Targeting the Schistosoma mansoni nutritional mechanisms to design new antischistosomal compounds

The chemical classes of semicarbazones, thiosemicarbazones, and hydrazones are present in various compounds, each demonstrating diverse biological activities. Extensive studies have revealed their potential as schistosomicidal agents. Thiosemicarbazones, in particular, have shown inhibitory effects on Schistosoma mansoni's cathepsin B1 enzyme (SmCB1), which plays a crucial role in hemoglobin degradation within the worm's gut and its nutrition processes. Consequently, SmCB1 has emerged as a promising target for novel schistosomiasis therapies. Moreover, chloroquinoline exhibits characteristics in its aromatic structure that hold promise for developing SmCB1 inhibitors, along with its interaction with hemoglobin's heme group, potentially synergizing against the parasite's gut. In this context, we report the synthesis of 22 hybrid analogs combining hydrazones and quinolines, evaluated against S. mansoni. Five of these hybrids demonstrated schistosomicidal activity in vitro, with GPQF-8Q10 being the most effective, causing worm mortality within 24 h at a concentration of 25 µM. GPQF-8Q8 proved to be the most promising in vivo, significantly reducing egg presence in feces (by 52.8%) and immature eggs in intestines (by 45.8%). These compounds exhibited low cytotoxicity in Vero cells and an in in vivo animal model (Caenorhabditis elegans), indicating a favorable selectivity index. This suggests their potential for the development of new schistosomiasis therapies. Further studies are needed to uncover specific target mechanisms, but these findings offer a promising starting point.

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.

2-Oxoquinoline-based-thiosemicarbazones as multitargeting neurotherapeutics against Alzheimer's disease: In vitro and in silico studies of MAO and ChE inhibitors

Alzheimer's disease (AD) presents a multifactorial neurological disorder with multiple enzyme involvement in its onset. Conventional monotherapies fall short in providing long-term relief, necessitating the exploration of alternative multitargeting approaches to address the complexity of AD. Therefore, the design, synthesis, and in vitro and in silico evaluation of 2-oxoquinoline-based thiosemicarbazones 9a-r as multipotent analogs, able to simultaneously inhibit the cholinesterase (ChE) and monoamine oxidase (MAO) enzymes for the potential treatment of AD, are reported. In the in vitro experimental evaluation of MAO and ChE inhibition, all tested compounds demonstrated remarkable potency exhibiting nonselective inhibition of both MAO-A and MAO-B, and selective inhibition of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE), with 9d, 9j, and 9m evolving as lead compounds for MAO-A, MAO-B, and AChE, displaying IC50 values of 0.35 ± 0.92, 0.50 ± 0.02, and 0.25 ± 0.13 μM, respectively. Moreover, the kinetic studies revealed that all tested compounds inhibited all three enzymes through a competitive mode of inhibition. Furthermore, the molecular docking studies of the most active compounds revealed several crucial interactions, particularly hydrogen bonding interactions. These interactions were observed between the nitrogen and sulfur atoms of thiosemicarbazone and the nitrogen and oxygen atoms of the quinoline ring with various amino acids, suggesting the strong interactions of these compounds with the enzymes.

Microwave-assisted solvent-free synthesis of some novel thiazole-substituted thiosemicarbazone analogues: antimicrobial and anticancer studies

The increased resistance to antibiotics has compelled researchers to devise novel active compounds targeting multidrug-resistant pathogenic microorganisms. A series of thiosemicarbazone derivatives was synthesized by reacting thiosemicarbazide with 2-aryl-4-formylthiazole, 2-aryl-5-formyl-4-methylthiazole, and/or 5-acetyl-2-aryl-4-methylthiazole compounds. These thiosemicarbazone-based thiazole adducts were evaluated for their inhibitory activities against tuberculosis H37Ra and Bovis BCG mycobacteria. Their cytotoxicity was assessed against two cancer cell lines: colonic carcinoma (HCT-116) and cervical cancer (HeLa). Notably, these thiosemicarbazones exhibited minimal cytotoxic effects on these cell lines even at their highest concentrations. Furthermore, the prepared thiosemicarbazone derivatives demonstrated significant antimicrobial efficacy against Bacillus subtilis and Staphylococcus aureus (Gram-positive bacterial pathogens) as well as Escherichia coli and Pseudomonas fluorescens (Gram-negative bacterial pathogens). While most of the prepared thiosemicarbazone derivatives exhibited moderate activity against Candida albicans (a fungal strain), their performance was notable. The thiosemicarbazone-based thiazole adducts were also successfully synthesized using a solvent-free approach under microwave irradiation. Compared with conventional reflux methods, the microwave-assisted technique yielded high thiazole yields within just 5 min, obviating the need for catalysis. This study signifies significant strides toward the rational design of more potent antimycobacterial agents.

Synthesis of novel coumarin-based thiosemicarbazones and their implications in diabetic management via in-vitro and in-silico approaches

Diabetes mellitus has a high prevalence rate and it has been deemed a severe chronic metabolic disorder with long-term complications. This research aimed to identify compounds that could potentially inhibit the vital metabolic enzyme α-glucosidase and thereby exert an anti-hyperglycemic effect. The main goal was to establish an effective approach to control diabetes. To proceed with this study, a series of novel coumarin-derived thiosemicarbazones 3a-3m was synthesized and examined using a variety of spectroscopic methods. Moreover, all the compounds were subjected to α-glucosidase inhibition bioassay to evaluate their antidiabetic potential. Fortunately, all the compounds exhibited several folds potent α-glucosidase inhibitory activities with IC50 values ranging from 2.33 to 22.11 µM, in comparison to the standard drug acarbose (IC50 = 873.34 ± 1.67 µM). The kinetic studies of compound 3c displayed concentration-dependent inhibition. Furthermore, the binding modes of these molecules were elucidated through a molecular docking strategy which depicted that the thiosemicarbazide moiety of these molecules plays a significant role in the interaction with different residues of the α-glucosidase enzyme. However, their conformational difference is responsible for their varied inhibitory potential. The molecular dynamics simulations suggested that the top-ranked compounds (3c, 3g and 3i) have a substantial effect on the protein dynamics which alter the protein function and have stable attachment in the protein active pocket. The findings suggest that these molecules have the potential to be investigated further as novel antidiabetic medications.

Novel alkyl-substituted 4-methoxy benzaldehyde thiosemicarbazones: Multi-target directed ligands for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder affecting mental ability and interrupts neurocognitive functions. Treating multifactorial conditions of AD with a single-target-directed drug is highly difficult. Thus, a multi-target-directed ligand (MTDL) development strategy has been developed as a promising approach for the treatment of AD. Herein, we have synthesized two novel thiosemicarbazones as MTDLs and reported their bioactivities against diverse neuropathological events involved in AD. In vitro studies revealed that both compounds exhibited promising anticholinesterase activity (AChE, IC50 = 15.98 μM, MZET and IC50 = 30.23 μM, MZMT), well supported by a detailed computational study. Both analogs have shown good thermodynamic behaviour and stability through interactions with characteristic amino acid residues throughout simulation of 100 ns against acetylcholinesterase enzyme. In an electrophysiology assay, these analogs have shown a characteristic inhibitory response against the GluN1-1a + GluN2B subunit of N-methyl-D-aspartate receptors. Pre-treatment of BV-2 microglial cells with MZET effectively decreased nitrite production compared to nitrite produced by lipopolysaccharide-treated cells alone. Further, the effect of MZMT and MZET on autophagy regulation was determined using stably transfected SH-SY5Y neuroblastoma cells. MZET significantly enhanced the autophagy flux in neuroblastoma cells. A significant decrease in copper-catalysed oxidation of amyloid-β in presence of synthesized thiosemicarbazones was also observed. Collectively, our findings indicated that these analogs have potential as effective anti-AD candidates and can be used as a prototype to develop more safer multi-targeted anti-AD drugs.

Design, synthesis, and biological evaluation of a series of benzofuran[3,2-d]pyrimidine-4(3H)-one derivatives containing thiosemicarbazone analogs as novel PARP-1 inhibitors

Poly ADP ribose polymerase-1 (PARP-1), one of the most important members of the PARP protein family, plays a crucial role in DNA damage repair, gene transcription, and apoptosis of cancer cells. In this work, benzofuran[3,2-d]pyrimidine-4(3H)-one was used as a framework to design and synthesize a series of novel PARP-1 inhibitors by introducing thiosemicarbazone or its derivatives into the scafford. Among all the target compounds, 19b and 19c were found to exhibit more potent inhibitory activity and higher selectivity against PARP-1 than Olaparib, especially the latter had an IC50 value of 0.026 μM against PARP-1 enzyme and a PARP-2/PARP-1 selectivity of 85.19-fold over Olapanib. Apart from strong cytotoxicity against the tested cancer cell lines, 19c was most sensitive to SK-OV-3 cells, with an IC50 value of 4.98 μM superior to Olaparib. Anti-cancer mechanism studies revealed that 19c could inhibit DNA single-strand breakage repair and aggravate DNA double-strand breakage by inhibiting PARP-1 activity, and promote the apoptosis of cancer cells through the mitochondrial apoptosis pathway.

Synthesis, biological evaluation and molecular modelling of 3-Formyl-6-isopropylchromone derived thiosemicarbazones as α-glucosidase inhibitors

Type-2 Diabetes Mellitus (T2DM) is one of the most common metabolic disorders in the world and over the past three decades its incidence has increased drastically. α-Glucosidase inhibitors are used to control the hyperglycemic affect of T2DM. Herein, we report the synthesis, α-glucosidase inhibition, structure activity relationship, pharmacokinetics and docking analysis of various novel chromone based thiosemicarbazones 3(a-r). The derivatives displayed potent activity against α-glucosidase with IC50 in range of 0.11 ± 0.01-79.37 ± 0.71 µM. Among all the synthesized compounds, 3a (IC50 = 0.17 ± 0.026 µM), 3 g (IC50 = 0.11 ± 0.01 µM), 3n (IC50 = 0.55 ± 0.02 µM), and 3p (IC50 = 0.43 ± 0.025 µM) displayed higher inhibitory activity as compared to the standard, acarbose. Moreover, we have developed a statistically significant 2D-QSAR model (R2tr:0.9693; F: 50.4647 and Q2LOO:0.9190), which can be used in future to further design potent thiosemicarbazones as inhibitors of α-glucosidase.

Theoretical, in Vitro Antiproliferative, and in Silico Molecular Docking and Pharmacokinetics Studies of Heteroleptic Nickel(II) and Copper(II) Complexes of Thiosemicarbazone-Based Ligands and Pefloxacin

Twelve new heteroleptic nickel(II) and copper(II) complexes of the type [M(L1-6 )(Pfx)2 ] (1-12), where L1-6 =2-benzylidenehydrazinecarbothioamide (L1 ), 2-benzylidene-N-methylhydrazinecarbothioamide (L2 ), 2-benzylidene-N-phenylhydrazinecarbothioamide (L3 ), 2-(4-methylbenzylidene)hydrazinecarbothioamide (L4 ), 2-(4-methylbenzylidene)-N-methylhydrazinecarbothioamide (L5 ) and 2-(4-methylbenzylidene)-N-phenylhydrazinecarbothioamide (L6 ), Pfx=pefloxacin and M=Ni(II) or Cu(II) have been synthesised, and their structures were confirmed by different spectral techniques. The spectral data and density functional theory (DFT) calculations supported the bonding of pefloxacin drug molecule via one of the carboxylate oxygen atoms and the pyridone oxygen atom, and the thiosemicarbazone ligand via the imine nitrogen and the thione sulfur atoms with the metal(II) ion, forming distorted octahedral geometry. In vitro antiproliferative activity of the synthesized complexes was evaluated against three human breast cancer (T47D, estrogen negative (MDA-MB-231) and estrogen positive (MCF-7)) as well as non-tumorigenic human breast epithelial (MCF-10a) cell lines, which showed the higher activity for the copper(II) complexes. The interaction of the synthesized complexes with an oncogenic protein H-ras (121 p) was explored by in silico molecular docking studies. Further, in silico pharmacokinetics and ADMET parameters were also analysed to predict the drug-likeness as well as non-toxic and non-carcinogenic behavior, and safe oral administration of the complexes.

Physical structure of constitutional isomers influences antiproliferation activity of thiosemicarbazone-alkylthiocarbamate copper complexes

A series of hybrid thiosemicarbazone-alkylthiocarbamate copper complexes with similar electronic environments but distinct physical structures have been prepared, characterized, and evaluated for antiproliferation activity. The complexes include the constitutional isomers (1-phenylpropane-1-imine-(O-ethylthiocarbamato)-2-one-(N-methylthiosemicarbazonato))copper(II) (CuL1) and (1-phenylpropane-1-one-(N-methylthiosemicarbazonato)-2-imine-(O-ethylthiocarbamato))copper(II) (CuL2) along with (1-propane-1-imine-(O-ethylthiocarbamato)-2-one-(N-methylthiosemicarbazonato))copper(II) (CuL3). Complexes CuL1 and CuL2 differ in the positions of the pendent thiosemicarbazone (TSC) and alkylthiocarbamate (ATC) moieties on the 1-phenylpropane backbone. Complex CuL3 employs a propane backbone with the TSC in the 2-position as in CuL1. The isomer pair CuL1 and CuL2 have equivalent electronic environments with indistinguishable CuII/I potentials (E1/2 = -0.86 V vs. ferrocenium/ferrocene) and electron paramagnetic resonance (EPR) spectra (g∥ = 2.26, g⊥ = 2.08). The electronic structure of CuL3 has a similar E1/2 of -0.84 V and identical EPR parameters to CuL1, 2. Single crystal X-ray diffraction studies confirm a consistent donor environment with no substantial variation in the CuN or CuS bond distances and angles between the complexes. The antiproliferation activities of the CuL1-3 were evaluated against the lung adenocarcinoma cell line (A549) and nonmalignant lung fibroblast cell line (IMR-90) using the MTT assay. CuL1 had the highest A549 activity (A549EC50 = 0.065 μM) and selectivity (IMR-90EC50/A549EC50 = 20). The constitutional isomer CuL2 displayed decreased A549 activity (0.18 μM) and selectivity (10.6). The complex CuL3 displayed activity (0.009 μM) similar to CuL1 but with a lack of selectivity (1.0). Cellular copper loading determined by ICP-MS was consistent with the activity and selectivity trends. The complexes CuL1-3 did not induce reactive oxygen species (ROS) generation.

Human serum albumin as a copper source for anticancer thiosemicarbazones

Thiosemicarbazones (TSCs) are a class of biologically active compounds with promising anticancer activity. Their typical mechanism, especially of the clinically far developed representative Triapine, is chelation of iron (Fe), with the Fe-containing enzyme ribonucleotide reductase as primary intracellular target. However, for the subclass of terminally disubstituted, nanomolar-active derivatives like Dp44mT and Me2NNMe2, recent findings suggest that the chelation, stability, and reduction properties of the copper(II) (Cu) complexes are essential for their modes of action. Consequently, it is important to elucidate whether blood serum Cu(II) is a potential metal source for these TSCs. To gain more insights, the interaction of Triapine, Dp44mT or Me2NNMe2 with purified human serum albumin (HSA) as the main pool of labile Cu(II) was investigated by UV-vis and electron paramagnetic resonance measurements. Subsequently, a size-exclusion chromatography inductively coupled plasma mass spectrometry method for the differentiation of Cu species in serum was developed, especially separating the non-labile Cu enzyme ceruloplasmin from HSA. The results indicate that the TSCs specifically chelate copper from the N-terminal Cu-binding site of HSA. Furthermore, the Cu(II)-TSC complexes were shown to form ternary HSA conjugates, most likely via histidine. Noteworthy, Fe-chelation from transferrin was not overserved, even not for Triapine. In summary, the labile Cu pool of HSA is a potential source for Cu-TSC complex formation and, consequently, distinctly influences the anticancer activity and pharmacological behavior of TSCs.

Bioactive Thiosemicarbazone Coordination Metal Complexes: Synthesis, Characterization, Theoretical analysis, Biological Activity, Molecular Docking and ADME analysis

Mn(II) and Cu(II) complexes having the formula [M(L)2 ]X2 of ligand, i. e., 2-acetyl-5-methylfuranthiosemicarbazone were synthesized. Various analytical and spectroscopic techniques described the structure of synthesized complexes. Molar conductance confirmed the electrolytic nature of the complexes. The theoretical study of the complexes explained the structural property and reactivity. The chemical reactivity, interaction and stability of the ligand and metal complexes were studied with the help of global reactivity descriptors. MEP analysis was used to investigate the charge transfer in the ligand. The biological potency was evaluated against two bacteria and two fungi. Complexes demonstrated superior inhibitory action to ligand. The inhibitory effect was also checked at the atomic scale using molecular docking, which confirmed the experimental results. Cu(II) complex was shown to have the most inhibitory effect in experimental and theoretical studies. To check the bioavailability and drug-likeness, ADME analysis was also done.

Inhibition of Topoisomerases by Metal Thiosemicarbazone Complexes

Topoisomerases, common targets for anti-cancer therapeutics, are crucial enzymes for DNA replication, transcription, and many other aspects of DNA metabolism. The potential anti-cancer effects of thiosemicarbazones (TSC) and metal-TSC complexes have been demonstrated to target several biological processes, including DNA metabolism. Human topoisomerases were discovered among the molecular targets for TSCs, and metal-chelated TSCs specifically displayed significant inhibition of topoisomerase II. The processes by which metal-TSCs or TSCs inhibit topoisomerases are still being studied. In this brief review, we summarize the TSCs and metal-TSCs that inhibit various types of human topoisomerases, and we note some of the key unanswered questions regarding this interesting class of diverse compounds.

The Effect of Metal Ions (Fe, Co, Ni, and Cu) on the Molecular-Structural, Protein Binding, and Cytotoxic Properties of Metal Pyridoxal-Thiosemicarbazone Complexes

Thiosemicarbazones and their transition metal complexes are biologically active compounds and anticancer agents with versatile structural properties. In this contribution, the structural features and stability of four pyridoxal-thiosemicarbazone (PLTSC) complexes with Fe, Co, Ni, and Cu were investigated using the density functional theory and natural bond orbital approach. Special emphasis was placed on the analysis of the donor atom-metal interactions. The geometry of compounds and crystallographic structures were further examined by Hirshfeld surface analysis, and the main intermolecular interactions were outlined. It has been shown that the geometry and the number of PLTSC units in the structure determine the type and contribution of the specific interactions. The binding of all four complexes to bovine and human serum albumin was investigated through spectrofluorometric titration. The dependency of the thermodynamic parameters on the present metal ion and geometry was explained by the possible interactions through molecular docking simulations. The binding of complexes to DNA, as one of the possible ways the compounds could induce cell death, was examined by molecular docking. The cytotoxicity was measured towards HCT116, A375, MCF-7, A2780, and MCF5 cell lines, with Cu-PLTSC being the most active, as it had the highest affinity towards DNA and proteins.

Structure-based discovery of thiosemicarbazones as SARS-CoV-2 main protease inhibitors

Aim: Discovery of novel SARS-CoV-2 main protease (Mpro) inhibitors using a structure-based drug discovery strategy. Materials & methods: Virtual screening employing covalent and noncovalent docking was performed to discover Mpro inhibitors, which were subsequently evaluated in biochemical and cellular assays. Results: 91 virtual hits were selected for biochemical assays, and four were confirmed as reversible inhibitors of SARS CoV-2 Mpro with IC50 values of 0.4-3 μM. They were also shown to inhibit SARS-CoV-1 Mpro and human cathepsin L. Molecular dynamics simulations indicated the stability of the Mpro inhibitor complexes and the interaction of ligands at the subsites. Conclusion: This approach led to the discovery of novel thiosemicarbazones as potent SARS-CoV-2 Mpro inhibitors.

Antitumor and Antibacterial Activity of Ni(II), Cu(II), Ag(I), and Hg(II) Complexes with Ligand Derived from Thiosemicarbazones: Characterization and Theoretical Studies

Four new complexes (Ni2+, Cu2+, Ag+, and Hg2+) were prepared from the ligand N-(4-chlorophenyl)-2-(phenylglycyl)hydrazine-1-carbothioamide (H2L). Analytical and spectroscopic techniques were used to clarify the structural composition of the new chelates. In addition, all chelates were tested against bacterial strains and the HepG2 cell line to determine their antiseptic and carcinogenic properties. The Ni(II) complex was preferable to the other chelates. Molecular optimization revealed that H2L had the highest reactivity, followed by Hg-chelate, Ag-chelate, Ni-chelate, and Cu-chelate. Moreover, molecular docking was investigated against two different proteins: the ribosyltransferase enzyme (code: 3GEY) and the EGFR tyrosine kinase receptor (code: 1m17).

Hydroxylated Coumarin-Based Thiosemicarbazones as Dual Antityrosinase and Antioxidant Agents

The design of novel antityrosinase agents appears extremely important in medical and industrial sectors because an irregular production of melanin is related to the insurgence of several skin-related disorders (e.g., melanoma) and the browning process of fruits and vegetables. Because melanogenesis also involves a nonenzymatic oxidative process, developing dual antioxidant and antityrosinase agents is advantageous. In this work, we evaluated the antioxidant and tyrosinase inhibition ability of two new bishydroxylated and two new monohydroxylated derivatives of (1E)-2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazine-1-carbothioamide (T1) using different experimental and computational approaches. The study was also carried out on another monohydroxylated derivative of T1 for comparison. Interestingly, these molecules have more potent tyrosinase-inhibitory properties than the reference compound, kojic acid. Moreover, the antioxidant activity appears to be influenced according to the number and substitution pattern of the hydroxyl groups. The safety of the compounds without (T1), with one (T3), and with two (T6) hydroxyl groups, has also been assessed by studying their cytotoxicity on melanocytes. These results indicate that (1E)-2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazine-1-carbothioamide and its hydroxylated derivatives are promising molecules for further drug development studies.

NSC19723, a Thiacetazone-Like Benzaldehyde Thiosemicarbazone Improves the Efficacy of TB Drugs In Vitro and In Vivo

The complexity and duration of tuberculosis (TB) treatment contributes to the emergence of drug resistant tuberculosis (DR-TB) and drug-associated side effects. Alternate chemotherapeutic agents are needed to shorten the time and improve efficacy of current treatment. In this study, we have assessed the antitubercular activity of NSC19723, a benzaldehyde thiosemicarbazone molecule. NSC19723 is structurally similar to thiacetazone (TAC), a second-line anti-TB drug used to treat individuals with DR-TB. NSC19723 displayed better MIC values than TAC against Mycobacterium tuberculosis and Mycobacterium bovis BCG. In our checkerboard experiments, NSC19723 displayed better profiles than TAC in combination with known first-line and recently approved drugs. Mechanistic studies revealed that NSC19723 inhibits mycolic acid biosynthesis by targeting the HadABC complex. Computational studies revealed that the binding pocket of HadAB is similarly occupied by NSC19723 and TAC. NSC19723 also improved the efficacy of isoniazid in macrophages and mouse models of infection. Cumulatively, we have identified a benzaldehyde thiosemicarbazone scaffold that improved the activity of TB drugs in liquid cultures, macrophages, and mice. IMPORTANCE Mycobacterium tuberculosis, the causative agent of TB is among the leading causes of death among infectious diseases in humans. This situation has worsened due to the failure of BCG vaccines and the increased number of cases with HIV-TB coinfections and drug-resistant strains. Another challenge in the field is the lengthy duration of therapy for drug-sensitive and -resistant TB. Here, we have deciphered the mechanism of action of NSC19723, benzaldehyde thiosemicarbazone. We show that NSC19723 targets HadABC complex and inhibits mycolic acid biosynthesis. We also show that NSC19723 enhances the activity of known drugs in liquid cultures, macrophages, and mice. We have also performed molecular docking studies to identify the interacting residues of HadAB with NSC19723. Taken together, we demonstrate that NSC19723, a benzaldehyde thiosemicarbazone, has better antitubercular activity than thiacetazone.

Synthesis of New Triazole-Based Thiosemicarbazone Derivatives as Anti-Alzheimer's Disease Candidates: Evidence-Based In Vitro Study

Triazole-based thiosemicarbazone derivatives (6a-u) were synthesized then characterized by spectroscopic techniques, such as 1HNMR and 13CNMR and HRMS (ESI). Newly synthesized derivatives were screened in vitro for inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. All derivatives (except 6c and 6d, which were found to be completely inactive) demonstrated moderate to good inhibitory effects ranging from 0.10 ± 0.050 to 12.20 ± 0.30 µM (for AChE) and 0.20 ± 0.10 to 14.10 ± 0.40 µM (for BuChE). The analogue 6i (IC₅₀ = 0.10 ± 0.050 for AChE and IC₅₀ = 0.20 ± 0.050 µM for BuChE), which had di-substitutions (2-nitro, 3-hydroxy groups) at ring B and tri-substitutions (2-nitro, 4,5-dichloro groups) at ring C, and analogue 6b (IC₅₀ = 0.20 ± 0.10 µM for AChE and IC₅₀ = 0.30 ± 0.10 µM for BuChE), which had di-Cl at 4,5, -NO₂ groups at 2-position of phenyl ring B and hydroxy group at ortho-position of phenyl ring C, emerged as the most potent inhibitors of both targeted enzymes (AChE and BuChE) among the current series. A structure-activity relationship (SAR) was developed based on nature, position, number, electron donating/withdrawing effects of substitution/s on phenyl rings. Molecular docking studies were used to describe binding interactions of the most active inhibitors with active sites of AChE and BuChE.

Iron Oxide Nanoparticles Conjugated to Thiosemicarbazone Reduce the Survival of Cancer Cells by Increasing the Gene Expression of MicroRNA let-7c in Lung Cancer A549 Cells

BACKGROUND

Cancer cells have a higher demand for iron to grow and proliferate. A new complex of iron nanoparticles and thiosemicarbazones was synthesized. Confirmation tests included UV-visible, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and zeta potential.

METHODS

MTT assay, flow cytometry and qRT-PCR were used to investigate anti-proliferative effect, amount of apoptosis and the effect of Fe3 O4 @Glu/BTSC on changes in gene expression of microRNA let-7c (let-7c), respectively. The specifications of Fe3 O4 @ Glu/BTSC were confirmed at 5 nm.

RESULTS

Fe3O4@Glu/BTSC was more effective than BTSC and Fe3 O4 on A549 cells (IC50=166.77 µg/mL) but its effect on healthy cells was smaller (CC50=189.15 µg/mL). The drug selectivity index (SI) was calculated to be 1.13. The initial apoptosis rate was 46.33% for Fe3 O4 @Glu/BTSC, 28.27% for BTSC and 26.02% for Fe3 O4 . BTSC and BTSC@Fe3 O4 inhibited the cell cycle progression in the Sub-G1 and S phases. let-7c expression was 6.9 times higher in treated cells compared to the control group. The expression rate was 2.2 with BTSC compared to the control group and 1.6 times for Fe3 O4.

CONCLUSION

Fe3 O4 @Glu/BTSC has proper anti-proliferative effects against lung cancer cells by increasing the expression of let-7c and inhibiting the cell cycle with the apoptosis activation pathway.

Synthesis, Characterization, and Cytotoxicity Studies of N-(4-Methoxybenzyl) Thiosemicarbazone Derivatives and Their Ruthenium(II)-p-cymene Complexes

The reaction of [Ru₂Cl₂(μ-Cl)₂(η⁶-p-cymene)₂] with two thiosemicarbazones obtained by the condensation of N-(4-methoxybenzyl) thiosemicarbazide and 1,4-hydroxy-3-methoxyphenyl)ethan-1-one (HL¹) or 2-fluoro-4-hydroxybenzaldehyde (HL²) was studied. The cationic complexes of formula [RuCl(η⁶-p-cymene)(HL)]⁺ were isolated as solid chloride and trifluoromethylsulfate (TfO) salts. A study of the solid state and NMR spectra suggests the presence in the material of two isomers that differ in the configuration in the iminic bond, C2=N3, of the coordinated thiosemicarbazone in the triflate salts and only the E isomer in the chloride. An X-ray study of single crystals of the complexes supports this hypothesis. The thiosemicarbazone ligand coordinates with the ruthenium center through the iminic and sulfur atoms to form a five-membered chelate ring. Furthermore, the isolation of single crystals containing the thiosemicarbazonate complex [Ru₂(μ-L²)₂(η⁶-p-cymene)₂]²⁺ suggests the easy labilization of the coordinated chloride in the complex. The redox behavior of the ligands and complexes was evaluated by cyclic voltammetry. It seems to be more difficult to oxidize the complex derived from HL¹ than HL². The ability of the complexes to inhibit cell growth against the NCI-H460, A549 and MDA-MB-231 lines was evaluated. The complexes did not show greater potency than cisplatin, although they did have greater efficacy, especially for the complex derived from HL¹.

Modulation of the lipophilicity and molecular size of thiosemicarbazone inhibitors to regulate tyrosinase activity

A group of 5-methylsalicylaldehyde thiosemicarbazone derivatives (HMTs) bearing different lipophilic and steric substituents attached at the 3-position of cresol ring were synthesized and investigated as mushroom tyrosinase (TYR) inhibitors. The ability of HMTs to inhibit the diphenolase activity of TYR was evaluated with L-DOPA as substrate by determining IC₅₀ values in relation to their structure modifications. HMTs displayed distinct inhibitory competencies towards TYR activity with IC₅₀ values in the range of 1.02-143.56 μM. A close correlation between their inhibition potency and both lipophilicity and molecular size was observed. The inhibitory effect of the hydroxyethyl-containing derivatives was much higher than the hydroxyethyl-free ones overall. Among them, HMT-NBO exhibited the most potent effect with IC₅₀ of 5.85 μM, which was nearly 25-fold and 3.8-fold lower than its parent HMT-NBE and the control kojic acid, respectively. The hydroxyethyl clearly benefited the improvement of the inhibitory competences and acted as a regulating group of lipophilicity of the inhibitors. The kinetic analyses showed that HMTs were reversible and mixed type inhibitors against mushroom TYR. The inhibition mechanism was studied by means of fluorescence spectroscopy, FT-IR, ESI-MS and molecular docking analysis. The results indicated that the observed inhibitory effect of HMTs was accomplished by acting on the amino acid residues rather than by chelating the centre copper ions of TYR. Each of HMTs can insert the hydrophobic pocket and interact with the residues of TYR through Van der Waals forces and hydrogen bonds, with additional electrostatic interactions for HMT-NEE and HMT-NEO further strengthening the affinity. Meanwhile, the inhibitors were observed to bind with L-DOPA or/and L-DOPAquinone forming 1:1 stoichiometric complexes, probably exerting indirect inhibition against TYR activity.

Synthesis, in vitro schistosomicidal activity and ultrastructural alterations caused by thiosemicarbazones and thiazolidinones against juvenile and adult Schistosoma mansoni worms (Sambon, 1907)

Schistosomiasis is a neglected disease that affects about 258 million people worldwide. Caused by Schistosoma mansoni, helminth which, in Brazil, it is present on 19 states and capital. Praziquantel (PZQ) treatment presents low efficacy and adverse effects in parasites juvenile stages. Thiosemicarbazones and thiazolidinones are rising as potent chemical groups that have biological activity wide spectrum, and with radical modifications, they may become more effective and selective. Aiming to evaluate the action of these molecules against S. mansoni, JF series thiosemicarbazones and thiazolidinones (LqIT/UFPE) were synthesized: JF30, JF31, JF33, JF34, JF35, JF36, JF38, JF39, JF42 and JF43. Several parameters were evaluated, such as: their cytotoxicity in VERO cells, in vitro schistosomicidal activity for juvenile and adult worms and their action on worms through ultrastructural changes. Cytotoxicity indices ranged from 272 µM to 725 µM. When evaluating mortality rate, adult and juvenile worms showed 100 % mortality rate within 24 h and 48 h, respectively, when exposed to the compounds JF31 and JF43 at a dose of 200 µM. Also, motility, mortality and oviposition parameters were evaluated: JF31 and JF43 presented a score of 0 in 24 h, meaning total absence of movement, whereas no eggs and soft tissue damage were observed under optical microscopy. Through scanning electron microscopy, integumentary alterations caused by the compounds JF31 and JF43 were observed, such as: exposure of the musculature, formation of integumentary bubbles, integuments with abnormal morphology and destruction of tubercles and spikes. The results shoerd that the compound JF31 was 2.39 times more selective for adult worms and JF43 was 3.74 times more selective for juvenile worms. Thus, the compounds JF43 and JF31 are the most promising for presenting schistosomicidal activity of S. mansoni.

Benzimidazole Bearing Thiosemicarbazone Derivatives Act as Potent α-Amylase and α-Glucosidase Inhibitors; Synthesis, Bioactivity Screening and Molecular Docking Study

Diabetes mellitus is one of the most chronic metabolic diseases. In the past few years, our research group has synthesized and evaluated libraries of heterocyclic analogs against α-glucosidase and α-amylase enzymes and found encouraging results. The current study comprises the evaluation of benzimidazole-bearing thiosemicarbazone as antidiabetic agents. A library of fifteen derivatives (7-21) was synthesized, characterized via different spectroscopic techniques such as HREI-MS, NMR, and screened against α-glucosidase and α-amylase enzymes. All derivatives exhibited excellent to good biological inhibitory potentials. Derivatives 19 (IC₅₀ = 1.30 ± 0.20 µM and 1.20 ± 0.20 µM) and 20 (IC₅₀ = 1.60 ± 0.20 µM and 1.10 ± 0.01 µM) were found to be the most potent among the series when compared with standard drug acarbose (IC₅₀ = 11.29 ± 0.07 and 11.12 ± 0.15 µM, respectively). These derivatives may potentially serve as the lead candidates for the development of new therapeutic representatives. The structure-activity relationship was carried out for all molecules which are mainly based upon the pattern of substituent/s on phenyl rings. Moreover, in silico docking studies were carried out to investigate the active binding mode of selected derivatives with the target enzymes.

Synthesis and biological evaluation of thiosemicarbazone derivatives

In this study, firstly, 22 thiosemicarbazone derivatives (3a-y) were synthesized. Then, ADME parameters, pharmacokinetic properties, drug-like structures, and suitability for medicinal chemistry of these molecules were studied theoretically by using SwissADME and admetSAR programs. According to the results of these theoretical studies, it can be said that the bioavailability and bioactivity of these compounds may be high. In silico molecular docking between ligands (thiosemicarbazone derivatives) and targeted proteins (protein-78 (GRP78) for C6 and quinone reductase-2 (4ZVM for MCF 7) was analyzed using Hex 8.0.0 docking software. According to the docking data, almost all molecules had higher negative E values than Imatinib (already used as a drug). For this, in vitro anticancer studies of these molecules were done. The cytotoxic activities of thiosemicarbazone derivatives (3a-y) were evaluated on C6 glioma and MCF7 breast cancer cell lines at 24 h, and Imatinib was used as the positive control. According to the results of the cytotoxicity assay, it can be said that the five compounds (3b, c, f, g, and m with IC₅₀ = 10.59-9.08 μg/mL; Imatinib IC₅₀ = 11.68 μg/mL) showed more potent cytotoxic activity than Imatinib on C6 cell line. Together with to these results ten compounds (3b, d, f, g, I, k, l, m, n, and r with IC₅₀ = 7.02-9.08 μg/mL; Imatinib IC₅₀ = 9.24 μg/mL) had a more effective cytotoxic activity against MCF7 cell line than Imatinib. Compound 3 m showed the highest antiproliferative effect against C6 and MCF7 cell lines.