Exploring binding affinity of oxaliplatin and carboplatin, to nucleoprotein structure of chromatin: Spectroscopic study and histone proteins as a target

Revisiting the Anti-Cancer Toxicity of Clinically Approved Platinating Derivatives

Cisplatin (CDDP), carboplatin (CP), and oxaliplatin (OXP) are three platinating agents clinically approved worldwide for use against a variety of cancers. They are canonically known as DNA damage inducers; however, that is only one of their mechanisms of cytotoxicity. CDDP mediates its effects through DNA damage-induced transcription inhibition and apoptotic signalling. In addition, CDDP targets the endoplasmic reticulum (ER) to induce ER stress, the mitochondria via mitochondrial DNA damage leading to ROS production, and the plasma membrane and cytoskeletal components. CP acts in a similar fashion to CDDP by inducing DNA damage, mitochondrial damage, and ER stress. Additionally, CP is also able to upregulate micro-RNA activity, enhancing intrinsic apoptosis. OXP, on the other hand, at first induces damage to all the same targets as CDDP and CP, yet it is also capable of inducing immunogenic cell death via ER stress and can decrease ribosome biogenesis through its nucleolar effects. In this comprehensive review, we provide detailed mechanisms of action for the three platinating agents, going beyond their nuclear effects to include their cytoplasmic impact within cancer cells. In addition, we cover their current clinical use and limitations, including side effects and mechanisms of resistance.

Coumarin 6H-fused fluorescent probe for highly sensitive detection of coralyne using oligonucleotide-modified silver nanoparticles

In this study, a novel, rapid, and sensitive fluorescence sensing platform was developed for the detection of coralyne (COR) by the conjugation of coumarin 6H (C6H) fluorescent dye with oligonucleotide-modified silver nanoparticles [(dT)₃₂-AgNPs]. In the presence of COR, a remarkable and rapid decrease in the fluorescence signal of the probe with a quenching efficiency of around 62% was observed. The quenching response of the system towards COR was possibly due to the displacement of thymidine-rich deoxyoligonucleotides by COR on the surface of AgNPs. The complementary experiments with an adenine-rich single strand as well as with two different secondary structures (i.e., duplex and triplex) revealed a favorable sequence specificity of the sensing platform. The influence of key parameters including the incubation time and temperature was evaluated and optimized to achieve the highest performance. The linear range of 10-183 nM with a correlation coefficient of R = 0.9982 and a limit of detection of 5.24 nM were obtained under the optimized conditions. The selectivity of the proposed probe towards COR was revealed by the evaluation of its response to other small molecules that have molecular structures similar to COR. Finally, the successful applicability of the system was shown with the obtained average recoveries in the range of 87.28-104.52% in human urine samples.

Analytical methods for the quantification of cisplatin, carboplatin, and oxaliplatin in various matrices over the last two decades

Background:

Platinum derivatives including cisplatin and its later generations carboplatin, and oxaliplatin remain the most largely used drugs in the therapy of malignant diseases. They exert notable anticancer activity towards numerous types of solid tumors such as gastric, colorectal, bladder, ovary, and several others. The chemotherapeutic activity of these compounds, however, is associated with many unwanted side effects and drug resistance problems limiting their application and effectiveness. Proper dosage is still an inherent problem, as these drugs are usually prescribed in small doses.

Objective:

Several analytical methods have been reported for the accurate quantification of cisplatin, carboplatin, and oxaliplatin and their metabolites either alone or in combination with other chemotherapeutic drugs, in different matrices such as pharmaceutical formulations, biological fluids, cancer cells, and environmental samples. The main goal of this review is to systematically study the analytical methods already used for the analysis of cisplatin, carboplatin, and oxaliplatin in various matrices during the last two decades.

Results and Conclusion:

In the literature, reviews showed that numerous analytical methods such as electroanalytical, UV-visible spectrophotometry, chromatographic, fluorescence, atomic absorption spectrophotometry, and other spectroscopic methods combined with mass spectrometry were used for the determination of these compounds in various matrices.

Synthesis, characterization and biological application of 5-quinoline 1,3,5-trisubstituted pyrazole based platinum(ii) complexes

Square planar mononuclear platinum(ii) complexes were synthesized in the presence of neutral bidentate heterocyclic (5-quinoline 1,3,5-tri-substituted pyrazole scaffold) ligands and K₂PtCl₄ salt. The synthesized compounds were characterized by micro-elemental analysis, FT-IR, UV-vis, ¹H NMR, ¹³C NMR, TGA, mass spectrometry and molar conductivity. Their biological activities were investigated by in vitro brine shrimp lethality bioassay, in vitro antimicrobial study against five different pathogens, in vivo cellular level cytotoxicity against Schizosaccharomyces pombe cells, and in vitro anti-proliferation assay. The binding constant K_sv, K_b, K_a values of the complexes were determined by DNA interaction studies. The gel electrophoresis assay was carried out to examine the effect of the complexes on the DNA nuclease of pUC19 plasmid DNA. The docking energies of the ligands (L¹-L⁵ ) and complexes (I-V) were observed in the range of -265.14 to -284.33 kJ mol^-1. The synthesized Pt(ii) complexes (I-V) were screened against the MCF-7 (human breast adenocarcinoma) and HCT-116 (human colon carcinoma) cancer cell lines.

Cooperativity effect involving drug-DNA/RNA intermolecular interaction: A B3LYP-D3 and MP2 theoretical investigation on ketoprofen⋯cytosine⋯H2O system

In order to examine the origin of the drug action and design new DNA/RNA-targeted drugs, the cooperativity effect involving drug-DNA/RNA intermolecular interaction in ketoprofen⋯cytosine⋯H₂O ternary system were investigated by the B3LYP, B3LYP-D3, and MP2 methods with the 6-311++G(2d,p) basis set. The thermodynamic cooperativity was also evaluated at 310.15 K. The N-H⋯O, O-H⋯O, O-H⋯N, C-H⋯N, and C-H⋯O H bonds coexist in ternary complexes. The intermolecular interactions obtained by B3LYP-D3 are close to those calculated by MP2. The steric effects and van der Waals interactions have little influence on the cooperativity effects. The anti-cooperativity effect in ket⋯cyt⋯H₂O is far more notable than the cooperativity effect, and the stability of the cyclic structure with anti-cooperativity effect is higher than that of the linear structure with cooperativity effect, as is confirmed by the AIM (atoms in molecules) and RDG (reduced density gradient) analysis. Thus, it can be inferred that, in the presence of H₂O, the anti-cooperativity effect plays a dominant role in the drug-DNA/RNA interaction, and the nature of the hydration in the binding of drugs to DNA/RNA bases is the H-bonding anti-cooperativity effect. Furthermore, the drug always links simultaneously with DNA/RNA base and H₂O, and only in this way can the biological activity of drugs play a role. In most cases, the enthalpy change is the major factor driving the cooperativity, as is different from most of biomacromolecule complexes.

Spectroscopic analysis of the interaction of valproic acid with histone H1 in solution and in chromatin structure

Histone H1 is a basic chromosomal protein which links adjacent nucleosomes in chromatin structure. Valproic acid (VPA), a histone deacetylase inhibitor, is widely used as an antiepileptic drug for the treatment of various cancers. In this study the interaction between VPA and histone H1, chromatin and DNA in solution was investigated employing spectroscopic techniques. The results showed that VPA binds cooperatively to histone H1 and chromatin but exhibited very weak interaction with DNA. The association constants demonstrated higher affinity of VPA to H1 compared to chromatin. Fluorescence emission intensity was reduced by quenching value (Ksv) of 2.3 and 0.83 for H1 and chromatin respectively. VPA also altered ellipticity of chromatin and H1 at 220nm indicating increase in α-helix content of H1/chromatin proteins suggesting that the protein moiety of chromatin is the site of VPA action. Moreover, thermal denaturation revealed hypochromicity in chromatin Tm profiles with small shift in Tm values without any significant change in DNA pattern. It is concluded that VPA, apart from histone deacetylase inhibition activity, binds strongly to histone H1 in chromatin structure, demonstrating that VPA may also exert its anticancer activity by influencing chromatin proteins which opens new insight into the mechanism of VPA action.

Investigation of the interaction between berberine and nucleosomes in solution: Spectroscopic and equilibrium dialysis approach

Berberine is a natural plant alkaloid with high pharmacological potential. Although its interaction with free DNA has been the subject of several reports, to date there is no work concerning the effect of berberine on nucleoprotein structure of DNA, the nucleosomes. The present study focuses on the binding affinity of berberine to nucleosomes and histone H1 employing various spectroscopic techniques, fluorescence, circular dichroism, thermal denaturation as well as equilibrium dialysis. The results showed that the binding of berberine to nucleosomes is positive cooperative with Ka=5.57×10³M^-1. Berberine quenched with the chromophores of protein moiety of nucleosomes and reduced fluorescence emission intensity at 335nm with Ksv value of 0.135. Binding of berberine to nucleosomes decreased the absorbance at 210 and 260nm, produced hypochromicity in thermal denaturation profiles and its affinity to nucleoprotein structure of nucleosomes was much higher than to free DNA. Berberine also exhibited high affinity to histone H1 in solution and the binding was positive cooperative with. Ka=3.61×10³M^-1. Moreover berberine decreased fluorescence emission intensity of H1 by quenching with tyrosine residue in its globular core domain. The circular dichroism profiles demonstrated that the binding of drug induced secondary structural changes in both DNA stacking and histone H1. It is concluded that berberine is genotoxic drug, interacts with nucleosomes and in this process histone H1 is involved to exert its anticancer activity.