Synthesis, characterization, DNA interaction, BSA/HSA binding activities of VO(IV), Cu(II) and Zn(II) Schiff base complexes and its molecular docking with biomolecules

Investigation of mono-nuclear cobalt(II) complexes with a tri-dentate quinoxalyl-hydrazone ligand for their potential in biological research and interaction with ct-DNA

The condensing reaction of 2-hydroxy-1-naphthaldehyde with quinoxalyl-2-carbohydrazide resulted in synthesizing of a novel derivative of hydrazone quinoxalyl ligand (H2dpq). The bonding behavior between H2dpq and Co(II) ion was investigated in molar ratios of 1: 1 and 2: 1 to produce two different complexes, Codpq and Co(dpq)2, respectively. Their chemical structure was verified using several spectroscopic approaches. The characterization envolved micro-C, H, and N-elemental analyses, thermogravimetric investigations, as well as the examination of their magnetic and conductance properties. The inhibitory effects of H2dpq (the free ligand) and its Co(II)-chelates on the growing up of three specific bacterial series, three specific fungal series, and three famous human cancer cell lines were evaluated based on their structure features. The study referred to the pivotal function of Co(II) and its ratio in the two complexes. The antioxidant activity was determined for all current compounds within DPPH and SOD assays, reporting respectable antioxidant reactivity. The interaction of H2dpq, Codpq, and Co(dpq)2 with calf thymus DNA (ct-DNA) was assessed by analyzing through the alterations in the viscometric and spectrophotometric properties. Determination of binding constant (Kb, 13.12, 16.02, and 16.82 × 107 mol-1 dm3), Gibb's free energy (∆Gb≠, were -40.21, -46.13, and -46.67 kJ mol-1), and the chromism mode (hypo-character) were employed for H2dpq, Codpq, and Co(dpq)2 to assess the interactive modes, respectively. Rewardingly, the monometallic-chelates Co(II)-complexes displayed modified binding action more than that of H2dpq against ct-DNA.

Insights into interaction of quaternary ammonium salt cationic surfactants with different branched-chain lengths and DNA: Multi-spectral analysis, viscosity method, and gel electrophoresis

In this study, the interactions between three quaternary ammonium salt (QAS) cationic surfactants with different branched-chain lengths (TMBAC, TEBAC, and TBBAC) and DNA are investigated by UV-vis absorption, fluorescence and CD spectroscopy, viscosity method, and gel electrophoresis. Berberine hydrochloride (BR) is utilized as a fluorescent probe. The three interaction modes and strengths are compared. The effects of surfactant concentrations, ratio of DNA and BR, and ionic strength on the interaction are estimated. DNA conformational changes are explored. The results indicate that three surfactants can interact with DNA through electrostatic interaction rather than groove and intercalation binding. The interaction results in DNA double helix compression. Also, interaction strength is TBBAC-DNA > TEBAC-DNA > TMBAC-DNA due to different branched-chain lengths. Moreover, fluorescence quenching extent is more obvious at 10.0:1.0 mol ratio (DNA: BR). The fluorescence quenching of three surfactant-DNA-BR systems is static. Three binding models are equal, and three interaction processes are spontaneous. The binding force of TBBAC-DNA is electrostatic, while that of TMBAC-DNA and TEBAC-DNA is Van der Waals forces and hydrogen bonding. Besides, DNA conformation keeps the B-form. It is expected to offer insights into the interaction of QAS cationic surfactants with different branched-chain lengths and DNA.

Synthesis and DFT calculations of metal(II) oxime complexes bearing cysteine as coligand and investigation of their biological evolutions in vitro and in silico

New complexes with the formula of [ML(Cys)(H2O)2] were obtained as a result of the reaction between the oxime ligand [HL: 4-(4-bromophenylaminoisonitrosoacetyl)biphenyl], cysteine (Cys), and the metal(II) salts (Mn, Ni, Co, Zn, Cu). The newly synthesized compounds were characterized using conventional techniques such as molar conductance, magnetic measurements, elemental analysis, infrared spectroscopy, and thermal analysis (TGA/DTA). Based on the conductivity measurements in DMF, it was determined that the complexes were non-electrolytes. The TGA/DTA analysis was performed to examine the thermal stability and degradation behavior of all samples, and results demonstrated that metal oxides or sulfides formed as a result of the decompositions. In conjunction with other data obtained, the elemental analysis confirmed the octahedral coordination of the complexes with deprotonated oxime (O, O-donor) and amino acid (N, S-donor) ligands and two coordinated waters. The compounds' optimized geometries, molecular electrostatic potential diagrams, and frontier molecular orbitals were computed at the DFT/B3LYP level using the 6-311 G(d,p) and LANL2DZ basis sets. The antibacterial and DNA cleavage activities of all synthesized compounds were also screened, and molecular docking simulations were performed. According to the results of molecular docking studies conducted with three different proteins, the best interaction was found to be between HL-1HNJ with a binding energy of -9.5 kcal/mol. The stability of the HL-1HNJ complex was also verified by a molecular dynamics simulation performed for 50 ns.Communicated by Ramaswamy H. Sarma.

Substituent effect on the chemical and biological properties of diisatin dihydrazone Schiff bases: DFT and docking studies

According to the considered role of lipophilicity-hydrophobicity on organic Schiff base hydrazones, different substituents of phenyl, ethyl, and methyl groups were inserted in the synthetic strategy of diisatin dihydrazones (L1-4). The biochemical enhancement was evaluated depending on their inhibitive potential of the growth power of three human tumor cells, fungi, and bacteria. The biochemical assays assigned the effected role of different substituents of phenyl, ethyl, and methyl groups on the effectiveness of their diisatin dihydrazone reagents. The interacting modes with calf thymus DNA (i.e. Ct-DNA) were studied via viscometric and spectrophotometric titration. The organo-reagent L1 with the oxalic derivative assigned a performed inhibitive action for the examined microbes and the human tumor cell lines growing up over the terephthalic (L4) > malonic (L2) > succinic (L3) ones. From Kb = binding constant, and ∆Gb≠ = Gibb's free energy values, the binding of interaction within Ct-DNA was evaluated for all compounds (L1-4), in which L1, L3, and L4 assigned the highest reactivity referring to the covalent/non-covalent modes of interaction, as given for (L1-4), 14.32, 13.28, 10.87, and 12.41 × 107 mol-1 dm3, and -45.17, -43.24, -43.75, and -44.05 kJ mol-1, respectively. DFT and docking studies were achieved to support the current work.

Cytotoxic potential of novel selenolato-bridged manganese(I)-based CORM and its molecular interaction with human serum albumin and DNA through spectroscopic and in silico docking studies

The prevalence of cancer is increasing steadily over the past few decades due to social and environmental factors. Several drugs and medications have also been reported, but with inevitable side effects. Herein comes the urgent need for the development of precision medicine, which increases the efficiency of the drug on the target tissue and minimizes systemic toxicity and non-specificity. One of the several approaches developed includes the formulation of smart or trigger-specific drugs for spatiotemporal delivery. In this view, an arena of carbon monoxide-releasing molecules (CORMs) that could be rendered trigger-specific using labile ligands has been developed. In the present investigation, one such novel, manganese based CORM (Mn-CORM) was synthesized and analysed for its selective cytotoxic potential. The Mn-CORM exerted a broad-spectrum cytotoxicity against cancer cells such as PAN C1 (pancreatic cancer), PC 3 (prostate cancer) and HT 29 (colon cancer). Present study further investigated the binding potential of Mn-CORM for human serum albumin (HSA), the major transporter of anticancer drugs and DNA using a multi-spectroscopic (UV-VIS absorption, quenching analysis, time resolved fluorescence spectroscopy, circular dichroism spectroscopy) and molecular docking techniques. The analysis of thermodynamic parameters ΔS0and ΔH0 showed that the binding of Mn-CORM to HSA was spontaneous and dominated by Van der Waals forces and hydrogen bonding. The binding potential of Mn-CORM for CT DNA was also investigated using spectroscopic studies, dye displacement assay, circular dichroism spectroscopy, thermal denaturation and DNA cleavage studies. Results demonstrated a good binding potential of Mn-CORM for CT DNA. The probable mode of binding of Mn-CORM and CT DNA was concluded to be a partial intercalation. All these experimental and computational results confirmed that the novel Mn-CORM used in the present study can be a promising anticancer agent.

A comprehensive investigation of the nano-[Cu2-(DIP)2-EA] effects on HSA through spectroscopic procedures and computer simulations

In this research, the toxicity of nano-[Cu2-(DIP)2-EA], a metal nano-complex consisting of ellagic acid and bathophenanthroline ligands, on human serum albumin (HSA) at a protein level was investigated. Molecular docking simulations and spectral analyses were conducted in a simulated physiological environment at pH 7.4 to explore the interaction of nano-[Cu2-(DIP)2-EA] with HSA. The results represented an increase in albumin absorption upon exposure to nano-[Cu2-(DIP)2-EA], demonstrating significant interaction between the two compounds. Steady-state and time-resolved fluorescence measurements pointed out that nano-[Cu2-(DIP)2-EA] induced static quenching of the albumin's intrinsic fluorescence with a high binding affinity of approximately 106 mol/L in a 1:1 interaction ratio. The thermodynamic variables clarified that binding of nano-[Cu2-(DIP)2-EA] to albumin occurs spontaneously and primarily driven by van der Waals interactions and H-bonds. The results of the computer simulations and the binding displacement experiments utilizing the site markers warfarin and ibuprofen revealed that nano-[Cu2-(DIP)2-EA] binds to site I within the subdomain IIA of albumin. Circular dichroism analysis elaborated that nano-[Cu2-(DIP)2-EA] slightly perturbed the microenvironment around of tryptophan residues and diminished the α-helix structure stability to a negligible amount.

Indole-based NNN donor Schiff base ligand and its complexes: Sonication-assisted synthesis, characterization, DNA binding, anti-cancer evaluation and in-vitro biological assay

A novel indole based NNN donor Schiff base ligand and its Ni(II), Zn(II) and Cd(II) complexes have been synthesized using sonication-assisted method which is a highly efficient eco-friendly mechanism. The synthesized complexes have been characterized using elemental analysis, UV-Vis spectroscopy, mass spectrometry, FT-IR, and NMR and are optimized using DFT approach, which provided their theoretical framework. The stoichiometry between the ligand and the metal ions was also determined using Job's method. The thermogravimetric (TGA/DSC) analyses confirm the stability for all complexes at room temperature followed by thermal decomposition in different steps. DNA binding activities have been assessed by employing UV-visible and fluorescence spectra using the CT-DNA. The estimated intrinsic binding constant (Kb) for NiL, ZnL, and CdL complexes was 6.00 × 105, 5.58 × 105, and 4.7 × 105, respectively. In accordance with the Kb value, the quenching constant (Ksv) values of NiL, ZnL, and CdL are 5.59 × 105 M-1, 4.3 × 105 M-1, and 4.08 × 105 M-1 respectively. The anticancer properties have been assessed using MTT Assay. It has been found that the Ni(II) complex (NiL) is the most potent among the series with IC50 of 169 µg/mL. An in-vitro antioxidant experiment using DPPH was used to evaluate the synthesizedcomplexes' ability to scavenge free radicals. The findings indicated that the complexes exhibited notable antioxidant properties. The antioxidant property ZnL has been found to be the highest with an IC50 of 2.91 µg/mL and it follows the order is ZnL > NiL > CdL > L. Using the egg albumin denaturation technique, the anti-inflammatory property have been assessed, and the amount of protein denaturation inhibition has been computed. NiL has the highest % inhibition among the series studied. Comparatively, the metal complexes have been reported to exhibit higher biological activities than the prepared Schiff base ligand. The reason for the excellent biological properties observed in the metal complexes could be attributed to the incorporation of the electron-withdrawing CH3COO- during complexation. Molecular docking studies have been performed on the 2GYT protein and it has been found that the complexes have excellent binding affinity, with NiL having the lowest binding energy of -6.93 Kcal mol-1. The values suggested that NiL is more effective against HePG2 cancer cells, which is also in accordance with the MTT Assay results.

Heterocyclic (pyrazine)carboxamide Ru(ii) complexes: structural, experimental and theoretical studies of interactions with biomolecules and cytotoxicity

Treatments of N-(1H-benzo[d]imidazol-2-yl)pyrazine-2-carboxamide (HL1) and N-(benzo[d]thiazol-2-yl)pyrazine-2-carboxamide carboxamide ligands (HL2) with [Ru(p-cymene)Cl2]2 and [Ru(PPh3)3Cl2] precursors afforded the respective Ru(ii) complexes [Ru(L1)(p-cymene)Cl] (Ru1), [Ru(L2)(p-cymene)Cl] (Ru2), [Ru(L1)(PPh3)2Cl] (Ru3), and [Ru(L2)(PPh3)2Cl] (Ru4). These complexes were characterized by NMR, FT-IR spectroscopies, mass spectrometry, elemental analyses, and crystal X-ray crystallography for Ru2. The molecular structure of complex Ru2 contains one mono-anionic bidentate bound ligand and display pseudo-octahedral piano stool geometry around the Ru(ii) atom. The interactions with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were investigated by spectroscopic techniques. The experimental binding studies suggest that complexes Ru1-Ru4 interact with DNA, primarily through minor groove binding, as supported by molecular docking results. Additionally, these complexes exhibit strong quenching of the fluorescence of tryptophan residues in BSA, displaying static quenching. The in vitro cytotoxicity studies of compounds Ru1-Ru4 were assessed in cancer cell lines (A549, PC-3, HT-29, Caco-2, and HeLa), as well as a non-cancer line (KMST-6). Compounds Ru1 and Ru2 exhibited superior cytotoxicity compared to Ru3 and Ru4. The in vitro cytotoxicity and selectivity of compounds Ru1 and Ru2 against A549, PC-3, and Caco-2 cell lines surpassed that of cisplatin.

Self-Assembled Molecular Complexes of 1,10-Phenanthroline and 2-Aminobenzimidazoles: Synthesis, Structure Investigations, and Cytotoxic Properties

Three new molecular complexes (phen)3(2-amino-Bz)2(H+)(BF4-)·3H2O 5, (phen)3(2-amino-5(6)-methyl-Bz)2(H+)(BF4-)·H2O 6, and (phen)(1-methyl-2-amino-Bz)(H+)(BF4-) 7, were prepared by self-assembly of 1,10-phenanthroline (phen) and various substituted 2-aminobenzimidazoles. Confirmation of their structures was established through spectroscopic methods and elemental analysis. The X-ray diffraction analysis revealed that the crystal structure of 7 is stabilized by the formation of hydrogen bonds and short contacts. In addition, the molecular geometry and electron structure of molecules 5 and 6 were theoretically evaluated using density functional theory (DFT) methods. According to the DFT B3LYP/6-311+G* calculations, the protonated benzimidazole (Bz) units act as NH hydrogen bond donors, binding two phenanthrolines and a BF4- ion. Non-protonated Bz unit form hydrogen bonds with the N-atoms of a third molecule phen. The molecular assembly is held together by π-π stacking between benzimidazole and phenanthroline rings, allowing for N-atoms to associate with water molecules. The complexes were tested in vitro for their tumor cell growth inhibitory effects on prostate (PC3), breast (MDA-MB-231 and MCF-7), and cervical (HeLa) cancer cell lines using MTT-dye reduction assay. The in vitro cytotoxicity analysis and spectrophotometric investigation in the presence of ct-DNA, showed that self-assembled molecules 5-7 are promising DNA-binding anticancer agents warranting further in-depth exploration.

Bimetallic bis-Aroyldihydrazone-Isatin Complexes of High O=V(IV) and Low Cu(II) Valent Ions as Effective Biological Reagents for Antimicrobial and Anticancer Assays

Due to the versatile bioreactivity of aroyldihydrazone complexes as cost-effective alternatives with different transition metals, two novel bimetallic homo-complexes (VOLph and CuLph) were prepared via the coordination of a terephthalic dihydrazone diisatin ligand (H2Lph) with VO2+ and Cu2+ ions, respectively. The structure elucidation was confirmed by alternative spectral methods. Biologically, the H2Lph ligand and its MLph complexes (M2+ = VO2+ or Cu2+) were investigated as antimicrobial and anticancer agents. Their biochemical activities towards ctDNA (calf thymus DNA) were estimated using measurable titration viscometrically and spectrophotometrically, as well as the gel electrophoresis technique. The growth inhibition of both VOLph and CuLph complexes against microbial and cancer cells was measured, and the inhibition action, MIC, and IC50 were compared to the inhibition action of the free H2Lph ligand. Both VOLph and CuLph showed remarkable interactive binding with ctDNA compared to the free ligand H2Lph, based on Kb = 16.31, 16.04 and 12.41 × 107 mol-1 dm3 and ΔGb≠ = 47.11, -46.89, and -44.05 kJ mol-1 for VOLph, CuLph, and H2Lph, respectively, due to the central metal ion (VIVO and CuII ions). VOLph (with a higher oxidation state of the V4+ ion and oxo-ligand) exhibited enhanced interaction with the ctDNA molecule compared to CuLph, demonstrating the role and type of the central metal ion within the performed electronegative and electrophilic characters.

Visible Light-Prompted Regioselective Synthesis of Novel 5-Aroyl/hetaroyl-2',4-dimethyl-2,4'-bithiazoles as DNA- and BSA-Targeting Agents

Organic transformations mediated by visible light have gained popularity in recent years as they are green, renewable, inexpensive, and clean and yield excellent products. The present study describes cyclo-condensation of 2-methylthiazole-4-carbothioamide with differently substituted α-bromo-1,3-diketones achieved by utilizing a white light-emitting diode (LED) (9W) to accomplish the regioselective synthesis of novel 5-aroyl/hetaroyl-2',4-dimethyl-2,4'-bithiazole derivatives as DNA/bovine serum albumin (BSA)-targeting agents. The structure characterization of the exact regioisomer was achieved unequivocally by heteronuclear two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy [1H-13C] HMBC; [1H-13C] HMQC; and [1H-15N] HMBC. In silico toxicity studies indicated that the synthesized compounds exhibit low toxicity risks and adhere to the rules of oral bioavailability without any exception. Computational molecular modeling of the bithiazole derivatives with the dodecamer sequence of the DNA duplex and BSA identified 5-(4-chlorobenzoyl)-2',4-dimethyl-2,4'-bithiazole 7g as the most suitable derivative that can interact effectively with these biomolecules. Furthermore, theoretical results concurred with the ex vivo binding mode of the 7g with calf thymus DNA (ct-DNA) and BSA through a variety of spectroscopic techniques, viz., ultraviolet-visible (UV-visible), circular dichroism (CD), steady-state fluorescence, and competitive displacement assay, along with viscosity measurements.

Synthesis, spectral, DFT calculation, antimicrobial, antioxidant, DNA/BSA binding and molecular docking studies of bio-pharmacologically active pyrimidine appended Cu(II) and Zn(II) complexes

A new pyrimidine derivative Schiff base (HL) [HL = 2-((4-amino-6-chloropyrimidin-2-ylimino)methyl)-4-nitrophenol] has been synthesized using 2,6-diamino-4-chloropyrimidine and 5-nitrosalicylaldehyde. Transition metal complexes of Cu(II) and Zn(II) complexes [CuL(OAc)] (1), [ZnL(OAc)] (2) are prepared with HL/metal(II) acetate with molar ratio of 1:1. The Schiff base (HL) and the complexes 1 and 2 are evaluated by UV-Visible, 1H-NMR, FT-IR, EI-MS and ESR spectral techniques. Complexes 1 and 2 are confirmed as square planar geometry. Electrochemical studies of the complexes 1 and 2 are used to analyse the quasi reversible process. Density Functional Theory (DFT) using the B3LYP/6-31++G(d,p) level basis set was used to get the optimised geometry and non-linear optical properties. The complexes 1 and 2 are good antimicrobial agents than Schiff base (HL). The interactions of the HL and complexes 1 and 2 with Calf Thymus (CT) DNA are investigated by electronic absorption methods and viscosity measurements. Various molecular spectroscopy techniques, such as UV absorption and fluorescence, were used to explore the mechanism of interaction between the BSA and the ligand HL and complexes 1 & 2 under physiological settings. Complexes 1 and 2 are act as potential antioxidants than free Schiff base (HL) by DPPH radical scavenging assay. Furthermore, the purpose of the molecular docking studies was to better understand how metal complexes interact with biomolecules (CT-DNA and BSA). From these biological analyses, complex 1 acts as good intercalator with CT DNA & BSA and potent antioxidant with DPPH radical than complex 2.Communicated by Ramaswamy H. Sarma.

Novel Bromo and methoxy substituted Schiff base complexes of Mn(II), Fe(III), and Cr(III) for anticancer, antimicrobial, docking, and ADMET studies

In this study, four new Mn(II), Fe(III), and Cr(III) complexes with two Schiff base ligands namely, 4-bromo-2-[(E)-{[4-(2-hydroxyethyl)phenyl]imino}methyl]phenol (HL1) and 2-[(E)-{[4-(2-hydroxyethyl)phenyl]imino}methyl]-4-methoxy phenol (HL2) have been synthesized and characterized. Different analytical and spectral methods have been used to characterize the ligands and their complexes. General formulas of [M(L)Cl2(H2O)2] for FeL1, CrL1 and CrL2, and [M(L)Cl(H2O)3] for MnL2 were proposed. HOMO and LUMO energies, as well as the electrical characteristics, have been calculated using DFT/B3LYP calculations with Gaussian 09 program. The optimized lowest energy configurations of the complexes are proven. The disc diffusion technique was used to test the pharmacological activities' antibacterial efficacy against diverse bacterial and fungus species. The MTT technique was used to assess the in vitro cytotoxicity of the ligands and their metal complexes on the Hep-G2 human liver carcinoma cell line and the MCF-7 human breast cancer cell line. All compounds displayed better activity compared to the free ligands. MnL2 complex showed predominant activity when compared to the other complexes with an IC50 value of 2.6 ± 0.11 μg/ml against Hep-G2, and against MCF-7 the IC50 value was 3.0 ± 0.2 μg/ml which is less than the standard drug cisplatin (4.0 μg/ml). UV-vis electronic spectrum and gel electrophoresis techniques have been used to investigate the compounds' affinity to bind and cleavage CT-DNA. The interaction's binding constants, or Kb, have been identified, and it was discovered that the new complexes' binding affinities are in the order of FeL1 > MnL2 > CrL2 > CrL1, and the binding mechanism has been suggested. To assess the kind of binding and binding affinity of the investigated drugs with human DNA, a molecular docking study was carried out (PDB:1bna). The acquired results supported the intercalation binding mechanism proposed in the experimental part and revealed that complexes may be inserted into the DNA molecule to stop DNA replication. According to ADMET data, the synthesized compounds have a high bioavailability profile and their physicochemical and pharmacological features remained within Lipinski's RO5 predicted limitations.

Biologically active oxovanadium(IV) Schiff base metal complex: antibacterial, antioxidant, biomolecular interaction and molecular docking studies

The oxovanadium(IV) Schiff base metal complex (ISNPV) have been synthesized as well as characterized by using micro analytical and traditional spectroscopic techniques. The spectral findings were utilized to validate the formation of ISNPV with structure exhibited square pyramidal geometry. The in vitro antibacterial activities of ISNPV were investigated to five different bacterial stains such as S. aureus, S. epidermidis, B. cereus, B. amyloliquefaciens and B. subtilis. The obtained result have suggested that the ISNPV has highest antibacterial activity against S. aureus than the other bacterial stains. The in vitro antioxidant activity like DPPH free radical scavenging assay method was studied by ISNPV in DMSO medium. Because it scavenges all free radicals, the ISNPV possesses higher antioxidant activity than the free ligand. UV-visible absorption and emission spectral techniques were used to investigate the binding of CT-DNA to the ISNPV. Both the spectral data indicate that the ISNPV binds the double helix structure of CT-DNA via an intercalation mode. Additionally, investigate the interactions of ISNPV with the protein molecules like BSA/HAS has been investigated using absorption and emission techniques. The absorption intensity of metal complex increases as well as the emission intensity of protein molecules ability decreases due to the binding nature of ISNPV with BSA/HSA protein molecules. The binding nature of ISNPV with bio molecules such as CT-DNA, BSA and HSA was also validated using molecular docking approach.

Fluorescence monitoring of binding of a Zn (II) complex of a Schiff base with human serum albumin

Zn (II) complexes of Schiff bases have potential applications in biomedical sciences as imaging agents, cancer therapeutics and diagnostics. Thus, it is important to understand their interaction with carrier proteins, like serum albumins. The present paper focuses on the binding interactions between Human serum albumin (HSA) and Znsalampy, making use of fluorescence spectroscopic techniques at ensemble as well as at single molecular level. An idea about the binding constant is obtained from the quenching of the single Trp (Tryptophan) residue of HSA by Znsalampy. Fluorescence correlation spectroscopy (FCS) has also been used to monitor the protein-ligand binding. The location of Znsalampy in its complex with HSA is determined by competitive binding experiments and molecular docking calculations. The binding constant obtained from the Znsalampy-HSA interaction falls in the ideal range for biological applications and the location is found to be in the proximity of Sudlow's site I. The esterase activity of HSA is retained in the presence of the Znsalampy. Hence, it is concluded that this Znsalampy may be a potential probe and biomarker in biomedical applications.

Equilibria of complexes in the aqueous cobalt(II)-N-(2-hydroxybenzyl)phenylalanine system and their biological activity compared to analogous Schiff base structures

Due to their excellent prospects in biological applications, Schiff bases and their complexes are a source of continuing interest. The present study examines the formation of four cobalt(II) complexes with the reduced Schiff base N-(2-hydroxybenzyl)phenylalanine (PhAlaSal) in alkaline aqueous solution by pH-metry. UV-Vis and ESI-MS studies confirmed the model of proposed species. Kinetic analysis indicated that the single- and bi-ligand cobalt(II) complexes transitioned from octahedral to tetrahedral structures. The Schiff base and its complexes detected under physiological pH were tested for antimicrobial abilities and compared with analogous structures of the Schiff base derivative, N-(2-hydroxybenzyl)alanine (AlaSal). The ability of these structures to influence cell growth was tested on L929 mouse fibroblasts and on cervix and gastric adenocarcinoma cancer cell lines. N-(2-hydroxybenzyl)phenylalanine demonstrates greater antimicrobial efficacy than N-(2-hydroxybenzyl)alanine but also higher cytotoxicity; however, it is nonetheless effective against cancer cells. In turn, AlaSal demonstrates low cytotoxicity for fibroblasts and high cytotoxicity for gastric adenocarcinoma epithelial cells at bacteriostatic concentration for Helicobacter pylori and Candida strains. The presence of these microorganisms in the gastric milieu supports the development of gastritis and gastric cancer; AlaSal therapy may be simultaneously effective against both. Due to their cytotoxicity, Schiff base complexes are not suitable for use against fungal and bacterial infections, but may effectively prevent cancer cell growth.

Data availability

Data will be made available on request.

Turn-off detection of Cr(III) with chelation enhanced fluorescence quenching effect by a naphthyl hydrazone Shiff base chemosensor

A thiophene substituted naphthyl hydrazone derivative NHT was synthesized using a one-step route for the detection of trivalent chromium (Cr³⁺). UV-visible absorption and emission spectra, density functional theory calculations as well as ¹H NMR titration confirmed that the probe underwent a turn-off response via the chelation enhanced fluorescence quenching effect upon exposure to Cr³⁺ and the NHT-Cr³⁺ complex was formed at a 1:1 binding stoichiometry. NHT exhibited a fast response rate of 2.3 min in buffer solution and a relatively low limit of detection of 41 nM. In addition, the Schiff base chemosensor exhibited excellent selectivity with high affinity towards Cr³⁺ in the presence of other competing cations. Bioimaging of the probe in PC3 cells further demonstrated the potential real life application of the probe in detecting Cr³⁺.

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).

Design, Synthesis, Characterization, Catalytic, Fluorometric Sensing, Antimicrobial and Antioxidant Activities of Schiff Base Ligand Capped AgNPs

In recent days, the usage of biological and non-biological pollutants increased which poses a significant threat to environmental and biological systems. Therefore, the present aim is to develop effective methods to treat such pollutants by using highly stable and small-sized Schiff base ligand capped silver nanoparticles (AgNPs) with a face-centered cubic (fcc) crystalline structure and the size range is 5-10 nm. The potent role of the resulting synthesized AgNPs was found to be on multiple platforms such as catalyst, sensor, antioxidant, and antimicrobial disinfectant. The synthesized AgNPs were characterized through UV-vis spectroscopy, PL, FTIR, XRD, SEM, and TEM. The FTIR spectrum of AgNPs exhibited the interacted functional groups of Schiff base and size was estimated by XRD and TEM. AgNPs were able to catalytically degrade approximately 95% of methylene blue (MB), rhodamine B (RhB), and eosin Y (EY) dyes within 80 min of reaction time using NaBH₄. The fluorometric sensor studies of synthesized AgNPs showed selective sensing of the potentially hazardous Fe²⁺ ion in water. As an antimicrobial agent, the AgNPs are effective against both Gram-positive and Gram-negative bacteria; as well as fungi, with the zones of clearance as approximately compatible with standard drugs. The AgNPs displayed a greater ability to scavenge free radicals, especially DPPH when compared with AgNPs and ascorbic acid. Thus, the results of this study validate the triple role of AgNPs derived via a simple synthesis as a catalyst, sensor, antioxidant, and antimicrobial agent for effective environmental remediation.

Synthesis, structural studies, interaction with DNA/HSA and antitumor evaluation of new Cu(ii) complexes containing 2-(1H-imidazol-2-yl)pyridine and amino acids

New Cu(ii) complexes with promising anticancer activity induce apoptosis in HepG2 cells through DNA damage and cytotoxic ROS-mediated mitochondrial dysfunction pathways.