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

Investigation on the Effect of Fluorescence Quenching of Calf Thymus DNA by Piperine: Caspase Activation in the Human Breast Cancer Cell Line Studies

In this study, we determined the interaction of piperine and calf thymus DNA (ct DNA) in Tris-HCl buffer solution at pH = 6.8 and also evaluated the binding mechanism through the data of multi-spectroscopic techniques along with thermal melting and viscosity measurements. The outcomes of fluorescence quenching confirmed the occurrence of interactions between piperine and ctDNA and pointed out the role of piperine as the quencher. In addition, the KSV values were measured at three different temperatures of 298, 303, and 308 K to be 4.5 × 107 M-1, 5.65 × 107 M-1, and 9.36 × 107 M-1, respectively, which suggested the dominance of dynamic mechanism as the fluorescence quenching of piperine-ctDNA. The thermodynamic parameters revealed the predominance of hydrophobic forces in the interaction of ctDNA with piperine. According to the resonance light scattering data, the formation of a complex between piperine and ctDNA led to the creation of a larger particle. Ethidium bromide (EB) and acridine orange (AO) displacement studies, along with the ionic effects of NaCl and KI assessments, confirmed the interaction of piperine-ctDNA through a groove binding mode. The melting temperature assay of ctDNA upon the addition of piperine concentration indicated the probable groove binding of piperine to ctDNA, which was affirmed by relative viscosity measurement as well. The lack of detecting any alterations in the circular dichroism (CD) spectrum of CD investigation verified as a characteristic sign of groove binding mechanism and also confirmed all the experimental results with regard to the binding of piperine-ctDNA complex. Next to observing a concentration and time-dependent cytotoxicity in MDA-MB-231 cells, the impact of piperine on increasing lipid peroxidation and decreasing the activity of superoxide dismutase was also noticed. Apparently, piperine is capable of inducing caspase-3 activity as well.

Synthesis, Structural Investigations, DNA/BSA Interactions, Molecular Docking Studies, and Anticancer Activity of a New 1,4-Disubstituted 1,2,3-Triazole Derivative

We report herein a new 1,2,3-triazole derivative, namely, 4-((1-(3,4-dichlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-hydroxybenzaldehyde, which was synthesized by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The structure of the compound was analyzed using Fourier transform infrared spectroscopy (FTIR), 1H NMR, 13C NMR, UV-vis, and elemental analyses. Moreover, X-ray crystallography studies demonstrated that the compound adapted a monoclinic crystal system with the P21/c space group. The dominant interactions formed in the crystal packing were found to be hydrogen bonding and van der Waals interactions according to Hirshfeld surface (HS) analysis. The volume of the crystal voids and the percentage of free spaces in the unit cell were calculated as 152.10 Å3 and 9.80%, respectively. The evaluation of energy frameworks showed that stabilization of the compound was dominated by dispersion energy contributions. Both in vitro and in silico investigations on the DNA/bovine serum albumin (BSA) binding activity of the compound showed that the CT-DNA binding activity of the compound was mediated via intercalation and BSA binding activity was mediated via both polar and hydrophobic interactions. The anticancer activity of the compound was also tested by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using human cell lines including MDA-MB-231, LNCaP, Caco-2, and HEK-293. The compound exhibited more cytotoxic activity than cisplatin and etoposide on Caco-2 cancer cell lines with an IC50 value of 16.63 ± 0.27 μM after 48 h. Annexin V suggests the induction of cell death by apoptosis. Compound 3 significantly increased the loss of mitochondrial membrane potential (MMP) levels in Caco-2 cells, and the reactive oxygen species (ROS) assay proved that compound 3 could induce apoptosis by ROS generation.

Cancer cells inhibition by cationic carbon dots targeting the cellular nucleus

Nucleus targeting is tremendously important in cancer therapy. Cationic carbon dots (CCDs) are potential nanoparticles which might enter cells and penetrate nuclear membranes. Although some CCDs have been investigated in nucleus targeting and applied in nuclear imaging, the CCDs derived from drugs, that are able to target the nucleus, bind with DNA and inhibit the growth of cancer cells have not been reported. In this project, 1, 2, 4, 5-benzenetetramine (Y15, a focal adhesion kinase inhibitor) derived cationic carbon dots (Y15-CDs) were prepared via a hydrothermal approach utilizing Y15, folic acid and 1,2-ethylenediamine as precursors. Based on the structural, optical, and morphologic characterizations, Y15-CDs possess rich amine groups and nitrogen in structure, an excitation-dependent photoluminescence emission, and a small particle size of 2 to 4 nm. The DNA binding experiments conducted through agarose gel electrophoresis, UV-vis absorption, fluorescence emission, and circular dichroism spectroscopies, prove that Y15-CDs might bind with DNA via electrostatic interactions and partially intercalative binding modes. In addition, the cell imaging and cytotoxicity studies in human foreskin fibroblasts (HFF), prostate cancer (PC3) and osteosarcoma cells (U2OS) indicate the nucleus targeting and anticancer abilities of Y15-CDs. Most interestingly, Y15-CDs exhibit a higher cytotoxicity to cancer cells (PC3 and U2OS) than to normal cells (HFF), inferring that Y15-CDs might be potentially applied in cancer therapy.

Imperative persistent interaction analysis of anticancer noscapine-ionic liquid with calf thymus DNA

In this study, we have shown the interaction between opium poppy alkaloid noscapine-based ionic liquid [Pip-Nos]OTf and ct-DNA using UV-visible absorption spectroscopy, fluorescence spectroscopy, CD, and computational studies. The absorption spectra showed a hypochromic shift with no shift in the absorption maxima suggesting groove or electrostatic binding. Fluorescence spectra showed an enhancement in fluorescence emission suggesting that the probable mode of binding should be groove binding. Ethidium bromide (EB) competitive and Ionic strength study showed the absence of intercalative and electrostatic modes of interaction. Further, CD analysis of ct-DNA suggested a groove binding mode of interaction of [Pip-Nos]OTf with ct-DNA. [Pip-Nos]OTf displayed a strong binding with the target ct-DNA with a molecular docking score of -41.47 kJ/mol with all 3D coordinates and full conformation. Also, molecular binding contact analyses depicted the stable binding of drug and ct-DNA with potential hydrogen bonds and hydrophobic interactions. The structural superimposition dynamics analysis showed the stable binding of [Pip-Nos]OTf with the ct-DNA model through RMSD statistics. Moreover, the ligand interaction calculations revealed the involvement of large binding energy along with a high static number of molecular forces including the hydrogen bonds and hydrophobic interactions in their complexation. These significant results report the potency of [Pip-Nos]OTf and its important futuristic role in cancer therapeutics.

Exploring the interaction of guanidine ligands Amiloride, Rimeporide and Cariporide with DNA for understanding their role as inhibitors of Na+/H+ exchangers (NHEs): A spectroscopic and molecular docking investigation

The inhibition of Na⁺/H⁺ Exchangers (NHEs) has shown efficacy in the pathology of several diseases like tumors, cardiovascular, and neurological disorders. The role of guanidine ligands such as amiloride, cariporide, and rimeporide as NHE inhibitors is very well documented but their interaction studies with genomic DNA are still unexplored. In this study, a combination of various biophysical and molecular docking studies was employed to investigate their binding aspects.UV-Visible, fluorescence, and circular dichroism (CD) studies indicated that guanidine ligands bind to the grooves of Calf Thymus DNA (ctDNA). Fluorescence titration studies depict that amiloride binds to ctDNA with a binding constant in the order of 10² M^-1 and free energy change (ΔG⁰) of -14.05 KJ mol^-1. Competitive fluorescence studies indicated the minor groove binding property of amiloride, whereas major groove binding mode was deduced for rimeporide and cariporide. Molecular docking studies were also found to be in accordance with the experimental results, revealing the information about the binding energy of the guanidine ligand-ctDNA complex. The docked structures depicted binding energy of -6.4 kcal mol^-1 for amiloride and - 6.6 kcal mol^-1 for rimeporide and cariporide. Such physicochemical studies of DNA-ligand interactions may facilitate the understanding of the mechanisms of NHE inhibition.

Synthesis, comparative in vitro antibacterial, antioxidant and UV fluorescence studies of bis indole Schiff bases and molecular docking with ct-DNA and SARS-CoV-2 Mpro

In this study, synthesis of 15 novel bis indole-based Schiff bases (SBs) 4a-4o was conducted by condensation of 2-(1-aminobenzyl)benzimidazole with symmetrical bis-isatins linked via five alkyl chains (n = 2-6). These were subjected to ADME (absorption, distribution, metabolism and excretion), physiochemical properties, molecular docking, in vitro antibacterial and antioxidant studies. The in silico studies indicated lower toxicity with metabolic stability for nearly all the derivatives proving reliability as drug candidates. The comparative antibacterial study against Staphylococcus aureus and Escherichia coli, also showed a superior inhibition than reference drug and their mono counterparts. The increase in linker alkyl chain length and variation of substituents in indole, further predicted increased inhibition, with maximum value for compound 4o at 50 μg/ml. The in vitro calf thymus DNA (ct-DNA) binding ability of compounds 4c, 4f, 4i, 4l, 4 m, 4n, and 4o was evaluated via ultraviolet-visible and fluorescence spectroscopy techniques. A hyperchromic effect was observed with no apparent wavelength shift which predicted for the groove binding mode. A moderate binding constant for 4o, in fluorescence results, confirms groove binding. The molecular docking of 4o with ct-DNA (PDBID:1BNA) and SARS-CoV-2 M^pro (3CL protease, PDBID:6LU7) prove its efficacy as potential DNA binder and antiviral agent.

Comparative binding analysis of noscapine and piperine with tRNA: A structural perturbation and energetic study

In this study, we have exploring the binding mechanisms of the two anticancer alkaloid noscapine (NOS) and piperine (PIP) with tRNA using different spectroscopy and computational method. Absorbance and emission spectra revealed that both the drugs show strong binding with tRNA, where NOS intercalate between the base pairs of tRNA and PIP binds in the groove of tRNA. Competitive binding study and steady state anisotropy further confirms the intercalative mode of binding between NOS and tRNA and groove binding in PIP-tRNA complex. The observed thermodynamic parameters suggested that NOS-tRNA complex formation is endothermic and entropy driven, however it was exothermic, and enthalpy driven in case of PIP-tRNA complex. CD and time resolved fluorescence studies show the structural perturbations and conformational change in tRNA structure with NOS as well as PIP. Molecular docking studies are comparable with experimental results and further confirmed that the hydrophobic interactions involved in the NOS-tRNA binding, whereas hydrogen binding and van der Waals interactions play important role in the PIP-tRNA complex formation. This study can be useful to understand the potential binding and resultant tRNA damage by alkaloids and deigned new target specific anticancer drug.