Development of DNA intercalative, HSA binder pyridine‐based novel Schiff base Cu(II), Ni(II) complexes with effective anticancer property: A combined experimental and theoretical approach

Novel pyridine bearing pentose moiety-based anticancer agents: design, synthesis, radioiodination and bioassessments

Pyridine compounds are one of the most important heterocyclic derivatives showing wide ranges in biological and pharmacological activities. Green chemistry eliminates or reduces the generation of hazardous compounds. It prevents pollution at a molecular level. The microwave technique used in heterocyclic compound synthesis is also an important branch of green chemistry techniques. In this study, we report designing and synthesizing a new pyridine-bearing pentose moiety via a one-pot multicomponent reaction using D-glucose and also investigate its behavior and reactivity toward some simple and heterocyclic amino derivatives. The chemical structures of the synthesized compounds were characterized and tested for their cytotoxic activities. Some of the test compounds exhibited slight to high cytotoxic activities against Caco2 (colon cancer) cells, HepG2 (hepatocellular carcinoma) cells and MCF-7 (human breast cancer) cells by MTT assay. The results showed clearly that compound 4 and compound 8 displayed strongest to moderate cytotoxic activity against the HepG2, Caco2 and MCF-7 respectively and compound 1 showed good activity against MCF-7 in comparison to the standard anticancer drug doxorubicin. These data were by cytopathological examination. An in-vivo radioactive tracing study of compound 4 proved its targeting ability to sarcoma cells in a tumor-bearing mice model. Our findings suggest that the synthesized compounds may be promising candidates as novel anticancer agents.

Small Molecule Interactions with Biomacromolecules: DNA Binding Interactions of a Manganese(III) Schiff Base Complex with Potential Anticancer Activities

A manganese(III) complex, [MnIII(L)(SCN)(enH)](NO3)·H2O (1•H2O) (H2L = 2-((E)-(2-((E)-2-hydroxy-3-methoxybenzylidene-amino)-ethyl-imino)methyl)-6-methoxyphenol), has been synthesized and characterized by single-crystal X-ray diffraction analysis. The interaction of 1•H2O with DNA was studied by monitoring the decrease in absorbance of the complex at λ = 324 nm with the increase in DNA concentration, providing an opportunity to determine the binding constant of the 1•H2O-ct-DNA complex as 5.63 × 103 M-1. Similarly, fluorescence titration was carried out by adding ct-DNA gradually and monitoring the increase in emission intensity at 453 nm on excitation at λex = 324 nm. A linear form of the Benesi-Hildebrand equation yields a binding constant of 4.40 × 103 M-1 at 25 °C, establishing the self-consistency of our results obtained from absorption and fluorescence titrations. The competitive displacement reactions of dyes like ethidium bromide, Hoechst, and DAPI (4',6-diamidine-2'-phenylindole dihydrochloride) from dye-ct-DNA conjugates by 1•H2O were analyzed, and the corresponding KSV values are 1.05 × 104, 1.25 × 104, and 1.35 × 104 M-1 and the Kapp values are 2.16 × 103, 8.34 × 103, and 9.0 × 103 M-1, from which it is difficult to infer the preference of groove binding over intercalation by these DNA trackers. However, the molecular docking experiments and viscosity measurement clearly indicate the preference for minor groove binding over intercalation, involving a change in Gibbs free energy of -8.56 kcal/mol. The 1•H2O complex was then evaluated for its anticancer potential in breast cancer MCF-7 cells, which severely abrogates the growth of the cells in both 2D and 3D mammospheres, indicating its promising application as an anticancer drug through a minor groove binding interaction with ct-DNA.

DNA/Protein Binding and Apoptotic-Induced Anticancer Property of a First Time Reported Quercetin-Iron(III) Complex Having a Secondary Anionic Residue: A Combined Experimental and Theoretical Approach

A new quercetin-based iron(III) cationic complex [Fe(Qr)Cl(H₂O)(MeO)] (complex 1) is created in the current study by condensation of quercetin with ferric chloride in the presence of Et₃N. Comprehensive spectroscopic analysis and conductometric measurement are used to pinpoint complex 1. The generated complex's +3-oxidation state has been verified by electron paramagnetic resonance (EPR) research. Density functional theory analysis was used to structurally optimize the structure of complex 1. Before biomedical use, a variety of biophysical studies are implemented to evaluate the binding capacity of complex 1 with DNA and human serum albumin (HSA) protein. The findings of the electronic titration between complex 1 and DNA, as well as the stunning fall in the fluorescence intensities of the HSA and EtBr-DNA/DAPI-DNA domain after complex 1 is gradually added, give us confidence that complex 1 has a strong affinity for both macromolecules. It is interesting to note that the displacement experiment confirms partial intercalation as well as the groove binding mechanism of the title complex with DNA. The time-dependent fluorescence analysis indicates that after interaction with complex 1, HSA will exhibit static quenching. The thermodynamic parameter values in the HSA-complex 1 interaction provide evidence for the hydrophobicity-induced pathway leading to spontaneous protein-complex 1 interaction. The two macromolecules' configurations are verified to be preserved when they are associated with complex 1, and this is done via circular dichroism spectral titration. The molecular docking investigation, which is a theoretical experiment, provides complete support for the experimental findings. The potential of the investigated complex to be an anticancer drug has been examined by employing the MTT assay technique, which is carried out on HeLa cancer cell lines and HEK-293 normal cell lines. The MTT assay results validate the ability of complex 1 to display significant anticancer properties. Finally, by using the AO/PI staining approach, the apoptotic-induced cell-killing mechanism as well as the detection of cell morphological changes has been confirmed.

Biological Activity of Two Anticancer Pt Complexes with a Cyclohexylglycine Ligand against a Colon Cancer Cell Line: Theoretical and Experimental Study

Because of their extraordinary ability to disrupt the natural structure of nucleic acids, metal complexes could be used in cancer therapy. In this study, cyclohexylglycine (HL) as a ligand and two new Pt complexes, [Pt(NH₃)₂(L)]NO₃ (1) and [Pt(bipy)(L)]NO₃ (2), were synthesized and characterized by elemental analysis, LC-MS, UV-vis spectrometry, FT-IR, ¹H NMR spectroscopy, ¹³C NMR spectroscopy, ¹⁹⁵Pt NMR spectroscopy, HPLC analysis, and single-crystal X-ray diffraction. Complex 2 crystallized in the orthorhombic Pbca space group, and density functional theory (DFT) was used to describe its structural parameters were described in detail. These complexes can be classified as oral medications and drug-like molecules based on a comparison of their absorption, distribution, metabolism, and excretion assessment. Quantum chemical descriptors (QCDs) were determined using DFT calculations to predict the tendency of DNA to approach these complexes. During the determination of the function of the metallodrug in DNA binding, the fluorescence data indicated that static quenching took place for all ligands and complexes with higher DNA binding affinity. CD and isothermal absorption studies indicate the presence of electrostatic and groove binding for the amine derivative and that DNA binds with the bipy moiety via groove binding. Furthermore, the interaction modes were determined using molecular docking to investigate the binding of these compounds with the target DNA molecule. According to docking investigations, binding energies of -5.7, -11.56, and -10.00 kcal/mol for HL and complexes 1 and 2, respectively, indicate partially electrostatic and groove binding. The anticancer activities of the Pt(II) complexes were tested against the HCT116 human colon cancer cell line, with IC₅₀ values of 35.51 and 51.33 μM for 1 and 2, respectively, after 72 h. These values show that the inhibitory effect of complex 1 was better than those of 2 and carboplatin (IC₅₀ = 51.94 μM).