Design, synthesis and preliminary biological evaluation of new [1,2,3]triazolo[4,5-d]pyrimidine/thiourea hybrids as antiproliferative agents

Structure-activity relationship and cytotoxicity of the new thiosemicarbazide derivatives and their Cu(II) complexes against prostate and melanoma cancer cells

In this study, eighteen new ligands (B1-B18) containing a thiosemicarbazide core were synthesized and characterized in terms of physicochemical properties, molecular docking and in vitro biological activity. The structures of eleven ligands were investigated using X-Ray diffraction and Hirschfeld Surface analysis. To study the structure-activity relationship, the organic ligands contained pyridin-2-ylmethyl, pyridin-3-ylmethyl or pyridin-4-ylmethyl moieties and various substituents. Their pharmakokinetic profiles and molecular docking results suggest high potential as new drug candidates. The complexing ability of the selected organic ligands was also evaluated, yielding five new Cu(II) complexes (Cu(B1)Cl2, Cu(B4)Cl2, Cu(B10)Cl2, Cu(B17)Cl2, Cu(B18)Cl2). The obtained results suggest the formation of the polymeric structures. All organic ligands and Cu(II) complexes were tested for anticancer activity against prostate and melanoma cancer cells (PC-3, DU-145, LNCaP, A375, G-361, SK-MEL-28) and normal fibroblasts (BJ), as well as antimicrobial activity against six selected bateria strains. Among B1-B18 compounds, B3, B5, B9, B10, B12 and B14 exhibited cytotoxic activity. The studied Cu(II) complexes were in general more active, with Cu(B1)Cl2 exhibiting antincancer activity agains all three prostate cancer cells and Cu(B10)Cl2 reaching the IC50 value equal to 88 μM against G-361 melanoma cells. Several compounds also exhibited antimicrobial activity against gram-positive and gram-negative bacteria. It was found that the type of specific substituents, especially the presence of -chloro and -dichloro substituents had a greated impact on the cytotoxicity than the position of the nitrogen atom in the pyridylacetyl moiety.

Synthesis of thiazole-based-thiourea analogs: as anticancer, antiglycation and antioxidant agents, structure activity relationship analysis and docking study

This work reports the convenient approach for the synthesis of thiazole based thiourea derivatives (1-21) from 2-bromo-1-(4-fluorophenyl)thiazole-1-one and phenyl isothiocyanates. The scope and diversity were achieved from readily available phenyl isothiocyanates. This protocol involves an oxidative C-S bond formation. Moreover, hybrid thiazole based thiourea scaffolds (1-21) according to literature known protocol were screened in vitro for anticancer Potential against breast cancer, antiglycation and antioxidant inhibitory profile. All newly developed scaffolds were showed moderate to good inhibitory potentials ranging from 0.10 ± 0.01 µM to 11.40 ± 0.20 µM, 64.20 ± 0.40 µM to 385.10 ± 1.70 µM and 8.90 ± 0.20 µM to 39.20 ± 0.50 µM against anticancer, antiglycation and antioxidant respectively. Among the series, compounds 12 (IC50 = 0.10 ± 0.01 µM), 10 (IC50 = 64.20 ± 0.40 µM) and 12 (IC50 = 8.90 ± 0.20 µM) with flouro substitution at phenyl ring of thiourea were identified to be the most potent among the series having excellent anticancer, antiglycation and antioxidant potential. The structure of all the newly synthetics scaffolds were confirmed by using different types of spectroscopic techniques such as HREI-MS, 1H- and 13C-NMR spectroscopy. To find structure-activity relationship, molecular docking studies were carried out to understand the binding mode of active inhibitors with active site of enzymes and results supported the experimental data.Communicated by Ramaswamy H. Sarma.

Prediction of anti-proliferation effect of [1,2,3]triazolo[4,5-d]pyrimidine derivatives by random forest and mix-kernel function SVM with PSO

In order to predict the anti-gastric cancer effect of [1,2,3]triazolo[4,5-d]pyrimidine derivatives (1,2,3-TPD), quantitative structure-activity relationship (QSAR) studies were performed. Based on five descriptors selected from descriptors pool, four QSAR models were established by heuristic method (HM), random forest (RF), support vector machine with radial basis kernel function (RBF-SVM), and mix-kernel function support vector machine (MIX-SVM) including radial basis kernel and polynomial kernel function. Furthermore, the model built by RF explained the importance of the descriptors selected by HM. Compared with RBF-SVM, the MIX-SVM enhanced the generalization and learning ability of the constructed model simultaneously and the multi parameters optimization problem in this method was also solved by particle swarm optimization (PSO) algorithm with very low complexity and fast convergence. Besides, leave-one-out cross validation (LOO-CV) was adopted to test the robustness of the models and Q² was used to describe the results. And the MIX-SVM model showed the best prediction ability and strongest model robustness: R² = 0.927, Q² = 0.916, MSE = 0.027 for the training set and R² = 0.946, Q² = 0.913, MSE = 0.023 for the test set. This study reveals five key descriptors of 1,2,3-TPD and will provide help to screen out efficient and novel drugs in the future.

Azole-pyrimidine Hybrid Anticancer Agents: A Review of Molecular Structure, Structure Activity Relationship and Molecular Docking

Cancer has emerged as one of the leading causes of deaths globally partly due to the steady rise in anticancer drug resistance. Pyrimidine and pyrimidine-fused heterocycles are some of the privileged scaffolds in medicine, as they possess diverse biological properties. Pyrimidines containing azole nucleus possesses inestimable anticancer potency and has enormous potential to conduct the regulation of cellular pathways for selective anticancer activity. The present review outlines the molecular structure of pyrimidine-fused azoles with significant anticancer activity. The structure activity relationship and molecular docking studies have also been discussed. The current review is the first complete compilation of significant literature on the proposed topic from 2016 to 2020. The information contained in this review offers a useful insight to chemists in the design of new and potent anticancer azole-pyrimidine analogues.

Advancement and recent trends in seeking less toxic and more active anti-cancer drugs: Insights into thiourea based molecules

The finding of potent anticancer agents with low toxicity and high selectivity has remained valuable for human health. Thiourea derivatives are the most significant organic compounds with integral and typical characteristics of numerous varieties of natural products and pharmaceutical agents. It exhibits various pharmacological properties, and its analogues confer a great deal of structural diversity that was proven to be the most advantageous in the search for novel therapeutic agents. Thiourea derivatives, which show beneficial antitumor activities, are typically considered the central core in various anticancer derivatives. They also have broad-ranging biological activities such as anti-inflammatory, antibacterial, antifungal, antitubercular, antihypertensive, antihistaminic, and antiviral activities. Several FDA-approved drugs of thiourea derivatives and their analogues in the market, currently in progress through various registration statuses or clinical stages, indicating that thiourea derivatives are the most promising drugs. The current review is intended to systematically provide comprehensive evidence in the recent developments of thiourea to treat numerous types of cancer. Furthermore, we hope that this review will be helpful for novel consideration in seeking rational designs of less toxic and more active drugs and more effective diagnostics agents.

Advance of structural modification of nucleosides scaffold

With Remdesivir being approved by FDA as a drug for the treatment of Corona Virus Disease 2019 (COVID-19), nucleoside drugs have once again received widespread attention in the medical community. Herein, we summarized modification of traditional nucleoside framework (sugar + base), traizole nucleosides, nucleoside analogues assembled by other drugs, macromolecule-modified nucleosides, and their bioactivity rules. 2'-"Ara"-substituted by -F or -CN group, and 3'-"ara" substituted by acetylenyl group can greatly influence their anti-tumor activities. Dideoxy dehydrogenation of 2',3'-sites can enhance antiviral efficiencies. Acyclic nucleosides and L-type nucleosides mainly represented antiviral capabilities. 5-F Substituted uracil analogues exihibit anti-tumor effects, and the substrates substituted by -I, -CF3, bromovinyl group usually show antiviral activities. The sugar coupled with 1-N of triazolid usually displays anti-tumor efficiencies, while the sugar coupled with 2-N of triazolid mainly represents antiviral activities. The nucleoside analogues assembled by cholesterol, polyethylene glycol, fatty acid and phospholipid would improve their bioavailabilities and bioactivities, or reduce their toxicities.

Synthesis of ticagrelor analogues belonging to 1,2,3-triazolo[4,5-d]pyrimidines and study of their antiplatelet and antibacterial activity

Based on the recent observation that the antiplatelet agent ticagrelor and one of its metabolite exert bactericidal activity against gram-positive bacteria, a series of 1,2,3-triazolo[4,5-d]pyrimidines structurally related to ticagrelor were synthesized and examined as putative antiplatelet and antibacterial agents. The aim was to assess the possibility of dissociating the two biological properties and to find novel 1,2,3-triazolo[4,5-d]pyrimidines expressing antiplatelet activity and devoid of in vitro antibacterial activity. The new compounds synthesized were known metabolites of ticagrelor as well as structurally simplified analogues. Some of them were found to express antiplatelet activity and to lose the antibacterial activity, supporting the view that the two activities were not necessarily linked.

Novel [1,2,3]triazolo[4,5-d]pyrimidine derivatives containing hydrazone fragment as potent and selective anticancer agents

In this paper, based on molecular hybridization, a series of [1,2,3]triazolo[4,5-d]pyrimidine derivatives containing hydrazine was synthesized and their antiproliferative activities against 5 cancer cell lines (MGC-803, PC3, PC9, EC9706 and SMMC-7721) were evaluated. We found that most of them exhibited obvious growth inhibition effects on these tested cancer cells, especially compound 34 on PC3 cells (IC₅₀ = 26.25 ± 0.28 nM). Meanwhile, compound 34 displayed best selectivity on PC3, compared with the other cancer cell lines, as well as excellent selectivity towards normal cell lines (Het-1A, L02 and GES-1). Further investigations demonstrated that 34 could significantly inhibit PC3 cells' colony formation, increase cellular ROS content, suppress EGFR expression and induce apoptosis. Our findings indicate that 34 may serve as a novel lead compound for the discovery of more triazolopyrimidine derivatives with improved anticancer potency and selectivity.

Structure and anticancer activity of Cu(II) complexes with (bromophenyl)thiourea moiety attached to the polycyclic imide

A series of nine copper complexes were synthesized by reacting 1,3-disubstituted thioureas with copper(II) chloride. The new compounds were characterized by elemental analysis, infrared, ultraviolet-visible and X-ray absorption spectroscopies as well as molecular modelling. The molecular structure of complexes in the solid state consists of two thiourea ligands chelated to the Cu(II) ion through the S and deprotonated N atoms (CuN₂S₂). The coordination polyhedron of metal cation in powdered samples exhibits two different geometries. Pseudo-tetrahedral structure is observed for noncentrosymmetric complexes with cis-N₂S₂ arrangement around Cu(II). A distorted square planar geometry is characteristic for centrosymmetric compounds with trans arrangements of chelating atoms around the central ion. All complexes after dissolving in dimethyl sulfoxide adopt a centrosymmetric coordination, while after diluting this solution with water, the reorganization of atoms around the metal cation is observed, leading to the formation of a tetrahedral compounds. Initial ligands and Cu(II) complexes were evaluated for their cytotoxicity. Two complexes with 4- and 3-bromophenyl attached to the (1,7,8,9,10-pentamethyl-3,5-dioxo-4-azatricyclo[5.2.1.0^2,6]dec-8-en-4-yl)thiourea moiety (Cu1, Cu3) are cytotoxic against SW480 and PC3 cells (IC₅₀ 4-19 μm), and non-cytotoxic against HaCaT cells (IC₅₀ ≥ 84 μm), being more selective than doxorubicin and cisplatin used as references. The compounds induced apoptosis in cancer cells, however, Cu3 was estimated to be highly active inducer of late apoptosis in SW480 and PC3 cells at lower toxicity against normal cells. The likely mechanism of action of complexes is correlated with decreasing release of IL-6 in cancer cell lines.

Discovery of new [1,2,4] Triazolo[1,5-a]Pyrimidine derivatives that Kill gastric cancer cells via the mitochondria pathway

Mitochondria are known as "powerhouse of cells" and play the role of a bridge in redox balance, cell apoptosis, and autophagy. ROS accumulation can cause mitochondria damage, while the injured mitochondria will further enhance ROS levels reciprocally. Herein, we synthesized a novel series of [1,2,4]triazolo[1,5-a]pyrimidine-based compounds 4a-4v and tested their anti-proliferation efficacy against gastric cancer cell line MGC-803. Among them, compounds 4o and 4p inhibited gastric cancer cells at micromolar level. Compound 4o caused G2/M arrest and induced mitochondria-dependent apoptosis in MGC-803 and SGC-7901. However, inhibiting apoptosis pathway cannot prevent the inhibitory activity of compound 4o against gastric cancer cell. To our surprising, ROS level was increased by compound 4o and elevation of ROS could be rescued by NAC. In accordance with that, NAC absolutely prevented the anti-proliferation efficacy of compound 4o. We further found that autophagy inhibitor CQ rather than 3-MA partially reversed inhibitory activity of compound 4o in MGC-803 cells. Taken together, compound 4o exhibited its anti-proliferative activity via increasing ROS level and inducing autophagy, thus leading to apoptosis of gastric cancer cells. Therefore, compound 4o may support further development of lead compounds for gastric cancer therapy via mitochondria pathway.

Synthesis, X-ray crystal structure elucidation and Hirshfeld surface analysis of N-((4-(1H-benzo[d]imidazole-2-yl)phenyl)carbamothioyl)benzamide: investigations for elastase inhibition, antioxidant and DNA binding potentials for biological applications

The interest in the present study pertains to the development of a new compound based upon a benzimidazole thiourea moiety that has unique properties related to elastase inhibition, free radical scavenging activity and its DNA binding ability. The title compound, N-(4-(1H-benzo[d]imidazol-2-yl)phenyl)-3-benzoyl thiourea (C21H18N4O2SH2O:TUBC), was synthesized by reacting an acid chloride of benzoic acid with potassium thiocyanate (KSCN) along with the subsequent addition of 4-(1H-benzo[d]imidazol-2-yl)benzenamine via a one-pot three-step procedure. The structure of the resulting benzimidazole based thiourea was confirmed by spectroscopic techniques including FTIR, 1H-NMR, 13C-NMR and single crystal X-ray diffraction and further examined by Hirshfeld surface analysis. TUBC was also investigated by using both in silico methodology including molecular docking for elastase inhibition along with quantum chemical studies and in vitro experimental methodology utilizing elastase inhibition and free radical scavenging assay along with DNA binding experiments. Docking results confirmed that TUBC binding was within the active region of elastase. In comparison to the reference drug oleanolic acid, the low IC50 value of TUBC also indicated its high tendency towards elastase inhibition. TUBC scavenged 80% of DPPH˙ radicals which pointed towards its promising antioxidant activity. TUBC-DNA binding by DFT, docking, UV-visible spectroscopy and viscosity measurements revealed TUBC to be a potential drug candidate that binds spontaneously and reversibly with DNA via a mixed binding mode. All theoretical and experimental findings pointed to TUBC as a potential candidate for a variety of biological applications.

Anti-gastric cancer activity of 1,2,3-triazolo[4,5-d]pyrimidine hybrids (1,2,3-TPH): QSAR and molecular docking approaches

Gastric cancer as a dreaded disease which occurs in the digestive system of human being remain a threat to the medical world. Bioactivity of series of designed and synthesized molecular compounds containing triazole and pyrimidine moieties were subjected to quantum chemical calculations using B3LYP/6-31+G∗. The calculated molecular descriptors such as the EHOMO (eV), ELUMO (eV), band gap (eV), chemical hardness (η), global nucleophilicity, dipole moment (Debye), chemical potential, log P, molecular weight (amu) and Ovality. The descriptors that describe anti-gastric cancer activity of the studied compounds were used for QSAR analysis using SPSS and Gretl software packages for multiple linear regression (MLR), XLSTAT for partial least square (PLS) and MATLAB for artificial neural network (ANN). The methods (MLR, PLS, and ANN) were predictive. Nevertheless, ANN performed better than MLR and PLS. More so, molecular docking study was executed on the studied compounds and gastric cancer cell line (PDB ID:4oum); the docking studies showed that 2-(1-(2-(3-benzyl-5-(benzylthio)-3H-[1,2,3]triazolo[4,5-d]pyrimidin-7-yl)hydrazono)ethyl)phenol (A22) having the lowest binding affinity (-8.40 kcal/mol); this was correlated to the observed inhibitory activity of the compound against gastric cancer. Thus, it showed better inhibition than other studied compounds. The amino acid residues that were involved in stabilizing A22 in the active site of the 4oum are: VAL-9, ALA-10, THR-49, ASN-48, PRO-47 and TYR-46. Also, a good relationship was observed between the calculated binding affinity and the observed inhibition concentration (IC50).

1,2,3-Triazole fused with pyridine/pyrimidine as new template for antimicrobial agents: Regioselective synthesis and identification of potent N-heteroarenes

The 1,2,3-triazole ring fused with pyridine/pyrimidine was explored as new template for the identification of potential antimicrobial agents. The regioselective synthesis of these pre-designed N-heteroarenes was achieved via exploring the application of Buchwald's strategy (i.e. C-N bond formation/reduction/diazotization/cyclization sequence) to the N-heteroarene system. Two of them showed promising antibacterial (comparable to streptomycin) and several showed potent antifungal (comparable to mancozeb) activities.

Asymmetrical meta-methoxylated diarylpentanoids: Rational design, synthesis and anti-cancer evaluation in-vitro

In the present study, a series of forty-five asymmetrical meta-methoxylated diarylpentanoids have been synthesized, characterized and evaluated for their in-vitro anti-cancer potential. Among the forty-five analogs, three compounds (20, 33 and 42) have been identified as lead compounds due to their excellent inhibition against five human cancer cell lines including SW620, A549, EJ28, HT1080 and MCF-7. Structure-activity relationship study on cytotoxicity of tested compounds suggested that the presence of meta-oxygenated phenyl ring played a critical role in enhancing their cytotoxic effects. Compounds 33 and 42 in particular, exhibited strongest cytotoxicity against tested cell lines with the IC₅₀ values ranging from 1.1 to 4.3 μM. Subsequent colony formation assay on SW620 cell line showed that both compounds 33 and 42 possessed strong anti-proliferative activity. In addition, flow cytometry based experiments revealed that these compounds could trigger intracellular ROS production thus inducing G2/M-phase cell arrest and apoptosis. All these results suggested that poly meta-oxygenated diarylpentnoid is a promising scaffold which deserved further modification and investigation in the development of natural product-based anti-cancer drug.