Thiazole, thio and semicarbazone derivatives against tropical infective diseases: Chagas disease, human African trypanosomiasis (HAT), leishmaniasis, and malaria

Recent Progress in Thiazole, Thiosemicarbazone, and Semicarbazone Derivatives as Antiparasitic Agents Against Trypanosomatids and Plasmodium spp

Neglected tropical diseases (NTDs), including Chagas disease, human African trypanosomiasis (HAT), leishmaniasis, and malaria, remain a major global health challenge, disproportionately affecting low-income populations. Current therapies for these diseases suffer from significant limitations, such as reduced efficacy, high toxicity, and emerging parasite resistance, highlighting the urgent need for new therapeutic strategies. In response, substantial efforts have been directed toward the synthesis of new molecules with improved potency, selectivity, and pharmacokinetic profiles. However, despite many of these compounds exhibiting favorable ADMET (absorption, distribution, metabolism, excretion, and toxicity) profiles and strong in vitro activity, their translation into in vivo models remains limited. Key challenges include the lack of investment, the absence of fully representative experimental models, and difficulties in extrapolating cell-based assay results to more complex biological systems. In this review, we analyzed the latest advancements (2019-2024) in the development of these compound classes, correlating predictive parameters with their observed biological activity. Among these parameters, we highlighted the partition coefficient (LogP), which measures a compound's lipophilicity and influences its ability to cross biological membranes, and Caco-2 cell permeability, an in vitro model widely used to predict intestinal drug absorption. Additionally, we prioritized the most promising molecules and structural classes for pharmaceutical development, discussing structure-activity relationships (SARs) and the remaining challenges that must be overcome to enable the clinical application of these compounds in the treatment of NTDs.

Targeting Blood-Stage Malaria: Design, Synthesis, Characterization, In Vitro, and In Silico Evaluation of Pyrrolidinodiazenyl Chalcones

Malaria is a pervasive and deadly threat to the global population, and the resources available to treat this disease are limited. There is widespread clinical resistance to the most commonly prescribed antimalarial drugs. To address this issue, we synthesized a range of 4'-pyrrolidinodiazenyl chalcones using a covalent bitherapy approach to study their potential antimalarial properties. We examined the structure-activity relationships of these compounds, which could explain their antimalarial activities. The in vitro blood stage antimalarial activity of the compounds was evaluated against the mixed-blood stage culture (ring, trophozoites and schizonts) of Plasmodium falciparum 3D7, and the 50% inhibitory concentrations (IC50s) ranged from 3.3 to 22.2 μg/mL after 48 h of exposure. Compounds 11, 19, and 22 displayed pronounced IC50 values of 7.6 μg/mL, 6.4 μg/mL, and 3.3 μg/mL, respectively. The in vitro cytotoxicity of the active compounds was evaluated on human-derived Mo7e cells and murine-derived BA/F3 cells. Compounds 11 and 19 were found to be noncytotoxic (> 40 μg/mL), whereas compound 22 displayed cytotoxicity at higher concentrations. Moreover, these compounds exerted negligible hemolytic effects on human RBCs at their active concentrations. Molecular docking of these compounds revealed good hydrophobic and hydrogen bonding interactions with the binding sites of Plasmodium falciparum-dihydrofolate reductase, providing a rationale for their antimalarial activity, which is consistent with the in vitro results.

Synthesis strategies and anti-parasitic evaluation of novel compounds for chagas disease: Advancing drug discovery through structure-activity relationships

This study presents a comprehensive exploration of the synthesis of novel compounds targeting Chagas Disease (CD) caused by Trypanosoma cruzi. It is a global health threat with over 6-7 million infections worldwide. Addressing challenges in current treatments, the investigation explores diverse compound classes, including thiazoles, thiazolidinone, imidazole, pyrazole, 1,6-diphenyl-1H-pyrazolo[3,4-b] pyridine, pyrrole, naphthoquinone, neolignan, benzeneacyl hydrazones, and chalcones-based compounds. Highlighting compounds with superior trypanocidal activity compared to standard drugs. The study elucidates structure-activity relationships, emphasizing the impact of substituents, fluorine presence, and substitution patterns. Noteworthy findings include neolignan derivatives demonstrating efficacy against intracellular amastigotes and free-moving trypomastigotes, with unsaturated side chains. Benzeneacylhydrazones and chalcones, as novel classes, showed varied efficacy, with certain compounds surpassing benznidazole. A novel series of triketone compounds exhibited strong anti-parasitic activity, outperforming standard drugs. Docking study revealed that the halogen and methoxy substituted phenyl ring, thiazole, thiazolidine-4-one, quinoline, isoindoline-1,3-dione, pyrrole heterocyclic motifs can play the key role in the designing of effective inhibitors of T. cruzi. Mutually, these insights placed the foundation for the development of innovative and effective treatments for CD, addressing the urgent need for improved therapeutic options.

Nanomolar activity of coumarin-3-thiosemicarbazones targeting Trypanosoma cruzi cruzain and the T. brucei cathepsin L-like protease

Trypanosoma cruzi (T. cruzi) and Trypanosoma brucei (T. brucei) urgently demand innovative drug development due to their impact on public health worldwide. Their cysteine proteases, Cruzain (CRZ) and the T. brucei Cathepsin L-like protease (TbrCATL) are established drug targets for these parasites. In this study, our coumarin-3-thiosemicarbazones demonstrated nanomolar IC50 values (22-698 nM) toward these proteases. Against T. cruzi amastigotes and T. brucei trypomastigotes, LASF-01 displayed a promising result. Herein, MCG-02, the most potent TbrCATL inhibitor, underwent comprehensive analyses, including cytotoxicity assessments and in vitro tests. Molecular dynamics (MD) simulations and a multiscale Quantum Mechanics/Quantum Mechanics (QM/QM) approach were used to generate insights into their binding modes. These suggested that MCG-02 could be a reversible, competitive covalent inhibitor. Further, confirmatory assays were experimentally performed changing different parameters to prove its efficacy. Additionally, the predicted pharmacokinetic profile showed that there is no violation of the Lipinski rule of five. Notably, coumarin-3-thiosemicarbazone hybrids emerged as promising candidates for designing highly active inhibitors against CRZ and TbrCATL. Overall, the integration of in silico and experimental approaches enhanced our understanding regarding the binding modes of MCG-02, which were experimentally corroborated, providing valuable insights for future drug development.

Design, Synthesis, and In Silico Molecular Docking Studies of Adamantanyl Hydrazinylthiazoles as Potential Antidiabetic Agents

Diabetes mellitus (DM) is a widespread disease that poses a major threat to millions of people. To address this issue, we have synthesized seventeen new 4-(adamantan-1-yl)-(2-(arylidene)hydrazinyl)thiazoles (3a-q) via Hantzsch synthetic approach. The molecular structures of all the compounds were confirmed using FT-IR, 1H- and 13C-NMR spectroscopy, and HR-mass spectrometry. Protein kinase, α-amylase, glycation, and oxidation inhibition potential of all compounds were also investigated, and it was found that compounds 3b, 3c, 3e-3g, and 3i-3q have shown excellent α-amylase inhibition (IC50 = 7.91 ± 0.07 to 28.57 ± 0.1 µM), compounds 3c, 3e, 3i, 3k, and 3p (IC50 = 30.6 ± 0.06 to 37.8 ± 0.005 ppm) were found to be highly potent anti-glycating agents, and compounds 3c, 3g, 3h, 3k, and 3m were found to be more potent protein kinase inhibitors as compared to standards. The compounds 3b, 3c, 3d, 3e, 3f, 3g, 3i, 3k, 3l, 3m, 3n, 3p, and 3q have shown good antioxidant potential (IC50 = 27.5 ± 0.09 to 48.8 ± 0.09 µM) as compared to standard ascorbic acid (IC50 = 51.3 ± 0.1 µM). The biocompatibility of all samples was also tested by employing brine shrimp lethality and in vitro hemolytic assays and was found to be safe to human erythrocytes at tested concentrations. Furthermore, the molecular docking simulation study also revealed that almost all synthesized compounds have potential interactions with target proteins at the molecular level.

Insights to Design New Drugs against Human African Trypanosomiasis Targeting Rhodesain using Covalent Docking, Molecular Dynamics Simulations, and MM-PBSA Calculations

BACKGROUND

Neglected tropical diseases (NTDs) are parasitic and bacterial diseases that affect approximately 149 countries, mainly the poor population without basic sanitation. Among these, Human African Trypanosomiasis (HAT), known as sleeping sickness, shows alarming data, with treatment based on suramin and pentamidine in the initial phase and melarsoprol and eflornithine in the chronic phase. Thus, to discover new drugs, several studies point to rhodesain as a promising drug target due to the function of protein degradation and intracellular transport of proteins between the insect and host cells and is present in all cycle phases of the parasite.

METHODS

Here, based on the previous studies by Nascimento et al. (2021) [5], that show the main rhodesain inhibitors development in the last decade, molecular docking and dynamics were applied in these inhibitors datasets to reveal crucial information that can be into drug design.

RESULTS

Also, our findings using MD simulations and MM-PBSA calculations confirmed Gly19, Gly23, Gly65, Asp161, and Trp184, showing high binding energy (ΔGbind between -72.782 to -124.477 kJ.mol-1). In addition, Van der Waals interactions have a better contribution (-140,930 to -96,988 kJ.mol-1) than electrostatic forces (-43,270 to -6,854 kJ.mol-1), indicating Van der Waals interactions are the leading forces in forming and maintaining ligand-rhodesain complexes. Thus, conventional and covalent docking was employed and highlighted the presence of Michael acceptors in the ligands in a peptidomimetics scaffold, and interaction with Gly19, Gly23, Gly65, Asp161, and Trp184 is essential to the inhibiting activity. Furthermore, the Dynamic Cross-Correlation Maps (DCCM) show more correlated movements for all complexes than the free rhodesain and strong interactions in the regions of the aforementioned residues. Principal Component Analysis (PCA) demonstrates complex stability corroborating with RMSF and RMSD.

CONCLUSION

This study can provide valuable insights that can guide researchers worldwide to discover a new promising drug against HAT.

Inhibitory Effects of Sulfur Derivatives on Leishmania tarentolae Cell Viability and Secreted Acid Phosphatase In Vitro

Sulfonamide drugs were the original class of antibiotics, demonstrating the antibacterial potential of dithiocarbazate and thiosemicarbazone Schiff base derivatives of syringaldehyde and 4-hydroxy-3,5-dimethylbenzaldehyde. We synthesized unique Schiff bases via the condensation of the aldehydes with hydrazine derivatives, which allows for the easy synthesis of several related compounds. These Schiff base derivatives were tested for antileishmanial properties against the parasitic protozoan Leishmania tarentolae. The inhibitory properties of these sulfur compounds were tested using a series of cell viability and secreted acid phosphatase (SAP) assays. The results demonstrated that compounds ZZ1-04 and ZZ1-20 had potent inhibitory effects on parasite cell viability and SAP, an enzyme that may play a role in infectivity. These results increase our understanding of the role of sulfur in inhibiting Leishmania, providing more knowledge of the structural activity relationships that may prove critical for their development into possible antileishmanial treatments.

Assessment of the Activity of Nitroisoxazole Derivatives against Trypanosoma cruzi

The development of new compounds to treat Chagas disease is imperative due to the adverse effects of current drugs and their low efficacy in the chronic phase. This study aims to investigate nitroisoxazole derivatives that produce oxidative stress while modifying the compounds' lipophilicity, affecting their ability to fight trypanosomes. The results indicate that these compounds are more effective against the epimastigote form of T. cruzi, with a 52 ± 4% trypanocidal effect for compound 9. However, they are less effective against the trypomastigote form, with a 15 ± 3% trypanocidal effect. Additionally, compound 11 interacts with a higher number of amino acid residues within the active site of the enzyme cruzipain. Furthermore, it was also found that the presence of a nitro group allows for the generation of free radicals; likewise, the large size of the compound enables increased interaction with aminoacidic residues in the active site of cruzipain, contributing to trypanocidal activity. This activity depends on the size and lipophilicity of the compounds. The study recommends exploring new compounds based on the nitroisoxazole skeleton, with larger substituents and lipophilicity to enhance their trypanocidal activity.

Antifungal efficacy of imidazo[1,2-a]pyrazine-based thiosemicarbazones and thiazolidinediones against Sporothrix species

Aim: To evaluate antifungal potential of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine hybrids based on thiosemicarbazones and thiazolidinediones against pathogenic Sporothrix species. Methods: Antifungal activity of nine compounds were assessed by broth microdilution. Interactions between active compounds and itraconazole were evaluated by the checkerboard assay using non-wild-type isolates. Cytotoxicity of the compounds was determined. Results: Four C-3 substituted analogs showed antifungal activity, unrelated to thiosemicarbazone or thiazolidinedione functions. Synergistic interactions between the four compounds and itraconazole, and low toxicity on mouse fibroblast cells were observed. Activity of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine hybrids against Sporothrix depended on the substitution on the imidazopyrazine ring. Conclusion: Antifungal potential, overcoming itraconazole resistance and low toxicity indicate the possible use of that series of compounds in a therapeutic alternative for treatment of sporotrichosis.

New Organotin (IV) Compounds Derived from Dehydroacetic Acid and Thiosemicarbazides: Synthesis, Rational Design, Cytotoxic Evaluation, and Molecular Docking Simulation

Organotin complexes were prepared through a one-pot reaction with three components by reacting thiosemicarbazide or 4-methyl-3-thiosemicarbazide or 4-phenylthiosemicarbazide, dehydroacetic acid (DHA) and dibutyl, diphenyl, dicyclohexyl, and bis[(trimethylsilyl)methyl]tin(IV) oxides; all complexes were characterized by infrared (IR), ultraviolet-visible (UV-vis), mass spectrometry (MS), and nuclear magnetic resonance (NMR) spectroscopy. The 119Sn NMR revealed chemical shifts corresponding to a pentacoordinated environment in solution. The X-ray crystallography of the two complexes evidenced the formation of monomeric complexes with a pentacoordinated geometry around tin via three donor atoms from the ligand, the sulfur of the thiol, the nitrogen of the imine group, and the oxygen of the pyran ring. The geometries of the five-coordinated complexes 3a (Bu2SnL3), 3c (Ph2SnL3), and 3d (Cy2SnL3) acid were intermediate between square pyramidal and trigonal bipyramidal, and complex 1a (Bu2SnL1) adopted a bipyramidal trigonal geometry (BPT). The sulforhodamine B assay assessed the cytotoxicity of organotin(IV) complexes against the MDA-MB-231 and MCF-7 (human mammary adenocarcinoma) cell lines and one normal COS-7 (African green monkey kidney fibroblast). The IC50 values evidenced a significant antiproliferative effect on cancer cells; the complexes were more potent than the positive cisplatin control and the corresponding ligands, dehydroacetic acid thiosemicarbazone (L1), dehydroacetic acid-N(4)-methylthiosemicarbazone (L2), and dehydroacetic acid-N(4)-phenylthiosemicarbazone (L3). The IC50 values also indicated that the organotin(IV) complexes were more cytotoxic against the triple-negative breast cell line MDA-MB-231 than MCF-7, inducing significant morphological alterations. The interactions of organotin(IV) 1c (Ph2SnL1), 1d (Cy2SnL1), and 1e (((CH3)3SiCH2)2SnL1) were evaluated with ss-DNA by fluorescence; intensity changes of the fluorescence were indicative of the displacement of ethidium bromide (EB), confirming the interaction of the organotin(IV) complexes with ss-DNA; the results showed a DNA binding affinity. The thermodynamic parameters obtained through isothermal titration calorimetry showed that the interaction of 1c (Ph2SnL1), with ss-ADN, was exothermic. Molecular docking studies also demonstrated that the organotin(IV) complexes were intercalated in DNA by conventional hydrogen bonds, carbon-hydrogen bonds, and π-alkyl interactions. These complexes furthermore showed a greater affinity towards DNA than cisplatin.

From Benznidazole to New Drugs: Nanotechnology Contribution in Chagas Disease

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi. Benznidazole and nifurtimox are the two approved drugs for their treatment, but both drugs present side effects and efficacy problems, especially in the chronic phase of this disease. Therefore, new molecules have been tested with promising results aiming for strategic targeting action against T. cruzi. Several studies involve in vitro screening, but a considerable number of in vivo studies describe drug bioavailability increment, drug stability, toxicity assessment, and mainly the efficacy of new drugs and formulations. In this context, new drug delivery systems, such as nanotechnology systems, have been developed for these purposes. Some nanocarriers are able to interact with the immune system of the vertebrate host, modulating the immune response to the elimination of pathogenic microorganisms. In this overview of nanotechnology-based delivery strategies for established and new antichagasic agents, different strategies, and limitations of a wide class of nanocarriers are explored, as new perspectives in the treatment and monitoring of Chagas disease.

4-Adamantyl-(2-(arylidene)hydrazinyl)thiazoles as potential antidiabetic agents: experimental and docking studies

Aim: To develop an efficient and cost-effective antidiabetic agent. Methods: A simple and convenient Hantzsch synthetic strategy was used to prepare 4-adamantyl-(2-(arylidene)hydrazinyl)thiazoles. Results: Fifteen newly established structures of 4-adamantyl-(2-(arylidene)hydrazinyl)thiazoles were tested for their α-amylase, antiglycation and antioxidant activities. Almost all tested compounds showed excellent α-amylase inhibition. Compounds 3a and 3j exhibited the highest potency, with IC₅₀ values of 16.34 ± 2.67 and 16.64 ± 1.12 μM, respectively. Compounds 3c and 3i exhibited comparable antiglycation potential with the standard, aminoguanidine. The antioxidant potential of compound 3g was found to be excellent, with an IC₅₀ value of 28.19 ± 0.2563 μM. The binding interactions of compound 3a (binding energy = -8.833 kcal/mol) with human pancreatic α-amylase identified 3a as a potent α-amylase inhibitor. Conclusion: Enrichment of established structures with more electron-donating functionalities may assist/lead to the development of more potent antidiabetic drugs.

Synthesis, characterization, antioxidant and antiparasitic activities new naphthyl-thiazole derivatives

In this work, 13 thiosemicarbazones (1a - m) and 16 thiazoles (2a - p) were obtained, which were properly characterized by spectroscopic and spectrometric techniques. The pharmacokinetic properties obtained in silico revealed that the derivatives are in accordance with the parameters established by lipinski and veber, showing that such compounds have good bioavailability or permeability when administered orally. In assays of antioxidant activity, thiosemicarbazones showed moderate to high antioxidant potential when compared to thiazoles. In addition, they were able to interact with albumin and DNA. Screening assays to assess the toxicity of compounds to mammalian cells revealed that thiosemicarbazones were less toxic when compared to thiazoles. In relation to in vitro antiparasitic activity, thiosemicarbazones and thiazoles showed cytotoxic potential against the parasites Leishmania amazonensis and Trypanosoma cruzi. Among the compounds, 1b, 1j and 2l stood out, showing inhibition potential for the amastigote forms of the two parasites. As for the in vitro antimalarial activity, thiosemicarbazones did not inhibit Plasmodium falciparum growth. In contrast, thiazoles promoted growth inhibition. This study shows in a preliminary way that the synthesized compounds have antiparasitic potential in vitro.

Tuning the nuclearity of [Mo2O2S2]2+-based assemblies by playing with the degree of flexibility of bis-thiosemicarbazone ligands

[MoV2O₂S₂]²⁺-based thiosemicarbazone complexes appear as very promising molecules for biological applications due to the intrinsic properties of their components. This paper deals with the synthesis and characterization of six coordination complexes obtained by the reaction of [MoV2O₂S₂]²⁺ clusters with bis-thiosemicarbazone ligands that contain flexible or rigid spacers between the two thiosemicarbazone units. Interestingly, structural characterization by single-crystal X-ray diffraction, MALDI-TOF MS technique and NMR spectroscopy revealed that the nuclearity of the complex is controlled by the nature of the spacer between the thiosemicarbazone units. Binuclear complexes, namely [MoV2O₂S₂(L^1-3)], are isolated with flexible spacers while tetranuclear complexes [(MoV2O₂S₂)₂(L^4-6)₂] are formed when the bis-thiosemicarbazone ligands are built on rigid spacers.

Synthesis of 4-(4-chlorophenyl)thiazole compounds: in silico and in vitro evaluations as leishmanicidal and trypanocidal agents

Neglected tropical diseases are a diverse group of communicable pathologies that mainly prevail in tropical and subtropical regions. Thus, the objective of this work was to evaluate the biological potential of eight 4-(4-chlorophenyl)thiazole compounds. Tests were carried out in silico to evaluate the pharmacokinetic properties, the antioxidant, cytotoxic activities in animal cells and antiparasitic activities were evaluated against the different forms of Leishmania amazonensis and Trypanosoma cruzi in vitro. The in silico study showed that the evaluated compounds showed good oral availability. In a preliminary in vitro study, the compounds showed moderate to low antioxidant activity. Cytotoxicity assays show that the compounds showed moderate to low toxicity. In relation to leishmanicidal activity, the compounds presented IC50 values that ranged from 19.86 to 200 µM for the promastigote form, while for the amastigote forms, IC50 ranged from 101 to more than 200 µM. The compounds showed better results against the forms of T. cruzi with IC50 ranging from 1.67 to 100 µM for the trypomastigote form and 1.96 to values greater than 200 µM for the amastigote form. This study showed that thiazole compounds can be used as future antiparasitic agents.

Potential of sulfur-selenium isosteric replacement as a strategy for the development of new anti-chagasic drugs

Current treatment for Chagas disease is based on only two drugs: benznidazole and nifurtimox. Compounds containing sulfur (S) in their structure have shown promising results in vitro and in vivo against Trypanosoma cruzi, the parasite causing Chagas disease. Notably, some reports show that the isosteric replacement of S by selenium (Se) could be an interesting strategy for the development of new compounds for the treatment of Chagas disease. To date, the activity against T. cruzi of three Se- containing groups has been compared with their S counterparts: selenosemicarbazones, selenoquinones, and selenocyanates. More studies are needed to confirm the positive results of Se compounds. Therefore, we have investigated S compounds described in the literature tested against T. cruzi. We focused on those tested in vivo that allowed isosteric replacement to propose their Se counterparts as promising compounds for the future development of new drugs against Chagas disease.

In Silico Antiprotozoal Evaluation of 1,4-Naphthoquinone Derivatives against Chagas and Leishmaniasis Diseases Using QSAR, Molecular Docking, and ADME Approaches

Chagas and leishmaniasis are two neglected diseases considered as public health problems worldwide, for which there is no effective, low-cost, and low-toxicity treatment for the host. Naphthoquinones are ligands with redox properties involved in oxidative biological processes with a wide variety of activities, including antiparasitic. In this work, in silico methods of quantitative structure-activity relationship (QSAR), molecular docking, and calculation of ADME (absorption, distribution, metabolism, and excretion) properties were used to evaluate naphthoquinone derivatives with unknown antiprotozoal activity. QSAR models were developed for predicting antiparasitic activity against Trypanosoma cruzi, Leishmania amazonensis, and Leishmania infatum, as well as the QSAR model for toxicity activity. Most of the evaluated ligands presented high antiparasitic activity. According to the docking results, the family of triazole derivatives presented the best affinity with the different macromolecular targets. The ADME results showed that most of the evaluated compounds present adequate conditions to be administered orally. Naphthoquinone derivatives show good biological activity results, depending on the substituents attached to the quinone ring, and perhaps the potential to be converted into drugs or starting molecules.

Synthesis, Structures, and Solution Studies of a New Class of [Mo2O2S2]-Based Thiosemicarbazone Coordination Complexes

This paper deals with the synthesis, structural studies, and behavior in solution of unprecedented coordination complexes built by the association of a panel of 14 representative thiosemicarbazone ligands with the cluster [Mo₂O₂S₂]²⁺. These complexes have been thoroughly characterized both in the solid state and in solution by XRD and by NMR, respectively. In particular, HMBC ¹H{¹⁵N} and ¹H DOSY NMR experiments bring important elements for understanding the complexes' behavior in solution. These studies demonstrate that playing on the nature and the position of various substituents on the ligands strongly influences the coordination modes of the ligands as well as the numbers of isomers in solution, mainly 2 products for the majority of complexes and up to 5 for some of them.

Methodological Appraisal of Literature Concerning the Analysis of Genetic Variants or Protein Levels of Complement Components on Susceptibility to Infection by Trypanosomatids: A Systematic Review

Background

Trypanosomatids are protozoa responsible for a wide range of diseases, with emphasis on Chagas Disease (CD) and Leishmaniasis, which are in the list of most relevant Neglected Tropical Diseases (NTD) according to World Health Organization (WHO). During the infectious process, immune system is immediately activated, and parasites can invade nucleated cells through a broad diversity of receptors. The complement system − through classical, alternative and lectin pathways − plays a role in the first line of defense against these pathogens, acting in opsonization, phagocytosis and lysis of parasites. Genetic modifications in complement genes, such as Single Nucleotide Polymorphisms (SNPs), can influence host susceptibility to these parasites and modulate protein expression.

Methods

In March and April 2021, a literature search was conducted at the PubMed and Google Scholar databases and the reference lists obtained were verified. After applying the inclusion and exclusion criteria, the selected studies were evaluated and scored according to eleven established criteria regarding their thematic approach and design, aiming at the good quality of publications.

Results

Twelve papers were included in this systematic review: seven investigating CD and five focusing on Leishmaniasis. Most articles presented gene and protein approaches, careful determination of experimental groups, and adequate choice of experimental techniques, although several of them were not up-to-date. Ten studies explored the association of polymorphisms and haplotypes with disease progression, with emphasis on lectin complement pathway genes. Decreased and increased patient serum protein levels were associated with susceptibility to CD and Visceral Leishmaniasis, respectively.

Conclusion

This systematic review shows the influence of genetic alterations in complement genes on the progression of several infectious diseases, with a focus on conditions caused by trypanosomatids, and contributes suggestions and evidence to improve experimental design in future research proposals.

Hybrid Quinoline-Thiosemicarbazone Therapeutics as a New Treatment Opportunity for Alzheimer's Disease‒Synthesis, In Vitro Cholinesterase Inhibitory Potential and Computational Modeling Analysis

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia worldwide. The limited pharmacological approaches based on cholinesterase inhibitors only provide symptomatic relief to AD patients. Moreover, the adverse side effects such as nausea, vomiting, loss of appetite, muscle cramps, and headaches associated with these drugs and numerous clinical trial failures present substantial limitations on the use of medications and call for a detailed insight of disease heterogeneity and development of preventive and multifactorial therapeutic strategies on urgent basis. In this context, we herein report a series of quinoline-thiosemicarbazone hybrid therapeutics as selective and potent inhibitors of cholinesterases. A facile multistep synthetic approach was utilized to generate target structures bearing multiple sites for chemical modifications and establishing drug-receptor interactions. The structures of all the synthesized compounds were fully established using readily available spectroscopic techniques (FTIR, ¹H- and ¹³C-NMR). In vitro inhibitory results revealed compound 5b as a promising and lead inhibitor with an IC₅₀ value of 0.12 ± 0.02 μM, a 5-fold higher potency than standard drug (galantamine; IC₅₀ = 0.62 ± 0.01 μM). The synergistic effect of electron-rich (methoxy) group and ethylmorpholine moiety in quinoline-thiosemicarbazone conjugates contributes significantly in improving the inhibition level. Molecular docking analysis revealed various vital interactions of potent compounds with amino acid residues and reinforced the in vitro results. Kinetics experiments revealed the competitive mode of inhibition while ADME properties favored the translation of identified inhibitors into safe and promising drug candidates for pre-clinical testing. Collectively, inhibitory activity data and results from key physicochemical properties merit further research to ensure the design and development of safe and high-quality drug candidates for Alzheimer’s disease.

Insight into Recent Drug Discoveries against Trypanosomatids and Plasmodium spp Parasites: New Metal-based Compounds

Scaffolds of metal-based compounds can act as pharmacophore groups in several ligands to treat various diseases, including tropical infectious diseases (TID). In this review article, we investigate the contribution of these moieties to medicinal inorganic chemistry in the last seven years against TID, including American trypanosomiasis (Chagas disease), human African trypanosomiasis (HAT, sleeping sickness), leishmania, and malaria. The most potent metal-based complexes are displayed and highlighted in figures, tables and graphics; according to their pharmacological activities (IC50 > 10µM) against Trypanosomatids and Plasmodium spp parasites. We highlight the current progresses and viewpoints of these metal-based complexes, with a specific focus on drug discovery.

Novel Bis-Thiazole Derivatives: Synthesis and Potential Cytotoxic Activity Through Apoptosis With Molecular Docking Approaches

A series of bis-thiazoles 5a-g were synthesized from bis-thiosemicarbazone 3 with hydrazonoyl chlorides 4a-g. Reaction of 3 with two equivalents of α-halocarbonyl compounds 6-8, 10, and 12a-d afforded the corresponding bis-thiazolidines 9, 11, and 13a-d, respectively. Condensation of bis-thiazolidin-4-one 9 with different aromatic aldehydes furnished bis-thiazolidin-4-ones 14a-d. Compounds 5a-g, 9, and 13a,c,d were screened in vitro for their cytotoxic activities in a panel of cancer cell lines. Compounds 5a-c, 5f-g, and 9 exhibited remarkable cytotoxic activities, especially compound 5c with potent IC50 value 0.6 nM (against cervical cancer, Hela cell line) and compound 5f with high IC50 value 6 nM (against ovarian cancer, KF-28 cell line). Compound 5f-induced appreciated apoptotic cell death was measured as 82.76% associated with cell cycle arrest at the G1 phase. The apoptotic pathways activated in KF-28 cells treated with 5a, 5b, and 5f were further investigated. The upregulation of some pro-apoptotic genes, bax and puma, and the downregulation of some anti-apoptotic genes including the Bcl-2 gene were observed, indicating activation of the mitochondrial-dependent apoptosis. Together with the molecular docking studies of compounds 5a and 5b, our data revealed potential Pim-1 kinase inhibition through their high binding affinities indicated by inhibition of phosphorylated C-myc as a downstream target for Pim-1 kinase. Our study introduces a set of bis-thiazoles with potent anti-cancer activities, in vitro.

An Overview of the Synthesis and Antimicrobial, Antiprotozoal, and Antitumor Activity of Thiazole and Bisthiazole Derivatives

Thiazole, a five-membered heteroaromatic ring, is an important scaffold of a large number of synthetic compounds. Its diverse pharmacological activity is reflected in many clinically approved thiazole-containing molecules, with an extensive range of biological activities, such as antibacterial, antifungal, antiviral, antihelmintic, antitumor, and anti-inflammatory effects. Due to its significance in the field of medicinal chemistry, numerous biologically active thiazole and bisthiazole derivatives have been reported in the scientific literature. The current review provides an overview of different methods for the synthesis of thiazole and bisthiazole derivatives and describes various compounds bearing a thiazole and bisthiazole moiety possessing antibacterial, antifungal, antiprotozoal, and antitumor activity, encouraging further research on the discovery of thiazole-containing drugs.

Synthesis, Crystal Structure, Biological Evaluation and in Silico Studies on Novel (E)-1-(Substituted Benzylidene)-4-(3-isopropylphenyl)thiosemicarbazone Derivatives

A series of (E)-1-(substituted benzylidene)-4-(3-isopropylphenyl)thiosemicarbazone derivatives were synthesized and characterized by FT-IR spectrum, elemental analysis, NMR spectrum, HR-MS spectrum, and X-ray single crystal diffraction technology. The crystal structures and packing of (E)-1-(4-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone and (E)-1-(3-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone were maintained through the intramolecular hydrogen bond (N3-H6⋅⋅⋅N1) and intermolecular hydrogen bonds (N2-H4⋅⋅⋅S1, C14-H14⋅⋅⋅F1 and C7-H7⋅⋅⋅S1). The results obtained by employing the DPPH free radicals scavenging assay indicated that (E)-1-(4-methoxylbenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had a more significant antioxidant activity compared with other compounds. The results measured by adopting the disc diffusion method elucidated that (E)-1-(4-trifluoromethylbenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone possessed a more prominent antifungal activity than other compounds. Molecular docking showed that (E)-1-(4-chlorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had the highest affinity with receptor protein (1NMT). Moreover, the drug-likeness characteristic, physicochemical properties, pharmacokinetic profiles, and bioactivity scores of all the compounds were predicted through in silico studies. The results illustrated that (E)-1-(4-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had the drug-likeness characteristic and all the compounds were considered as moderately biological active molecules.

New Scheme of Intermittent Benznidazole Administration in Patients Chronically Infected with Trypanosoma cruzi: Clinical, Parasitological, and Serological Assessment after Three Years of Follow-Up

In a pilot study, we showed that the intermittent administration of benznidazole in chronic Chagas disease patients resulted in a low rate of treatment suspension and therapeutic failure, as assessed by quantitative PCR (qPCR) at the end of treatment. Here, a 3-year posttreatment follow-up study of the same cohort of patients is presented. The treatment scheme consisted of 12 doses of benznidazole at 5 mg/kg of body weight/day in two daily doses every 5 days. Parasite load, Trypanosoma cruzi-specific antibodies, and serum chemokine levels were measured prior to treatment and after a median follow-up of 36 months posttreatment by DNA minicircle kinetoplastid and nuclear DNA satellite sequence qPCR methods, conventional serological techniques, a Luminex-based assay with recombinant T. cruzi proteins, and a cytometric bead array. At the end of follow-up, 14 of 17 (82%) patients had negative qPCR findings, whereas three of 17 (18%) had detectable nonquantifiable findings by at least one of the qPCR techniques. A decline in parasite-specific antibodies at 12 months posttreatment was confirmed by conventional serological tests and the Luminex assays. Monocyte chemoattractant protein 1 levels increased after treatment, whereas monokine induced by gamma interferon levels decreased. New posttreatment electrocardiographic abnormalities were observed in only one patient who had cardiomyopathy prior to treatment. Together, these data strengthen our previous findings by showing that the intermittent administration of benznidazole results in a low rate of treatment suspension, with treatment efficacy comparable to that of a daily dose of 5 mg/kg for 60 days.

Selenium as an interesting option for the treatment of Chagas disease: A review

Chagas disease is one of the most prevalent tropical neglected diseases and causes high mortality and morbidity in endemic countries. Current treatments for this disease, nifurtimox and benznidazole, are ineffective in the chronic phase of the disease and produce severe adverse effects. Therefore, novel therapies are urgently required. The trace element selenium has an important role in human health, due to its antioxidant, antiinflammatory and pro-immune properties. Actually, its deficiency has been related to several diseases and supplementation with this element has been proven to be beneficial for multiple pathologies. Furthermore, the usefulness of organic-selenium compounds has been studied in many disorders, showing promising results. The aim of this review is to analyse the available literature regarding the role of selenium in Chagas disease in order to determine whether its use could be beneficial for the management of this pathology.

Characterization and Release Behavior of a Thiosemicarbazone from Electrospun Polyvinyl Alcohol Core-Shell Nanofibers

Mats of polyvinyl alcohol (PVA) core-shell nanofibers were produced using coaxial electrospinning in the presence of a thiosemicarbazone (TSC) N4-(S)-1-phenylethyl)-2-(pyridin-2-yl-ethylidene)hydrazine-1-carbothioamide (HapyTSCmB). Monolithic fibers with 0% or 5% TSC and core-shell fibers with 10% TSC in the spinning solution were studied to compare stability and release rates. SEM showed the formation of uniform, bead-free, cylindrical, and smooth fibers. NMR spectroscopy and thermal analysis (TG/DTA) gave proof for the chemical integrity of the TSC in the fiber mats after the electrospinning process. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy showed no TSC on the surface of the PVA/TSC-PVA fibers confirming the core-shell character. The TSC release profiles of the fibers as studied using UV-vis absorption spectroscopy showed a slower release from the PVA/TSC-PVA core-shell structure compared with the monolithic PVA/TSC fibers as well as lower cumulative release percentage (17%). Out of several release models, the Korsmeyer-Peppas model gave the best fit to the experimental data. The main release phase can be described with a Fick-type diffusion mechanism. Antibacterial properties were tested against the Gram-positive Staphylococcus aureus bacterium and gave a minimal inhibitory concentration of 12.5 μg/mL. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT)-based cytotoxicity experiments showed that the cell viability of fibroblast at different contents of TSC was slightly decreased from 1.5% up to 3.5% when compared to control cells.

Single-crystal structure and intracellular localization of Zn(II)-thiosemicarbazone complex targeting mitochondrial apoptosis pathways

Tracking of drugs in cancer cells is important for basic biology research and therapeutic applications. Therefore, we designed and synthesised a Zn(II)-thiosemicarbazone complex with photoluminescent property for organelle-specific imaging and anti-cancer proliferation. The Zn(AP44eT)(NO₃)₂ coordination ratio of metal to ligand was 1:1, which was remarkably superior to 2-((3-aminopyridin-2-yl) methylene)-N, N-diethylhydrazinecarbothioamide (AP44eT·HCl) in many aspects, such as fluorescence and anti-tumour activity. Confocal fluorescence imaging showed that the Zn(AP44eT)(NO₃)₂ was aggregated in mitochondria. Moreover, Zn(AP44eT)(NO₃)₂ was more effective than the metal-free AP44eT·HCl in shortening the G2 phase in the MCF-7 cell cycle and promoting apoptosis of cancer cells. Supposedly, the effects of these complexes might be located mainly in the mitochondria and activated caspase-3 and 9 proteins.

Synthesis and Biological Activity of Some Aminothiazole Derivatives as Antileishmanial Agents

Background:

Leishmaniasis is a major health problem which is caused by the protozoan parasite of the genus Leishmania. Cutaneous leishmaniasis is one type of leishmaniasis and selflimited in most of the cases. However, when the lesions come with scars, they make a deep lifelong stigma. Despite being WHO's research priority, the optimum treatment for this disease has not been found yet. The current study aimed to synthesize and assess the activity of some new aminothiazole compounds against Leishmania major-induced cutaneous leishmaniasis in BALB/c mice.

Methods:

Eight new aminothiazole derivatives were synthesized and their chemical structures were characterized by spectral data 1H-NMR spectroscopy, Mass spectrophotometry and elemental analysis. L. major parasites were inoculated into the tail base of BALB/c mice and the induced lesions were treated every other day with three different doses of the synthesized compounds against meglumine antimoniate as the drug reference for two weeks. Size of the lesions was observed for three weeks and the collected data were analyzed by SPSS software. Also, these compounds are docked into the active site of 14- α-demethylase as the targets in the treatment of leishmaniasis.

Results:

Among the synthesized aminothiazole derivatives, compounds 1, 2, 3, 4, and 7 had good leishmanicidal effects. Docking binding energies showed that the synthesized compounds could act as inhibitors for 14- α-demethylase.

Conclusions:

Among the synthesized compounds, compound 3, (N-((4-chlorophenyl)(phenyl) methyl)thiazol-2-amine) was the most promising one which deserves future studies for the treatment of leishmaniasis.

Synthesis, crystal structure and antiproliferative mechanisms of gallium(iii) complexes with benzoylpyridine thiosemicarbazones

We have prepared six thiosemicarbazone ligands and synthesized the corresponding Ga(iii) complexes. The antitumor activity of the ligand increases with its lipophilicity, and the antitumor activity of the Ga(iii) complexes is affected by the ligands. Since C6 has the highest anticancer proliferative activity (0.14 ± 0.01 μM) against HepG-2 (Human hepatocarcinoma cell line), we characterized its structure by X-ray single crystal diffraction and explored its antiproliferation mechanism. Anti-tumor mechanism results show that Ga(iii) complex (C6) promoted HepG-2 cell cycle arrest in the G1 phase by regulating the expression of cell cycle-associated proteins (Cdk 2, cyclin A and cyclin E). Ga(iii) complex (C6) promotes apoptosis by consuming intracellular iron, enhancing intracellular reactive oxygen species (ROS), activating caspase-3/9, releasing cytochromes and apoptotic protease activating factor-1 (apaf-1).

Synthesis and Biological Evaluation of Novel (thio)semicarbazone-Based Benzimidazoles as Antiviral Agents against Human Respiratory Viruses

Respiratory RNA viruses are responsible for recurrent acute respiratory illnesses that still represent a major medical need. Previously we developed a large variety of benzimidazole derivatives able to inhibit these viruses. Herein, two series of (thio)semicarbazone- and hydrazone-based benzimidazoles have been explored, by derivatizing 5-acetyl benzimidazoles previously reported by us, thereby evaluating the influence of the modification on the antiviral activity. Compounds 6, 8, 16 and 17, bearing the 5-(thio)semicarbazone and 5-hydrazone functionalities in combination with the 2-benzyl ring on the benzimidazole core structure, acted as dual inhibitors of influenza A virus and human coronavirus. For respiratory syncytial virus (RSV), activity is limited to the 5-thiosemicarbazone (25) and 5-hydrazone (22) compounds carrying the 2-[(benzotriazol-1/2-yl)methyl]benzimidazole scaffold. These molecules proved to be the most effective antiviral agents, able to reach the potency profile of the licensed drug ribavirin. The molecular docking analysis explained the SAR of these compounds around their binding mode to the target RSV F protein, revealing the key contacts for further assessment. The herein-investigated benzimidazole-based derivatives may represent valuable hit compounds, deserving subsequent structural improvements towards more efficient antiviral agents for the treatment of pathologies caused by these human respiratory viruses.

New thiazole, pyridine and pyrazole derivatives as antioxidant candidates: synthesis, DFT calculations and molecular docking study

Novel heterocyclic compounds containing pyrazole, thiazole and pyridine moieties were designed and prepared based on the condensation reaction between 1,3-thiazole or aminopyridine derivatives and 1H-pyrazole,3,5-dimethyl-1H-pyrazole or 1,2,4-triazole. Their structures were confirmed with FTIR, ¹H and ¹³C NMR analyses. DPPH scavenging assay was used to evaluate their antioxidant potential. The ligand 4 showed the best antioxidant activity with an IC₅₀ = 4.67 μg/mL, while IC₅₀ values of the other compounds were found to be ranging from 20.56 to 45.32 μg/mL. DFT and molecular docking studies were performed in order to gain better insights and to understand the relationship between the structures of the studied compounds and their antioxidant activities. The results obtained revealed a good agreement between the experimental and the theoretical findings.

Synthesis and evaluation of novel 2,4-disubstituted arylthiazoles against T. brucei

2-{2-[3-(1-Adamantyl)-4-fluorophenyl]thiazol-4-yl}ethan-1-amine (1a) and 2-{2-[4-(1-adamantyl)phenyl]thiazol-4-yl}ethan-1-amine (2a) exhibit activity against T. brucei in the range of IC₅₀ = 0.42 μM and IC₅₀ = 0.80 μM, respectively.

The design, synthesis and pharmacological evaluation of the 4-substituted-2-[3-(adamant-1-yl)-4-fluorophenyl]thiazoles 1a–j, the 4-substituted-2-[4-(adamant-1-yl)phenyl]thiazoles 2a–h, the 2-substituted-4-[4-(adamant-1-yl)phenyl]thiazoles 3a–e, the N-substituted 2-phenylthiazol-4-ethylamides 4a, b and the N-substituted 4-phenylthiazol-2-ethylamides 4c, d is described. Compounds 1a and 2a exhibit trypanocidal activity in the range of IC₅₀ = 0.42 μM and IC₅₀ = 0.80 μM, respectively. Both of these derivatives bear a lipophilic end, which consists of a 4-(1-adamantyl) phenyl or a 3-(1-adamantyl)phenyl moiety, a 1,3-thiazole ring and a functional end, which comprises of an alkylamine and can be considered as promising candidates for the treatment of Trypanosoma brucei infections.

Trypanocidal Mechanism of Action and in silico Studies of p-Coumaric Acid Derivatives

Trypanosoma species are responsible for chronic and systemic infections in millions of people around the world, compromising life quality, and family and government budgets. This group of diseases is classified as neglected and causes thousands of deaths each year. In the present study, the trypanocidal effect of a set of 12 ester derivatives of the p-coumaric acid was tested. Of the test derivatives, pentyl p-coumarate (7) (5.16 ± 1.28 μM; 61.63 ± 28.59 μM) presented the best respective trypanocidal activities against both epimastigote and trypomastigote forms. Flow cytometry analysis revealed an increase in the percentage of 7-AAD labeled cells, an increase in reactive oxygen species, and a loss of mitochondrial membrane potential; indicating cell death by necrosis. This mechanism was confirmed by scanning electron microscopy, noting the loss of cellular integrity. Molecular docking data indicated that of the chemical compounds tested, compound 7 potentially acts through two mechanisms of action, whether by links with aldo-keto reductases (AKR) or by comprising cruzain (CZ) which is one of the key Trypanosoma cruzi development enzymes. The results indicate that for both enzymes, van der Waals interactions between ligand and receptors favor binding and hydrophobic interactions with the phenolic and aliphatic parts of the ligand. The study demonstrates that p-coumarate derivatives are promising molecules for developing new prototypes with antiprotozoal activity.

New dicationic DABCO-based ionic liquids: a scalable metal-free one-pot synthesis of bis-2-amino-5-arylidenethiazol-4-ones

Herein, a novel DABCO-based dicationic ionic liquid (bis-DIL) was easily prepared from the sonication of DABCO with 1,3-dichloro-2-propanol and then characterized by several techniques. Thereafter, under the ultimate green conditions, the performance of the bis-DIL was examined for the sono-synthesis of a new library of bis-2-amino-5-arylidenethiazol-4-ones via one-pot pseudo-five-component Knoevenagel condensation reaction of appropriate dialdehydes, rhodanine and amines. This protocol is tolerant towards several mono- and dialdehydes, excellently high yielding and affording access to the desired products in a single step within a short reaction time. Compared with the conventional methodologies, the proposed method displayed several remarkable merits such as milder reaction conditions without any side product, green solvent media, recording well in a variety of green metrics and applicability in gram-scale production. The recyclability of the bis-DIL was also investigated with an average recovered yield of 97% for six sequential cycles without any significant loss of the activity.

Araticum (Annona crassiflora Mart.) as a source of nutrients and bioactive compounds for food and non-food purposes: A comprehensive review

Araticum (Annona crassiflora Mart.) is a fruitful tree native to the Brazilian Cerrado biome that holds high nutritional, functional and economic potential. This plant has been used since ancient times by folk medicine for the treatment of several pathological conditions. There has been increasing interest in the development of pulp-based food products as well as the by-products utilization to obtain value-added ingredients. Understanding the chemical composition and biological activities of different botanical parts of Annona crassiflora Mart. provides a basis to support future researches and applications. In this context, this paper carries out an exhaustive review of the scientific literature, on the main phytochemicals of different botanical parts of Annona crassiflora Mart. (fruit, leaves, stem and root) and their biological activities, assessing their potential uses for several industrial segments. Annona crassiflora Mart. fruits and especially their by-products (peel and seeds) and leaves have been shown a wide range of bioactive compounds such as phenolic compounds, alkaloids, annonaceous acetogenins, tocols, carotenoids, phytosterols, dietary fiber, vitamins, minerals and essential oils. These compounds contribute to various biological activities, including antioxidant, hepatoprotective, anti-inflammatory, antitumoral, analgesic, antidiabetic, skin healing, antidiarrhoeic, antimicrobial, antiparasitic, insecticide and herbicide activities of Annona crassiflora Mart. extracts. Therefore, these findings demonstrate that Annona crassiflora Mart. fruit, by-products and leaves can be excellent candidates to be used as functional foods and/or sources for obtaining bioactive compounds for the food, cosmetics and pharmaceutical applications.