Study binding of Al-curcumin complex to ds-DNA, monitoring by multispectroscopic and voltammetric techniques

Enhanced anticancer efficacy of aluminum-curcumin complex compared to curcumin in colorectal cancer cells

The evaluation of anti cancer treatments involves various methods, one of which is the use of biomarkers for therapeutic strategy. This study aimed to compare the anticancer effects of Aluminum curcumin (ACC) with curcumin (CC) in human CRC cells. In this study, the cells were classified into four groups: Group A as control cells, Group B included untreated CRC cells, and Groups C and D comprised cancer cells treated with CC and ACC, respectively. After determining the IC50 values for the drugs using the MTT assay, gene expression was analyzed through RT-PCR. The results of the study showed in group D, there was a more significant decrease in the expression of anti-apoptotic genes, including telomerase (0.67 ± 0.438), Bcl-2 (0.34 ± 0.077), and miRNA-21 (0.51 ± 0.056), compared to group C, where the expression levels were higher for the same genes: telomerase (1.5 ± 0.134), Bcl-2 (1.31 ± 0.014), and miRNA-21 (1.32 ± 0.085). Additionally, group D exhibited a more significant increase in the expression of pro-apoptotic genes, including BAX (3.15 ± 0.813), miRNA-122 (2.61 ± 0.056), and FASLG (1.89 ± 0.014), compared to group C, where the gene expression levels were lower: BAX (0.86 ± 0.106), miRNA-122 (1.01 ± 0.276), and FASLG (0.98 ± 0.099). Significant differences were observed between the majority of groups (P < 0.05). Furthermore, a higher number of apoptotic regions were observed in group D compared to group C. ACC as a new compound demonstrates enhanced anti-cancer potential compared to curcumin alone, due to the aluminum component's ability to stimulate the immune system. This synergy offers a promising therapeutic strategy for cancer treatment, with greater efficacy in targeting and eliminating cancer cells.

Structural investigation of erdafitinib, an anticancer drug, with ctDNA: A spectroscopic and computational study

The interaction of drugs with DNA is crucial for understanding their mechanism of action, particularly in the context of gene expression regulation. Erdafitinib (EDB), a pan-FGFR (fibroblast growth factor receptor) inhibitor approved by the FDA, is a potent anticancer agent used primarily in the treatment of urothelial carcinoma. In this study, the binding interaction between EDB and calf thymus DNA (ctDNA) was assessed using molecular docking, UV-absorption spectroscopy, fluorescence spectroscopy, and circular dichroism (CD) spectroscopy. The absorption spectra indicated a hypochromic effect when EDB was combined with ctDNA. The binding constant (Ka) of EDB-ctDNA complex was calculated as 7.84 × 103 M-1, corresponds to a free energy change (ΔG) value of approximately -5.06 kcal/mol, indicating a moderate binding affinity. Fluorometric analysis revealed a static binding mechanism in the ground state, with a bimolecular enhancement constant (KB) of 7.56 × 1011 M-1. Displacement experiments demonstrated that EDB preferentially binds to the minor groove of ctDNA, with a Ksv value of 5.14 × 104 M-1. Further, KI quenching and CD spectroscopy confirmed the minor groove binding mode, which was associated with a decrease in the Tm from 68.28 °C to 65.84 °C, reflecting a destabilizing effect on DNA helix. Molecular docking supported these findings, showing that EDB exhibits a strong affinity for the minor groove of ctDNA and hydrogen bonding and Vander Waal interactions are the major forces involved in the binding. These results suggest that EDB primarily binds to the minor groove of ctDNA, which may play a role in its anticancer activity.

Anticancer behaviour of 2,2'-(pyridin-2-ylmethylene)bis(5,5-dimethylcyclohexane-1,3-dione)-based palladium(II) complex and its DNA, BSA binding propensity and DFT study

Herein, we report the synthesis and biological evaluation of [Pd(L)(OH2)Cl] complex (where L = 2,2'-(pyridin-2-ylmethylene)bis(5,5-dimethylcyclohexane-1,3-dione) as a novel promising anticancer candidate. The complex was characterized by single-crystal X-ray diffraction and other various spectroscopic techniques. Besides, the optimized structure was determined through DFT calculations revealing that the coordination geometry of [Pd(L)(OH2)Cl] complex is square planar. The binding propensity of [Pd(L)(OH2)Cl] complex with DNA and BSA was assessed by the spectrophotometric method. The antimicrobial profile of the ligand and its [Pd(L)(OH2)Cl] complex was screened against clinically important bacterial strains. [Pd(L)(OH2)Cl] complex showed promising activity against these microorganisms. Pd(L)(OH2)Cl] complex exhibited a potent antiproliferative potential compared to its ligand against different human cancer cells (A549, HCT116, MDA-MB-231, and HepG2) with less toxic effect against normal cells (WI-38). Additionally, [Pd(L)(OH2)Cl] complex exerted its anticancer effects against the most responsive cells (HCT116 cells; IC50 = 11 ± 1 μM) through suppressing their colony-forming capabilities and triggering apoptosis and cell cycle arrest at S phase. Quantitative PCR analysis revealed a remarkable upregulation of the mRNA expression level of p53 and caspase-3 by 4.8- and 5.9-fold, respectively, relative to control. Remarkable binding properties and non-covalent interactions between L and its [Pd(L)(OH2)Cl] complex with the binding sites of different receptors including CDK2, MurE ligase, DNA, and BSA were established using molecular docking. Based on our results, [Pd(L)(OH2)Cl] complex is an intriguing candidate for future investigations as a potential anticancer drug for the treatment of colon cancer.

Exploring the interaction of tepotinib with calf thymus DNA using molecular dynamics simulation and multispectroscopic techniques

In recent times, there has been a surge in the discovery of drugs that directly interact with DNA, influencing gene expression. As a result, understanding how biomolecules interact with DNA has become a major area of research. One such drug is Tepotinib (TPT), an FDA-approved anti-cancer medication known as a MET tyrosine kinase inhibitor, used in chemotherapy for metastatic non-small cell lung cancer (NSCLC) with MET exon 14 skipping alterations. In our study, we adopted both biophysical and in-silico methods to investigate the binding relationship of TPT and ctDNA. The absorption spectra of ctDNA exhibited a hypochromic effect when titrated with TPT and the binding constant of TPT-ctDNA complex was calculated, Ka = 9.91 × 104 M-1. By computing bimolecular enhancement constant (KB) and thermodynamic enhancement constant (KD) in fluorometric investigations, it was found that the fluorescence enhancement is a result of a static process involving the ctDNA-TPT complex formation in the ground state, as opposed to a dynamic process. The displacement assay results further supported this finding, showing that TPT exhibits a binding preference for minor groove of ct-DNA and was also demonstrated by KI quenching and CD spectroscopy. The molecular docking and molecular dynamic simulations validated TPT's groove binding nature and binding pattern with ctDNA, respectively. Thus, the results of our present investigation offer valuable insights into the interaction between TPT and ctDNA. It is evident that TPT, as an anti-cancer medication, binds to the minor groove of ctDNA.

Curcumin Electrochemistry-Antioxidant Activity Assessment, Voltammetric Behavior and Quantitative Determination, Applications as Electrode Modifier

Curcumin (CU) is a polyphenolic compound extracted from turmeric, a well-known dietary spice. Since it has been shown that CU exerts beneficial effects on human health, interest has increased in its use but also in its analysis in different matrices. CU has an antioxidant character and is electroactive due to the presence of phenolic groups in its molecule. This paper reviews the data reported in the literature regarding the use of electrochemical techniques for the assessment of CU antioxidant activity and the investigation of the voltammetric behavior at different electrodes of free or loaded CU on various carriers. The performance characteristics and the analytical applications of the electrochemical methods developed for CU analysis are compared and critically discussed. Examples of voltammetric investigations of CU interaction with different metallic ions or of CU or CU complexes with DNA as well as the CU applications as electrode modifiers for the enhanced detection of various chemical species are also shown.

Intercalative binding of two new five-coordinated anticancer Pt(II) complexes to DNA: experimental and computational approaches

Binding interaction of two organoplatinum complexes, [Pt(C^N)Cl(dppa)], 1, and [Pt(C^N)Cl(dppm)], 2, (C^N = N(1), C(2')-chelated, deprotonated 2-phenylpyridine, dppa = bis(diphenylphosphino)amine, dppm = bis(diphenylphosphino)methane), as anti-tumor agents, with calf thymus DNA (CT-DNA) under pseudo-physiological conditions has been investigated using various biophysical techniques viz., UV-Vis and fluorescence spectroscopies, viscosity measurements, and thermal denaturation experiments. A hypochromic shift in UV-Vis absorption titration, fluorescence enhancement of Pt(II) complexes in the presence of CT-DNA, fluorescence quenching in competitive ethidium bromide displacement assay, and an uptrend in the viscosity (η) and melting temperature (Tm) indicated the existence of a tight intercalative interaction of Pt(II) complexes with CT-DNA. The fluorescence quenching of CT-DNA was a combined quenching of static and dynamic with Stern-Volmer quenching constants of 7.520 × 103 M-1 for complex 1 and 5.183 × 103 M-1 for complex 2, at low concentrations of Pt(II) complexes. Besides the experimental studies, computational studies were done. Molecular modeling studies confirmed the intercalation of the studied complexes by the phenyl groups of dppa and dppm, leading to π-π interactions but with a certain steric hindrance because of the size and shape of the considered complexes. The combination of experimental and computational data showed that reported Pt(II) complexes are promising structures and could be developed for cancer therapeutic applications.Communicated by Ramaswamy H. Sarma.

Multi-spectroscopic and molecular simulation methods of analysis to explore the mode of binding of Mebendazole drug with calf-thymus DNA

UV-vis, fluorescence, circular dichroism (CD) and ¹H NMR spectroscopic techniques have been employed to explore the mode of binding of Mebendazole (MBZ) drug with calf thymus DNA (CT-DNA). UV-vis and fluorescence spectral studies suggested a complex formation between the drug and nucleic acid. The fluorescence of MBZ was found to enhance upon binding with CT-DNA through a ground state complex formation with K_b in the order of 10⁴ M^-1. The thermodynamic aspects indicated that the complex formation is a spontaneous process and an entropy-driven one. ΔH⁰ > 0 and ΔS⁰ > 0 revealed that hydrophobic interaction plays a dominant role in the stabilization of the complex. Competitive dye displacement assays with ethidium bromide (EB) and Hoechst 33258 dyes and viscosity measurements pointed out that MBZ binds with CT-DNA via intercalation mode, which is confirmed by CD and ¹H NMR spectral studies as well as denaturation studies. Molecular docking analysis could not match well with the experimental results. However, molecular simulation studies and the resultant free energy surface (FES) analysis clearly showed that the benzimidazole ring of MBZ intercalated between the base pairs of the nucleic acid, which is in excellent agreement with the results of the various biophysical experiments.

DNA Binding and Cleavage, Stopped-Flow Kinetic, Mechanistic, and Molecular Docking Studies of Cationic Ruthenium(II) Nitrosyl Complexes Containing “NS4” Core

This work aimed to evaluate in vitro DNA binding mechanistically of cationic nitrosyl ruthenium complex [RuNOTSP]+ and its ligand (TSPH2) in detail, correlate the findings with cleavage activity, and draw conclusions about the impact of the metal center. Theoretical studies were performed for [RuNOTSP]+, TSPH2, and its anion TSP−2 using DFT/B3LYP theory to calculate optimized energy, binding energy, and chemical reactivity. Since nearly all medications function by attaching to a particular protein or DNA, the in vitro calf thymus DNA (ctDNA) binding studies of [RuNOTSP]+ and TSPH2 with ctDNA were examined mechanistically using a variety of biophysical techniques. Fluorescence experiments showed that both compounds effectively bind to ctDNA through intercalative/electrostatic interactions via the DNA helix’s phosphate backbone. The intrinsic binding constants (Kb), (2.4 ± 0.2) × 105 M−1 ([RuNOTSP]+) and (1.9 ± 0.3) × 105 M−1 (TSPH2), as well as the enhancement dynamic constants (KD), (3.3 ± 0.3) × 104 M−1 ([RuNOTSP]+) and (2.6 ± 0.2) × 104 M−1 (TSPH2), reveal that [RuNOTSP]+ has a greater binding propensity for DNA compared to TSPH2. Stopped-flow investigations showed that both [RuNOTSP]+ and TSPH2 bind through two reversible steps: a fast second-order binding, followed by a slow first-order isomerization reaction via a static quenching mechanism. For the first and second steps of [RuNOTSP]+ and TSPH2, the detailed binding parameters were established. The total binding constants for [RuNOTSP]+ (Ka = 43.7 M−1, Kd = 2.3 × 10−2 M−1, ΔG0 = −36.6 kJ mol−1) and TSPH2 (Ka = 15.1 M−1, Kd = 66 × 10−2 M, ΔG0 = −19 kJ mol−1) revealed that the relative reactivity is approximately ([RuNOTSP]+)/(TSPH2) = 3/1. The significantly negative ΔG0 values are consistent with a spontaneous binding reaction to both [RuNOTSP]+ and TSPH2, with the former being very favorable. The findings showed that the Ru(II) center had an effect on the reaction rate but not on the mechanism and that the cationic [RuNOTSP]+ was a more highly effective DNA binder than the ligand TSPH2 via strong electrostatic interaction with the phosphate end of DNA. Because of its higher DNA binding affinity, cationic [RuNOTSP]+ demonstrated higher cleavage efficiency towards the minor groove of pBR322 DNA via the hydrolytic pathway than TSPH2, revealing the synergy effect of TSPH2 in the form of the complex. Furthermore, the mode of interaction of both compounds with ctDNA has also been supported by molecular docking.

A Review of the Role of Curcumin in Metal Induced Toxicity

Metal toxicity poses a potential global threat to the environment and living beings. Their numerous agricultural, medical, industrial, domestic, and technological applications result in widespread distribution in the environment which raises concern on the potential effects of metals in terms of health hazards and environmental pollution. Chelation therapy has been the preferred medical treatment for metal poisoning. The chelating agent bounds metal ions to form complex cyclic structures known as 'chelates' to intensify their excretion from the body. The main disadvantage of synthetic chelators is that the chelation process removes vital nutrients along with toxic metals. Natural compounds are widely available, economical, and have minimal adverse effects compared to classical chelators. Herbal preparations can bind to the metal, reduce its absorption in the intestines, and facilitate excretion from the body. Curcumin, a bioactive substance in turmeric, is widely used as a dietary supplement. Most studies have shown that curcumin protects against metal-induced lipid peroxidation and mitigates adverse effects on the antioxidant system. This review article provides an analysis to show that curcumin imparts promising metal toxicity-ameliorative effects that are related to its intrinsic antioxidant activity.

Biological activity of bis-(morpholineacetato)palladium(II) complex: Preparation, structural elucidation, cytotoxicity, DNA-/serum albumin-interaction, density functional theory, in-silico prediction and molecular modeling

In an effort to discover a novel potential bioactive compound, a mono-nuclear Pd(II) complex with an amino acid derivative as ligand was synthesized and characterized through experimental and computational methodologies. A square-planar configuration was suggested for palladium(II) complex utilizing density functional theory. MEP map and Mulliken atomic charge were detected electrophilic and nucleophilic regions of the compound for reactions. The lipophilicity and cytotoxic activity of the complex was more effective than cisplatin. Also, OSIRIS DataWarrior revealed proper oral bioavailability and good drug-likeness for the compound. In-vitro binding behavior of the Pd(II) complex with DNA and serum albumin (BSA) were fully determined via variety of procedures including fluorescence, UV-Vis, CD, viscosity, gel electrophoresis experiments and molecular simulation. The negative signs of ΔH° and ΔS° for Pd(II) complex-CT-DNA/-BSA systems indicated the existence of hydrogen bonding/van der Waals interactions for both binding systems. Additionally, docking simulation illustrated the interaction of Pd(II) complex with the minor groove of DNA and the hydrophobic cavity of the BSA (drug binding site I).

Effect of environmental factors on the aggregation behavior of astaxanthin in water

Molecular aggregation is a common phenomenon widely found in natural organisms, which is crucial for some specific functions of biological systems. To study the aggregating behavior of hydrophobic carotenoids in water, astaxanthin was employed and dispersed under different surroundings to induce aggregation. The results showed that astaxanthin tended to form J- or H-type aggregates when the water content was higher than 60%. Both hydrochloric acid (HCl) and sodium hydroxide (NaOH) were beneficial for the formation of astaxanthin J-aggregates, but they were not good for inducing H-aggregates. Small-molecule electrolytes, like sodium salts, mostly played an enormous hindrance role to the formation of astaxanthin H- and J-aggregates, except for sodium chloride (NaCl) which helped astaxanthin to form J-aggregates. Both sodium periodate (NaIO₄) and sodium acetate (CH₃COONa) could prevent the formation of astaxanthin H- and J-aggregates, but sodium chloride (NaCl) could only hinder the formation of H-aggregates. As for polyelectrolytes chitosan and DNA, the difference of chain structure led to different aggregation effects. The soft single chain of chitosan tended to induce J-aggregates formation, while double-stranded DNA preferred to guide the formation of H-aggregates. By choosing and integrating the advantageous environmental factors that facilitate each type of astaxanthin aggregates, J- and H-type astaxanthin aggregates were stably loaded in DNA/CS nanoparticles with distinct particle sizes. Controlled preparation of either H- or J-type aggregates is of great significance for further studies concerning the structure-activity relationship of carotenoid aggregates.

Synthesis, Characterization, Biological Evaluation and DNA Interaction Studies of 4-Aminophenol Derivatives: Theoretical and Experimental Approach

In the present study, five 4-aminophenol derivatives (4-chloro-2-(((4-hydroxyphenyl)imino)methyl)phenol(S-1), 4-((4-(dimethylamino)benzylidene)amino)phenol(S-2), 4-((3-nitrobenzylidene)amino)phenol(S-3), 4-((thiophen-2-ylmethylene)amino)phenol(S-4) and 4-(((E)-3-phenylallylidene)amino)phenol(S-5)) were synthesized and characterized by FT-IR, ¹H-NMR, ¹³C-NMR and elemental analyses. The synthesized compounds were tested for their antimicrobial (Gram-positive and Gram-negative bacteria and Saccharomyces cervesea fungus) and antidiabetic (α-amylase and α-glucosidase inhibitory) activities. All the compounds showed broad-spectrum activities against the Staphylococcus aureus (ATCC 6538), Micrococcus luteus (ATCC 4698), Staphylococcus epidermidis (ATCC 12228), Bacillus subtilis sub. sp spizizenii (ATCC 6633), Bordetella bronchiseptica (ATCC 4617) and Saccharomyces cerevisiae (ATCC 9763) strains. The newly synthesized compounds showed a significant inhibition of amylase (93.2%) and glucosidase (73.7%) in a concentration-dependent manner. Interaction studies of Human DNA with the synthesized Schiff bases were also performed. The spectral bands of S-1, S-2, S-3 and S-5 all showed hyperchromism, whereas the spectral band of S-4 showed a hypochromic effect. Moreover, the spectral bands of the S-2, S-3 and S-4 compounds were also found to exhibit a bathochromic shift (red shift). The present studies delineate broad-spectrum antimicrobial and antidiabetic activities of the synthesized compounds. Additionally, DNA interaction studies highlight the potential of synthetic compounds as anticancer agents. The DNA interaction studies, as well as the antidiabetic activities articulated by the molecular docking methods, showed the promising aspects of synthetic compounds.

What Can Electrochemical Methods Offer in Determining DNA-Drug Interactions?

The interactions of compounds with DNA have been studied since the recognition of the role of nucleic acid in organisms. The design of molecules which specifically interact with DNA sequences allows for the control of the gene expression. Determining the type and strength of such interaction is an indispensable element of pharmaceutical studies. Cognition of the therapeutic action mechanisms is particularly important for designing new drugs. Owing to their sensitivity, simplicity, and low costs, electrochemical methods are increasingly used for this type of research. Compared to other techniques, they require a small number of samples and are characterized by a high reliability. These methods can provide information about the type of interaction and the binding strength, as well as the damage caused by biologically active molecules targeting the cellular DNA. This review paper summarizes the various electrochemical approaches used for the study of the interactions between pharmaceuticals and DNA. The main focus is on the papers from the last decade, with particular attention on the voltammetric techniques. The most preferred experimental approaches, the electrode materials and the new methods of modification are presented. The data on the detection ranges, the binding modes and the binding constant values of pharmaceuticals are summarized. Both the importance of the presented research and the importance of future prospects are discussed.

Unraveling the binding mechanism of an Oxovanadium(IV) - Curcumin complex on albumin, DNA and DNA gyrase by in vitro and in silico studies and evaluation of its hemocompatibility

An oxovanadium(IV) - curcumin based complex, viz. [VO(cur)(2,2´-bipy)(H₂O)] where cur is curcumin and bipy is bipyridine, previously synthesized, has been studied for interaction with albumin and DNA. Fluorescence emission spectroscopy was used to evaluate the interaction of the complex with bovine serum albumin (BSA) and the BSA-binding constant (K_b) was calculated to be 2.56 x 10⁵ M^-1, whereas a single great-affinity binding site was revealed. Moreover, the hemocompatibility test demonstrated that the complex presented low hemolytic fraction (mostly below 1%), in all concentrations tested (0-250 μΜ of complex, 5% DMSO) assuring a safe application in interaction with blood. The binding of the complex to DNA was also investigated using absorption, fluorescence, and viscometry methods indicating a binding through a minor groove mode. From competitive studies with ethidium bromide the apparent binding constant value to DNA was estimated to be 4.82 x 10⁶ M^-1. Stern-Volmer quenching phenomenon gave a Κ_SV constant [1.92 (± 0.05) x 10⁴ M^-1] and k_q constant [8.33 (± 0.2) x 10¹¹ M^-1s^-1]. Molecular docking simulations on the crystal structure of BSA, calf thymus DNA, and DNA gyrase, as well as pharmacophore analysis for BSA target, were also employed to study in silico the ability of [VO(cur)(2,2´-bipy)(H₂O)] to bind to these target bio-macromolecules and explain the observed in vitro activity.

Insight into the binding mechanism of macrolide antibiotic; erythromycin to calf thymus DNA by multispectroscopic and computational approaches

In the present study, the interactions between Erythromycin drug and calf thymus deoxyribonucleic acid (ct-DNA) were explored by multi spectroscopic techniques (UV-Visible, fluorescence, circular dichroism spectroscopies), viscosity, molecular docking simulation, and atomic force microscopy (AFM). In addition, the values of binding constant were calculated by the UV-Visible and fluorescence spectroscopy. Competitive fluorescence study with methylene blue (MB), acridine orange (AO), and Hoechst 33258 were indicated that the Erythromycin drug could displace the DNA-bound Hoechst, which displays the strong competition of Erythromycin with Hoechst to interact with the groove binding site of DNA. In addition, the observed complexes in AFM analysis comprise the chains of ct-DNA and Erythromycin with an average size of 314.05 nm. The results of thermodynamic parameter calculations (ΔS° = -332.103 ± 14 J mol^-1 K^-1 and ΔH° = -115.839 ± 0.02 kJ mol^-1) approved the critical role of van der Waals forces and hydrogen bonds in the complexation of Erythromycin-DNA. Fluorescence spectroscopy results demonstrate the existence of a static enhancement mechanism in the interaction of Erythromycin-DNA. According to the obtained results, Erythromycin drug interacts with the major groove of ct-DNA. These consequences were further supported by the molecular docking study, and it could be determined that DNA-Erythromycin docked model was in a rough correlation with our experimental results.Communicated by Ramaswamy H. Sarma.

Investigation of biological activity of nickel (II) complex with naproxen and 1,10-phenanthroline ligands

After the accidental discovery of cis-platinum, extensive attempts have centralized on the rational design of metallic compounds for cancer treatment. Here a solvent-dependent complex of nickel (II) with 1,10-phenanthroline and naproxen, [Ni(1,10-phenanthroline)(naproxen)₂(solvent)], solvent = 83% H₂O and 17% EtOH in the crystal structure, has been synthesized and specified by the X-ray structure analysis. It's in vitro DNA binding was inspected by the multispectroscopic methods and gel electrophoresis. The data of DNA-viscosity and competition fluorimetric test by methylene blue (MB) and Hoechst 33258 confirm groove binding mode of the complex to CT-DNA. Comparison of the results of this binding study with previous work revealed that the mode of binding of small compounds to DNA is highly influenced by the structure of the compounds. The DNA cleavage potency of the complex was appraised by the agarose gel electrophoretic and it was found that the complex does not have any momentous cleavage potency on the pUC18 plasmid DNA. The cytotoxicity of the complex on HT 29, HepG2 and HEK-293 cell lines by MTT method indicates that %inhibition of the complex on HT 29 is better than HepG2, compared with cisplatin drug. On HEK-293 cells, %inhibition growth of normal cells of the complex is less than cisplatin. Flow cytometry analysis of the complex on the HT 29 cells indicated the apoptosis cell death. RT-PCR studies revealed down-regulation of BCL2 expression, while the expression of BAX, caspase 3 and BAX/BCL2 genes was up-regulated in HT 29 cells by the complex. HighlightsA solvent-dependent nickel (II) with naproxen and 1,10-phenanthroline with aqueous solubility was synthesized and characterized.All experimental results indicate a groove mode of binding of the complex to CT-DNA.Potential biological characteristics confirmed that the complex is a promising candidate as anticancer agent.Communicated by Ramaswamy H. Sarma.

Energy transfer mechanisms in pH-tuned aggregates of curcumin

Curcumin ((1,7-bis-(4-hidroxi-3-metoxifenil)-1,6-heptadieno-3,5-diona)), is a natural yellow-orange polyphenol dye, obtained from Curcuma longa rhizomes, with vast potential in the biotechnology field, such as anti - inflammatory and cancer preventive properties, and a very environmental-sensible structure, mostly resulting in aggregate formations, with low solubility in aqueous solvents and remarkable pH dependence. Hence, it is essential to comprehend its aggregation mechanisms, optical properties and conformational equilibrium to develop curcumin-based drugs and biomaterials for several applications. With the purpose of understand such concepts and its properties, the results presented in this work, obtained through spectroscopic measurements and the Hill's modeling, show a conformational equilibrium, driven by pH, between the enol-enolate and aggregated forms in curcumin, and the respective energy transfer processes between these species. Additionally, the photophysical mechanisms for the energy transfer between aggregated forms, observed with the ellipsometry measurements, showed an "all-or-nothing" character, pointing to a very complex conformation for curcumin aggregates.

Synthesis, DNA Binding, and Molecular Docking Studies of Dimethylaminobenzaldehyde-Based Bioactive Schiff Bases

A new series of p-dimethylaminobenzaldehyde derivatives were tested for therapeutic potential by exploring their properties through characterization. The derivatives were synthesized by 1 : 1 condensation reaction of p-dimethylaminobenzaldehyde and substituted amines. The synthesized compounds 1–8 were characterized by different characterization techniques including IR, mass, 1H NMR, and 13C NMR spectroscopy, elemental analysis, and mass spectrometry. Furthermore, binding of these Schiff bases to Ct-DNA was examined by absorption spectroscopy, fluorescence quenching, circular dichroic, viscosity measurement, molecular docking, and molecular dynamics simulation methods. Schiff bases were tested for antimicrobial activity against bacterial species Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus by the disc diffusion method. The pharmacological treatment of Schiff bases showed that 1–8 have promising potential against tested bacterial strains. The molecular docking study of the target compounds was also carried out against B-DNA dodecamer d(CGCGAATTCGCG)2, and it has been found that 1–8 can bind to Ct-DNA via an intercalative mode. DPPH free radical and hydrogen peroxide scavenging assays were employed to assess the antioxidant potential of synthesized Schiff bases.

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.

Nonionic but water soluble, [Glycine-Pd-Alanine] and [Glycine-Pd-Valine] complexes. Their synthesis, characterization, antitumor activities and rich DNA/HSA interaction studies

Two novel, neutral and water soluble Pd(II) complexes of formula [Pd(Gly)(Ala)] (1) and [Pd(Gly)(Val)] (2) (Gly, Ala, and Val are anionic forms of glycine, alanine, and valine amino acids, respectively) have been synthesized and characterized by FT-IR, UV-Vis, ¹H-NMR, elemental analysis, and molar conductivity measurement. The data revealed that each amino acid binds to Pd(II) through the nitrogen of -NH₂ and the oxygen of -COO^- groups and acts as a bidentate chelate. These complexes have been assayed against leukemia cells (K₅₆₂) using MTT method. The results indicated that both of the complexes display more cytotoxicity than the well-known anticancer drug, cisplatin. The interaction of the compounds with calf thymus DNA (CT-DNA) and human serum albumin (HSA) were assayed by a series of experimental techniques including electronic absorption, fluorescence, viscometry, gel electrophoresis, and FT-IR. The results indicated that the two complexes have interesting binding propensities toward CT-DNA as well as HSA and the binding affinity of (1) is more than (2). The fluorescence data indicated that both complexes strongly quench the fluorescence of ethidium bromide-DNA system as well as the intrinsic fluorescence of HSA via static quenching procedures. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) calculated from the fluorescence studies showed that hydrogen bonds and van der Waals interactions play a major role in the binding of the complexes to DNA and HSA. We suggest that both of the Pd(II) complexes exhibit the groove binding mode with CT-DNA and interact with the main binding pocket of HSA. Communicated by Ramaswamy H. Sarma.

The evaluation of Cr-curcumin-DNA complexation by experimental and theoretical approaches

Chromium(III) chloride mediates DNA-DNA cross-linking. Some chromium complexes promote programmed cell death in specific ligand environment through binding to DNA. One strategy that can be supposed for reduction of Cr³⁺ binding affinity to DNA is using curcumin as a chelator. In the current study, the [Cr(Curcumin)(EtOH)₂](NO₃)₂ (CCC) was synthesized and characterized by UV/Vis, FT-IR, CHN and spectrophotometric titration techniques. The mole ratio plot revealed a 1:1 complex between Cr³⁺ and curcumin in solution. Binding interaction of this complex with calf thymus-DNA (CT-DNA) was investigated using UV/Vis, circular dichroism (CD), FT-IR and cyclic voltammetry. The intrinsic binding constants of CCC with DNA, measured by UV/Vis and cyclic voltammetry, were 1.60 × 10⁵ and 1.13 × 10⁵, respectively. The thermodynamic studies showed that the reaction is enthalpy and entropy favoured. CD analysis revealed that only Λ-CCC interacts with DNA and Δ-CCC form has no tendency towards DNA. Based on FT-IR studies, it was understood that CCC interacts with DNA via minor groove binding. The docking simulation was carried out for finding the binding mode of CCC to DNA, too. All of data demonstrated that the curcumin significantly reduced the affinity of Cr³⁺ to the DNA and the form of Δ-CCC has no interaction with DNA.

Development of a UPLC-FLD Method for Detection of Aflatoxin B1 and M1 in Animal Tissue to Study the Effect of Curcumin on Mycotoxin Clearance Rates

Aflatoxin B1 (AFB1) and its metabolite aflatoxin M1 (AFM1) are well-known carcinogens for humans and animals health. In this study, an ultra-high performance liquid chromatography linked with fluorescence detection (UPLC-FLD) method was optimized and validated. In addition, we investigated for the first time, the influence of curcumin on residue depletion of AFB1 and AFM1 in liver, kidney, and muscle tissues of broiler chickens and estimated a necessary clearance time required for AFB1 and AFM1 residues. The results showed that the average recoveries of AFB1 varied in liver, kidney, and muscles between 82.32-85.56, 85.34-88.45, and 84.88-89.73% respectively, while the average recoveries of AFM1 in liver, kidney, and muscles varied between 92.17-95.03, 94.12-97.21, and 95.32-98.51%, respectively. The detection limit of aflatoxin B1 was 0.008 ng/ml, while for aflatoxin M1 was 0.003 ng/ml. The limit of quantification (LOQ) for AFB1 and AFM1 was 0.02 and 0.01 ng/ml, respectively. Clearance time for AFB1 and AFM1 residues were analyzed in two experimental groups of broilers. One group fed with dietary AFB1 (5.0 mg/kg feed) and other with curcumin+AFB1 diet (curcumin; 300 mg/kg feed, AFB1; 5.0 mg/kg feed). AFB1 and AFM1 residues clearance time was calculated based on LOQ using withdrawal time calculation software (WT1.4). Clearance time analyzed for AFB1 ranged from 11 to 19 days and for AFM1 ranged from 10 to 12 days at 95% confidence level. Interestingly, curcumin supplementation in the diet reduced the clearance time of AFM1 in liver and kidney but not in muscle tissues. Conclusively, the developed method can be appropriately used for the quality control testing of commercial broiler-meat processing companies, food manufacturers, and quality control laboratories.

Experimental and computational studies on the effects of valganciclovir as an antiviral drug on calf thymus DNA

DNA-binding properties of an antiviral drug, valganciclovir (valcyte) was studied by using emission, absorption, circular dichroism, viscosity, differential pulse voltammetry, fluorescence techniques, and computational studies. The drug bound to calf thymus DNA (ct-DNA) in a groove-binding mode. The calculated binding constant of UV-vis, K_a, is comparable to groove-binding drugs. Competitive fluorimetric studies with Hoechst 33258 showed that valcyte could displace the DNA-bound Hoechst 33258. The drug could not displace intercalated methylene blue from DNA double helix. Furthermore, the induced detectable changes in the CD spectrum of ct-DNA as well as changes in its viscosity confirm the groove-binding mode. In addition, an integrated molecular docking was employed to further investigate the binding interactions between valcyte and calf thymus DNA.

Metal complexes of curcumin--synthetic strategies, structures and medicinal applications

This Tutorial Review presents an overview on the synthesis, characterization and applications of metal complexes containing curcumin (=1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) and its derivatives as ligands. Innovative synthetic strategies leading to soluble and crystallizable metal curcumin complexes are outlined in detail. Special emphasis is placed on the highly promising and exciting medicinal applications of metal curcumin complexes, with the three most important areas being anticancer activity and selective cytotoxicity, anti-Alzheimer's disease activity, and antioxidative/neuroprotective effects. Overall, this Tutorial Review provides the first general overview of this emerging and rapidly expanding field of interdisciplinary research.

Spectroscopic and molecular docking studies on the interaction of the drug olanzapine with calf thymus DNA

The present study investigated the binding interaction between olanzapine and calf thymus DNA (ct-DNA) using emission, absorption, circular dichroism, viscosity measurements and molecular modeling. Thermodynamic parameters (ΔH<0 and ΔS<0) indicated that hydrogen bond and van der Waals play main roles in the binding of the drug to ct-DNA. Spectrophotometric studies of the interaction of olanzapine with DNA have shown that it could bind to ct-DNA (Kb=2×10(3)M(-1)). The binding constant is comparable to standard groove binding drugs. Competitive fluorimetric studies with Hoechst 33258 have shown that olanzapine exhibits the ability to displace the DNA-bound Hoechst 33258 indicating that binds strongly in minor groove of DNA helix. Furthermore, the drug induces detectable changes in the CD spectrum of ct-DNA as well as changes in its viscosity. All of the experimental results prove that the groove binding must be predominant. The results obtained from experimental data were in good agreement with molecular modeling studies.

Proposed model for binding of permethrin and deltamethrin insecticides with ct-DNA, a structural comparative study

In this work, the interaction of two synthetic pyrethroid insecticides, permethrin (PER) and deltamethrin (DEL), with ct-DNA has been studied by cyclic voltammetry (CV), circular dichroism (CD), competitive fluorescence, atomic force microscopy (AFM), UV-vis spectroscopy, thermodynamic measurements, Fourier-transform infra-red (FT-IR), high performance liquid chromatography (HPLC) and two-layered ONIOM (our N-layered integrated molecular orbital+molecular mechanics) (DFT B3LYP, 6-31++G(d, p):UFF) molecular modeling methods. The last four methods were also utilized to study the binding of DEL with DNA. The results revealed that the PER may interact through partial intercalation and groove binding process while the PER only interacts through groove binding. Finally, the insecticides structure effect on interaction is discussed.

Spectroscopic and molecular modeling based approaches to study on the binding behavior of DNA with a copper (II) complex

Blocking the division of tumor cells by small-molecules is currently of great interest for the design of new antitumor drugs. The interaction of a new metal complex with DNA was investigated through several techniques. Absorption spectroscopy and gel electrophoresis studies on the interaction of the Cu-complex of (2a-4mpyH)2 [Cu(pyzdc)2 (H2O)2].6 H2O with DNA have shown that this complex can bind to CT-DNA with binding constant 3.99 × 10(5) M(-1). The cyclic voltammetry (CV) responses of the metal complex in the presence of CT-DNA have shown that the metal complex can bind to CT-DNA through partial intercalation mode and this is consistent with molecular docking analysis, quenching process and thermal denaturation experiments. The cytotoxicity of this complex has been evaluated by MTT assay. The results of cell viability assay on DU145 cell line revealed that the metal complex had cytotoxic effects.

Experimental and molecular docking studies on DNA binding interaction of adefovir dipivoxil: advances toward treatment of hepatitis B virus infections

The toxic interaction of adefovir dipivoxil with calf thymus DNA (CT-DNA) was investigated in vitro under simulated physiological conditions by multi-spectroscopic techniques and molecular modeling study. The fluorescence spectroscopy and UV absorption spectroscopy indicated drug interacted with CT-DNA in a groove binding mode. The binding constant of UV-visible and the number of binding sites were 3.33±0.2×10(4) L mol(-1)and 0.99, respectively. The fluorimetric studies showed that the reaction between the drug and CT-DNA is exothermic (ΔH=34.4 kJ mol(-1); ΔS=184.32 J mol(-1) K(-1)). Circular dichroism spectroscopy (CD) was employed to measure the conformational change of CT-DNA in the presence of adefovir dipivoxil, which verified the groove binding mode. Furthermore, the drug induces detectable changes in its viscosity. The molecular modeling results illustrated that adefovir strongly binds to groove of DNA by relative binding energy of docked structure -16.83 kJ mol(-1). This combination of multiple spectroscopic techniques and molecular modeling methods can be widely used in the investigation on the toxic interaction of small molecular pollutants and drugs with bio macromolecules, which contributes to clarify the molecular mechanism of toxicity or side effect in vivo.

Synthesis of a novel water-soluble zinc phthalocyanine and its CT DNA-damaging studies

A novel 3-(4-methoxybenzylamino) propanoic acid substituted water-soluble zinc phthalocyanine (CNPcZn) was synthesized. The interaction between CNPcZn with calf thymus DNA (CT DNA) was studied using spectroscopic methods. The studies indicated that CNPcZn has strong affinity to CT DNA, and furthermore, CNZnPc showed excellent photodamaging activity to CT DNA. Above results indicated that such CNPcZn has great potential to be used as an effective photosensitizer in the field of photodynamic therapy.