Molecular docking, structural characterization, DFT and cytotoxicity studies of metal(II) Schiff base complexes derived from thiophene-2-carboxaldehyde and l-histidine

Silver(I), Zinc(II) and Gallium(III) thiophene-2-carboxylates: Synthesis, solution and solid state characterization and bioevaluation

Three 2-thiophenecarboxylate (Tio2c) complexes with different central atoms Ag(I), Zn(II) and Ga(III), [Ag(Tio2c)]2 (AgTio2c), {[Zn2(Tio2c)4]2}n (ZnTio2c) and [Ga(Tio2c)3]·H2O (GaTio2c), were synthesized and elemental, spectral and thermal analyses were used for their characterization. The AgTio2c and ZnTio2c single crystal structures confirmed the most common bidentate bridging coordination mode with typical strong argentophilic interactions in the case of AgTio2c complex. Complexes' stability in biological test stock solution were confirmed by 1H NMR spectroscopy. Potentiometric data analysis by BSTAC program resulted in the determination of the stability constants of four complex species, [Zn(Tio2c)]+ (log β110 = 2.06 ± 0.04), [Zn(Tio2c)(OH)] (log β11-1 = -5.0 ± 0.1), [Zn(Tio2c)(OH)2]- (log β11-2 = -12.9 ± 0.4) and [Zn(Tio2c)2(OH)2]2- (log β12-2 = -8.54 ± 0.04) with low abundance in aqueous solution. Theoretical estimation of the complex species in aqueous solution indicates a rather monodentate Tio2c coordination mode in the [Zn(Tio2c)]+ species, while the hydroxido complex species prefer a rather bidentate O,O'-bond of the carboxylate. Antimicrobial and anticancer bioassays clearly confirmed the highest biological activity (toxicity) of the AgTio2c complex. The activity of ZnTio2c was slightly higher (or the same) compared to GaTio2c. The HSA (human serum albumin) binding behaviour of the AgTio2c, ZnTio2c and GaTio2c complexes was investigated using fluorescence spectroscopy and results revealed that the calculated Kb values were in the order of 104 M-1.

Cytotoxicity Profile of Schiff Base Organotin(IV) Complexes: Experimental and Theoretical Approach

Present work deals with the synthesis, characterization and biological investigation of Schiff base ((E)N'(2,3-dihydroxybenzylidene)isonicotinohydrazide (L)) and its diorganotin(IV) complexes (R2SnL, diphenyltin(IV) complex R = Ph (1), dimethyltin(IV) complex R = Me(2))by experimental and theoretical approach. All the complexes were characterized by spectroscopic techniques including FTIR, multinuclear NMR and theoretical studies. Theoretical calculations were carried out using Gaussian 09 software which also supports the experimental analysis. Molecular docking studies using Autodock software were carried out to predict the binding pose and affinity of the complexes towards particular proteins. DNA binding studies by UV titrations and in-silico studies showed the superior binding of diphenyltin(IV) complex (1) and dimethyltin(IV) complex (2) in an intercalative mode. In- vitro cytotoxicity analysis of L and its complexes (1, 2) was carried out against two cancer cell lines using MTT assay. Diphenyltin(IV) complex (1) was more potent and cytotoxic against studied cancer cell lines i.e.C6 Glioblastoma cells and SH-SY5Y Neuroblastoma cells.

Medicinal chemistry-based perspectives on thiophene and its derivatives: exploring structural insights to discover plausible druggable leads

Thiophene is a privileged pharmacophore in medicinal chemistry owing to its diversified biological attributes. The thiophene moiety has been ranked 4th in the US FDA drug approval of small drug molecules, with around 7 drug approvals over the last decade. The present review covers USFDA-approved drugs possessing a thiophene ring system. Our analysis reveals that 26 drugs possessing thiophene nuclei have been approved under different pharmacological classes. The review further covers reported thiophene and its substituted analogues with diverse biological activities, including anti-diabetic, anticancer, anti-inflammatory, anticonvulsant, and antioxidant activity. Besides, a section is dedicated to appreciating the implications of structural bioinformatics in drug discovery. Additionally, the manuscript delves into structure-activity relationship studies to explore the chemical groups responsible for eliciting potential therapeutic activities. The review may provide invaluable insights for researchers working with thiophene nuclei in developing novel analogues with greater efficacy and fewer side effects.

Exploring Thermal Stability, Vibrational Properties, and Biological Assessments of Dichloro(l-histidine)copper(II): A Combined Theoretical and Experimental Study

Dichloro(l-histidine)copper(II) crystal ([Cu(l-His)Cl2] complex) was obtained by the slow evaporation method and characterized concerning its thermal stability, phase transformations, and electronic and vibrational properties. X-ray diffraction (XRPD) confirmed that this complex crystallizes with an orthorhombic structure (P212121 space group). Thermal analyses (TG and DTA) demonstrate stability from ambient temperature up to 460 K, followed by a phase transition from the orthorhombic structure to the amorphous form around 465 K, as confirmed by temperature-dependent XRPD studies. The active modes in Fourier transform infrared (FT-IR) and Raman spectroscopy spectra were suitably assigned via density functional theory (DFT) calculations. Additionally, Hirshfeld surface analysis uncovered the prominence of Cl···H, O···H, and H···H interactions as the primary intermolecular forces within the crystal structure. The antimicrobial activity of the [Cu(l-His)Cl2] complex was investigated, demonstrating significant efficacy against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa), and fungi (Candida albicans). The minimum inhibitory concentration and cell viability tests showed that the complex inhibits the growth of S. aureus bacteria at a concentration of 1.5 μM without causing damage to the human cell line. The pharmacokinetic parameters corroborate the other tested parameters and highlight the [Cu(l-His)Cl2] complex as a promising alternative for future clinical trials and medicinal applications. The alignment of the pharmacokinetic parameters with other tested criteria highlights the potential of the [Cu(l-His)Cl2] complex as a promising candidate for future clinical studies.

Anticancer Potential of the S-Heterocyclic Ring Containing Drugs and its Bioactivation to Reactive Metabolites

Sulfur-containing heterocyclic derivatives have been disclosed for binding with a wide range of cancer-specific protein targets. Various interesting derivatives of sulfur-containing heterocyclics such as benzothiazole, thiazole, thiophene, thiazolidinedione, benzothiophene, and phenothiazine, etc have been shown to inhibit diverse signaling pathways implicated in cancer. Significant progress has also been made in molecular targeted therapy against specific enzymes such as kinase receptors due to potential binding interactions inside the ATP pocket. Sulfur-containing heterocyclic ring metal complexes i. e., benzothiazole, thiazole, thiophene, benzothiophene and phenothiazines are among the most promising active anticancer compounds. However, sulfur heteroaromatic rings, particularly thiophene, are of high structural alert due to their metabolism to reactive metabolites. The mere presence of a structural alert itself does not determine compound toxicity therefore, this review focuses on some specific findings that shed light on factors influencing the toxicity. In the current review, synthetic strategies of introducing the sulfur core ring in the synthesized derivatives are discussed with their structure-activity relationships to enhance our understanding of toxicity mechanisms and develop safer therapeutic options. The sulfur-containing marketed anticancer drugs included in this review direct the synthesis of novel compounds and will help in the development of potent, safer sulfur-based anticancer drugs in near future.

The Tissue Browning and Concomitant Toughening of Yellow Flammulina filiformis Stipes Is Caused by Oxidative Damage-Mediated Metabolic Disorder and Cell Wall Glycan Remodeling

The browning and associated toughening of fruiting body stipes are the main causes of declines in the commercial production of yellow Flammulina filiformis. The dynamic metabolic changes from the top to bottom stipe sections of yellow F. filiformis fruiting bodies were investigated by integrating physiological, transcriptomic, and metabolomic analyses. The results indicated that oxidative stress levels gradually increased accompanying the degree of tissue browning and toughening from the top to bottom sections of F. filiformis stipes. In-depth analysis showed that there were remarkable changes in the expression of genes, and the content of metabolites correlated with the primary and secondary metabolism of F. filiformis stipes. Interestingly, the expression levels of genes participating in chitosan biosynthesis and the degree of deacetylation of chitosan increased from top to bottom in F. filiformis stipes, implying that cell wall glycan remodeling may contribute to concomitant toughening of the browning of F. filiformis stipes.

Synthesis and Characterization of Zinc(II), Cadmium(II), and Palladium(II) Complexes with the Thiophene-Derived Schiff Base Ligand

Zn(II), Pd(II), and Cd(II) complexes, [L _TH MCl ₂ ] (M = Zn, Pd; X = Br, Cl) and [L _TH Cd(μ-X)X] _n (X = Cl, Br; n = n, 2), supported by the (E)-N ¹,N ¹-dimethyl-N ²-(thiophen-2-ylmethylene)ethane-1,2-diamine (L _TH ) ligand are synthesized and structurally characterized. Density functional theory (DFT) electronic structure calculations and variable-temperature NMR support the presence of two conformers and a dynamic interconversion process of the minor conformer to the major one in solution. It is found that the existence of two relevant complex conformers and their respective ratios in solution depend on the central metal ions and counter ions, either Cl^- or Br^-. Among the two relevant conformers, a single conformer is crystallized and X-ray diffraction analysis revealed a distorted tetrahedral geometry for Zn(II) complexes, and a distorted square planar and square pyramidal geometry for Pd(II) and Cd(II) complexes, respectively. It is shown that [L _TH MCl ₂ ]/LiO ⁱ Pr (M = Zn, Pd) and [L _TH Cd(μ-Cl)Cl] _n /LiO ⁱ Pr can effectively catalyze the ring-opening polymerization (ROP) reaction of rac-lactide (rac-LA) with 94% conversion within 30 s with [L _TH ZnCl ₂ ]/LiO ⁱ Pr at 0 °C. Overall, hetero-enriched poly(lactic acid)s (PLAs) were provided by these catalytic systems with [L _TH ZnCl ₂ ]/LiO ⁱ Pr producing PLA with higher heterotactic bias (P _r up to 0.74 at 0 °C).

Anti-proliferative, apoptotic potential of synthesized selenium nanoparticles against breast cancer cell line (MCF7)

Nano-biotechnology has grown rapidly and become an integral part of modern disease diagnosis and treatment. The aim of this survey was to evaluate the anticancer activity of synthesized selenium nanoparticles (Se-NPs) against breast cancer cells (MCF-7). The prepared Se-NPs were examined by ultraviolet-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDX). Antioxidant activity of Se-NPs property was studied by radical scavenging (DPPH) assay. The in-vitro cytotoxicity of Se-NPs was evaluated by MTT assay. In addition; the biological assessment (antioxidant and cytotoxicity) of synthesized Se-NPs was examined via molecular docking simulations. Synthesis of Se-NPs was characterized by several studies such as UV-absorbance, showing peak values in the range of 268 nm. Nanoparticle sizes of the nanoparticles are confirmed by dynamic light scattering analysis, indicating that average size is about 203 nm. The quantity of selenium in Se-NPs is 90.15% by weight, as confirmed by EDX. Synthesized Se-NPs have anti-proliferative effects on MCF-7 cell lines. Cytotoxicity and apoptotic potential assays exhibited a dose-dependent effect against MCF-7 cells using an MTT assay. Like anti-cancer activity, anti-oxidant activity of Se-NPs was dose-dependent. Findings showed that the Se-NPs complexes have the highest inhibitory effect against cytotoxic and antioxidant receptors. Results of this study demonstrated that Se-NPs had strong potential to scavenge free radicals and are cytotoxic against the MCF-7 cancer cell line.

Thiophene-Based Compounds with Potential Anti-Inflammatory Activity

Rheumatoid arthritis, arthrosis and gout, among other chronic inflammatory diseases are public health problems and represent major therapeutic challenges. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most prescribed clinical treatments, despite their severe side effects and their exclusive action in improving symptoms, without effectively promoting the cure. However, recent advances in the fields of pharmacology, medicinal chemistry, and chemoinformatics have provided valuable information and opportunities for development of new anti-inflammatory drug candidates. For drug design and discovery, thiophene derivatives are privileged structures. Thiophene-based compounds, like the commercial drugs Tinoridine and Tiaprofenic acid, are known for their anti-inflammatory properties. The present review provides an update on the role of thiophene-based derivatives in inflammation. Studies on mechanisms of action, interactions with receptors (especially against cyclooxygenase (COX) and lipoxygenase (LOX)), and structure-activity relationships are also presented and discussed. The results demonstrate the importance of thiophene-based compounds as privileged structures for the design and discovery of novel anti-inflammatory agents. The studies reveal important structural characteristics. The presence of carboxylic acids, esters, amines, and amides, as well as methyl and methoxy groups, has been frequently described, and highlights the importance of these groups for anti-inflammatory activity and biological target recognition, especially for inhibition of COX and LOX enzymes.

Coordination of Redox Ions within a Membrane-Binding Peptide: A Tale of Aromatic Rings

The amino-terminal-copper-and-nickel-binding (ATCUN) motif, a tripeptide sequence ending with a histidine, confers important functions to proteins and peptides. Few high-resolution studies have been performed on the ATCUN motifs of membrane-associated proteins and peptides, limiting our understanding of how they stabilize Cu²⁺/Ni²⁺ in membranes. Here, we leverage solid-state NMR to investigate metal-binding to piscidin-1 (P1), a host-defense peptide featuring F1F2H3 as its ATCUN motif. Bound to redox ions, P1 chemically and physically damages pathogenic cell membranes. We design ¹³C/¹⁵N correlation experiments to detect and assign the deprotonated nitrogens produced and/or shifted by Ni²⁺-binding. Occupying multiple chemical states in P1-apo, H3 and the neighboring H4 respond to metalation by populating only the τ-tautomer. H3, as a proximal histidine, directly coordinates the metal, compared to the distal H4. Density functional theory calculations reflect this noncanonical arrangement and point toward cation-π interactions between the F1/F2/H4 aromatic rings and metal. These structural findings, which are relevant to other ATCUN-containing membrane peptides, could help design new therapeutics and materials for use in the areas of drug-resistant bacteria, neurological disorders, and biomedical imaging.

Tridentate imidazole-based Schiff base metal complexes: molecular docking, structural and biological studies

A novel Schiff base was synthesized by the condensation of imidazole-2-carboxaldehyde with l-histidine in an equimolar ratio. The prepared Schiff base was characterized by elemental analysis and spectral characterization techniques. It was then complexed with a series of 3-d metal(II) ions like manganese, iron, cobalt, nickel, copper and zinc. The coordination properties, nature of bonding and stability of the complexes were deduced from elemental analysis, IR, UV-vis, ¹H NMR, mass, electronic spectra, magnetic, conductivity and thermogravimetric analysis. IR studies support the tridentate behaviour of Schiff base as well as its coordination to the central metal ion through an azomethine nitrogen, deprotonated carboxylic oxygen and imidazole ring nitrogen atoms of histidine. The electronic spectra and magnetic moment data demonstrate that the complexes have an octahedral geometry, except zinc complex, which has a tetrahedral geometry. In vitro antimicrobial activity of the synthesized compounds has been shown to exhibit excellent antibacterial and antifungal activities. The antibacterial property of the prepared Schiff base was further confirmed by conducting a docking study of target proteins involved in the antibacterial mechanism.Communicated by Ramaswamy H. Sarma.

Dual-emission CdTe quantum dot@ZIF-365 ratiometric fluorescent sensor and application for highly sensitive detection of l-histidine and Cu2

l-histidine acts as a semi-essential amino acid, which is medically used in the treatment of gastric ulcer, anemia, allergies. However, the overuse of l-histidine will result in terrible damage to heart disease, slow growth of animals and water pollution in the environment. In addition, Cu²⁺ pollution is common environmental pollution in the industry. It has the characteristics of high accumulation, migration, and persistence. Given this, through the post-synthesis strategy, CdTe quantum dots (QDs) were the first time to introduce into zeolitic imidazolate framework-ZIF-365 to synthesis dual-emission hybrid material CdTe@ZIF-365 with high quantum yield. TEM mappings and N₂ absorption tests are applied to confirm the combination mode between CdTe quantum dots and ZIF-365. It should be noted that CdTe@ZIF-365 can be successfully utilized as a bi-functional ratiometric sensor for highly sensitive discrimination of l-histidine and Cu²⁺. Firstly, CdTe@ZIF-365 is applied to a fluorescent ratiometric sensor for Cu²⁺ with high sensitivity (the K_sv value is 2.7417✕10⁷ [M^-1]) and selectivity in the mixed cation ions' solution. On the other hand, CdTe@ZIF-365 also behaved as the first example for an excellent ratiometric fluorescent senor for l-histidine with high sensitivity (the K_sv value is 6.0507✕10⁸ [M^-1]) and selectivity in the mixed amino acids' solutions.