Evaluation of cytotoxic potential of structurally well-characterized RNA targeted ionic non-steroidal anti-inflammatory (NSAID) Cu(ii) & Zn(ii) DACH–mefenamato drug conjugates against human cancer cell lines

A review on the recent advances of interaction studies of anticancer metal-based drugs with therapeutic targets, DNA and RNAs

Metal-based drugs hold promise as potent anticancer agents owing to their unique interactions with cellular targets. This review discusses recent advances in our understanding of the intricate molecular interactions of metal-based anticancer compounds with specific therapeutic targets in cancer cells. Advanced computational and experimental methodologies delineate the binding mechanisms, structural dynamics and functional outcomes of these interactions. In addition, the review sheds light on the precise modes of action of these drugs, their efficacy and the potential avenues for further optimization in cancer-treatment strategies and the development of targeted and effective metal-based therapies for combating various forms of cancer.

Repurposing the antihistamine drug bilastine as an anti-cancer metallic drug entity: synthesis and single-crystal X-ray structure analysis of metal-based bilastine and phen [Co(II), Cu(II) and Zn(II)] tailored anticancer chemotherapeutic agents against resistant cancer cells

Bilastine (BLA), 2-(4-(2-(4-(1-(2-ethoxyethyl)-1H-benzo[d]imidazole-2-yl)-piperidin-1-yl)-ethyl)-phenyl)-2-methylpropanoic acid, is an active antihistamine drug. With the idea of repurposing drugs from the existing pool of 'active' pharmaceutical ingredients, the therapeutic potency of bilastine as an anticancer agent was investigated via the tailored synthesis of a metal-based anticancer drug formulation of the type [BLA(phen)2M(II)]+·X-, where M = Co, Cu, and Zn and X- = NO3 and ClO4. The synthesized metal-based chemotherapeutics derived from the bilastine drug that acts as a ligand were thoroughly characterized using spectroscopic techniques, namely, UV-vis, FT-IR, and EPR (in the case of 1 and 2); 1H-NMR and 13C-NMR (in the case of 3); ESI-MS and single-crystal X-ray diffraction studies. Comprehensive biological studies (DNA binding, cleavage, and cytotoxic activity) using various biophysical and gel electrophoretic methods were carried out to validate their potential as anticancer agents. The cytotoxic activity of 'therapeutically promising' copper(II)-based drug candidate 2 was evaluated against MCF-7, MBA-MD-231, HeLa, HepG2, and Mia-PaCa-2 cancer cells via an SRB assay, and the results demonstrated 2 as a potent anticancer agent at low nanomolar concentrations against all tested cancer cells, preferably with a much superior anticancer efficacy against human pancreatic cancer cells.

Structural insights into interactions of new polymeric (μ-oxo) bridged Cu(II) complexes of taurine with yeast tRNA by spectroscopic and computational approaches and its application towards chemoresistant cancer lines

RNA-targeted drugs are considered as safe treatment option for the cure of many chronic diseases preventing off-targeted delivery and acute toxic manifestations. FDA has approved many such RNA therapies in different phases of clinical trials, validating their use for the treatment of various chronic diseases. We report herein, new water-soluble (μ-oxo) bridged polymeric Cu(II) complexes of taurine (2-aminoethane sulfonic acid) complexes 1 and 2. The therapeutic potency of 1 and 2 was ascertained by studying biophysical interactions with tRNA/ct-DNA. The experimental results demonstrated that the complexes interacted avidly to nucleic acids through intercalation mode depicting a specific preference for tRNA in comparison to ct-DNA and, moreover 2 showed higher binding propensity than 1. The electrophoretic behaviour of the complexes with plasmid pBR322 DNA and tRNA were examined by gel mobility assay that revealed a concentration-dependent activity with complex 2 performing more efficient cleavage as compared to complex 1. Cytotoxicity results on cancer cell strains displayed higher cytotoxicity than complex 1 against treated cancer cells. The synthesized copper(II) taurine complexes have met the basic criteria of anticancer drug design as they are structurally well-characterized, exhibiting good solubility in water, lipophilic in nature with superior intercalating propensity towards tRNA and cytotoxic in nature.

New Apoptosis Inducers Containing Anti-inflammatory Drugs and Pnictogen Derivatives: A New Strategy in the Development of Mitochondrial Targeting Chemotherapeutics

{[Ag₈(Mef)₈(μ₂-S,O-DMSO)₂(μ₂-O-DMSO)₂(O-DMSO)₈]·2(H₂O)} (1), [Ag(Mef)(tpP)₂] (2), [Ag(Mef)(tpAs)₃] (3), and {2 [Ag(Mef)(tpSb)₃] (DMSO)} (4) were obtained by the conjugation of mefenamic acid (MefH), a nonsteroidal anti-inflammatory drug (NSAID), with a mitochondriotropic derivative of pnictogen tpE (tp = triphenyl group; E = P, As, and Sb) through silver(I). Their hydrophilicity was adjusted by their dispersion into sodium lauryl sulfate (SLS), forming SLS@1-4. 1-4 and SLS@1-4 were characterized by their spectral data and X-ray crystallography. They inhibit the proliferation of human breast adenocarcinoma cells MCF-7 (hormone-dependent (HD)) and MDA-MB-231 (hormone-independent (HI)). X-ray fluorescence reveals the Ag cellular uptake. The in vitro and in vivo nongenotoxicity was confirmed with micronucleus (MN), Artemia salina, and Allium cepa assays. Their mechanism of action was studied by cell morphology, DNA fragmentation, acridine orange/ethidium bromide (AO/EB) staining, cell cycle arrest, mitochondrial membrane permeabilization tests, DNA binding affinity, and LOX inhibitory activity and was rationalized by regression analysis.

Progress of Metal-Based Anticancer Chemotherapeutic Agents in Last two Decades and their Comprehensive Biological (DNA/RNA Binding, Cleavage and Cytotoxicity Activity) Studies

During last two decades, there has been an enormous growth in the discovery of innovative active inorganic anticancer complexes (exerting remarkable cytotoxicity at sub micro-molar levels) derived from myriad ligand scaffolds, mainly acting on cancerous vs healthy cells by either halting or inhibiting their uncontrolled growth. The phenomenal success of cisplatin to treat numerous forms of solid malignancies has placed metal-based drugs to the forefront of treatment strategies against cancers. More than 10,000 platinum anticancer complexes have been developed during the past 40 years, but only five drugs have been approved for usage in humans while ten more complexes are currently undergoing clinical trials. Most of the compounds have failed either at R&D stages or in preclinical trails. This has led to extensive investigations by researchers of medicinal chemistry, including our group to design and prepare tailored 3d-metallo-drugs and organotin(IV) compounds from some naturally occurring bioactive compounds, such as amino-acids, peptides, chromone derivatives and NSAID's etc. that were used either alone or in cocktail combination, capable of specifically targeting DNA, lnc RNAs and proteins. Furthermore, 3d-metal ions such as copper, cobalt and zinc etc. incorporated in these ligand framework are biocompatible and induce a unique multi-modal mechanism of cytotoxic action involving angiogenesis, ROS-induced DNA damage, apoptosis by p53 mitochondrial genes and caspases etc. The results observed a positive correlation between the binding affinity of complexes with DNA (as quantified by intrinsic binding constant values) and their cytotoxic behavior. Complexes with high DNA binding propensity were typically lethal against a diverse panel of malignant cell types compared to normal cells.

Mutations Associated with Pyrazinamide Resistance in Mycobacterium tuberculosis: A Review and Update

Pyrazinamide (PZA) has remained a keystone of tuberculosis (TB) therapy, and it possesses high imperative sterilizing action that can facilitate reduction in the present chemotherapy regimen. The combination of PZA works both with first- and second-line TB drugs, notably fluoroquinolones, clofazimine, bedaquiline, delamanid and pretomanid. Pyrazinamide inhibits various targets that are involved in different cellular processes like energy production (pncA), trans-translation (rpsA) and pantothenate/coenzyme A (panD) which are required for persistence of the pathogen. It is well known that pncA gene encoding pyrazinamidase is involved in the transition of PZA into the active form of pyrazinoic acid, which implies that mutation in the pncA gene can develop PZA resistance in Mycobacterium tuberculosis (M. tuberculosis) strain leading to a major clinical and public health concern. Therefore, it is very crucial to understand its resistance mechanism and to detect it precisely to help in the management of the disease. Scope of this review is to have a deep understanding of molecular mechanism of PZA resistance with its multiple targets which would help study the association of mutations and its resistance in M. tuberculosis. This will in turn help learn about the resistance of PZA and develop more accurate molecular diagnostic tool for drug-resistant TB in future TB therapy.

Facile synthesis of a glutathione-depleting Cu(II)-half-salamo-based coordination polymer for enhanced chemodynamic therapy

Chemodynamic therapy (CDT), utilizing Fenton catalysts to convert intracellular H₂O₂ into toxic hydroxyl radicals (˙OH) to kill cancer cells, has a wide application prospect in tumor treatment because of its high selectivity. Its anticancer effect, however, is unsatisfactory due to the overexpressed glutathione (GSH). Herein, a GSH-depleting Cu(II)-half-salamo-based coordination polymer (CuCP) was prepared and validated by single crystal X-ray crystallography, Hirshfeld surface analyses and DFT calculations. The Cu(II) ions in the coordination polymer are five-coordinated bearing slightly twisted square pyramidal coordination environments and are bridged by phenoxy and alkoxy groups. After internalization by tumor cells, the CuCP could be biodegraded and reduced by GSH to generate a large amount of Cu(I), simultaneously depleting GSH. Subsequently, the Cu(I) ions interact with H₂O₂ to generate toxic ˙OH through a Fenton-like reaction to enhance their anticancer efficacy. Our study provides useful insights into designing smarter metal-based anticancer agents to improve the CDT efficiency in cancer therapy.

NSAID-Based Coordination Compounds for Biomedical Applications: Recent Advances and Developments

After the serendipitous discovery of cisplatin, a platinum-based drug with chemotherapeutic effects, an incredible amount of research in the area of coordination chemistry has been produced. Other transition metal compounds were studied, and several new relevant metallodrugs have been synthetized in the past few years. This review is focused on coordination compounds with first-row transition metals, namely, copper, cobalt, nickel or manganese, or with zinc, which have potential or effective pharmacological properties. It is known that metal complexes, once bound to organic drugs, can enhance the drugs’ biological activities, such as anticancer, antimicrobial or anti-inflammatory ones. NSAIDs are a class of compounds with anti-inflammatory properties used to treat pain or fever. NSAIDs’ properties can be strongly improved when included in complexes using their compositional N and O donor atoms, which facilitate their coordination to metal ions. This review focuses on the research on this topic and on the promising or effective results that complexes of first-row transition metals and NSAIDs can exhibit.

Chromone‐Appended Zn(II) tRNA‐Targeted Potential Anticancer Chemotherapeutic Agent: Structural Details, in vitro ct‐DNA/tRNA Binding, Cytotoxicity Studies And Antioxidant Activity

A 3‐formyl‐chromone‐appended zinc(II) intercalator drug candidate of the formulation [bis(chromone)(H 2 O)2 Zn(II)] was prepared as a potent anticancer agent and thoroughly characterized by multi‐spectroscopic and single X‐ray crystallographic studies.   Preliminary binding studies of complex 1 with ct‐DNA/tRNA were carried out employing various complementary biophysical techniques and the corroborative results of these experiments suggested strong binding propensity via  intercalation binding mode towards ct‐DNA/tRNA  therapeutic targets, with higher preference for tRNA as quantified by  binding constant { K b , K and K sv } parameters. The cleavage studies with pBR322 DNA were performed which implied that 1 cleaved the DNA by hydrolytic cleavage pathway which was further validated by T4 religation assay. Moreover, 1  was found to exhibit the tRNA cleavage behavior in a concentration and time‐dependent manner. The cytotoxicity of complex 1 was evaluated against Huh‐7, DU‐145 and the PNT2 cell lines by MTT assay. A dose‐dependent growth inhibition of the Huh‐7 and DU‐145 cells at low micromolar concentrations was observed and in another set of experiments, lipid peroxidation & glutathione (GSH) depletion were induced in the presence of the tested drug candidate. Interestingly, drug candidate 1 demonstrated selective cytotoxic activity for the DU‐145 cancer cell line with LC50 value of 3.2 μM which was further visualized by confocal microscopy.

A gama-turn mimetic for selective sensing of Cu(II) and combinatorial multiple logic gate

We have designed and synthesized a gama-turn mimetic using fenamic acid and α-aminoisobutyricacid (Aib), the conformation and optoelectronic properties of which can be changed by appropriate external stimuli. From single-crystal...

Interaction of Carrier Protein with Potential Metallic Drug Candidate N-Glycoside 'GATPT': Validation by Multi-Spectroscopic and Molecular Docking Approaches

Lysozyme is often used as a model protein to study interaction with drug molecules and to understand biological processes which help in illuminating the therapeutic effectiveness of the drug. In the present work, in vitro interaction studies of 1-{(2-hydroxyethyl)amino}-2-amino-1,2-dideoxy-d-glucose triphenyl tin (IV) (GATPT) complex with lysozyme were carried out by employing various biophysical methods such as absorption, fluorescence, and circular dichroism (CD) spectroscopies. The experimental results revealed efficient binding affinity of GATPT with lysozyme with intrinsic binding (Kb) and binding constant (K) values in the order of 105 M-1. The number of binding sites and thermodynamic parameters ΔG, ΔH, and ΔS at four different temperatures were also calculated and the interaction of GATPT with lysozyme was found to be enthalpy and entropy driven. The CD spectra revealed alterations in the population of α-helical content within the secondary structure of lysozyme in presence of GATPT complex. The morphological analysis of the complex with lysozyme and lysozyme-DNA condensates was carried out by employing confocal and SEM studies. Furthermore, the molecular docking studies confirmed the interaction of GATPT within the larger hydrophobic pocket of the lysozyme via several non-covalent interactions.

Insights into metalloproteins and metallodrugs from electron paramagnetic resonance spectroscopy

Metal ions play an important role in diverse biological processes, and much of the basic knowledge derived from studying native bioinorganic systems are applied in the synthesis of new molecules with the aim of diagnosing and treating diseases. At first glance, metalloproteins and metallodrugs are very different systems, but metal ion coordination, redox chemistry and substrate binding play essential roles in advancing both of these research fields. In this article, we discuss recent metalloprotein and metallodrug studies where electron paramagnetic resonance spectroscopy served as a major tool to gain a better understanding of metal-based structures and their function.

Water soluble ionic Co(II), Cu(II) and Zn(II) diimine-glycinate complexes targeted to tRNA: structural description, in vitro comparative binding, cleavage and cytotoxic studies towards chemoresistant prostate cancer cells

Four new water soluble Co(ii), Cu(ii) and Zn(ii) ionic metal complexes (1-4) [Cu(diimine)(H2O)2(glycinate)]+[glycinate]-, [Co(diimine)(H2O)4]+[glycinate]- and [Zn(diimine) (H2O)4]+[glycinate]-, where diimine = 2,2'-bipyridine (1-3) and 1,10-phenanthroline (4) were synthesized and thoroughly characterized by spectroscopic and single X-ray crystallographic studies. Complex 1 possesses a triclinic crystal system with a penta-coordinated geometry whereas complexes 2-4 crystallized in an isostructural monoclinic system having distorted octahedral geometry. Density functional theory (DFT) studies for complexes 1-4 were performed to correlate their geometrical parameters and to calculate the energy of frontier molecular orbitals. The corroborative results of spectroscopic and voltammetric studies with ct-DNA and tRNA revealed that the complexes bind noncovalently via an electrostatic mode of binding with specificity for tRNA as compared to ct-DNA. Gel electrophoresis experiments revealed that all the complexes unwind the plasmid pBR322 DNA at low micromolar concentrations (2-9 μM) following an oxidative mechanism for Cu(ii) and Co(ii) complexes (1, 2 and 4) whereas the Zn(ii) complex (3) mediates DNA cleavage by the hydrolytic pathway. The tRNA cleavage showed concentration and time dependent activity of the complexes to promote RNA hydrolysis. Furthermore, the BSA binding ability of complexes 1-4 was monitored, which revealed that the complexes could quench the intrinsic fluorescence in a static manner. Complexes 1-4 were found to be non-toxic towards normal prostate epithelial cells, PNT2, but were potent against chemoresistant metastatic prostate cancer cells, Du145, with GI50 values ranging from 12.75-37 μM. Complexes 1 and 2 also showed cytotoxic activity against cancer stem cells having GI50 values of 14.70 and 14.90 μM, respectively. Molecular docking studies were performed with DNA and tRNA which further validated the spectroscopic analysis demonstrating the higher binding affinity of the complexes towards tRNA.

New Tailored RNA-Targeted Organometallic Drug Candidates against Huh7 (Liver) and Du145 (Prostate) Cancer Cell Lines

New organometallic drug candidates [Ph2Sn(HL)], 1, and [Ru(η6--p-cymene)(HL)Cl], 2, were designed and synthesized by in situ reaction of a Schiff base ligand (HL) and diphenyltin dichloride and [RuCl2(p-cymene)]2, respectively. The drug candidates 1 and 2 have been characterized by spectroscopic methods (Fourier-transform infrared spectroscopy, UV-vis, and 1H/13C NMR), elemental analysis, and single X-ray crystallographic studies (in case of 1). The ground-state geometry optimization of 1 and 2 was performed by density functional theory calculations. The interaction of 1 and 2 with tRNA was assessed by absorption spectroscopy, cyclic voltammetry, circular dichroism, and ethidium bromide displacement assay using fluorescence emission spectroscopy to determine their potential to act as antitumor agents. The cytotoxicity of 1 and 2 was screened against human liver carcinoma (Huh7), prostate cancer (Du145), and the normal prostate cell line (PNT 2). The results implicated a dose-dependent growth inhibition of the two cancer cells at concentrations (2.5-15 μM) of 1 and 2 with the treatment after 48 h. Interestingly, 1 revealed good selective activity toward the liver cancer cell line (Huh7). Furthermore, both the drug candidates 1 and 2 were found to be nontoxic toward the PNT 2 normal cell line. These studies lay a paradigm for rational efficacious drug design for chemotherapeutic intervention in cancers using new tailored organometallic drug entities; organotin(IV) and organoruthenium(II) have been demonstrated to be viable for the safe administration and specific targeted drug uptake by the resistant cancerous cell lines at low intracellular concentrations.

Comparative in vitro cytotoxicity and binding investigation of artemisinin and its biogenetic precursors with ctDNA

Artemisinin (ART) and its biogenetic precursors artemisinic acid (AA) and dihydroartemisinic acid (DHAA) are important traditional medicinal herb compounds with tumor growth inhibition properties. Herein, we have studied the cytotoxicity of ART, AA, and DHAA on different cancer cell lines (H1299, A431, and HCT 116) and investigated in detail their binding mechanisms with ctDNA by using spectroscopy, cyclic voltammetry, and computational methods. The UV absorbance, cyclic voltammetry, DNA helix melting, competition binding, and circular dichroism studies suggested that the complex formation of ART-ctDNA and AA-ctDNA occurs through groove binding. However, in the case of DHAA-ctDNA interaction, electrostatic interaction plays a major role. The thermodynamic parameters, viz., ΔG 0, ΔH 0, and ΔS 0 were calculated, which showed the involvement of hydrogen bonds and van der Waals interactions for drug-ctDNA interaction. FTIR and molecular docking results suggested that ART, AA, and DHAA were bound to the A-T rich region in the minor groove of ctDNA.