Pyrimidine: a review on anticancer activity with key emphasis on SAR

Fabrication of folic acid-conjugated pyrimidine-2(5H)-thione-encapsulated curdlan gum-PEGamine nanoparticles for folate receptor targeting breast cancer cells

In this study 5-((2-((3-methoxy benzylidene)-amino)-phenyl)-diazenyl)-4,6-diphenyl pyrimidine-2(5H)-thione was synthesized. The pharmacological applications of pyrimidine analogs are restricted due to their poor pharmacokinetic properties. As a solution, a microbial exopolysaccharide (curdlan gum) was used to synthesize folic acid-conjugated pyrimidine-2(5H)-thione-encapsulated curdlan gum-PEGamine nanoparticles (FA-Py-CG-PEGamine NPs). The results of physicochemical properties revealed that the fabricated FA-Py-CG-PEGamine NPs were between 100 and 400 nm in size with a majorly spherical shaped, crystalline nature, and the encapsulation efficiency and loading capacity were 79.04 ± 0.79 %, and 8.12 ± 0.39 % respectively. The drug release rate was significantly higher at pH 5.4 (80.14 ± 0.79 %) compared to pH 7.2. The cytotoxic potential of FA-Py-CG-PEGamine NPs against MCF-7 cells potentially reduced the number of cells after 24 h with 42.27 μg × mL-1 as IC50 value. The higher intracellular accumulation of pyrimidine-2(5H)-thione in MCF-7 cells leads to apoptosis, observed by AO/EBr staining and flow cytometry analysis. The highest pyrimidine-2(5H)-thione internalization in MCF-7 cells may be due to folate conjugated on the surface of curdlan gum nanoparticles. Further, internalized pyrimidine-2(5H)-thione increases the intracellular ROS level, leading to apoptosis and inducing the decalin in mitochondrial membrane potential. These outcomes demonstrated that the FA-Py-CG-PEGamine NPs were specificity-targeting folate receptors on the plasma membranes of MCF-7 Cells.

One-Pot Sustainable Synthesis of Highly Substituted Pyrimidines via Acceptorless Dehydrogenative Annulation of Alcohols Using Pincer Ni(II)-NNS Catalysts

We report an efficient and sustainable synthesis of highly substituted pyrimidines promoted by nickel(II)-NNS pincer-type complexes via acceptorless dehydrogenative annulations of readily available alcohols, malononitrile, and guanidine/benzamidine salt under eco-friendly conditions for the first time. Different sets of Ni(II) complexes (C1-C3) encapsulated in NNS pincer-type thiosemicarbazone ligands have been synthesized and authenticated by analytical and spectroscopic (Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry) techniques. The solid state three-dimensional structure of a representative complex (C2) has been determined with the aid of single crystal XRD analysis and confirms a square planar architecture around the nickel ion. Further, the well-defined Ni(II) complexes have been employed as efficient catalysts for the fabrication of a wide range of 4-aminopyrimidine-5-carbonitrile derivatives (33 examples) from readily available alcohols with suitable coupling partners such as malononitrile and guanidine/benzamidine under eco-friendly conditions. The current catalytic approach affords maximum yields up to 95% utilizing 3 mol % catalyst loading and water/hydrogen as the only byproduct. A feasible catalytic pathway has been proposed based on the different control experiment reactions, which clearly indicate that the coupling reaction proceeds via aldehyde and benzylidenemalononitrile intermediates. The practicability of the current protocol has been demonstrated by the large-scale synthesis of one of the products, 4-amino-2,6-diphenylpyrimidine-5-carbonitrile, and a short synthesis of a cytosine antifungal analogue.

Cu(II)/PTABS-Promoted, Chemoselective Amination of HaloPyrimidines

Chemoselective amination is a highly desired synthetic methodology, given its importance as a possible strategy to synthesize various drug molecules and agrochemicals. We, herein, disclose a highly chemoselective Cu(II)-PTABS-promoted amination of pyrimidine structural feature containing different halogen atoms.

Molecular docking and simulation studies of some pyrazolone-based bioactive ligands targeting the NF- κ B signaling pathways

NF-κB has become a predominant regulator responsible for multiple physiological and pathological processes. NF-κB signaling pathway has canonical and non-canonical components which strategize the cancer-related metabolic processes. Non-canonical NF-κB pathways are known to contribute towards the chemoresistance of cancer cells. Consequently, NF-κB can be utilized as a potential therapeutic target for modifying the behaviour of tumor cells. In view of this, we herein report a series of pyrazolone-based bioactive ligands that potentially target NF- κB and, thereby, unveil their anticancer properties. The pharmacological screening of the synthesized compounds were carried out using various virtual screening techniques. The anticancer studies of synthesized pyrazolones showed that APAU exhibited the most potent effect against the MCF-7 cells with an IC50 value of 30 μg/ml. Molecular docking studies revealed that the pyrazolones inhibited cell proliferation by targeting the NFκB signaling pathway. The molecular dynamics simulation studies predicted the stability and flexibility of pyrazolone-based bioactive ligands.

Transition-Metal Catalyzed Synthesis of Pyrimidines: Recent Advances, Mechanism, Scope and Future Perspectives

Pyrimidine is a pharmacologically important moiety that exhibits diverse biological activities. This review reflects the growing significance of transition metal-catalyzed reactions for the synthesis of pyrimidines (with no discussion being made on the transition metal-catalyzed functionalization of pyrimidines). The effect of different catalysts on the selectivity/yields of pyrimidines and catalyst recyclability (wherever applicable) are described, together with attempts to illustrate the role of the catalyst through mechanisms. Although several methods have been researched for synthesizing this privileged scaffold, there has been a considerable push to expand transition metal-catalyzed, sustainable, efficient and selective synthetic strategies leading to pyrimidines. The aim of the authors with this update (2017-2023) is to drive the designing of new transition metal-mediated protocols for pyrimidine synthesis.

Synthesis, biological evaluation, and In silico molecular docking of N-(4-(4-substitutedphenyl)-6-(substituted aryl) pyrimidin-2-yl)-2-(2-isonicotinoyl hydrazinyl) acetamide

Isonicotinohydrazide is the first-line medication in the prevention and treatment of tuberculosis. Antitubercular, antibacterial, antifungal, antiviral, anti-inflammatory, antimalarial activity, anticancer, antineoplastic activity, and anti-HIV activity are all demonstrated by drugs with a pyrimidine ring. The current study focuses on the synthesis of N-(4-(substituted-phenyl)-6-(substituted-aryl) pyrimidin-2-yl)-2-(2-isonicotinoylhydrazinyl) acetamide from isonicotinohydrazide. Newly synthesized compounds were characterized by spectral studies (IR, 1 H-NMR, 13 C-NMR, and mass spectroscopy). They were screened for their antituberculosis, antimalarial, and antiprotozoal activities and compared with standard drugs. Molecular docking of isonicotinohydrazide-bearing pyrimidine motifs was also done for some of the active compounds.

Harnessing pyrimidine as a building block for histone deacetylase inhibitors

Histone deacetylase (HDAC) inhibitors are well-established multifaceted bioactive agents against tumors and neurodegenerative disorders. Pyrimidine and its fused and substituted derivatives were employed as a surface recognition moiety of HDAC inhibitors. De facto, the literature was loaded with different success stories of pyrimidine-based HDAC inhibitors that garnered much interest. Provoked by our continuous interest in HDAC inhibitors, we summarized and elaborated on the successful harnessing of the pyrimidine scaffold in this regard. Furthermore, we dissect our perspective that may guide medicinal chemists for an effective future design of more active chemotherapeutic agents with potential clinical applications.

Development of pyrolo[2,3-c]pyrazole, pyrolo[2,3-d]pyrimidine and their bioisosteres as novel CDK2 inhibitors with potent in vitro apoptotic anti-proliferative activity: Synthesis, biological evaluation and molecular dynamics investigations

Inhibiting the CDK2/cyclin A2 enzyme has been validated in multiple clinical manifestations related to multiple types of cancer. Herein, novel series of pyrolo[2,3-c]pyrazole, pyrolo[2,3-c]isoaxazole and pyrolo[2,3-d]pyrimidine, pyrolo[3,2-c]pyridine & indole based analogs were designed, synthesized and biologically evaluated for their in vitro antiproliferative activity where the obtained results revealed that most of the newly synthesized compounds showed significant cytotoxic activity towards MCF-7 (breast cancer cell lines) and HepG-2 (hepatocellular carcinoma) with IC50 ranging from 3.20 µM to 10.05 µM & from 2.18 µM to 13.49 µM, respectively, compared to that of Sorafenib (IC50 9.76 & 13.19 µM, respectively). The in vitro inhibitory profile of the most promising compounds (9, 11, 14, 15, 16, 17 and 20) towards CDK2/CyclinA2 was evaluated. Compounds 14 & 15 exhibited potent inhibitory profile against CDK2 with (IC50 0.11 and 0.262 µM, respectively comparable to Sorafenib IC50 0.184 µM. Western blotting of 14 & 15 at MCF-7 cell line confirmed the diminishing activity on CDK2. Furthermore, both compounds exserted a significant cell cycle arrest and apoptosis. Moreover, the normal cell line cytotoxicity for both compounds revealed low cytotoxic results in normal cells rather than cancer cells. Molecular docking and dynamic simulation validated the potentiality of the newly synthesized compounds to have high binding affinity within CDK2 binding pocket. 3DQSAR pharmacophore, in-silico ADME/TOPKAT studies and drug-likeness showed proper pharmacokinetic properties and helped in structure requirements prediction. The obtained model and pattern of substitution could be used for further development of CDK2 inhibitors.

Development of Stable Amino-Pyrimidine-Curcumin Analogs: Synthesis, Equilibria in Solution, and Potential Anti-Proliferative Activity

With the clear need for better cancer treatment, naturally occurring molecules represent a powerful inspiration. Recently, curcumin has attracted attention for its pleiotropic anticancer activity in vitro, especially against colorectal and prostate cancer cells. Unfortunately, these encouraging results were disappointing in vivo due to curcumin's low stability and poor bioavailability. To overcome these issues, herein, the synthesis of eight new pyrimidine-curcumin derivatives is reported. The compounds were fully characterized (1H/13C NMR (Nuclear Magnetic Resonance), LC-MS (Liquid Chromatography-Mass Spectrometri), UV-Vis spectroscopy), particularly their acid/base behavior; overall protonation constants were estimated, and species distribution, as a function of pH, was predicted, suggesting that all the compounds are in their neutral form at pH 7.4. All the compounds were extremely stable in simulated physiological media (phosphate-buffered saline and simulated plasma). The compounds were tested in vitro (48 h incubation treatment) to assess their effect on cell viability in prostate cancer (LNCaP and PC3) and colorectal cancer (HT29 and HCT116) cell lines. Two compounds showed the same anti-proliferative activity as curcumin against HCT116 cells and improved cytotoxicity against PC3 cells.

2-Alkyl-Substituted-4-Amino-Thieno[2,3-d]Pyrimidines: Anti-Proliferative Properties to In Vitro Breast Cancer Models

Thienopyrimidines are structural analogs of quinazolines, and the creation of new 2-alkyl derivatives of ethyl 4-aminothienopyrimidine-6-carboxylates for the study of their anti-proliferative properties is of great pharmacological interest. Some 2-alkyl-4-amino-thieno[2,3-d]pyrimidines 2-5 were synthesized, and their cyto- and phototoxicity against BALB 3T3 cells were established by an in vitro 3T3 NRU test. The obtained results indicate that the tested compounds are not cytotoxic or phototoxic, and that they are appropriate to be studied for their anti-proliferative and anti-tumor properties. The anti-proliferative potential of the compounds was investigated on MCF-7 and MDA-MB-231 cancer cells, as well as a MCF-10A cell line (normal human mammary epithelial cells). The most toxic to MCF-7 was thienopyrimidine 3 with IC50 13.42 μg/mL (IC50 0.045 μM), followed by compound 4 (IC50 28.89 μg/mL or IC50 0.11 μM). The thienopyrimidine 4 revealed higher selectivity to MCF-7 and lower activity (IC50 367 μg/mL i.e., 1.4 μM) than compound 3 with MCF-10A cells. With respect to MDA-MB-231 cells, ester 2 manifested the highest effect with IC50 52.56 μg/mL (IC50 0.16 μM), and 2-ethyl derivative 4 revealed IC50 62.86 μg/mL (IC50 0.24 μM). It was estimated that the effect of the substances on the cell cycle progression was due to cell cycle arrest in the G2 stage for MDA-MB-231, while arrest in G1 was detected for the estrogen (ER)-positive MCF-7 cell line. The tested compound's effects on the change of the zeta potential in the tumorigenic cells utilized in this study were determined. The calculation which we performed of the physicochemical properties and pharmacokinetic parameters influencing the biological activity suggested high intestinal absorption, as well as drug-likeness.

G2/M-Phase-Inhibitory Mitochondrial-Depolarizing Re(I)/Ru(II)/Ir(III)-2,2'-Bipyrimidine-Based Heterobimetallic Luminescent Complexes: An Assessment of In Vitro Antiproliferative Activity and Bioimaging for Targeted Therapy toward Human TNBC Cells

Triple-negative breast cancer (TNBC) is an extremely vicious subtype of human breast cancer having the worst prognosis along with strong invasive and metastatic competency. Hence, it can easily invade into blood vessels, and presently, no targeted therapeutic approach is available to annihilate this type of cancer. Metal complexes have successfully stepped into the anticancer research and are now being applauded due to their anticancer potency after the discovery of cisplatin. Many of these metal complexes are also well recognized for their activity toward breast cancer. As the TNBC is a very dangerous subtype and has long been a challenging ailment to treat, we have intended to develop a few brand new mixed metallic Ru(II)/Ir(III)/Re(I)-2,2'-bipyrimidine complexes [L'Re2], [L'RuRe], and [L'IrRe] to abate the unbridled proliferation of TNBC cells. The potency of the complexes against TNBC cells has been justified using MDA-MB-468 TNBC cell lines where complex [L'IrRe] has displayed significant potency among all the three complexes with an IC₅₀ value of 24.12 μM. The complex [L'IrRe] has been competent to cause apoptosis of TNBC cells through inhibition of the G2/M phase in the cell cycle in association with a profuse amount of ROS generation and mitochondrial depolarization.

Drug repurposing strategy II: from approved drugs to agri-fungicide leads

Epidemic diseases of crops caused by fungi deeply affected the course of human history and processed a major restriction on social and economic development. However, with the enormous misuse of existing antimicrobial drugs, an increasing number of fungi have developed serious resistance to them, making the diseases caused by pathogenic fungi even more challenging to control. Drug repurposing is an attractive alternative, it requires less time and investment in the drug development process than traditional R&D strategies. In this work, we screened 600 existing commercially available drugs, some of which had previously unknown activity against pathogenic fungi. From the primary screen at a fixed concentration of 100 μg/mL, 120, 162, 167, 85, 102, and 82 drugs were found to be effective against Rhizoctonia solani, Sclerotinia sclerotiorum, Botrytis cinerea, Phytophthora capsici, Fusarium graminearum and Fusarium oxysporum, respectively. They were divided into nine groups lead compounds, including quinoline alkaloids, benzimidazoles/carbamate esters, azoles, isothiazoles, pyrimidines, pyridines, piperidines/piperazines, ionic liquids and miscellaneous group, and simple structure-activity relationship analysis was carried out. Comparison with fungicides to identify the most promising drugs or lead structures for the development of new antifungal agents in agriculture.

Anti-cancer drug molecules targeting cancer cell cycle and proliferation

Cancer, a vicious clinical burden that potentiates maximum fatality for humankind, arises due to unregulated excessive cell division and proliferation through an eccentric expression of cell cycle regulator proteins. A set of evolutionarily conserved machinery controls the cell cycle in an extremely precise manner so that a cell that went through the cycle can produce a genetically identical copy. To achieve perfection, several checkpoints were placed in the cycle for surveillance; so, errors during the division were rectified by the repair strategies. However, irreparable damage leads to exit from the cell cycle and induces programmed cell death. In comparison to a normal cell, cancer cells facilitate the constitutive activation of many dormant proteins and impede negative regulators of the checkpoint. Extensive studies in the last few decades on cell division and proliferation of cancer cells elucidate the molecular mechanism of the cell-cycle regulators that are often targeted for the development of anti-cancer therapy. Each phase of the cell cycle has been regulated by a unique set of proteins including master regulators Cyclins, and CDKs, along with the accessory proteins such as CKI, Cdc25, error-responsive proteins, and various kinase proteins mainly WEE1 kinases, Polo-like kinases, and Aurora kinases that control cell division. Here in this chapter, we have analytically discussed the role of cell cycle regulators and proliferation factors in cancer progression and the rationale of using various cell cycle-targeting drug molecules as anti-cancer therapy.

Antiproliferative Activity of (-)-Isopulegol-based 1,3-Oxazine, 1,3-Thiazine and 2,4-Diaminopyrimidine Derivatives

A series of novel heterocyclic structures, namely 1,3‐oxazines, 1,3‐thiazines and 2,4‐diaminopyrimidines, were designed and synthesised. The bioassay tests demonstrated that, among these analogues, 2,4‐diaminopyridine derivatives showed significant antiproliferative activity against different human cancer cell lines (A2780, SiHa, HeLa, MCF‐7 and MDA‐MB‐231). Pyrimidines substituted with N²‐(p‐trifluoromethyl)aniline, in particular, displayed a potent inhibitory effect on the growth of cancer cells. Structure–activity relationships were also studied from the aspects of stereochemistry on the aminodiol moiety as well as exploring the effects of substituents on the pyrimidine scaffold.

Synthesis, characterization, molecular docking, and anticancer activities of new 1,3,4-oxadiazole-5-fluorocytosine hybrid derivatives

Analogs of pyrimidine and 1,3,4-oxadiazole are two well established class of molecules proven as potent antiviral and anticancer agents in the pharmaceutical industry. We envisioned designing new molecules where these two heterocycles were conjugated with the goal of enhancing biological activity. In this vein, we synthesized a series of novel pyrimidine-1,3,4-oxadiazole conjugated hybrid molecules as potential anticancer and antiviral agents. Herein, we present a new design for 5-fluorocytosine-1,3,4-oxadiazole hybrids (5a-h) connected via a methylene bridge. An efficient synthesis of new derivatives was established, and all compounds were fully characterized by NMR and MS. Eight compounds were evaluated for their cytotoxic activity against fibrosarcoma (HT-1080), breast (MCF-7 and MDA-MB-231), lung carcinoma (A-549), and for their antiviral activity against SARS-CoV-2. Among all compounds tested, the compound 5e showed marked growth inhibition against all cell lines tested, particularly in HT-1080, with IC50 values of 19.56 µM. Meanwhile, all tested compounds showed no anti-SARS-CoV-2 activity, with EC50 >100 µM. The mechanism of cell death was investigated using Annexin V staining, caspase-3/7 activity, and analysis of cell cycle progression. The compound 5e induced apoptosis by the activation of caspase-3/7 and cell-cycle arrest in HT-1080 and A-549 cells at the G2M phase. The molecular docking suggested that the compound 5e activated caspase-3 via the formation of a stable complex protein-ligand.

Divergent Synthesis, Antiproliferative and Antimicrobial Studies of 1,3-Aminoalcohol and 3-Amino-1,2-Diol Based Diaminopyrimidines

A series of novel diaminopyrimidines containing pinane moieties were synthesized via an efficient methodology starting from pinane-based aminoalcohols, aminodiols and 2,4-dichloropyrimidines. Bioassay tests demonstrated that compound 18a displayed much stronger antiproliferative activities against four human cancer cell lines (HeLa, Siha, MDA-MB-231, MCF-7 and A2780) than positive control cisplatin. In particular, compound 22a was found to be selective in inhibiting HeLa cell proliferation with cancer cell growth inhibition values higher than 95 %. Moreover, the in vitro screening of prepared compounds against different bacterial and fungal strains is reported. The results revealed that 12b and 17a, the most promising compounds, displayed selective inhibition for the Gram-positive bacteria (B. subtilis and S. aureus) with percent inhibition values ranging from 75 to 95 % at 10 μg/mL concentration. Both selective inhibition and the in vitro activity values demonstrated that these compounds have the potential to be developed into clinically important therapeutic choices for the treatment of infections caused by B. subtilis and S. aureus.

Synthesis of New Spiro-Cyclopropanes Prepared by Non-Stabilized Diazoalkane Exhibiting an Extremely High Insecticidal Activity

The synthesis of new insecticidal gem-dimethyspiro-cyclopropanes derived from pyrrolidine-2,3-dione have been described, and their biological effect against different insect species has been evaluated. The presented results demonstrate the excellent insecticidal activity of cyclopropane 5c against Aedes aegypti and Musca domestica. Cyclopropane 5c showed the quickest knockdown and the best killing against Aedes aegypti and Musca domestica compared to trans-chrysanthemic acid and pyrethrin. The biological results of the high insecticidal activity were confirmed by the results of docking. This is evident in the binding affinity obtained for cyclopropane 5c, indicating good binding with an important active amino acid residue of the 5FT3 protein.

Benzimidazole hybrids as anticancer drugs: An updated review on anticancer properties, structure-activity relationship, and mechanisms of action (2019-2021)

Cancer, characterized by a deregulation of the cell cycle which mainly results in a progressive loss of cellular differentiation and uncontrolled cellular growth, remains a prominent cause of death across the world. Almost all currently available anticancer agents used in clinical practice have developed multidrug resistance, creating an urgent need to develop novel chemotherapeutics. Benzimidazole derivatives could exert anticancer properties through diverse mechanisms, inclusive of the disruption of microtubule polymerization, the induction of apoptosis, cell cycle (G2/M) arrest, antiangiogenesis, and blockage of glucose transport. Moreover, several benzimidazole-based agents have already been approved for the treatment of cancers. Hence, benzimidazole derivatives are useful scaffolds for the development of novel anticancer agents. In particular, benzimidazole hybrids could exert dual or multiple antiproliferative activities and had the potential to overcome drug resistance, demonstrating the potential of benzimidazole hybrids as potential prototypes for clinical deployment in the control and eradication of cancers. The purpose of the present review article is to provide a comprehensive landscape of benzimidazole hybrids as potential anticancer agents, and the structure-activity relationship as well as mechanisms of action are also discussed to facilitate the further rational design of more effective candidates, covering articles published from 2019 to 2021.

Novel Pyridothienopyrimidine Derivatives: Design, Synthesis and Biological Evaluation as Antimicrobial and Anticancer Agents

The growing risk of antimicrobial resistance besides the continuous increase in the number of cancer patients represents a great threat to global health, which requires intensified efforts to discover new bioactive compounds to use as antimicrobial and anticancer agents. Thus, a new set of pyridothienopyrimidine derivatives 2a,b–9a,b was synthesized via cyclization reactions of 3-amino-thieno[2,3-b]pyridine-2-carboxamides 1a,b with different reagents. All new compounds were evaluated against five bacterial and five fungal strains. Many of the target compounds showed significant antimicrobial activity. In addition, the new derivatives were further subjected to cytotoxicity evaluation against HepG-2 and MCF-7 cancer cell lines. The most potent cytotoxic candidates (3a, 4a, 5a, 6b, 8b and 9b) were examined as EGFR kinase inhibitors. Molecular docking study was also performed to explore the binding modes of these derivatives at the active site of EGFR-PK. Compounds 3a, 5a and 9b displayed broad spectrum antimicrobial activity with MIC ranges of 4–16 µg/mL and potent cytotoxic activity with IC₅₀ ranges of 1.17–2.79 µM. In addition, they provided suppressing activity against EGFR with IC₅₀ ranges of 7.27–17.29 nM, higher than that of erlotinib, IC₅₀ = 27.01 nM.

DFT, ADMET and Molecular Docking Investigations for the Antimicrobial Activity of 6,6'-Diamino-1,1',3,3'-tetramethyl-5,5'-(4-chlorobenzylidene)bis[pyrimidine-2,4(1H,3H)-dione]

Heterocyclic compounds, including pyrimidine derivatives, exhibit a broad variety of biological and pharmacological activities. In this paper, a previously synthesized novel pyrimidine molecule is proposed, and its pharmaceutical properties are investigated. Computational techniques such as the density functional theory, ADMET evaluation, and molecular docking were applied to elucidate the chemical nature, drug likeness and antibacterial function of molecule. The viewpoint of quantum chemical computations revealed that the molecule was relatively stable and has a high electrophilic nature. The contour maps of HOMO-LUMO and molecular electrostatic potential were analyzed to illustrate the charge density distributions that could be associated with the biological activity. Natural bond orbital (NBO) analysis revealed details about the interaction between donor and acceptor within the bond. Drug likeness and ADMET analysis showed that the molecule possesses the agents of safety and the effective combination therapy as pharmaceutical drug. The antimicrobial activity was investigated using molecular docking. The investigated molecule demonstrated a high affinity for binding within the active sites of antibacterial and antimalarial proteins. The high affinity of the antibacterial protein was proved by its low binding energy (-7.97 kcal/mol) and a low inhibition constant value (1.43 µM). The formation of four conventional hydrogen bonds in ligand-protein interactions confirmed the high stability of the resulting complexes. When compared to known standard drugs, the studied molecule displayed a remarkable antimalarial activity, as indicated by higher binding affinity (B.E. -5.86 kcal/mol & Ki = 50.23 M). The pre-selected molecule could be presented as a promising drug candidate for the development of novel antimicrobial agents.

Design, Synthesis, and Biological Evaluation of 5,6,7,8-Tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidines as Microtubule Targeting Agents

A series of eleven 4-substituted 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidines were designed and synthesized and their biological activities were evaluated. Synthesis involved the Gewald reaction to synthesize ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate ring, and S_NAr reactions. Compound 4 was 1.6- and ~7-fold more potent than the lead compound 1 in cell proliferation and microtubule depolymerization assays, respectively. Compounds 4, 5 and 7 showed the most potent antiproliferative effects (IC₅₀ values < 40 nM), while compounds 6, 8, 10, 12 and 13 had lower antiproliferative potencies (IC₅₀ values of 53–125 nM). Additionally, compounds 4–8, 10 and 12–13 circumvented Pgp and βIII-tubulin mediated drug resistance, mechanisms that diminish the clinical efficacy of paclitaxel (PTX). In the NCI-60 cell line panel, compound 4 exhibited an average GI₅₀ of ~10 nM in the 40 most sensitive cell lines. Compound 4 demonstrated statistically significant antitumor effects in a murine MDA-MB-435 xenograft model.