Antibacterial Activity Studies Research Articles

Synthesis and characterization of novel Schiff base ligands and their Cu (II), Zn (II), Co (II), and Ni (II) complexes: DNA binding, antibacterial activity, and docking studies

In this paper, we describe the process of synthesizing and characterizing of cu (II), Ni (II), Co (II) and Zn (II) coordination compounds of 4,4’-((1E,1’E) -((4chloro-1,2phenylene) bis(azanylylidine)bis (methanylylidine)) bis (naphthalene-2-ol) [CAMD] Schiff base. Elemental analysis, molar conductance, spectral data (FT-IR, 1H NMR & 13C NMR, UV-visible, EPR, XRD and mass spectra), and thermogravimetric analysis (TGA) were used to establish their formation and validate their structures. All the complexes obtained as monomeric structure and the metal center moieties are four-coordinated with square planar geometry, according to the spectral analysis. Thermogravimetric analysis (TGA) was castoff to consider the decomposition of the complexes and Schiff base ligand. Herein, the calf thymus DNA (CT DNA) binding Goldfeather#12#kinships of complexes have been examined by UV–visible spectroscopy. All complexes interact with DNA through an intercalating way. In a series of dilution experiments with Kanamycin and Fluconazole as standards, the ligand and its metallic complexes (1-4) demonstrated antimicrobial activity against a variety of bacterial and fungal species, including Gram-positive (Staphylococcus aureus, Pseudomonas aeruginosa) and Gram-negative (Escherichia coli, Bacillus Subtilis, Salmonella Typhi), as well as fungal infections, as well as fungal infections, as well as fungal infections, as well as fungal infections, yeast infections, and yeast infections. The preliminary in vitro antimicrobial screening revealed that the newly synthesised Schiff base inhibits bacterial and fungal growth significantly, compared to standard drugs. Additionally in silico studies of molecular docking were also done for Schiff base ligand and its multiplexes in the active site of DNA Gyrase enzyme (PDB code:6TCK), demonstrating strong hydrogen bonding interactions of drug targets and can be used as antibacterial drugs angainst pathogens. The performance of complexes closely matched the reactivity order seen in in-vitro studies. Overall, the complexes are intriguing candidates for antimicrobial development. We intend to use these compounds in a therapeutic context. Synthesized substances were determined to be non-toxic after undergoing ADME/T analysis to assess their drug-likeness.

In vitro study of antibacterial and anticancer activities of biosynthesized Ag-doped ZnO nanoparticles from Anisochilus Carnosus, Nephelium Lappaceum, Calotropis Gigantea

As nanoparticles exhibit various noticeable properties, showing outstanding results in nanomedicine and environmental-related problems, especially in therapeutic systems such as drug carriers for targeting the sites, etc. In this work, Ag-doped ZnO nanoparticles were synthesized via the bio-extraction method using three different plants, namely Calotropis gigantea, Nephelium lappaceum, and Anisochilus carnosus. The obtained samples were mentioned as S1, S2, and S3, respectively, and the comparison of these samples was studied. The prepared samples were further examined for their structural, morphological, and functional group studies using XRD, TEM, SEM-EDS, BET, FTIR, FT-Raman, UV, Zeta potential, and photoluminescence spectra. The results showed that the nanoparticles were highly crystalline, with a particle size ranging between 15 and 20 nm. TEM-SEM images confirmed the hexagonal, clustered, and flowered shape of the particles, with a UV absorption peak between 350 and 390 nm. The surface area of the particles in the range of 65–77 m2 g-1 with less porosity was confirmed by BET results, and the stability of the nanoparticles was confirmed by Zeta potential. Further antibacterial and anticancer activity was investigated, in which the IC50 value for a colon [HT-29] cancer cell was found to be 44.5µg/ml (S1), 39.14µg/ml (S2), and 21.81µg/ml (S3); hence, sample S3 showed higher potential cytotoxicity than the other two samples. Thus, Ag-doped ZnO nanoparticles synthesized by Anisochilus Carnosus can be considered a strong anticancer agent compared to the other two samples.

Hydroxypropyl methylcellulose stabilized clove oil nanoemulsified orodispersible films: Study of physicochemical properties, release profile, mucosal permeation, and anti-bacterial activity

Hydroxypropyl methylcellulose (HPMC)-based nanoemulsions for quick dissolving orodispersible (OD) films were prepared to encapsulate clove oil (CO) to harness its anti-bacterial properties. The influence of additives maltodextrin, pectin, and glycerol on the OD films was studied. The nanoemulsion particle size varied from 135 nm to 195 nm. A decrease in tensile strength and, an increase in elongation at break and opacity were observed in OD films compared to neat HPMC film. The AFM images showed an increase in HPMC films' average roughness from 6.95 to 90 nm after adding CO and additives. The additives controlled CO in-vitro release from HPMC following the Higuchi model. The ex-vivo permeation through porcine mucosal membrane was 9–33 % while the permeation coefficient and flux were 0.282–0.879 cm s−1 and 0.191–1.318 μg cm−2 s−1, respectively. The OD films exhibited significant inhibition of Staphylococcus aureus, Streptococcus mutans, and Porphyromonas gingivalis suggesting their therapeutic potential in oral healthcare.

Exploring Teucrium aureo-candidum Essential Oil as a Promising Alternative to Triclosan for Targeting Enoyl-Acyl Carrier Protein Reductase: Chemical Composition, Antibacterial Activity, and Molecular Docking Study.

The chemical composition of the essential oil isolated from the aerial parts of Teucrium aureo-candidum, an endemic aromatic shrub collected from Moghrar and Djeniene Bourezg in the Nâama region (Algeria), was determined for the first time using GC/FID and GC/MS. A total of 45 constituents were identified, representing 87.73% of the oil. Characterized by unique chemical variability, it was primarily composed of sesquiterpene hydrocarbons (29.53%) and oxygenated sesquiterpenes (30.06%), with the major compounds being γ-cadinene (5.24%), δ-cadinene (4.24%), α-muurolene (4.04%), τ-muurolol (11.35%), and α-cadinol (3.30%). However, monoterpene hydrocarbons and oxygenated monoterpenes accounted for 23.98% and 1.64%, respectively, contributing to a relatively low fraction. The essential oil demonstrated notable antibacterial activity, particularly against Gram-positive bacteria. Due to safety concerns associated with triclosan, a known inhibitor of the Enoyl-Acyl Carrier Protein Reductase (FabI) enzyme, the essential oil components from this plant were explored as alternatives through a combination of experimental approaches and in silico molecular docking studies. The results revealed that α-cadinol, spathulenol, caryophyllene, and α-muurolene exhibited strong FabI inhibition, with better bioavailability and lower toxicity than triclosan, highlighting their potential in combating antibiotic-resistant bacteria.

Synthesis and characterization of a cobalt(II) complex with 5-amino-1-tosyl-1h-1,2,4-triazole as a sulfonamide ligand: antibacterial and molecular docking studies

A new cobalt(II) complex, [Co(L)4Cl2]·2C9H10N4O2S (1), was prepared by reaction of CoCl2·6H2O with a sulfonamide, 5-amino-1-tosyl-1H-1,2,4-triazole (L), in double-distilled water and ethanol (1:1 v/v). The sulfonamide was characterized by elemental analysis, and infrared and 1H-NMR spectroscopy, while the Co(II) complex was characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. The X-ray structure analysis reveals that 1 consists of a mononuclear cobalt(II) complex, [Co(L)4Cl2], and two molecules of the co-crystallized ligand (5-amino-1-tosyl-1H-1,2,4-triazole). The cobalt(II) in 1 is coordinated by four triazole ligands and two chlorides in an octahedral environment. The antimicrobial activity and molecular docking of ligand and 1 were investigated. Antibacterial and antifungal activity studies of L and 1 show that both have moderate-to-significant activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria and fungi (Aspergillus niger and Candida albicans). According to molecular docking results, 1 could be a promising compound for developing antibacterial drugs. The docking results provide detailed evidence for the interactions of 1 with dihydropteroate synthase protein (DHPS). The microbial evaluation and molecular docking simulation results may lead to development of new drug candidates against bacterial and fungal strains.

Fabrication of Antibacterial and Flexible Hydrogels Based on Citric Acid Containing Tannic Acid for Wound Dressing

ABSTRACTIn this research, a biomonomer based on hydroxyethyl methacrylate, citric acid, and polyethylene glycol (HEMA‐CA‐PEG) was synthesized. After confirming the reaction through 1H‐NMR and FT‐IR tests and obtaining the intended monomer, a flexible hydrogel was synthesized as a wound dressing, and its mechanical properties were evaluated using tensile strength, DMTA, and rheometry tests. This synthesized hydrogel exhibited sufficient mechanical properties. To enhance the efficiency of this hydrogel wound dressing and its effectiveness in facilitating wound healing, tannic acid (TA), as an antibacterial and antioxidant substance, was incorporated into it. In the second phase, antibacterial activity and animal studies were conducted. The comparison of the CA–based hydrogel with and without TA demonstrated that the TA–containing hydrogel achieved more than 99.9% inhibition and elimination of bacteria. The use of CA–based hydrogel with TA shown in treating burns on the backs of rats caused the wound to close after 17 days, and hair growth was observed by the 21st day. This synthesized flexible hydrogel wound dressing, along with suitable mechanical properties, exceptional antibacterial activity, increased granulation tissue formation, re‐epithelialization, angiogenesis, and collagen deposition, showed good performance in wound healing.

Dual drug molecular salt of antibacterial: Formulation, physicochemical properties study, theoretical calculations and evaluation of antibacterial activity

A molecular salt combined with the fluoroquinolone antibacterial gatifloxacin (GAT) and the sulfonamides antibacterial sulfamerazine (SMZ) is designed and synthesized successfully, which is the first report of the dual-drug cocrystallization of gatifloxacin. The precise structure of the acquired molecule salt GAT-SMZ has been characterized via single crystal X-ray diffraction and other techniques. Single crystal diffraction analysis displays that due to the transfer of protons from SMZ to GAT, the molecular salt of GAT-SMZ is formed, and the supramolecular network is dominated by charge-assisted one-dimensional hydrogen bond chain and two-dimensional accumulation layer in the crystal. Such structural feature endows molecular salt with superior physicochemical properties, including enhanced solubility and permeability. More importantly, the superior pharmaceutical performances of the dual-drug salt resulted in enhanced antibacterial activity against the tested strains. These observations are strongly supported by theoretical studies based on Hirshfeld surface and molecular docking analyses. Thus, this contribution not only highlights the validity of combining theory with experiment to drive the problem of physicochemical properties of drugs through co-crystallization methods, but also fills in the previous studies gatifloxacin dual-drug salt synergistic antibacterial research blank.

Development of a Thermoresponsive Core–Shell Hydrogel for Sequential Delivery of Antibiotics and Growth Factors in Regenerative Endodontics

Background: Regenerative endodontics requires an innovative delivery system to release antibiotics/growth factors in a sequential trend. This study focuses on developing/characterizing a thermoresponsive core–shell hydrogel designed for targeted drug delivery in endodontics. Methods: The core–shell chitosan–alginate microparticles were prepared by electrospraying to deliver bone morphogenic protein-2 for 14 days and transforming growth factor-beta 1 (TGF-β1) for 7–14 days. Methylcellulose (MC) and gelatin were utilized to create the core–shell hydrogel to load a modified triple antibiotic combination (penicillin G/metronidazole/ciprofloxacin (PMC)) and growth factor-loaded microparticles in the shell and the core compartments, respectively. Morphological assessment, core–shell structural analysis, FTIR analysis, rheological analysis, swelling, and degradation rate studies were conducted for characterization. The viability of dental pulp stem cells (DPSCs) upon antibiotic exposure, antibacterial activity, and release studies of PMC and growth factors were investigated. Cellular studies (cell viability, alkaline phosphatase (ALP) activity, osteo/odontoblast gene expression (using Reverse transcription-polymerase chain reaction (RT-PCR)) and in vivo studies (inflammatory response and differentiation potential of the developed hydrogel by subcutaneous implantation in rats via histological examination) were assessed. Results: The hydrogel showed a porous microstructure with interconnected pores. Core–shell structure analysis confirmed the successful extrusion of the MC hydrogel to the surface. FTIR analysis revealed interactions between MC and gelatin. Rheological analysis indicated time-dependent gel formation, supporting thermosensitivity at 37 °C. Swelling occurred rapidly, and degradation reached 62.42% on day 45. Further, antibiotics exhibited no cytotoxicity on DPSCs. Sequential release of antibiotics and growth factors was observed for up to 5 and 14 d, respectively. The hydrogel showed antibacterial activity. DPSCs exhibited increased proliferation, ALP activity, and odontoblast gene expression. In vivo studies showed that the biocompatible drug-loaded hydrogel exhibited more mineralization than the control. Conclusions: The developed core–shell hydrogel containing PMC and growth factor-loaded core–shell microparticles provided a versatile and biocompatible platform for sequential drug delivery in regenerative endodontics. The system demonstrates promising characteristics for dentin regeneration, making it a potential candidate for clinical applications.

Alpinia officinarum Hance Essential Oil as Potent Antipseudomonal Agent: Chemical Profile, Antibacterial Activity, and Computational Study.

Alpinia officinarum Hance, is an aromatic and medicinal herb with a very interesting history and prominent chemical and biological prospects. We aimed to investigate the antibacterial activity of Alpinia officinarum essential oil and the preferred molecular targets of its constituents together with their pharmacokinetic properties and toxicity profile. According to GC-MS analysis, eucalyptol was the main compound (27.52 %) identified in Alpinia officinarum essential oil, followed by α-terpineol, and β-sesquiphellandrene. As opposed to the weak antiradical activity estimated by DPPH and ABTS tests, the essential oil caused inhibition of all the bacteria following well-diffusion and microdilution methods, especially the gram-negative Pseudomonas aeruginosa and Escherichia coli. It displayed exceptionally remarkable activity against Pseudomonas aeruginosa by totally inhibiting its growth on the agar plate exceeding the effect of chloramphenicol standard. This bactericidal effect was confirmed by very low MIC and MBC values of 0.82 and 6.562 μg/mL, respectively. The molecular docking showed interesting binding affinity between the major compounds and various drug targets in Pseudomonas aeruginosa, also good pharmacokinetic and toxicity behavior. These encouraging findings are particularly relevant in light of the increasingly pressing challenge to find alternative substances with antibacterial aptitude to address the issue of antibiotic resistance among infectious bacteria.

Physico-mechanical properties, hydroxyapatite conversion, biodegradability and antibacterial activity studies of melt-derived BGs based on SiO2-CaO-Na2O-P2O5 quaternary system

The slow biodegradation and low hydroxyapatite (HA) conversion of silicate-based bioactive glasses (BGs) have severely limited their compatibility with biological tissues. To address these challenges, four samples in the form of (52-x)SiO2-24Na2O-24CaO-xP2O5, where x is 2, 4, 6, and 8 mol%, were prepared by a unified melt-quenching method, and the feasibility of P2O5 content fine-tuning in improving glass structure, biodegradability, bioactivity, and antibacterial efficiency was evaluated. The results indicated that as the degree of P2O5 substitution increased, the network structure of the glass became looser, which provided favourable conditions for its degradation. The variation in activation energy for Si4+ ion release from 0.39 eV to 0.25 eV also supported this observation. After 7 days of immersion in simulated body fluid (SBF), analyses by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) confirmed that the Ca-P compounds deposited on the glass surfaces were essentially hydroxycarbonated apatite (HCA), and scanning electron microscopy (SEM) images revealed that the generation rate of the HCA were positively correlated with the P2O5 content in the glass system. Meanwhile, antibacterial studies showed that after 24 h of incubation, the antibacterial activity of the four glass samples against Escherichia coli (E. coli) successively increased, with the highest percentage reaching 87.13 ± 2.51 %. In conclusion, this study demonstrates that controllable degradation and high-level bioactivity can be achieved by modulating the P2O5 content in silicate-based BGs, which proves to be an effective and practicable strategy.

Antibacterial activity study of Urea-Trimesic acid and 2, 3-dihydro-1,5- benzodiazepine-picric acid based cocrystals

The antibacterial activity of two cocrystals of Urea-Trimesic acid (1) and 2,3-dihydro-1,5- benzodiazepine-Picric acid (2) is reported. Cocrystals 1 and 2 show antibacterial effects with Escherichia coli and Staphylococcus aureus via the Disk Diffusion Test method with the zone of inhibition as comparable to the positive control Chloramphenicol whereas the individual coformers are found to be less potent under the same condition. The insilico molecular docking has been used to acquire binding modes and binding affinities for both the cocrystals 1 and 2 and the respective of conformers where the protein structure (d-lactate dehydrogenase) (DLDH) of E. coli and Staphylococcus aureus show remarkable binding affinity with cocrystals 1 and 2 as compared to the respective coformers.

Synthesis and characterization of hydrazone derivative and its antibacterial, antifungal, antimalarial and antituberculosis activity studies

Synthesis and characterization of hydrazone derivative and its antibacterial, antifungal, antimalarial and antituberculosis activity studies

Disease-Inspired Design of Biomimetic Tannic Acid-Based Hybrid Nanocarriers for Enhancing the Treatment of Bacterial-Induced Sepsis.

This study explored the development of novel biomimetic tannic acid-based hybrid nanocarriers (HNs) for targeted delivery of ciprofloxacin (CIP-loaded TAH-NPs) against bacterial-induced sepsis. The prepared CIP-loaded TAH-NPs exhibited appropriate physicochemical characteristics and demonstrated biocompatibility and nonhemolytic properties. Computational simulations and microscale thermophoresis studies validated the strong binding affinity of tannic acid (TA) and its nanoformulation to human Toll-like receptor 4, surpassing that of the natural substrate lipopolysaccharide (LPS), suggesting a potential competitive inhibition against LPS-induced inflammatory responses. CIP released from TAH-NPs displayed a sustained release profile over 72 h. The in vitro antibacterial activity studies revealed that CIP-loaded TAH-NPs exhibited enhanced antibacterial efficacy and efflux pump inhibitory activity. Specifically, they showed a 3-fold increase in biofilm eradication activity against MRSA and a 2-fold increase against P. aeruginosa compared to bare CIP. Time-killing assays demonstrated complete bacterial clearance within 8 h of treatment with CIP-loaded TAH-NPs. In vitro DPPH scavenging and anti-inflammatory investigations confirmed the ability of the prepared hybrid nanosystem to neutralize reactive oxygen species (ROS) and modulate LPS-induced inflammatory responses. Collectively, these results suggest that CIP-loaded TAH-NPs may serve as an innovative nanocarrier for the effective and targeted delivery of antibiotics against bacterial-induced sepsis.

Parkinsonia praecox bark as a new source of antibacterial and anticancer compounds

IntroductionParkinsonia praecox is used in traditional medicine to treat various diseases; however, the antibacterial and anticancer properties from its bark have not been reported. Thus, this study aimed to evaluate the antibacterial activity, cytotoxicity and chemical study of methanolic extract of Parkinsonia praecox bark (PpBM). MethodsThe PpBM antibacterial activity was determined against pathogen strains using the broth microdilution method, the cytotoxic effect was assessed on cancerous (HepG2, SKOV-3 and HeLa) and non-cancerous (J774A.1 and HaCaT) cells using the crystal violet assay, the in vitro hemotoxicity was evaluated using the hemolysis assay on human erythrocytes and the identification of major compounds derived from PpBM was performed by 1H and 13C NMR and 2D NMR experiments. ResultsPpBM (2000 µg/mL) demonstrated antibacterial activity against Listeria monocytogenes, a potential breakthrough in the fight against this pathogen. PpBM decreased cell viability of HepG2 liver cancer cells (IC50, 104.56 µg/mL) with a selectivity index of 1.38 regarding J774A.1 macrophages and 2.04 to HaCaT keratinocytes, suggesting a selective anticancer potential. On the other hand, PpBM did not cause hemolysis to high concentrations (1000 µg/mL) or alterations in the morphology of human erythrocytes at doses lower than 200 µg/mL. For the first time, lupenone, germanicone, 3-oxo-oleanane-18-en-28-ol, and combretol were identified in P. praecox. PpBM showed antibacterial, selective anticancer, and non-hemotoxic properties. These activities may be related to the major compounds, such as lupenone. ConclusionP. praecox bark is a new option for obtaining bioactive compounds, further in vitro and in vivo studies are required to confirm their efficacy and safety.

Rapid in-situ green synthesis and antibacterial properties of silver nanoparticles

In-situ green synthesis of silver nanoparticles (AgNPs) using hydroxypropyl-methylcellulose (HPMC) as a reducing and stabilizing agent is presented in this paper. A simple solution-casting method is used for preparing nanocomposite films. The reduction of silver ions to silver elementary particles was completed when the alkaline pH was maintained. The initial confirmation of AgNPs was visualized by the brown color of the prepared solution and later confirmed by the surface Plasmon resonance peak obtained from the UV–visible absorption study. X-ray diffraction measurement study revealed the crystalline nature of the AgNPs with FCC structure. The uniform distribution of AgNPs in the HPMC matrix is witnessed by Scanning electron microscope. The spherical shape of the prepared AgNPs is observed by transmission electron microscopic images with an average size of 11 nm. Dynamic light scattering experiment exposed the hydrodynamic size distribution and good stability of AgNPs. Thermogravimetric analysis showed high thermal stability of nanocomposites. Mechanical studies showed increased elongation at break and tensile strength of the prepared nanocomposites. Dielectric constant and dielectric loss were ascertained to decrease with an increase in frequency. Further, the antibacterial activity study showed an excellent activity of AgNPs in contrast to human bacterial pathogens viz.,Staphylococcus aureusandEscherichia coli.

IN VITRO EVALUATION OF THE ANTIBACTERIAL EFFECT OF CHITOSAN COATED TEICOPLANIN-LOADED LIPID NANOPARTICLES AGAINST STAPHYLOCOCCUS AUREUS

Objective: The aim of this research is to formulate teicoplanin-loaded solid lipid nanoparticles (SLN) coated with chitosan to sustain teicoplanin release for effective antibacterial therapy. Material and Method: “Double emulsion-solvent evaporation technique was used for the production of SLNs. The nanoparticles were characterised in terms of morphology, size, encapsulation efficacy, in-vitro drug release and antibacterial activity studies after optimization of process and formulation parameters. Result and Discussion: Transmission electron microscopy images confirmed the formation of spherical SLNs. With chitosan coating, the size increased (from 80 nm to 106 nm) and the negative value of zeta potential (- 11.29) changed to positive (+34.41). The in-vitro release data showed prolonged release of teicoplanin from optimized SLN and chitosan-coated SLN (c-SLN) formulations over 1 week. The antibacterial activity study (S. aureus and Methicillin-resistant S. aureus) showed the activity of the teicoplanin loaded SLN formulations. In conclusion, this study demonstrated the potential of c-SLN for effective delivery of teicoplanin.

Si/Polymer/Natural Drug Materials Prepared by Sol–Gel Route: Study of Release and Antibacterial Activity

AbstractThis study aims to develop a new class of versatile silica‐based materials for medical applications, synthesized via the sol–gel method. Different molecules are incorporated into the silica matrix to improve its biological properties and to use these materials as better‐performing implants. Polyethylene glycol (PEG) is added to silica‐based materials to improve biocompatibility, increase hydrophilicity, and enhance cellular adhesion and growth. The effect of loading the silica/PEG matrix with chlorogenic acid (CGA), a natural compound present in different types of plants, is investigated to understand how the material is affected. The interactions among different components in the hybrid materials are studied by Fourier‐transform infrared (FTIR) spectroscopy. Furthermore, the materials are encapsulated in 2% w/v of alginate to evaluate the different releases of CGA, using UV‐Vis Spectrophotometer. Finally, antimicrobial assessment against Escherichia coli and Pseudomonas aeruginosa of the several hybrids is observed by measuring the diameter of the zone of inhibition.

Chemical Composition, Antibacterial Activity, and ADME Studies of Leaf Essential Oil of Piper betle

Chemical Composition, Antibacterial Activity, and ADME Studies of Leaf Essential Oil of Piper betle

Study of Total Phenols, Flavonoids, Antioxidant and Antibacterial Activities from Dioscorea hispida Tubers

The tubers of Dioscorea hispida Dennst., a Dioscoreaceae plant, contain flavonoid molecules and plant secondary metabolites that are antioxidants and antibacterials. In this study, the total phenolic content and flavonoids from the ethanol extract and fraction (n-hexane and ethyl acetate) of Dioscorea tuber were investigated for their antioxidant and antibacterial properties. Fractionation with n-hexane and ethyl acetate followed by diffusion with 96% ethanol. The Folin-Ciocalteau reagent measured total phenol at 765 nm, and the AlCl3 method measured total flavonoid at 440 nm using a visible spectrophotometer. The DPPH assessed the antioxidant activity, whereas the antibacterial activity against Staphylococcus aureus and Escherichia coli was determined using agar diffusion on paper discs. The extract, n-hexane fraction, and ethyl acetate exhibited total phenolic content of 33.02, 5.95, and 156.33 mg GAE/g extract, respectively. Similarly, the total flavonoid content was measured at 20.26, 14.31, and 74.02 mg QE/g extract. The extract, n-hexane fraction, and ethyl acetate of the Dioscorea tuber exhibited minimum inhibitory concentrations (MICs) of 8.25, 7.76, and 10.30 mg/mL against S. aureus and 8.51, 8.31, and 12.05, against E. coli, respectively. The findings of this study indicate that the ethanol extract and n-hexane fraction derived from Dioscorea tubers exhibited comparatively diminished antioxidant and antibacterial properties in comparison to the ethyl acetate fraction. Furthermore, the ethyl acetate fraction exhibited elevated concentrations of total phenols and total flavonoids in comparison to the remaining fractions.

Arene ruthenium(II) complexes with 3-acetyl coumarin derivatives bearing a 3-hydroxy-2-naphthoic hydrazide moiety: Synthesis, DFT calculations and antioxidant studies

The reaction of [(arene)RuCl2]2 with coumarin hydrazone ligands in methanol yielded neutral chelating mononuclear N∩O metal complexes having the general formula [(arene)Ru(L)Cl] where arene = p-cymene, benzene; and L = 3‑hydroxy-N'-(1-(2-oxo-2H-chromen-3-yl)ethylidene)-2-naphthohydrazide (L1), 3‑hydroxy-N'-(1-(7‑methoxy-2-oxo-2H-chromen-3-yl)ethylidene)-2-naphthohydrazide (L2), (E)-N'-(1-(6‑bromo-2-oxo-2H-chromen-3-yl)ethylidene)-3‑hydroxy-2-naphthohydrazide (L3) and 3‑hydroxy-N'-(1-(3-oxo-3H-benzo[f]chromen-2-yl)ethylidene)-2-naphthohydrazide (L4)}. All complexes (1–8) were fully characterized by spectroscopic techniques like IR, UV–Vis, NMR and ESI-MS spectral methods. The solid-state molecular structures of the three complexes were determined using a single-crystal X-ray diffraction study. The studies revealed that the ligands binding mode to the ruthenium metal centers is through the azomethine nitrogen and the imidolate oxygen forming a five-membered chelating ring. All the complexes and the ligands were screened for antibacterial and antioxidant activity studies. Some of the complexes exhibited antioxidant activity that is more prominent than their respective ligands.