Exploring the binding properties of DNA/BSA and cytotoxicity studies with new terpyridine-ester-based metal complexes (M = Fe(III), Ni(II), Cu(II) and Ru(III)) - A comparative analysis

Many terpyridines and their metal complexes are known to exhibit remarkable potential for the interaction of biological targets. Notably, a subtle change in the structure of the ligand can influence these interactions significantly. In this regard, it would be very interesting to assess the binding affinity of functionalized molecules with DNA/BSA. In this work, a novel ester-based terpyridine (L) and the corresponding four metal complexes with Ni(II) (MC1), Cu(II) (MC2), Fe(III) (MC3) and Ru(III) (MC4) were prepared and structurally characterized using various spectroscopic and analytical techniques including the validation of molecular structures of ligand (L) and Ni(II)-Tpy complex (MC1). The EPR data demonstrate that MC1 is diamagnetic and other complexes (MC2-MC4) exhibit paramagnetic behavior. Additionally, the structures of ligands and metal complexes were determined using DFT studies and the same were utilized for the docking studies. Interestingly, MC3 and MC4 exhibit a predominant lowest binding energy of -9.62 Kcal/mol (with DNA) and -10.05 Kcal/mol (with BSA) respectively. The binding affinity of the ligand and its complexes with protein and DNA was evaluated by spectroscopic techniques. Notably, the cytotoxicity studies of L and MC1-MC4 were performed against the MCF-7 (human breast cancer) cell lines. The complex MC4 displayed great activity with an IC50 of 3.5 ± 1.75 μM among all synthesized compounds and comparable with cisplatin.

Protein interactions, molecular docking, antimicrobial and antifungal studies of terpyridine ligands

Resistance to antibiotics/antibacterials/antifungals in pathogenic microbes has been developing over the past few decades and has recently become a commonplace public-health peril. Thus, alternative nontoxic potent antibiotic agents are covertly needed to control antibiotic-resistant outbreaks. In an effort to combat the challenges posed by the co-occurrence of multidrug resistance, two terpyridine ligands 4'-(4-N,N'-dimethylaminophenyl)-2,2':6',2″-terpyridine (L1) and 4'-(4-tolyl)-2,2':6',2″-terpyridine (L2) have been designed, prepared and confirmed their structure by spectral studies. Thereafter, antimicrobial assay was performed against gram positive and negative bacterial strains along with fungal strains. Both compounds L1 and L2 exhibited remarkable inhibitory activities against bacteria, Escherichia coli and Staphylococcus aureus at MIC values 6.25 and 3.125 µg/ml, respectively. In addition, in silico molecular docking studies were ascertained with bacterial DNA gyrase and fungal demethylase. Furthermore, both L1 and L2 could bind Bovine Serum Albumin (BSA) protein and binding interaction has been studied with the help of UV-Visible and fluorescence spectroscopy. While fluorescence of BSA unperturbed in the presence of L2, an addition of L1 to the solution of BSA resulted significant quenching. The binding constant calculations at different temperature confirmed that the fluorescence quenching between BSA and L1 is predominantly static in nature. The toxicity of L1 and L2 was checked using Drosophila melanogaster. The toxicity analysis suggest both the dyes are non-cytotoxic in nature.Communicated by Ramaswamy H. Sarma.

Synthesis, characterization and anticancer properties: A series of highly selective palladium(II) substituted-terpyridine complexes

Ten new palladium(II) complexes [PdCl(L^1-10)]Cl have been synthesized by the reaction of palladium(II) chloride and ten 4'-(substituted-phenyl)-2,2':6',2''-terpyridine ligands bearing hydrogen(L¹), p-hydroxyl(L²), m-hydroxyl (L³), o-hydroxyl (L⁴), methyl (L⁵), phenyl (L⁶), fluoro (L⁷), chloro (L⁸), bromo (L⁹), or iodo (L¹⁰). Their structures were confirmed by FT-IR, ¹H NMR, elemental analysis and/or single crystal X-ray diffraction analysis. Their in vitro anticancer activities were investigated based on five cell lines, including four cancer cell lines (A549, Eca-109, Bel-7402, MCF-7) and one normal cell line (HL-7702). The results show that these complexes possess a strong killing effect on the cancer cells but a weak proliferative inhibition on the normal cells, implying their high inhibitory selectivity for the proliferation of the cancer cell lines. Flow cytometry characterization reveals that these complexes affect cell proliferation mainly in the G0/G1 phase and induce the late apoptotic of the cells. The quantity of palladium(II) ion in extracted DNA was determined by ICP-MS, which proved that these complexes target genomic DNA. And the strong affinity of the complexes with CT-DNA were confirmed by UV-Vis spectrum and circular dichroism (CD). The possible binding modes of the complexes with DNA were further explored by molecular docking. As the concentration of complexes 1-10 gradually increases, the fluorescence intensity of bovine serum albumin (BSA) decreases by a static quenching mechanism.

A New Concept of Enhancing the Anticancer Activity of Manganese Terpyridine Complex by Oxygen-Containing Substituent Modification

Eleven manganese 4'-substituted-2,2':6',2″-terpyridine complexes (1a-1c and 2a-2h) with three non-oxygen-containing substituents (L^1a-L^1c: phenyl, naphthalen-2-yl and naphthalen-1-yl, L^1a-L^1c) and eight oxygen-containing substituents (L^2a-L^2h: 4-hydroxyl-phenyl, 3-hydroxyl-phenyl, 2-hydroxyl-phenyl, 4-methoxyl-phenyl, 4-carboxyl-phenyl, 4-(methylsulfonyl)phenyl, 4-nitrophenyl and furan-2-yl) were prepared and characterized by IR, elemental analysis or single crystal X-ray diffraction. In vitro data demonstrate that all of these show higher antiproliferative activities than cisplatin against five human carcinoma cell lines: A549, Bel-7402, Eca-109, HeLa and MCF-7. Compound 2d presents the strongest antiproliferative effect against A549 and HeLa cells, with IC₅₀ values being 0.281 μM and 0.356 μM, respectively. The lowest IC₅₀ values against Bel-7402 (0.523 μM) Eca-109 (0.514 μM) and MCF-7 (0.356 μM) were obtained for compounds 2h, 2g and 2c, respectively. Compound 2g with a nitro group showed the best results on the whole, with relevantly low IC₅₀ values against all the tested tumor cells. The DNA interactions with these compounds were studied by circular dichroism spectroscopic and molecular modeling methods. Spectrophotometric results revealed that the compounds have strong affinities in binding with DNA as intercalators, and the binding induces DNA conformational transition. Molecular docking studies indicate that the binding is contributed by the π-π stacking and hydrogen bonds. The anticancer activities of the compounds are correlated with their DNA binding ability, and the modification of oxygen-containing substituents significantly enhanced the anticancer activity, which could provide a new rationale for the future design of terpyridine-based metal complexes with antitumor potential.

Nuclease-like metalloscissors: Biomimetic candidates for cancer and bacterial and viral infections therapy

Despite the extensive and rapid discovery of modern drugs for treatment of cancer, microbial infections, and viral illnesses; these diseases are still among major global health concerns. To take inspiration from natural nucleases and also the therapeutic potential of metallopeptide antibiotics such as the bleomycin family, artificial metallonucleases with the ability of promoting DNA/RNA cleavage and eventually affecting cellular biological processes can be introduced as a new class of therapeutic candidates. Metal complexes can be considered as one of the main categories of artificial metalloscissors, which can prompt nucleic acid strand scission. Accordingly, biologists, inorganic chemists, and medicinal inorganic chemists worldwide have been designing, synthesizing and evaluating the biological properties of metal complexes as artificial metalloscissors. In this review, we try to highlight the recent studies conducted on the nuclease-like metalloscissors and their potential therapeutic applications. Under the light of the concurrent Covid-19 pandemic, the human need for new therapeutics was highlighted much more than ever before. The nuclease-like metalloscissors with the potential of RNA cleavage of invading viral pathogens hence deserve prime attention.

In vitro cytotoxicity and antibacterial activity of [Pd(AMTTO)(PPh3)2]: a novel promising palladium(ii) complex

The synthesis and characterization of a novel palladium complex based on a bioactive 3-mercapto-1,2,4-triazine derivative have been investigated. The Pd(ii) complex showed excellent anticancer and antibacterial activity.

Terpyridines as promising antitumor agents: an overview of their discovery and development

INTRODUCTION

The fused aromatic system of terpyridines makes them good, innocent ligands for various metals. The resulting complexes have been extensively studied for both their biological activity and physico-chemical properties. However, although free ligands also have an interesting biological activity, their share in recent research is considerably limited.

AREAS COVERED

This review covers the literature on the anticancer activity of terpyridines with special attention being paid to their use as free ligands. Whenever possible, the mechanism of action has been discussed, thereby providing evidence of the substantial differences between sole ligands or less stable complexes and those that have heavier elements.

EXPERT OPINION

The existing literature indicates that there is a specific attitude for investigating terpyridines and their transition metal complexes. While the latter have been well explored and recognized in the scientific community, the free terpyridines are considered to be useful solely due to their complexing ability. At the same time, terpyridines could have similar or even higher anticancer potency than their complexes. Moreover, a mechanistic analysis of the stability and intracellular activity would provide information that would be useful for designing new drugs.

Pd(ii) and Pt(ii) complexes of tridentate ligands with selective toxicity against Cryptococcus neoformans and Candida albicans

Novel Pd(ii) and Pt(ii) complexes of the tridentate 2,6-bis(1-ethyl-benzimidazol-2'-yl)pyridine (L^BZ), and 4'-(2-pyridyl)-2,2':6',2''-terpyridine (L^PY) ligands were synthesized, characterized using a variety of analytical and spectroscopic tools, and screened for their potential antimicrobial properties against some bacterial and fungal strains as well as cytotoxicity against healthy human embryonic kidney (HEK293) cells. The electronic structures of the complexes were investigated by time-dependent density functional theory calculations. The free ligand L^PY and benzimidazole complexes exhibited selective toxicity against Cryptococcus neoformans and Candida albicans, while displaying no cytotoxicity against HEK293. In the case of Cryptococcus neoformans, the antifungal activities of the benzimidazole-based complexes (MIC = 1.58-2.62 μM) are higher than those of the reference drug fluconazole (26.1 μM).

Evaluation of the Anticancer and DNA-Binding Characteristics of Dichloro(diimine)zinc(II) Complexes

Several metal diimine complexes have been reported to possess anticancer properties. To evaluate the anticancer properties of tetrahedral zinc(II) diimine complexes, six complexes were synthesized with the general formula M(N^N)Cl2 {where M = Zn, Pt and N^N = 2,2’-biquinoline (1), 2,2’-dipyridylketone (2) and 4-((pyridine-2-ylmethylene)amino)phenol (3)}. In general, the intrinsic DNA-binding constants for the different compounds exhibited values within close proximity; the changes in the viscosity of the CT-DNA upon binding to the compounds suggest intercalation-binding mode. Molecular docking study predicted that complexes containing the highly planar ligand 2,2’-biquinoline are capable to establish π–π interactions with nucleobases of the DNA; the other four complexes engaged in donor–acceptor interactions with DNA nucleobases. The six complexes and two reference drugs (cisplatin and sunitinib) were tested against two cancer cell lines (COLO 205 and RCC-PR) and one normal cell line (LLC-MK2), highlighting the better performance of the zinc(II) complexes compared to their platinum(II) analogues. Moreover, zinc(II) complexes have higher selectivity index values than the reference drugs, with promising anticancer properties.

Antitumor activity of tridentate pincer and related metal complexes

Pincer complexes featuring tunable tridentate ligand frameworks are one of the most actively studied classes of metal-based complexes. Currently, growing attention is devoted to the cytotoxicity of pincer and related metal complexes. The antiproliferative activity of numerous pincer complexes has been reported. Pincer tridentate ligand scaffolds show different coordination modes and offer multiple options for directed structural modifications. This review summarizes the significant progress in the research studies of the antitumor activity of pincer and related platinum(ii), gold(iii), palladium(ii), copper(ii), iron(iii), ruthenium(ii), nickel(ii) and some other metal complexes, in order to provide a reference for designing novel metal coordination drug candidates with promising antitumor activity.

The palladacycle, BTC2, exhibits anti-breast cancer and breast cancer stem cell activity

In women globally, breast cancer is responsible for most cancer-related deaths and thus, new effective therapeutic strategies are required to treat this malignancy. Platinum-based compounds like cisplatin are widely used to treat breast cancer, however, they come with limitations such as poor solubility, adverse effects, and drug resistance. To overcome these limitations, complexes containing other platinum group metals such as palladium have been studied and some have already entered clinical trials. Here we investigated the anti-cancer activity of a palladium complex, BTC2, in MCF-7 oestrogen receptor positive (ER+) and MDA-MB-231 triple negative (TN) human breast cancer cells as well as in a human breast cancer xenograft chick embryo model. BTC2 exhibited an average IC₅₀ value of 0.54 μM, a desirable selectivity index of >2, inhibited the migration of ER+ and TN breast cancer cells, and displayed anti-cancer stem cell activity. We demonstrate that BTC2 induced DNA double strand breaks (increased levels of γ-H2AX) and activated the p-ATM/p-CHK2 and p-p38/MAPK pathways resulting in S- and G2/M-phase cell cycle arrests. Importantly, BTC2 sensitised breast cancer cells by triggering the intrinsic (cleaved caspase 9) and extrinsic (cleaved caspase 8) apoptotic as well as necroptotic (p-RIP3 and p-MLKL) cell death pathways and inhibiting autophagy and its pro-survival role. Furthermore, in the xenograft in vivo model, BTC2 displayed limited toxicity and arrested the tumour growth of breast cancer cells over a 9-day period in a manner comparable to that of the positive control drug, paclitaxel. BTC2 thus displayed promising anti-breast cancer activity.

Toxicity profiling of metallosurfactant based ruthenium and ruthenium oxide nanoparticles towards the eukaryotic model organism Saccharomyces cerevisiae

In the present study, a facile method was used to synthesize the ruthenium and ruthenium oxide (RuO₂) nanoparticles (NPs) derived from three different metallosurfactants. Firstly, three metallosurfactants were fabricated i.e. RuCTAC (Bishexadecyltrimethylammonium ruthenium tetrachloride), RuDDA (Bisdodecylamine ruthenium dichloride), and RuHEXA (Bishexadecylamine ruthenium dichloride) and characterized by CHN, FTIR, and ¹HNMR. These metallosurfactants were further utilized to fabricate the mixed type of NPs (Ru and RuO₂ NPs) using the biocompatible microemulsion technique and NPs were then characterized. Subsequently, the nanotoxicity of mixed NPs (Ru & RuO₂) was studied towards Saccharomyces cerevisiae. The detailed study of nanotoxicity against the S. cerevisiae cells was done by employing optical microscopy, FESEM, anti-yeast activity assay, circular dichroism, and gel electrophoresis techniques. FESEM and optical microscopy analyses indicated that RuCTAC nanosuspension (Ns) has the most toxic effect on the S. cerevisiae cells. FESEM analysis confirmed the harmful impact of Ru and RuO₂ NPs on the S. cerevisiae cells. From the FESEM analysis, complete alteration in the morphology, cell membrane breakage, and formation of the holes on the cell wall of S. cerevisiae was affirmed in presence of all three types of Ns i.e. RuCTAC, RuDDA, and RuHEXA Ns. Genotoxicity of the NPs was confirmed by circular dichroism and gel electrophoresis and it was found that RuCTAC and RuHEXA Ns have the most damaging influence on the yeast genomic DNA.

Spectroscopic Studies on the Interaction of Naphthyridines with DNA and Fluorescent Detection of DNA in Agarose Gel

Four new naphthyridine derivatives (R1-R4) possessing amino acid or boronic acid moieties have been synthesized and characterized using ¹H and ¹³C NMR, FT-IR, and mass spectral techniques. The mechanism of binding of these probes with calf thymus DNA (CT-DNA) has been delineated through UV-Vis, fluorescence, and circular dichroism (CD) spectral techniques along with thermodynamic and molecular docking studies. Small hypochromicity in absorption maximum of the probes without any shift in wavelength of absorption suggests groove binding mode of interaction of these probes with CT-DNA, confirmed by CD and 1H NMR spectral data competitive binding assay with ethidium bromide (EB). CT-DNA quenches the fluorescence of these probes via a static quenching mechanism. In the case of R1 and R4, the observed ΔH^o < 0 and ΔS^o > 0suggest that these probes interact with CT-DNA through H-bonding and hydrophobic interactions, while in the interaction of R2 and R3, van der Walls and H-boding forces are found to be dominant (ΔH^o < 0 and ΔS^o < 0). Results of molecular docking investigations corroborate well with that of spectral studies, and these probes bind in the minor groove of DNA. These probes are found to be effective fluorescent staining agents for DNA in agarose gel in gel electrophoresis experiment with sensitivity comparable to that of EB, and DNA amounts as low as 37.5 ng are visually detectable in the gel.

Synthesis and structure of a new thiazoline-based palladium(II) complex that promotes cytotoxicity and apoptosis of human promyelocytic leukemia HL-60 cells

Cisplatin is one of the most widely used chemotherapeutic agents in the treatment of different tumors but has high toxicity and side effects. Therefore, the synthesis of new chemotherapeutic agents is necessary, so that they are effective in the treatment of cancer while avoiding such toxicity. In this study, we have synthesized and characterized a palladium(II) complex, [PdCl2(µ-PyTT)2]Cl2·4H2O (PdPyTT), with 2-(2-pyridyl)imine-N-(2-thiazolin-2-yl)thiazolidine (PyTT) as a ligand; besides, its cytotoxicity and pro-apoptotic capacity was tested in human promyelocytic leukemia HL-60 cell line. Similar to cisplatin, PdPyTT produced a time- and dose-dependent decrease in cell viability. Additionally, the palladium complex increased both the proportion of cells with apoptotic morphology and the activation of caspase-3 and -9. PdPyTT, like cisplatin, also increased intracellular ROS production and DNA oxidative damage. Therefore, our findings demonstrated the promising application of palladium(II) complexes as novel anti-leukemic agents.

Extreme enhancement of secondary chirality through coordination-driven steric changes of terpyridyl ligand in glutamide-based molecular gels

Aggregation-induced chirality is potentially useful in sensor technology applications. Herein we show extreme enhancement of secondary chirality through coordination-driven steric changes of terpyridyl ligand in molecular gels. The secondary chirality reflecting on enhancement of chiral signals (i.e., circular dichroism (CD) and circularly polarised luminescence (CPL)) of the molecular gels formed from glutamide-attached terpyridine (G-tpy) is extremely enhanced by the coordination of its terpyridyl groups to metal ions such as Cu²⁺, Zn²⁺ and Ru²⁺, which is due to dramatic changes in the stacked structure of the chromophore groups through the formation of metal ion complex. Metal-free terpyridine exists in a non-planar geometry, which suppress π–π stacking interactions among aggregates. The planarity of the terpyridyl group is improved through metal-ion complexation, which induces the metal-ion-coordinated terpyridyl groups to stack. The thermal stabilities of the CD signals are strongly affected by the metal-ion species. CPL signal is generated in the molecular gel formed from G-tpy–Zn²⁺ complex accompanied by chelation-enhanced fluorescence. It is expected that large and sensitive coordination-driven secondary chirality signals (CD and CPL) are useful for sensing guest molecules and the surrounding environment.

Dramatic changes of secondary chirality reflecting on enhancement of chiral signals (i.e., CD and CPL) is induced through coordination-derived steric changes of terpyridyl ligand attached on glutamide-based molecular gels.

RK, Pillegowda M, Periyasamy G, Suchetan PA, Butcher RJ, Foro S, Nagaraju G. Synthesis, crystal structures, photophysical, electrochemical studies, DFT and TD-DFT calculations and Hirshfeld analysis of new 2,2′:6′,2′′-terpyridine ligands with pendant 4′-(trimethoxyphenyl) groups and their homoleptic ruthenium complexes

[Ru(L1)₂](PF₆)₂ (1) and [Ru(L2)₂](PF₆)₂ (2): X-ray structures, CH⋯F/O, OH⋯F/N, CH⋯O/π, π⋯π interactions, absorption and emission spectra, DFT/TD-DFT, Hirshfeld analysis.

para metallation of 3-acetyl-chromen-2-one Schiff bases in tetranuclear palladacycles: focus on their biomolecular interaction and in vitro cytotoxicity

Three tetranuclear (1-3) complexes and a mononuclear (4) palladium(ii) complex were synthesized from 3-acetyl-chromen-2-one Schiff base ligands [H₂-3MAC-Rtsc] (where R = H [H₂-3MAC-tsc]; CH₃[H₂-3MAC-mtsc]; C₂H₅[H₂-3MAC-etsc] or C₆H₅[H₂-3MAC-ptsc]) and potassium tetrachloropalladate. Their formation was confirmed by spectroscopic techniques and X-ray crystallographic analysis. Their ability to bind with DNA and albumin was analysed by using absorption and emission titrations. The MTT assay was carried out to analyze the anticancer potential of the ligands and synthesized complexes against HepG2 (human liver cancer) and HT-29 (human colon cancer) cells. In addition, the compounds were less toxic when tested against the human normal keratinocyte cells (HaCaT). Ligands and complexes displayed better cytotoxicity with lower IC₅₀ values than the standard drug cisplatin. Further AO-EB and DAPI staining assays were carried out to detect the mode of cell death induced by the complexes i.e. apoptosis or necrosis. The complex 3 showed better cytotoxicity and was further subjected to flow cytometric analysis. The results suggested that the complex 3 induced apoptotic cell death.

Water-soluble binary and ternary palladium(ıı) complexes containing amino acids and intercalating ligands: synthesis, characterization, biomolecular interactions and cytotoxicities

Novel water soluble palladium(ii) complexes have been synthesized and characterized. Moreover, the cytotoxicities of these complexes against different human tumor and healthy cell lines were investigated by the XTT assay.

K, Bodke YD, Malojirao VH, T. R. RN, Kandagalla S, B. T. P. Synthesis, characterization and tumor inhibitory activity of a novel Pd(ii) complex derived from methanethiol-bridged (2-((1H-benzo[d]imidazol-2-yl)methylthio)-1H-benzo[d]imidazol-6-yl)(phenyl)methanone

This manuscript demonstrates the synthesis and tumor inhibitory activity of (2-((1H-benzo[d]imidazol-2-yl)methylthio)-1H-benzo[d]imidazol-6-yl)(phenyl)methanone and its Pd(ii) complex.

DNA G-quadruplexes binding and antitumor activity of palladium aryl oxime ligand complexes encapsulated in either albumin or algal cellulose nanoparticles

The interactions between two Pd complexes, designated as [Pd₃(C,N-(C₆H₄C(Cl) = NO)-4)₆] (complex 1) and [Pd₃(C₁₂H₈C = NO)₆] (complex 2), with the human telomeric G-quadruplex DNA, 5'-G₃(T₂AG₃)₃-3' (HTG21), were monitored using spectroscopic, biological, and molecular modeling studies. According to the UV-vis results, these complexes can strongly induce and stabilize G-quadruplex DNA structure with K_b1 = 4.5(±0.3) × 10⁶ M^-1 and K_b2 = 1.0(±0.2) × 10⁷ M^-1via groove mode in comparison with duplex DNA. The release mechanism of the Pd complexes from BSA nanoparticles followed a biphasic pattern unlike that of algal cellulose nanoparticles in vitro. In addition, the cytotoxicity of these complexes on MCF-7 cancer cells and PBMC normal cells was evaluated and compared with cisplatin under similar experimental conditions. Furthermore, to determine and verify the interaction mode of these compounds with G-quadruplex, the molecular docking technique was also performed. Our data clearly demonstrated that complex 2 had higher activity and cytotoxicity than that of complex 1 and could be further investigated in the future as a drug discovery platform.

Cationic double chained metallosurfactants: synthesis, aggregation, cytotoxicity, antimicrobial activity and their impact on the structure of bovine serum albumin

Bovine serum albumin (BSA) is one of the most copious and significant blood proteins with dynamic structure. The understanding of the structural functionality of BSA and its interaction with metal ions is desired for various biological functions. Herein, three different metallosurfactants containing different transition metals and the same hydrophobic tail were engaged to investigate the structural transition of BSA. The metallosurfactants have been prepared by a combination of metal ions (M = Fe, Co and Ni) with cetylpyridinium chloride surfactant via the ligand insertion method and were characterized by elemental, FTIR, 1H-NMR, and thermogravimetric analysis (TGA). The obtained results reveal that insertion of a metal ion perturbs the aggregation behavior of the surfactant. Incorporation of a metal-ion has been found to decrease the CMC value of the surfactant, which has been supported by conductivity, surface tension and small angle X-ray scattering (SAXS). These metallosurfactants were employed to study the interaction and binding mechanism of BSA under physiological conditions. SDS-PAGE analysis points out a weak effect of metallosurfactants on the primary structure of BSA, whereas CD spectra implied a significant change in secondary structure with the decreased α-helical content of BSA. Fluorescence spectroscopy indicates the effect of metallosurfactants on the tertiary structure of BSA, whereas absorption spectra demonstrated static quenching with a blue shift in the presence of metallosurfactants. Moreover, unfolding of BSA in the presence of metallosurfactants has also been confirmed by SAXS studies. The overall results indicate that insertion of the metal ion into the framework of the surfactant structure enhances its protein binding/folding/unfolding abilities, which would be helpful in clinical as well as in life sciences.

In vitro assessment of antimicrobial and genotoxic effect of metallosurfactant based nickel hydroxide nanoparticles against Escherichia coli and its genomic DNA

In the present study, we have synthesized nickel hydroxide nanosuspensions (Ns) using microemulsion technique. This approach is eco-friendly and makes use of Tween 80 (a non-ionic biocompatible surfactant) and newly synthesized metallosurfactants for the formation of uniform nanoparticles in the form of nanosuspensions (Ns). The nickel hydroxide Ns's were derived from three different metallosurfactants i.e. NiCTAC (Bishexadecyltrimethylammonium nickel tetrachloride), NiDDA (Bisdodecylamine nickel dichloride) and NiHEXA (bishexadecylamine nickel dichloride). Three different nickel-based metallosurfactants were synthesized and characterized using various methods such as CHN, ¹HNMR, and FTIR. Fabrication of nanosuspension was confirmed using different characterization methods such as Transmission electron microscopy (TEM), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), pH and Zeta potential. These particles were further investigated for their genotoxic and cytotoxic effects on gram-negative bacteria, Escherichia coli (E. coli). Effect of nanosuspensions on E. coli was confirmed using colony forming unit count, agar well diffusion, and gram staining method. Through colony forming unit count method, nanosuspensions influence on the colony-forming capacity of E. coli cells was confirmed. Agar well diffusion method provides the estimation of antimicrobial activity, and the largest inhibition zone was observed for NiCTAC Ns and smallest for NiHEXA Ns which is related to maximum and minimum bactericidal properties of Ns, respectively. The interaction behavior of bacterial DNA with Ni nanosuspension was analyzed using agarose gel electrophoresis and circular dichroism. Along with, the role of different chemical scavengers was also evaluated in DNA damage using gel electrophoresis. Furthermore, the antioxidant activity of Ni nanosuspension was also confirmed using DPPH assay.

Fabrication of iron oxide nanocolloids using metallosurfactant-based microemulsions: antioxidant activity, cellular, and genotoxicity toward Vitis vinifera

The present work aims at the fabrication of iron oxide nanocolloids using biocompatible microemulsion and their cytotoxic, genotoxic effect on Vitis vinifera plant has been evaluated. The three iron-based metallosurfactant complexes were synthesized. Nanosuspensions (Ns) were prepared using microemulsion technique and for the purpose, the microemulsion was prepared using oleic acid, butanol, tween 80 and as synthesized iron metallosurfactant. In this technique, no additional capping agent and/or reducing agent was added. Tween 80 which is a biocompatible surfactant acted as a reducing agent as well as stabilizing for the iron oxide Ns. Characterization of Ns's was done using TEM, FESEM, EDX, XRD, AFM, and zeta potential. Mixed type of iron oxide nanoparticles i.e. magnetite (Fe₃O₄), and maghemite (Fe₂O₃) with a size range of 1-16 nm was found to be present in the nanosuspensions prepared from all the three precursors. The antioxidant activity of the Fe Ns was also confirmed using DPPH assay, with order of activity FeDDA > FeCTAC > FeHEXA. The cellular toxicity of Ns was evaluated by observing the morphological changes on V. vinifera plant (petiole) using a light microscope. Further, the interactions of iron oxide Ns with V. vinifera's DNA (plant-DNA) was assessed using circular dichroism (CD) and gel electrophoresis. For the case of FeCTAC Ns, a decrease in the intensity of bands was observed indicating fragmentation or adduct formation resulting in DNA damage. In the case of FeDDA, a modest decrease in the intensity of bands was observed. However, for FeHEXA Ns, complete neutralization of bands was confirmed implying maximum damage to the plant DNA. CD, gel electrophoresis and antioxidant activity confirmed that FeHEXA Ns were most toxic and FeDDA Ns were safest among the three as-fabricated nanosuspensions.

Postsynthetic modification of single Pd sites into uncoordinated polypyridine groups of a MOF as the highly efficient catalyst for Heck and Suzuki reactions

A novel Pd-HoMOF catalyst was prepared, which displayed good thermal stability and high activity in Heck and Suzuki cross-coupling reactions.

Synthesis, characterization, X-ray crystal structure and DFT calculations of 4-([2,2':6',2''-terpyridin]- 4'-yl)phenol

La síntesis de derivados terpiridinicos (Tpy) se ha investigado ampliamente debido a su potencial para la conversión de  energía solar. En este artículo se sintetizó  y caracterizó el 4-([2,2':6',2'' terpiridin]-4'-il)fenol (TpyOH), a través de varias metodologías como la cristalografía de rayos X y herramientas computacionales. El análisis de rayos X de monocristal mostró que el TpyOH es plano, con ángulos diedros de 5,03° entre el piridinilo central y el anillo fenólico, con presencia de ángulos de 6,05 y 12,2º en la porción terpiridínica. En el cristal, las moléculas están unidas por  enlaces  de  hidrógeno intermoleculares  y  mediante  interacciones  de apilamiento  π-π. Utilizando cálculos DFT dependientes del tiempo (TD-DFT) y teniendo en cuenta el efecto de los  disolventes, se investigaron y  compararon los  espectros  de absorción  y fluorescencia  de TpyOH. Las energías de transición TD-DFT de S0→Sn y S1→S0 concuerdan con los resultados experimentales. El análisis de orbitales moleculares de frontera mostró que la banda de absorción de baja energía corresponde a transferencia de carga intraligando (ICT); mientras que la banda de alta energía es común en las transiciones π-π* del resto Tpy. La emisión debido a la transición S1→S0 corresponde  a  ICT,  con  una  contribución  del 90%  proveniente  de  transiciones HOMO→LUMO.

Platinum, palladium, gold and ruthenium complexes as anticancer agents: Current clinical uses, cytotoxicity studies and future perspectives

Metallodrugs offer potential for unique mechanism of drug action based on the choice of the metal, its oxidation state, the types and number of coordinated ligands and the coordination geometry. This review illustrates notable recent progress in the field of medicinal bioinorganic chemistry as many new approaches to the design of innovative metal-based anticancer drugs are emerging. Current research addressing the problems associated with platinum drugs has focused on other metal-based therapeutics that have different modes of action and on prodrug and targeting strategies in an effort to diminish the side-effects of cisplatin chemotherapy. Examples of metal compounds and chelating agents currently in clinical use, clinical trials or preclinical development are highlighted.