Antimicrobial Activity Studies Research Articles

Algorithm for the development of a multicomponent pharmaceutical substance of plant origin with antimicrobial action: from science search to dosage form

Introduction. Despite the proven clinical efficacy of antifungal and anti-inflammatory drugs for the prevention and treatment of seborrheic dermatitis, the search for new targets and the development of new substances with a beneficial effect on the scalp microflora, with a low risk of antimicrobial resistance and adverse effects, are relevant.Aim. Development of the antimicrobial multicomponent pharmaceutical substance of plant origin in stages: from a literature search for promising substances, analysis of their composition by GC-MS, in silico evaluation of the affinity of individual components to pathogenetic targets, selection of the optimal composition of a multicomponent substance based on the results of in vitro research of antimicrobial action and the making of a medical dosage form based on it – a medicinal shampoo for the treatment of seborrheic dermatitis.Materials and methods. Objects of research: tea tree essential oil, 1,8-cineole, α-(-)-bisabolol and the multicomponent substance based on them. Methods: molecular docking (AutoDock version 4.2), prediction of pharmacological activity (Phyto4Health), TLC, GC-MS, study of antimicrobial activity in vitro.Results and discussion. Based on the results of a literature search, 3 promising substances were selected for the development of a multicomponent plant-based substance: tea tree essential oil, 1,8-cineole and α-(-)-bisabolol. Molecular docking predicted the targeted activity of the phytochemicals of tea tree essential oil, 1,8-cineole and α-(-)-bisabolol on the domains of ABC-transporters of microorganisms involved in the pathogenesis of seborrheic dermatitis and justified the possibility of use for therapy. The multicomponent substance has been developed based on tea tree essential oil, 1,8-cineole and α-(-)-bisabolol in a mass ratio of 1 : 1 : 1. The qualitative composition of the substance was assessed by TLC and GC-MS methods, and 15 terpenes were quantitatively identified in its composition with a predominance of terpinen-4-ol (16.98 %), 1,8-cineole (25.63 %) and α-(-)-bisabolol (27.67 %). The synergistic antimicrobial activity of the substance has been established against S. epidermidis, S. aureus, C. albicans and M. furfur in comparison with benzalkonium chloride, ketoconazole and climbazole. The composition of a new medical shampoo based on the investigated substance has been developed, which has a pronounced antifungal effect (more than 99.0 %) against M. furfur without visible suppression of normal microflora. For the novel substance of plant origin and medical shampoo, quality parameters were assessed in accordance with the Russian Pharmacopoeia of XIV edition.Conclusion. A substance of plant origin with synergistic and targeted antimicrobial activity has been developed. It has an interest for further study as a drug and API for new products for the treatment of seborrheic dermatitis.

Search for new biologically active compounds: in vitro studies of antitumor and antimicrobial activity of dirhodium(II,II) paddlewheel complexes.

Four neutral Rh1-Rh4 complexes of the general formula [Rh2(CH3COO)4L2], where L is an N-alkylimidazole ligand, were synthesized and characterized using various spectroscopic techniques, and in the case of Rh4 the crystal structure was confirmed. Investigation of the interactions of these complexes with HSA by fluorescence spectroscopy revealed that the binding constants Kb are moderately strong (∼104 M-1), and site-marker competition experiments showed that the complexes bind to Heme site III (subdomain IB). Competitive binding studies for CT DNA using EB and HOE showed that the complexes bind to the minor groove, which was also confirmed by viscosity experiments. Molecular docking confirmed the experimental data for HSA and CT DNA. Antimicrobial tests showed that the Rh2-Rh4 complexes exerted a strong inhibitory effect on G+ bacteria B. cereus and G- bacteria V. parahaemolyticus as well as on the yeast C. tropicalis, which showed a higher sensitivity compared to fluconazole. The cytotoxic activity of Rh1-Rh4 complexes tested on three cancer cell lines (HeLa, HCT116 and MDA-MB-231) and on healthy MRC-5 cells showed that all investigated complexes elicited more efficient cytotoxicity on all tested tumor cells than on control cells. Investigation of the mechanism of action revealed that the Rh1-Rh4 complexes inhibit cell proliferation via different mechanisms of action, namely apoptosis (increase in expression of the pro-apoptotic Bax protein and caspase-3 protein in HeLa and HCT116 cells; changes in mitochondrial potential and mitochondrial damage; release of cytochrome c from the mitochondria; cell cycle arrest in G2/M phase in both HeLa and HCT116 cells together with a decrease in the expression of cyclin A and cyclin B) and autophagy (reduction in the expression of the protein p62 in HeLa and HCT116 cells).

Isolation, chemical characterization, antimicrobial activity, and molecular docking studies of 2,6-dimethoxy benzoquinone isolated from medicinal plant Flacourtia jangomas.

The online version contains supplementary material available at 10.1007/s13205-024-04002-w.

Study of Antioxidant, Antimicrobial and Cytotoxic Activities of Ag-Co Bimetallic Nanoparticles Biosynthesized from Red Alga (Amphiroa sp.)

Study of Antioxidant, Antimicrobial and Cytotoxic Activities of Ag-Co Bimetallic Nanoparticles Biosynthesized from Red Alga (Amphiroa sp.)

Copper substituted hydroxyapatite reinforced gelatin/polyvinyl alcohol/silk fibre-based scaffold for bone tissue engineering application

In order to restore the function of the damaged tissues, it is essential to find suitable ways which are capable of customizing tissue engineering constructs for each patient. The present study presents the hydrothermal synthesis of copper hydroxyapatite (Cu-HAP), as well as the electrospinning fabrication of gelatin/PVA/silk fibre-Cu-HAP scaffolds. The fabricated scaffold was characterized using XRD, FT-IR, SEM-EDAX in order to confirm the phase formation, functional group, surface topography and elemental composition respectively. The gelatin-PVA-silk fibre with 60 wt % Cu-HAP showed highest porosity (99 %) and highest mechanical strength (96. 13 MPa). To fulfil the requirements of bone tissue engineering the biological application such as antimicrobial activity, hemocompatibility, bioactivity and cell-line studies were carried out. Gelatin/PVA/silk fibre with 60 wt % Cu-HAP scaffold showed excellent zone of inhibition (E. coli - 75 ± 1.38 mm, S. aureus - 65 ± 1.40 mm, C. albicans - 68 ± 1.26 mm), good hemocompatibility (1.20 ± 0.06) with human blood and surface was uniformly covered with HAP in bioactivity studies. That the fabricated gelatin-PVA-silk fibre/Cu-HAP could be effective and suitable as a bone graft material.

The Synthesis and Antibacterial Activity of N-((1H-benzimidazol-2- yl)methyl)-2-substituted-3H- benzimidazol-5-amine Derivatives

Abstract: The increasing commonality of multi-drug-resistant bacteria as well as fungi is the motive for the development of new active antimicrobial agents. Heterocyclic compounds are major contributors in medical chemistry and are also found in biomolecules like vitamins, enzymes, natural products, etc. Benzimidazole is one of the nitrogens-containing heterocyclic compounds. Derivatives of benzimidazole have been found active against various bacterial diseases. Benzimidazole derivatives containing two benzimidazole rings also showed various pharmacological activities. In view of these, we aim to synthesize a new series of benzimidazole derivatives, N-((1H-benzimidazol-2-yl)methyl)-2-substituted-3H- benzimidazol-5-amine (6a–f) by the reaction of substituted 5-aminobenzimidazol derivatives with 2-chloromethyl benzimidazole and study their predicted bioactivity and actual antibacterial activity. To confirm the structures of the synthesized compounds, spectroscopic techniques like IR, 1H NMR,13C NMR and mass spectra were used. Initially, predicted bioactivity was studied using Molinspiration software. Among the synthesized compounds (6a-f), compounds 6a, 6d, 6e, and 6f showed good predicted activity. Then all the synthesized compounds 6a–f were screened for their antibacterial activity against E. coli (NCIM-2931), S. aureus (NCIM-2079), K. pnuemoniae (NCIM-2719) and P. aeruginosa (NCIM-2053) bacterial strains using the Ditchplate and Well Diffusion Method. Among them, compound 6f was found to be active against all used bacterial strains. Objectives: Synthesis and study of antimicrobial activity of benzimidazole derivatives. Methods: Simple, known laboratory methods are used for the synthesis of all new benzimidazole derivatives (6a-f). Predicted bioactivity was studied using Molinspiration software. The antibacterial activity of synthesized derivatives was studied against E. coli (NCIM-2931), S. aureus (NCIM-2079), K. pnuemoniae (NCIM-2719) and P. aeruginosa (NCIM-2053) bacterial strains using Ditch-plate and Well diffusion methods. Results: We successfully synthesized new bis-benzimidazole derivatives using simple laboratory methods and studied their antimicrobial activity. Among the synthesized derivatives, N-((1H-benzimidazol-2-yl)methyl)-2-(pyridin-3-yl)-3H-benzimidazol-5-amine (6f) showed good activity against used bacterial strains. Conclusion: In this paper, we report the synthesis of novel and biological activity benzimidazole derivatives by a simple and efficient method. The carried out predicted bioactivity as well as actual bioactivity was reported, and it was observed that predicted bioactivity and actual antibacterial activity showed similar results. The incorporation of a pyridine ring in a benzimidazole derivative increased bioactivity.

Analysis of the effectiveness of a new antimicrobial agent for disinfection in veterinary practice

The loss of effectiveness of standard treatment methods and the increased risk of rapid spread of infections are serious consequences of this problem. This underscores the need to develop new approaches to combating pathogen resistance and ensuring effective control of infections. Studies of antimicrobial activity were conducted on strains of C. albicans, A. niger, and B. subtilis. The minimal fungicidal concentration was determined based on the growth of microorganisms C. albicans, A. niger on Sabouraud agar media containing different concentrations of a new substance – a derivative of thiadiazole. The sporicidal activity was determined by culturing the test culture B. subtilis in meat-peptone broth, followed by seeding on meat-peptone agar. Sporicidal activity was determined by inoculating the test culture of B. subtilis into meat-peptone broth, followed by plating on meat-peptone agar. Control assays were performed by inoculating the test cultures on corresponding media without the test substances. The new disinfectant – a derivative of thiadiazole – demonstrated high antimicrobial activity. The aim of this research was to study the new chemical substance for antimicrobial (antifungal and sporicidal) activity and the creation of new types of biocides. The studies showed that the minimum fungicidal concentration of the 0.3% solution in a 30% alcohol solution against C. albicans RCPGY401 was 1.56 ± 1.06 μg/mL, A. niger 137a – 1.56 ± 1.29 μg/mL. Furthermore, the material exhibited sporicidal activity against B. subtilis ATCC 10702, with an effective concentration of – 3.12 ± 1.34 μg/mL. The research confirms the activity of the new compound against the studied microorganisms and allows for its recommendation for further study (treatment regimens, safety, control methods, etc.) for use in veterinary practice for various treatment purposes.

Formulation of silymarin surface modified vesicles: In vitro characterization to cell viability assessment

Silymarin (SLR) is a poorly water-soluble bioactive compound with a wide range of therapeutic activities. Nanosized silymarin vesicles (F1–F6) were prepared by the solvent evaporation rehydration method. The silymarin vesicles were evaluated for vesicle size, surface charge, entrapment efficiency, and drug release studies. The optimized SLR lipid vesicle (F3) was further modified with the addition of the cationic polymer chitosan. After that, the modified vesicle (F3C1) was assessed for permeation flux, antimicrobial activity, cell viability, and molecular docking studies. The silymarin vesicles showed nanometric size (<250 nm), low polydispersibility index (<0.05), negative surface charge, and high SLR entrapment (85–95 %). The drug release study result demonstrated a maximum drug release of 91.2 ± 2.8 %. After adding chitosan to the surface, there was a significant change in the size, polydispersibility index, surface charge (positive), and encapsulation efficiency. The drug release was found to be prolonged, and the permeation flux was also increased in comparison to free SLR. A comparative antimicrobial result was observed in comparison to the free SLR and standard drug. The cell viability assay also demonstrated a low IC50 value for F3C1 against the cell line.

A comparative study of antioxidative, antimicrobial, and anticancer activities of ginger and lemon peel extracts

A comparative study of antioxidative, antimicrobial, and anticancer activities of ginger and lemon peel extracts

Synthesis, Characterization, Antimicrobial Activity, and Molecular Docking Study of Newer Chalcone-based Triazolo Pyrimidine Compounds

Abstract:: In this work, we present the synthesis of a newer series of 15 chalcone-based pyrimidine compounds 4a-o. All the compounds were characterized by elemental analysis, melting point determination, mass, FTIR, and NMR analysis. We have evaluated the antimicrobial activity of these compounds. The compounds showed good inhibition activity towards different bacterial and fungal species such as S. aureus, S. pneumonia, E. coli, P. aeruginosa, Candida albicans, Aspergillus niger, and Alternaria alternata. Compounds 4c, 4h, 4k, and 4g showed comparable activities to those of commercially available drugs. Molecular docking study showed good interaction between each of the compounds and DNA gyrase enzyme. The docking score of the compounds ranges between -8.0 to -8.9 kcal/mol. Further, the ADMET analysis indicated the potential of the compounds as a drug candidate.

Synthesis, characterization, anti-microbial activity studies of salicylic acid and 2-aminopyridine derivatives salts and their Cu(II) complexes

Four salts (1-4) obtained between salicylic acid (H2salic) and 2-amino-Xpyridine {X = (2ap), 3-methyl (2a3mp), 4-methyl (2a4mp) and 5-methyl (2a5mp)} and the Cu(II) complex of H2salic (5) by methods available in the literature and new Cu(II) complexes (6-9) of the salts (1-4) has been prepared. The Cu(II) complexes (6-9) were suggested by elemental analysis, FT-IR, AAS, UV-Vis and magnetic susceptibility techniques. The spectroscopic research results indicated that complexes 6-9 have tetrahedral geometries. Additionally, antimicrobial activities of free ligands (H2salic, 2ap, 2a3mp, 2a4mp and 2a5mp), 1-9 were studied against Candida albicans (F89) yeast, Staphylococcus aureus (NRRL B-767), Pseudomonas aeruginosa (ATCC 27853), Bacillus subtilis, Listeria monocytogenes (ATCC 7644), Escherichia coli (ATCC25922) and Enterococcus faecalis (ATCC 29212) bacteria. The results were comparisoned with the control compounds (Fluconazole, Vancomycin, Cefepime and Levofloxacin). All compounds showed activity against bacteria and yeasts.

Design, Synthesis, Drug-Likeness, anti-Inflammatory, Antimicrobial Activity, and Molecular Docking Studies of Pyrimidine Analogs

Grounded on medicinal significances of pyrimidines, herein we are reporting initially the design and synthesis of 1-(2-benzylthiopyrimidin-4-yl)-benzimidazol-2-thioacetic acid/thioacetate 2(a, b), 1-(2-benzylthiopyrimidin-4-yl)-3,5 diaryl-2-pyrazoline (3) and 1-(2-benzylthiopyrimidin-4-yl)-3,5-dimethylpyrazole (4). In silico screening such as molecular docking studies of these compounds with inflammation-causing enzyme cyclooxagenase-2 (COX-2) suggests that only 2a has shown a strong affinity for the COX-2 (−9.0 kcal/mol) and forms three hydrogen bonds with active amino acid residues in comparison with standard anti-inflammatory drugs celecoxib (-8.8 kcal/mol) and indomethacin (-7.7 kcal/mol). However, in vitro, anti-inflammatory activity reveals that IC50 of compound 2a was 3.5 μM compared to celecoxib with IC50 of 0.65 μM. Also, 2a has displayed comparable activity of standard antibacterial drug gentamycin against E. coli with MIC 6.5 μM. Furthermore, the drug-likeness of potent compounds was studied using Swiss ADME and Mol inspiration software. All the compounds showed optimum drug-likeness without violating Lipinski’s rule of five. With our best observation and based on comparative SAR studies of these analogs with celecoxib and indomethacin, we conclude that compound 2a could develop as a therapeutically potent anti-inflammatory agent.

2,3-Dichloronaphthoquinone derivatives: Synthesis, antimicrobial activity, molecular modelling and ADMET studies

In the present study, an intermediate namely 2-(3-bromopropylamino)-3-chloronaphthalene-1,4-dione was initially synthesized via the nucleophilic addition–elimination reaction between 2,3-dichloro-1,4-naphthoquinone and 3-bromo-1-aminopropane. Then a coupling reaction between the intermediate and piperazine derivatives yielded a number of 1,4-naphthoquinone derivatives. Spectroscopic analysis successfully characterized the products that were obtained in good yields. In vitro antibacterial properties of the compounds were examined against different bacterial strains. In vitro antibacterial properties of the compounds were examined against the bacterial strains S. Aureus, E. Faecalis, E. Coli and P. Aeruginosa. While compound 9 was found to be effective against all bacterial strains used, compound 12 was active against three strains and compounds 10 and 11 were effective against the two. None of the compounds are effective against C. albicans strain. In silico molecular docking studies revealed that all compounds had docking scores comparable to the antibacterial drugs ciprofloxacin and gentamicin and might be considered as DNA gyrase B inhibitors. Molecular dynamics simulations were also conducted for a better understanding of the stability and the selected docked complexes. Additionally, the drug similarity of the synthesized compounds and ADMET characteristics were examined in conjunction with the antibiotic ciprofloxacin, and drug potentials were then evaluated. Compatible predictions were found with the drug similarity and ADMET parameters.

Synthesis, characterization and antimicrobial study of silver nanoparticles using methanolic fraction of Artemisia vulgaris leaf

Rational selection of active biomolecules in the synthesis of nanoparticles for reducing the precursor and functionalizing the nanoparticles (NPs) can offer remarkable comeback of biocompatibility and biological applicability. This work aimed at the synthesis of a cost-effective, ecofriendly, and a facile approach of silver nanoparticles (AgNPs) using methanolic leaf extract of Artemisia vulgaris. The phytochemical constituents present in the methanolic extract were characterized by qualitative chemical tests and spectroscopic measurements and employed for the reduction of silver nitrate into silver nanoparticles. Formation of AgNPs was monitored by UV-visible spectroscopic measurement. Fourier transform infrared (FTIR) spectroscopy reflected the presence of characteristic functional groups associated with the phytochemical constituents involved in the formation of nanoparticles. The crystalline phase and morphology of the NPs were assessed form X-ray diffraction (XRD) spectra and field emission scanning electron microscopy (FESEM), respectively. XRD pattern revealed the crystalline nature of nanoparticles with grain size of ∼ 28 nm based on the Debye Scherer formula. Study of antimicrobial activity of AgNPs against Gram-positive bacteria Bacillus subtili, Gram-negative bacteria Escherichia coli, and fungus Candida albicans exhibited good potential to control the bacterial and fungal growth.

Phytochemical Properties and In vitro Antimicrobial Activity of Methanolic Leaf Extract of Durio zibethinus Murr. on Selected Clinical Isolates

Bacterial and viral infections represent the most challenging diseases to treat in humans due to resistance to most of the therapeutic agents. The advent of drug resistance factors that have challenged the effectiveness of all antimicrobial agents prompted the investigation of antimicrobial activity studies of the methanolic leaf extract of Durio zibethinus Murr. This study is focused on evaluating the phytochemical and antimicrobial activity of the leaf extract of D. zibethinus Murr. on selected clinical isolates: Staphylococcus aureus and Staphylococcus epidermidis (gram-positive bacterial strains), Klebsiella pneumonia, Escherichia coli, Salmonella typhi (gram-negative bacterial strains) while Candida albicans and Microsporum audouinii (fungi strains) using the standard agar disc diffusion technique. Alkaloids, saponins, flavonoids, terpenoids, steroids, glycosides, and phenolic chemicals have all been identified via phytochemical investigation. The result indicated that the leaf extract exhibited antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Candida albicans and Microsporum audouinii at a range of 10.34–16.02 mm at a concentration of 150 mg/mL relative to standard gentamicin and fluconazole antibiotics. The minimum inhibitory concentration (MIC) for S. aureus was 0.250 mg/mL; for E. coli, it was 0.125 mg/mL; whereas it was 0.250 mg/mL for the two fungal strains, C. albicans and M. audouinii. Our investigation revealed that the D. zibethinus Murr. leaf extract exhibited the highest antibacterial activity against S. aureus and E. coli whereas the extract exhibited the highest antifungal activity against M. audouinii. Our research concluded that the Durio zibethinus Murr. leaf extract had potent antibacterial and antifungal properties, suggesting that it could be utilized to treat various pathogenic diseases.

Greener Approach for Synthesis of δ-MnO2 Nanoparticles: Access to Pharmaceutically Important Pyrimidines and their Antimicrobial Activity Studies.

A sustainable approach for pharmaceutically important pyrimidine derivatives is achieved by using biogenically produced single-phase δ-MnO2 NPs under external ligand-free conditions. The phytochemicals that comprise the extract of Areca Nut Husk (ANH) have been discovered to serve as reducing agents. The role of phytochemicals is not only to aid in the reduction of Mn(VII) into Mn(IV), but they also have an important role in stabilizing the catalyst. The establishment of δ-MnO2 NPs was confirmed inveterate by FE-SEM, p-XRD, ICP-OES (Mn content = 43.17% w/w), EDX, and with an active Mn content of 43.17% w/w. A series of pyrimidine derivatives were prepared in good yields using a one-pot multicomponent synthesis approach under atmospheric conditions. In addition, hot filtration tests, control experiments, gram-scale synthesis, and mechanistic investigations were demonstrated. Additionally, antimicrobial activity studies of δ-MnO2 NPs and pyrimidine derivatives against the Gram-negative bacteria E. coli, growth curve and minimum inhibitory concentration were studied.

Oxacyanopyridine-Benzofuran Hybrids: Synthesis, in silico Toxicity Assessment, in vitro Antimicrobial Activity and Dual Target Docking Studies

This study emphasizes the synthesis and characterization of a novel series of oxa cyano pyridine heterocyclic molecular hybrids (OCP 1-6), integrating pyridine and benzofuran motifs. Meticulously designed from 5-chlorosalicylaldehyde in a multistep process, the synthesized compounds were structurally confirmed through IR spectroscopy, 1H NMR spectroscopy, and mass spectrometry. Computational predictions highlighted diverse properties, including antitubercular and antibacterial attributes, bioactivity scores, toxicity profiles and potential molecular targets. In vitro assessments and Schrödinger docking simulations revealed binding affinities to enzymes viz. Mycobacterium tuberculosis enoyl-ACP reductase and Escherichia coli Topoisomerase IV. Compounds, particularly OCP 2, 3, 4 and 5, exhibited significant antitubercular and antibacterial activities in both in vitro assessments and docking simulations. This study underscores the substantial potential of the synthesized hybrids as promising candidates for further lead optimization, positioning them as valuable contributors to the development of pharmaceutical agents with heightened potency and enhanced safety profiles.

Synchronous semi-solid extrusion and photopolymerization of antimicrobial dressing hydrogel for wound healing

Bacterial infections at wound sites require more time for a fast and efficient wound-healing process. Antibacterial methyl cellulose-based hydrogel wound dressing can be an excellent option because it can show antibacterial action, absorb wound exudates, and have a cooling and soothing effect on the wound bed. The ultraviolet (UV) ray-assisted semi-solid extrusion 3D printing technique was used to prepare 3D printed construct into a high surface area mesh-like structure utilizing UV radiation for photocrosslinking of hydrogel matrix in the presence of Poly (ethylene glycol) Diacrylate. The prepared hydrogel was characterized for contact angle, and rheological analysis before semi-solid extrusion-based 3D printing. After optimization of printing parameters, the 3D printed mesh was subjected to physicochemical characterizations like dimensional analysis, swelling study, drug content, in vitro drug release, and in vitro antimicrobial activity study. A rheological analysis confirmed the viscosity, thixotropy, and viscoelastic nature of prepared hydrogel. Drug release study showed approximately 50 % release in 4 h, and >80 % drug release in 24 h. After optimization of one batch, hydrogel polymerization was done by functional group analysis followed by validation of thread thickness by electron microscopy images and mechanical property assessment. The 3D-printed mesh was further evaluated for its in-vitro antibacterial performance against Escherichia coli and Staphylococcus aureus. The area of inhibition was one-fold more in Staphylococcus aureus and two-fold in E. coli, ensuring diffusion of the drug from 3D printed mesh and killing of bacteria. The work reported herein represents a universal platform to generate multifunctional and customized hydrogels with various functional substances for wound dressing applications.

Antimicrobial Activity of Citrate-Coated Cerium Oxide Nanoparticles.

The purpose of this study was to investigate the antimicrobial activity of citrate-stabilized sols of cerium oxide nanoparticles at different concentrations via different microbiological methods and to compare the effect with the peroxidase activity of nanoceria for the subsequent development of a regeneration-stimulating medical and/or veterinary wound-healing product providing new types of antimicrobial action. The object of this study was cerium oxide nanoparticles synthesized from aqueous solutions of cerium (III) nitrate hexahydrate and citric acid (the size of the nanoparticles was 3-5 nm, and their aggregates were 60-130 nm). Nanoceria oxide sols with a wide range of concentrations (10-1-10-6 M) as well as powder (the dry substance) were used. Both bacterial and fungal strains (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Candida albicans, Aspergillus brasielensis) were used for the microbiological studies. The antimicrobial activity of nanoceria was investigated across a wide range of concentrations using three methods sequentially; the antimicrobial activity was studied by examining diffusion into agar, the serial dilution method was used to detect the minimum inhibitory and bactericidal concentrations, and, finally, gas chromatography with mass-selective detection was performed to study the inhibition of E. coli's growth. To study the redox activity of different concentrations of nanocerium, we studied the intensity of chemiluminescence in the oxidation reaction of luminol in the presence of hydrogen peroxide. As a result of this study's use of the agar diffusion and serial dilution methods followed by sowing, no significant evidence of antimicrobial activity was found. At the same time, in the current study of antimicrobial activity against E. coli strains using gas chromatography with mass spectrometry, the ability of nanoceria to significantly inhibit the growth and reproduction of microorganisms after 24 h and, in particular, after 48 h of incubation at a wide range of concentrations, 10-2-10-5 M (48-95% reduction in the number of microbes with a significant dose-dependent effect) was determined as the optimum concentration. A reliable redox activity of nanoceria coated with citrate was established, increasing in proportion to the concentration, confirming the oxidative mechanism of the action of nanoceria. Thus, nanoceria have a dose-dependent bacteriostatic effect, which is most pronounced at concentrations of 10-2-10-3 M. Unlike the effects of classical antiseptics, the effect was manifested from 2 days and increased during the observation. To study the antimicrobial activity of nanomaterials, it is advisable not to use classical qualitative and semi-quantitative methods; rather, the employment of more accurate quantitative methods is advised, in particular, gas chromatography-mass spectrometry, during several days of incubation.

Implementation of Silver Nanoparticles Green Synthesized with Leaf Extract of Coccinia grandis as Antimicrobial Agents Against Head and Neck Infection MDR Pathogens.

Head and neck infections (HNI) associated with multidrug resistance (MDR) offer several health issues on a global scale due to inaccurate diagnosis. This study aimed to identify the bacteria and Candidal isolates and implement the silver nanoparticles green synthesized with leaf extract of Coccinia grandis (Cg-AgNPs) as a therapeutic approach against HNI pathogens. The Cg-AgNPs were characterized by the UV-visible spectrophotometer, FT-IR analysis, Zeta particle size, Zeta potential, and field emission scanning electron microscope (FESEM) analysis to validate the synthesis of nanoparticles. Additionally, the antimicrobial activity of Cg-AgNPs was presented by the zone of inhibition (ZOI), minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration (MBC/MFC), and antibiofilm assay. Moreover, the cell wall rupture assay was visualized on SEM for the morphological study of antimicrobial activities, and the in-vivo toxicity was performed in a swiss mice model to evaluate the impact of Cg-AgNPs on various biological parameters. Different bacterial strains (Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and Candida sp. (Candida albicans, Candida tropicalis, Candida orthopsilosis, and Candida glabrata) were identified. The MIC, MBC, and antibiofilm potential of Cg-AgNPs were found to be highest against A. baumannii: 1.25 μg/ml, 5 μg/ml, and 85.01±5.19% respectively. However, C. albicans and C. orthopsilosis revealed 23mm and 21mm of ZOI. Subsequently, the micromorphology of the cell wall rupture assay confirmed the efficacy of Cg-AgNPs, and no significant alterations were seen in biochemical and hematological parameters on the swiss mice model in both acute and subacute toxicity studies. The green synthesized Cg-AgNPs have multifunctional activities like antibacterial, anticandidal, and antibiofilm activity with no toxicity and can be introduced against the HNI pathogens.