Synthesis, Characterization, and DNA Binding Studies of a New Pt(II) Complex Containing the Drug Levetiracetam: Combining Experimental and Computational Methods

Study of anticancer effects of platinum levetiracetam and levetiracetam via cancer biomarkers genes expression on HepG2 cell line

BACKGROUND

High expression of some anticancer biomarkers such as telomerase and B cell lymphoma-2(Bcl-2), microRNA-21(miRNA-21), and low expression FAS ligand (FASLG) are reported in many cancers. Some anticancer drugs such as Levetiracetam(Lev) produce their effects via the change of expression of these biomarkers. The present study aimed to evaluate the anti-cancer effects of a new compound, Platinum Levetiracetam(Pt-Lev), gene expression of mentioned biomarkers on hepatocyte G2 (HepG2) cells compared to Lev.

METHODS AND RESULTS

In this study, Human Dermal fibroblast cells (HDF) were used as the negative control group (group A) HepG2 cells were divided into three groups: untreated cancer cells as positive group (group B), groups C and D were treated with, Lev and Pt-Lev, respectively. After evaluating lethal concentration 50% (LC50) for the examined drugs using the MTT test, biomarker gene expression was evaluated by real-time PCR. No Apoptotic cell was found in groups C or D before drug treatment, but it was present using different concentrations of the drugs. Results indicated that telomerase and miRNA-21 genes expression was significantly lower and FASLG was higher in group D compared with group C but there was no significant difference for Bcl-2 expression between these two groups.

CONCLUSIONS

For the first time, it was indicated that Pt-Lev has anticancer effects by inhibiting telomerase and Bcl-2 and miRNA-21 and increasing FASLG gene expression and its effects were more than Lev. It effectively exerted its anticancer effects by extending apoptosis on HepG2 cells.

Ruthenium(II)-diphosphine complexes containing acylthiourea ligands are effective against lung and breast cancers

We have synthesized and characterized three new ruthenium(II) diphosphine complexes containing an acylthiourea ligand, with the general formula [Ru(DPEPhos)(O,S)(bipy)]PF₆, where DPEPhos = bis(2-(diphenylphosphino)phenyl)ether, bipy = 2,2'-bipyridine, and O,S = N,N-dimethyl-N'-(benzoyl)thiourea (1), N,N-dimethyl-N'-(furoyl)thiourea (2), and N,N-dimethyl-N'-(thiophenyl)thiourea (3), by several physicochemical techniques. We evaluated the ruthenium complexes for their cytotoxicity against two human cancer cell lines, A549 (lung) and MDA-MB-231 (breast), and two corresponding lines of non-cancer cells, MRC-5 (lung) and MCF-10A (breast). All the complexes are cytotoxic against the cancer cell lines; the IC₅₀ values lie in the micromolar range (0.07-0.70 μM). Ruthenium complex 1 is more selective (7 times more active) toward lung cancer cells (A549) than toward non-cancer cells (MRC-5) and is 160 times more cytotoxic than cisplatin against A549 cells. Investigations of the mechanism of action of complex 1 in A549 cells demonstrated that it inhibits colony formation and promotes cell cycle arrest in the G1 phase and apoptotic cell death. DNA binding studies revealed that complexes 1-3 interact with the biomolecule via minor grooves. These complexes also interact with human serum albumin (HSA) and have affinity for site I by hydrophobic forces. Therefore, this new class of ruthenium complexes can act as cytotoxic agents, mainly for lung cancer treatment.

The in Vitro Antiplasmodial and Antiproliferative Activity of New Ferrocene-Based α-Aminocresols Targeting Hemozoin Inhibition and DNA Interaction

The conjugation of organometallic complexes to known bioactive organic frameworks is a proven strategy revered for devising new drug molecules with novel modes of action. This approach holds great promise for the generation of potent drug leads in the quest for therapeutic chemotypes with the potential to overcome the development of clinical resistance. Herein, we present the in vitro antiplasmodial and antiproliferative investigation of ferrocenyl α-aminocresol conjugates assembled by amalgamation of the organometallic ferrocene unit and an α-aminocresol scaffold possessing antimalarial activity. The compounds pursued in the study exhibited higher toxicity towards the chemosensitive (3D7) and -resistant (Dd2) strains of the Plasmodium falciparum parasite than to the human HCC70 triple-negative breast cancer cell line. Indication of cross-resistance was absent for the compounds evaluated against the multi-resistant Dd2 strain. Structure-activity analysis revealed that the phenolic hydroxy group and rotatable σ bond between the α-carbon and NH group of the α-amino-o-cresol skeleton are crucial for the biological activity of the compounds. Spectrophotometric techniques and in silico docking simulations performed on selected derivatives suggest that the compounds show a dual mode of action involving hemozoin inhibition and DNA interaction via minor-groove binding. Lastly, compound 9 a, identified as a possible lead, exhibited preferential binding for the plasmodial DNA isolated from 3D7 P. falciparum trophozoites over the mammalian calf thymus DNA, thereby substantiating the enhanced antiplasmodial activity of the compounds. The presented research demonstrates the strategy of incorporating organometallic complexes into known biologically active organic scaffolds as a viable avenue to fashion novel multimodal compounds with potential to counter the development drug resistance.

Intercalation of manganese-mefenamic acid complex into double stranded of calf thymus DNA

The interaction of the [Mn(mef)₂(phen)H₂O] complex in which mef is mefenamic acid drug and phen is 1,10 phenanthrolin ligand with calf thymus DNA (ct-DNA) was studied by using different spectroscopic methods, molecular docking and viscometery. The competitive fluorescence and UV-Vis absorption spectroscopy indicated that the complex interacted with ctDNA via intercalating binding mode with the binding constant of 1.16 × 10⁴ Lmol^-1. The thermodynamic studies showed that the reaction between the complex and ctDNA is exothermic. Furthermore, the complex induced changes in DNA viscosity. Circular dichroism spectroscopy (CD) was employed to measure the conformational changes of ctDNA in the presence of the complex and verified intercalation binding mode. The molecular modeling results illustrated that the complex interacted via intercalation by relative binding energy of -28.45 kJ mol^-1.

Synthesis, characterization and DNA binding studies of a new ibuprofen-platinum(II) complex

The study is focused on the synthesis of a novel complex of ibuprofen and Platinum(II). The formation of the product was characterized through analytical tools including Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, ultraviolet-visible spectroscopy, mass spectrometry as well as density functional theory. Using the continuous variation method, the stoichiometry of Pt(HIb)₂(Cl)₂ binding on DNA (ct-DNA) determines as a single class of binding. Based on the results of Stern-Volmer analysis on the fluorescence quenching data, the quenching mechanism was determined to be static in nature. The studies indicated that the complex could bind DNA molecules via groove binding for four major reasons. Initially, the complex-DNA binding constant determined based on spectrophotometric data were found to be comparable to those of groove-binding drugs. In addition, the competitive fluorimetric based on the applications of Hoechst 33258 proved the ability of Pt(HIb)₂(Cl)₂ to displace with Hoechst in its DNA-bounded form, reflecting the competition between Pt(HIb)₂(Cl)₂ and Hoechst for groove binding. Further, no considerable changes were observed in the intensity of the methylene blue (MB)-DNA system after adding the Pt(HIb)₂(Cl)₂ complex, reflecting the stability of MB molecules in the DNA helix and a non-intercalative bonds of Pt(HIb)₂(Cl)₂ interaction on DNA. Finally, minor changes in the viscosity of DNA in the presence of Pt(HIb)₂(Cl)₂, indicated that changes in the length of DNA in the presence of the complex are negligible, supporting the assumption of DNA groove-binding. Also induced CD spectral changes and docking simulations were in favor of the groove mechanism for the Pt(HIb)₂(Cl)₂-DNA binding.Communicated by Ramaswamy H. Sarma.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, DFT, and DNA-Binding Studies of (E)-2-(3-Hydroxy-4-Methoxybenzylidene)Hydrazinecarbothioamide

(E)-2-(3-Hydroxy-4-methoxybenzylidene)hydrazinecarbothioamide 3 was synthesized by reacting thiosemicarbazide with 2-hydorxy-3-methoxybenzaldehyde in dry ethanol. The structure was elucidated by spectroscopic (FT-IR, ¹H NMR, and ¹³C NMR) and single crystal X-ray diffraction techniques. A detailed analysis of the intermolecular interactions has been performed based on the Hirshfeld surfaces and their associated two-dimensional fingerprint plots. DFT, spectroscopic, and electrochemical DNA-binding analysis confirmed that the compound is reactive to bind with DNA. Viscometric studies suggested that compound 3 has a mixed mode of interaction and intercalated into the DNA base pairs predominantly along with the possibility of electrostatic interactions. Graphical Abstract.

Half Sandwich Rhodium(III) and Iridium(III) Complexes as Cytotoxic and Metallonuclease Agents

Half sandwich complexes of the type [(η5-C₅Me₅)M(L^1-3)Cl]Cl.2H₂O were synthesized using [{(η⁵-C₅Me₅)M(μ-Cl)Cl}₂], where M = Rh(III)/Ir(III) and L^1-3 = pyrimidine-based ligands. The complexes were characterized by spectral analysis. DNA interaction studies by absorption titration and hydrodynamic measurement and suggest intercalative mode of binding of complexes with CT-DNA. The molecular docking study also supports intercalation of the complexes between the stacks of nucleotide base pairs. The gel electrophoresis assay demonstrated the ability of the complexes to interact and cleave plasmid DNA. Minimum inhibitory concentrations (MIC) of the complexes were investigated by the microdilution broth method. The cytotoxic properties of the metal complexes were evaluated using brine shrimp lethality bioassay.

Hybrid pharmacophore approach for bio-relevant di-imines based homobimetallic complexes incorporating functionalized dicarboxylates as co-ligands: Synthesis, spectral and structural activity dependent biological insights (in-vitro DNA and HSA binding, antioxidant and cytotoxicity)

Synthesis of bio-efficient homobimetallic complexes, [Cu₂(L¹)₂(dipic)](NO₃)₂.3H₂O (1), [Zn₂(L¹)₂(dipic)](NO₃)₂.4H₂O (2), [Cu₂(L²)₂(oxa)](NO₃)₂.4H₂O (3) and [Zn₂(L²)₂(oxa)] (NO₃)₂.5H₂O (4) was carried out using Schiff bases [(N¹E,N²E)-N¹,N²-bis(5-chlorothiophen-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L¹] and [(N¹E,N²E)-N¹,N²-bis(5-chlorofuran-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L²] as main ligands and dicarboxylate moieties of 2,6-pyridine dicarboxylic acid (H₂-dipic) and oxalic acid (H₂-oxa) as co-ligands, respectively in order to apprehend their structure activity relationships on the basis of pharmacophore hybrid approach. The stoichiometry, geometry, thermal stability, morphology and crystallite size of the compounds were inferred by analytical, spectral (FT-IR, ¹H NMR and ¹³C NMR and Mass), thermal (TGA/DTA), SEM and XRD studies. In-vitro DNA and HSA binding profiles of complexes were analysed by different biophysical measurements. The absorption study divulged that the observed alterations in the physico-chemical properties of complexes upon binding with DNA connoted their intercalative binding mode while fluorescence quenching mechanism was quantified by using Stern Volmer constant (K_SV)_; 1.73×10⁴ (1), 1.47×10⁴ (2), 5.65×10³ (3) and 3.60×10³M^-1 (4) which discerned that hybrid pharmacophore active metal complexes (1 and 2) exhibited efficient quenching effect with Ct-DNA in comparison to complexes (3 and 4) due to greater planarity and extent of conjugation (π-π interactions). The intercalative binding mode of complexes is further supported by competitive displacement assay by using fluorogenic dyes (EtBr and Hoechst 33258). The results of HSA fluorescence study divulged static quenching of the complexes (1-4) with K_SV values of 7.24×10⁴ (1), 6.03×10⁴ (2), 5.06×10⁴ (3) and 2.85×10⁴ (4) while K_b values; 1.16×10⁵ (1), 2.01×10⁴ (2), 5.84×10³ (3) and 8.60×10² (4) suggested them potent avid binder of HSA. Additionally, comparative estimation of scavenging properties using DPPH, superoxide(O₂^.-), hydroxyl (OH^-) and ABTS method and in-vitro cytotoxicity against different cell lines (MCF-7, HeLa and Hep G2) brought out distinct biopotency of complexes due to diverse structural features and chelation effect.

Theoretical and Instrumental Studies of the Competitive Interaction Between Aromatic α-Aminobisphosphonates with DNA Using Binding Probes

Fluorescence spectroscopy, UV-visible absorption spectroscopy, circular dichroism (CD) spectroscopy, viscometry, cyclic voltammetry (CV), and differential pulse voltammetry (DPV) were applied to investigate the competitive interaction of DNA with two aromatic α-aminobisphosphonates and neutral red dye (NR, intercalator) and Hoechst (Ho, groove binder) as spectroscopic probes, in a Tris-hydrogen chloride buffer solution (pH 7.4). The principal component analysis (PCA) was applied to determine the number of chemical components presented in complexation equilibrium of DNA with the aromatic α-aminobisphosphonates (B₁ and B₂). The spectroscopic and voltammetric studies showed that the groove binding mode of interaction is predominant in the solution containing DNA and α-aminobisphosphonates. Furthermore, the results indicated that α-aminobisphosphonate with the lengthy N-alkyl chains had a stronger interaction. The PCA and theoretical quantum mechanical and molecular mechanic methods were also utilized to determine the structure of DNA with the two α-aminobisphosphonates (B₁ and B₂).

Studying non-covalent drug-DNA interactions

Drug-DNA interactions have been extensively studied in the recent past. Various techniques have been employed to decipher these interactions. DNA is a major target for a wide range of drugs that may specifically or non-specifically interact with DNA and affect its functions. Interaction between small molecules and DNA are of two types, covalent interactions and non-covalent interactions. Three major modes of non-covalent interactions are electrostatic interactions, groove binding and intercalative binding. This review primarily focuses on discussing various techniques used to study non-covalent interactions that occur between drugs and DNA. Additionally, we report several techniques that may be employed to analyse the binding mode of a drug with DNA. These techniques provide data that are reliable and simple to interpret.

A structural and biological study on the new 3,5-diacetyl-1,2,4-triazol bis(p-chlorophenylthiosemicarbazone) ligand and its bimetallic complexes

Preparation and characterization of the new ligand 3,5-diacetyl-1,2,4-triazol bis(⁴N-p-chlorophenylthiosemicarbazone), H₅L¹, and its bimetallic complexes [Pd(μ-H₃L¹)]₂ and [Pt(μ-H₃L¹)]₂, are described.

Mechanistic and conformational studies on the interaction of a platinum(II) complex containing an antiepileptic drug, levetiracetam, with bovine serum albumin by optical spectroscopic techniques in aqueous solution

Fluorescence spectroscopy in combination with circular dichroism (CD) and ultraviolet-visible (UV-vis) absorption spectroscopy were employed to investigate the binding of a new platinum(II) complex containing an antiepileptic drug "Levetiracetam" to bovine serum albumin (BSA) under the physiological conditions. In the mechanism discussion, it was proved that the fluorescence quenching of BSA by Pt(II) complex is a result of the formation of Pt(II) complex-BSA complex. The thermodynamic parameters ΔG, ΔH, and ΔS at different temperatures (283, 298, and 310 K) were calculated, and the negative value for ΔH and ΔS indicate that the hydrogen bonds and van der Waals interactions play major roles in Pt(II) complex-BSA association. Binding studies concerning the number of binding sites (n~1) and apparent binding constant K b were performed by fluorescence quenching method. The site marker competitive experiments indicated that the binding of Pt(II) complex to BSA primarily took place in site II. Based on the Förster's theory, the average binding distance between Pt(II) complex and BSA was obtained (r = 5.29 nm). Furthermore, UV-vis, CD, and synchronous fluorescence spectrum were used to investigate the structural change of BSA molecules with addition of Pt(II) complex. These results indicate that the binding of Pt(II) complex to BSA causes apparent change in the secondary structure of BSA and do affect the microenvironment around the tryptophan residue.