. This infection is transmitted to humans through oocysts released in the feces of the felines into the environment or by ingestion of undercooked meat. This implies that toxoplasmosis is a zoonotic disease and T. gondii is a foodborne pathogen. In addition, chronic toxoplasmosis in goats and sheep is the cause of recurrent abortions with economic losses in the sector. It is also a health problem in pets such as cats and dogs. Although there are therapies against this infection in its acute stage, they are not able to permanently eliminate the parasite and sometimes they are not well tolerated. To develop better, safer drugs, we need to elucidate key aspects of the biology of T. gondii. In this review, we will discuss the importance of the homologous recombination repair (HRR) pathway in the parasite's lytic cycle and how components of these processes can be potential molecular targets for new drug development programs. In that sense, the effect of different DNA damage agents or HHR inhibitors on the growth and replication of T. gondii will be described. Multitarget drugs that were either associated with other targets or were part of general screenings are included in the list, providing a thorough revision of the drugs that can be tested in other scenarios.

Imidazole derivatives as antiparasitic agents and use of molecular modeling to investigate the structure-activity relationship

Toxoplasmosis is a common parasitic disease caused by Toxoplasma gondii. Limitations of available treatments motivate the search for better therapies for toxoplasmosis. In this study, we synthesized a series of new imidazole derivatives: bis-imidazoles (compounds 1-8), phenyl-substituted 1H-imidazoles (compounds 9-19), and thiopene-imidazoles (compounds 20-26). All these compounds were assessed for in vitro potential to restrict the growth of T. gondii. To explore the structure-activity relationships, molecular analyses and bioactivity prediction studies were performed using a standard molecular model. The in vitro results, in combination with the predictive model, revealed that the imidazole derivatives have excellent selectivity activity against T. gondii versus the host cells. Of the 26 compounds screened, five imidazole derivatives (compounds 10, 11, 18, 20, and 21) shared a specific structural moiety and exhibited significantly high selectivity (> 1176 to > 27,666) towards the parasite versus the host cells. These imidazole derivatives are potential candidates for further studies. We show evidence that supports the antiparasitic action of the imidazole derivatives. The findings are promising in that they reinforce the prospects of imidazole derivatives as alternative and effective antiparasitic therapy as well as providing evidence for a probable biological mechanism.

Synthesis of Novel Fluorine Compounds Substituted-4-thiazolidinones Derived from Rhodanine Drug as Highly Bioactive Probes

Aim and Objective:

It is known that rhodanine drug has various biocidal activities. The aim of this work was to improve the structure of rhodanine drug via alkylation at N, S, and O- centers in addition to the introduction of fluorine atoms. The new fluorinated modified rhodanines 2-16 were evaluated as enzymatic probes for cellobiase activity produced by fungi and as CDK2 inhibitors of tumor cells.

Materials and Methods:

Novel fluorine substituted N-alkyl, S-alkyl and amino-rhodanines were obtained via Hydroxy methylation, Mannich reactions, chlorination and amination of 5-(4'-fluorophenylene)-2-thioxo-thiazolidin-4-one, and the enzymatic effects of cellobiase produced by fungi and /or CDK2 inhibition of tumor cells were evaluated.

Results:

Most of the targets were obtained in high yield and in the form of very pure crystals with characteristic colors. Only compounds 5, 8, 10, 13, and 14 exhibited a higher activity as cellobiase while compounds 2 and 5 showed a highly enzymatic effect on tumor cells. In addition, compounds 2 and 10 can be used as Olomoucine (standard referees).

Conclusion:

Various N, S and O-alkyl derivatives of fluorine-substituted rhodanines were prepared via a simple method and used as enzymatic probes for cellobiase activity produced by fungi and CDK2 inhibitors for tumor cells. The more bioactive compounds had rich fluorine atoms as p-fluorophenyl and p-fluorobenzoyl bearing N, S, O-alkyl rhodanine. The highly active compounds may be used as enzymatic materials for various biological transformations in the future.

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.

Design of a Thiosemicarbazide-Functionalized Calix[4]arene Ligand and Related Transition Metal Complexes: Synthesis, Characterization, and Biological Studies

In this study, we synthesized a new thiosemicarbazide-functionalized calix[4]arene L and its Co2+, Ni2+, Cu2+, and Zn2+ transition metal complexes. For characterization several techniques were employed: Fourier-transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), 13C-NMR, 15N-NMR, correlation spectroscopy (COZY), nuclear Overhauser enhancement spectroscopy (NOESY), electrospray ionization (ESI)-mass spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and elemental analysis. To explore the capability of the thiosemicarbazide function hosted on a calix[4]arene scaffold for growth inhibition of bacteria, fungi, and cancerous tumor cells, a series of biological evaluations were performed. For L, the antimicrobial tests revealed a higher antibacterial activity against gram-positive Bacillus subtilis and a lower activity against gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), whereas the gram-positive Staphylococcus aureus shows resistance. All examined metal derivatives show an enhancement of the antibacterial activity against gram-negative E. coli bacteria, with a more significant improvement for the Ni2+ and Zn2+ complexes. MTT assays showed a considerable in vitro anticancer activity of Co2+, Ni2+, and Cu2+ complexes against Saos-2 bone cancer cell lines. The activity is ascribable to the inorganic ions rather than calixarene ligand. Hemolysis assay results demonstrated that all compounds have high blood compatibility.

Synthesis and In Vitro Anti-Toxoplasma gondii Activity of Novel Thiazolidin-4-one Derivatives

Recent findings on the biological activity of thiazolidin-4-ones and taking into account the lack of effective drugs used in the treatment of toxoplasmosis, their numerous side effects, as well as the problem of drug resistance of parasites prompted us to look for new agents. We designed and synthesized a series of new thiazolidin-4-one derivatives through a two-step reaction between 4-substituted thiosemicarbazides with hydroxybenzaldehydes followed by the treatment with ethyl bromoacetate; maleic anhydride and dimethyl acetylenedicarboxylate afforded target compounds. The thiazolidin-4-one derivatives were used to assess the inhibition of Toxoplasma gondii growth in vitro. All active thiazolidine-4-one derivatives (12 compounds) inhibited T. gondii proliferation in vitro much better than used references drugs both sulfadiazine as well as the synergistic effect of sulfadiazine + trimethoprim (weight ratio 5:1). Most active among them derivatives 94 and 95 showed inhibition of proliferation at about 392-fold better than sulfadiazine and 18-fold better than sulfadiazine with trimethoprim. All active compounds (82–88 and 91–95) against T. gondii represent values from 1.75 to 15.86 (CC₃₀/IC₅₀) lower than no cytotoxic value (CC₃₀).

Discovery of Potent and Selective Halogen-Substituted Imidazole-Thiosemicarbazides for Inhibition of Toxoplasma gondii Growth In Vitro via Structure-Based Design

Employing a simple synthetic protocol, a series of highly effective halogen-substituted imidazole-thiosemicarbazides with anti-Toxoplasma gondii effects against the RH tachyzoites, much better than sulfadiazine, were obtained (IC_50s 10.30—113.45 µg/mL vs. ~2721.45 µg/mL). The most potent of them, 12, 13, and 15, blocked the in vitro proliferation of T. gondii more potently than trimethoprim (IC₅₀ 12.13 µg/mL), as well. The results of lipophilicity studies collectively suggest that logP would be a rate-limiting factor for the anti-Toxoplasma activity of this class of compounds.

Systematic Identification of Thiosemicarbazides for Inhibition of Toxoplasma gondii Growth In Vitro

One of the key stages in the development of new therapies in the treatment of toxoplasmosis is the identification of new non-toxic small molecules with high specificity to Toxoplasma gondii. In the search for such structures, thiosemicarbazide-based compounds have emerged as a novel and promising leads. Here, a series of imidazole-thiosemicarbazides with suitable properties for CNS penetration was evaluated to determine the structural requirements needed for potent anti-Toxoplasma gondii activity. The best 4-arylthiosemicarbazides 3 and 4 showed much higher potency when compared to sulfadiazine at concentrations that are non-toxic to the host cells, indicating a high selectivity of their anti-toxoplasma activity.

Synthesis and Aldose Reductase Inhibitory Effect of Some New Hydrazinecarbothioamides and 4-Thiazolidinones Bearing an Imidazo[2,1-b]Thiazole Moiety

Objectives

To synthesize and characterize 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-alkyl/arylhydrazinecarbothioamide and 3-alkyl/aryl-2-[((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)acetyl)hydrazono]-5-nonsubstituted/methyl-4-thiazolidinone derivatives and evaluate them for their aldose reductase (AR) inhibitory effect.

Materials and Methods

2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-alkyl/arylhydrazinecarbothioamides (3a-f) and 3-alkyl/aryl-2-[((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)acetyl)hydrazono]-5-nonsubstituted/methyl-4-thiazolidinones (4a-j) were synthesized from 2-[6-(4-bromophenyl)imidazo[2,1-b]thiazole-3-yl]acetohydrazide (2). Their structures were elucidated by elemental analyses and spectroscopic data. The synthesized compounds were tested for their ability to inhibit rat kidney AR.

Results

Among the synthesized compounds, 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-benzoylhydrazinecarbothioamide (3d) showed the best AR inhibitory activity.

Conclusion

The findings of this study indicate that the different derivatives of the compounds in this study may be considered interesting candidates for future research.

Protein targets of thiazolidinone derivatives in Toxoplasma gondii and insights into their binding to ROP18

Background

Thiazolidinone derivatives show inhibitory activity (IC₅₀) against the Toxoplasma gondii parasite, as well as high selectivity with high therapeutic index. To disclose the target proteins of the thiazolidinone core in this parasite, we explored in silico the active sites of different T. gondii proteins and estimated the binding-free energy of reported thiazolidinone molecules with inhibitory effect on invasion and replication of the parasite inside host cells. This enabled us to describe some of the most suitable structural characteristics to design a compound derived from the thiazolidinone core.

Results

The best binding affinity was observed in the active site of kinase proteins, we selected the active site of the T. gondii ROP18 kinase, because it is an important factor for the virulence and survival of the parasite. We present the possible effect of a derivative of thiazolidinone core in the active site of T. gondii ROP18 and described some characteristics of substituent groups that could improve the affinity and specificity of compounds derived from the thiazolidinone core against T. gondii.

Conclusions

The results of our study suggest that compounds derived from the thiazolidinone core have a preference for protein kinases of T. gondii, being promising compounds for the development of new drugs with potential anti-toxoplasmosis activity. Our findings highlight the importance of use computational studies for the understanding of the action mechanism of compounds with biological activity.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5223-7) contains supplementary material, which is available to authorized users.

A Perspective on Thiazolidinone Scaffold Development as a New Therapeutic Strategy for Toxoplasmosis

Toxoplasma gondii is one of the most successful parasites due to its ability to infect a wide variety of warm-blooded animals. It is estimated that one-third of the world's population is latently infected. The generic therapy for toxoplasmosis has been a combination of antifolates such as pyrimethamine or trimethoprim with either sulfadiazine or antibiotics such as clindamycin with a combination with leucovorin to prevent hematologic toxicity. This therapy shows limitations such as drug intolerance, low bioavailability or drug resistance by the parasite. There is a need for the development of new molecules with the capacity to block any stage of the parasite's life cycle in humans or in a different type of hosts. Heterocyclic compounds are promissory drugs due to its reported biological activity; for this reason, thiazolidinone and its derivatives are presented as a new alternative not only for its inhibitory activity against the parasite but also for its high selectivity-level with high therapeutic index. Thiazolidinones are an important scaffold known to be associated with anticancer, antibacterial, antifungal, antiviral, antioxidant, and antidiabetic activities. The molecule possesses an imidazole ring that has been described as an antiprotozoal agent with antiparasitic properties and less toxicity. Thiazolidinone derivatives have been reportedly as building blocks in organic chemistry and as scaffolds for drug discovery. Here we present a perspective of how structural modifications of the thiazolidinone core could generate new compounds with high anti-parasitic effect and less toxic results.

In Vitro Anti-Toxoplasma gondii and Antimicrobial Activity of Amides Derived from Cinnamic Acid

Most cinnamic acids, their esters, amides, aldehydes, and alcohols present several therapeutic actions through anti-inflammatory, antitumor, and inhibitory activity against a great variety of microorganisms. In this work, eight amines derived from cinnamic acid were synthesized and tested against host cells infected with Toxoplasma gondii and the bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and three strains of Staphylococcus aureus. Compounds 3 and 4 showed the best result against intracellular T. gondii, presenting antiparasitic activity at low concentrations (0.38 and 0.77 mM). The antibacterial activity of these compounds was also evaluated by the agar microdilution method, and amides 2 and 5 had a minimum inhibitory concentration of 250 µg mL⁻¹ against two strains of S. aureus (ATCC 25923 and bovine strain LSA 88). These also showed synergistic action along with a variety of antibiotics, demonstrating that amines derived from cinnamic acid have potential as pharmacological agents.

Retracted: Novel spiro-thiazolidin-4-one and thioether derivatives of benzylidene flavanones: New leads in cancer and microbial chemotherapy

The above article from Archiv der Pharmazie, published online on 12 March 2018 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor-in-Chief, Prof. Holger Stark, and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. The retraction has been agreed due to errors in the spectroscopic data of the investigated new compounds.

REFERENCE TO RETRACTION

S. Mukhtar, M. A. Alsharif, M. I. Alahmdi, H. Parveen, A. U. Khan, Arch. Pharm. Chem. Life Sci. 2018;1-12. DOI: 10.1002/ardp.201700397.

Drugs in development for toxoplasmosis: advances, challenges, and current status

Toxoplasma gondii causes fatal and debilitating brain and eye diseases. Medicines that are currently used to treat toxoplasmosis commonly have toxic side effects and require prolonged courses that range from weeks to more than a year. The need for long treatment durations and the risk of relapsing disease are in part due to the lack of efficacy against T. gondii tissue cysts. The challenges for developing a more effective treatment for toxoplasmosis include decreasing toxicity, achieving therapeutic concentrations in the brain and eye, shortening duration, eliminating tissue cysts from the host, safety in pregnancy, and creating a formulation that is inexpensive and practical for use in resource-poor areas of the world. Over the last decade, significant progress has been made in identifying and developing new compounds for the treatment of toxoplasmosis. Unlike clinically used medicines that were repurposed for toxoplasmosis, these compounds have been optimized for efficacy against toxoplasmosis during preclinical development. Medicines with enhanced efficacy as well as features that address the unique aspects of toxoplasmosis have the potential to greatly improve toxoplasmosis therapy. This review discusses the facets of toxoplasmosis that are pertinent to drug design and the advances, challenges, and current status of preclinical drug research for toxoplasmosis.

A Systematic Review of In vitro and In vivo Activities of Anti-Toxoplasma Drugs and Compounds (2006-2016)

The currently available anti-Toxoplasma agents have serious limitations. This systematic review was performed to evaluate drugs and new compounds used for the treatment of toxoplasmosis. Data was systematically collected from published papers on the efficacy of drugs/compounds used against Toxoplasma gondii (T. gondii) globally during 2006-2016. The searched databases were PubMed, Google Scholar, Science Direct, ISI Web of Science, EBSCO, and Scopus. One hundred and eighteen papers were eligible for inclusion in this systematic review, which were both in vitro and in vivo studies. Within this review, 80 clinically available drugs and a large number of new compounds with more than 39 mechanisms of action were evaluated. Interestingly, many of the drugs/compounds evaluated against T. gondii act on the apicoplast. Therefore, the apicoplast represents as a potential drug target for new chemotherapy. Based on the current findings, 49 drugs/compounds demonstrated in vitro half-maximal inhibitory concentration (IC50) values of below 1 μM, but most of them were not evaluated further for in vivo effectiveness. However, the derivatives of the ciprofloxacin, endochin-like quinolones and 1-[4-(4-nitrophenoxy) phenyl] propane-1-one (NPPP) were significantly active against T. gondii tachyzoites both in vitro and in vivo. Thus, these compounds are promising candidates for future studies. Also, compound 32 (T. gondii calcium-dependent protein kinase 1 inhibitor), endochin-like quinolones, miltefosine, rolipram abolish, and guanabenz can be repurposed into an effective anti-parasitic with a unique ability to reduce brain tissue cysts (88.7, 88, 78, 74, and 69%, respectively). Additionally, no promising drugs are available for congenital toxoplasmosis. In conclusion, as current chemotherapy against toxoplasmosis is still not satisfactory, development of well-tolerated and safe specific immunoprophylaxis in relaxing the need of dependence on chemotherapeutics is a highly valuable goal for global disease control. However, with the increasing number of high-risk individuals, and absence of a proper vaccine, continued efforts are necessary for the development of novel treatment options against T. gondii. Some of the novel compounds reviewed here may represent good starting points for the discovery of effective new drugs. In further, bioinformatic and in silico studies are needed in order to identify new potential toxoplasmicidal drugs.

Synthesis and biological evaluation of new 1,3-thiazolidine-4-one derivatives of nitro-l-arginine methyl ester

BACKGROUND

l-Arginine is a semi-essential aminoacid with important role in regulation of physiological processes in humans. It serves as precursor for the synthesis of proteins and is also substrate for different enzymes such as nitric oxide synthase. This amino-acid act as free radical scavenger, inhibits the activity of pro-oxidant enzymes and thus acts as an antioxidant and has also bactericidal effect against a broad spectrum of bacteria.

RESULTS

New thiazolidine-4-one derivatives of nitro-l-arginine methyl ester (NO2-Arg-OMe) have been synthesized and biologically evaluated in terms of antioxidant and antibacterial/antifungal activity. The structures of the synthesized compounds were confirmed by (1)H, (13)C NMR, Mass and IR spectral data. The antioxidant potential was investigated using in vitro methods based on ferric/phosphomolybdenum reducing antioxidant power and DPPH/ABTS radical scavenging assay. The antibacterial effect was investigated against Gram positive (Staphylococcus aureus ATCC 25923, Sarcina lutea ATCC 9341) and Gram negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) bacterial strains. The antifungal activity was also investigated against Candida spp. (Candida albicans ATCC 10231, Candida glabrata ATCC MYA 2950, Candida parapsilosis ATCC 22019).

CONCLUSIONS

Synthesized compounds showed a good antioxidant activity in comparison with the NO2-Arg-OMe. The antimicrobial results support the selectivity of tested compounds especially on P. aeruginosa as bacterial strain and C. parapsilosis as fungal strain. The most proper compounds were 6g (R = 3-OCH3) and 6h (R = 2-OCH3) which showed a high free radical (DPPH, ABTS) scavenging ability and 6j (R = 2-NO2) that was the most active on both bacterial and fungal strains and also it showed the highest ABTS radical scavenging ability.Graphical abstract1: ethyl 3-aminopropionate hydrochloride, 2a-j: aromatic aldehydes, 3: thioglycolic acid, 4a-j: thiazolidine-propionic acid derivatives , 5: Nω-nitro-L-arginine methyl ester hydrochloride, 6a-j: thiazolidine-propionyl-nitro-L-arginine methyl ester derivatives.

Stereochemical Investigations of Diastereomeric N-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Some new N-[2-(aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides were synthesized and their structures were investigated by IR, NMR (1H, 13C, and 2D), and mass spectra. The presence of C-2 and C-5 stereogenic centers on the thiazolidinone ring resulted in diastereoisomeric pairs. The configurations of two stereogenic centers were assigned based upon 1H NMR analysis of coupling constants and 2D nuclear overhauser enhancement spectroscopy (NOESY) experiment. Resolution of the diastereoisomers was performed by high performance liquid chromatography (HPLC) using a chiral stationary phase.