Antibacterial Activity againstS Research Articles

Inhibition of MurA Enzyme from Escherichia coli by Flavonoids and Their Synthetic Analogues.

MurA catalyzes the first step of peptidoglycan (PG) biosynthesis and is a validated target for the development of new antimicrobial agents. In this study, a library of 49 plant flavonoids and their synthetic derivatives were evaluated for their inhibitory properties against MurA fromEscherichia coli. The compounds were tested with and without preincubation and with the addition of DTT to understand the mechanism of inhibition. Thirteen compounds were identified as reversible, time-dependent inhibitors, with inhibition levels ranging from 480 nM to 57 μM, and ampelopsin as the most potent compound. To investigate the major pharmacophore elements responsible for the activity, 2D-QSAR and docking analyzes were performed. The results showed that the catechol moiety and an additional aromatic system were the most important features contributing to the activity of the compounds. However, most of the compounds did not show antibacterial activity againstE. coli andStaphylococcus aureusstrains, suggesting that their inhibitory activity against MurA may not be strong enough to induce antibacterial effects. Nevertheless, our results suggest that flavonoids are a promising starting point to develop new inhibitors of MurA and show great potential for further steps in drug development.

Green synthesis, characterization, cytotoxicity, and antimicrobial activity of iron oxide nanoparticles usingNigella sativaseed extract

AbstractGreen synthesis of nanoparticles (NPs) is a more sustainable, safe, and environmentally friendly method. This study aimed to investigate the synthesis procedure of iron oxide nanoparticles (IONPs) using the seed extract ofNigella sativa(N. sativa) as a strong reducing agent and to estimate their cytotoxic and antibacterial properties. The obtained IONPs were characterized by field-emission scanning electron microscopy, X-ray diffraction, dynamic light scattering (DLS), zeta potential (ZP), and Fourier-transform infrared spectroscopy analyses. The cytotoxicity of the biosynthesized IONPs was demonstrated by the MTT on a Vero cell line. Furthermore, the antibacterial activity of the fabricated biosynthesis metal oxide NPs was tested onEscherichia coli(E. coli) (ATCC 35218) andStaphylococcus aureus(S. aureus) (ATCC 29213) bacterial strains using the Kirby–Bauer disk diffusion method. This study showed the formation of a well-dispersed, highly stable (ZPζ= −51.8 mV) IO NPs with an average diameter of about 31.45 nm. Moreover, the biosynthetic NPs (IONPs) exhibited a significantly noncytotoxic effect when analyzed by the MTT assay. The biosynthetic NPs (NS-IONPs) exhibited excellent antibacterial activity againstE. coliandS. aureus, where the inhibition zones were 12.34 ± 0.58 and 11.52 ± 0.58, respectively.

매실 추출물의 Streptococcus mutans KCCM 40105 균주에 대한 항균활성 및 안정성

In this study, natural materials with antibacterial activity against the Streptococcus mutans KCCM 40105 strain were selected, and the most efficient extraction conditions were observed. The active substance was stable under various treatment conditions. Of the 10 food materials groups, only Prunus mume fruit showed antibacterial activity against S. mutans strains. The antimicrobial activity by the various extraction solvents was 18.66 mm (clear zone diameter) in the ethanol extract and 20.18 mm in the water extract. Measurements of the antibacterial activity according to the mixing ratio of the two solvents revealed the 30% ethanol extract to have the highest activity (20.49 mm). Measurements of the minimum inhibitory concentration (MIC) showed activity at a concentration of 3.0 mg/mL. The stability to heat was observed, but the extract was not active at pH 6.0 or higher. The antimicrobial activity of the 30% ethanol extract of P. mume treated with enzymes was the same with both 10 ppm and 100 ppm of the nine enzymes. On the other hand, the activity tended to decrease slightly at 1,000 ppm. The activity of the catazyme enzyme and hydrogen peroxide treatment decreased at the treatment concentration of 100 ppm.

묵은지로부터 바이오제닉 아민을 분해하는 프로바이오틱 유산균의 분리 및 동정

The aim of this study was to evaluate biogenic amines (BA)-forming and -degrading abilities of lactic acid bacteria (LAB) and yeasts isolated from over-ripened kimchi and to investigate probiotic characteristics of the BA-degrading and -degrading microorganism. There were significantly more BA-forming LAB and yeasts in over-ripened kimchi prepared with fish sauce or salted fish than sun-dried salt. The BA-forming ability of the microorganisms was highly strain-dependent. Among the isolated microorganisms, the BA degradation ability was found in LAB including Leuconostoc mesenteroides subsp. mesenteroides CML01, Enterococcus faecium KML12, Lactobacillus fermentum MML21, Lactobacillus sakei MML23, Enterococcus faecalis MML26, and Pediococcus pentosaceus SML34. However, all yeast tested did not show the BA degradtion ability. In addition, L. sakei MML23 and P. pentosaceus SML34 exhibited probiotic characteristics including tolerance to gastric acid and bile salt, adhesion capacity to intestinal epithelial cells, and antibiotic susceptibility. Furthermore, the bacteriocin produced by L. sakei MML23 and P. pentosaceus SML34 showed antibacterial activity against E. faecium KML15, Saccharomyces cerevisiae MMY28, and Lactobacillus brevis MML24. Consequently, the bacteriocin produced by probiotic L. sakei MML23 and P. pentosaceus SML34 seemed to be effective in reducing the risk of BA toxicity by inhibiting the growth of histamine, cadaverine, and putrescine-forming bacteria.

Synthesis and Characterization of Some New 1,3,4-thiadiazole Compounds Derived from 3,4-(Methylenedioxy)cinnamic Acid and their Antimicrobial Activities

Some new 1,3,4-thiadiazole compounds derived from 3,4-(methylenedioxy)cinnamic acid were synthesized in this study. Their structures were determined using UV-Vis, IR, 1H-NMR, and 13C-NMR spectroscopy. Moreover, the antibacterial activities of the new 1,3,4-thiadiazole derivatives were tested against Gram positive (Enterococcus durans, Bacillus subtilis, and Staphylococcus aureus) and gram negative (Salmonella typhimurium, Escherichia coli, Salmonella enteritidis, Salmonella infantis, Salmonella kentucky, Enterobacter aerogenes) bacteria using the disk diffusion method. Furthermore, their antifungal activity was tested against Candida albicans using the disk diffusion method. Some of the synthesized compounds (V, VII, XIII, and XIV) showed antibacterial activity against S. aureus. Also, one synthesized compound (VIII) showed antibacterial activity against E. coli, exhibiting 8 and 9 mm inhibition zones using 50 and 80 µL. One compound (IX) showed antibacterial activity against E. aerogenes, exhibiting a 12 mm inhibition zone using 80 µL. One compound (XIII) showed antibacterial activity against S. kentucky, exhibiting an inhibition zone of about 9 mm using 80 µL. Also, one compound (VII) showed antibacterial activity against E. durans, exhibiting 7, 7, and 8 mm inhibition zones using 30, 50, and 80 µL. None of the compounds (I-XV) showed antifungal activity against C. albicans. These results showed that some of the synthesized compounds could be used as antibacterial agents.

Tomatidine Is a Lead Antibiotic Molecule That Targets Staphylococcus aureus ATP Synthase Subunit C.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of deadly hospital-acquired infections. The discovery of anti-Staphylococcus antibiotics and new classes of drugs not susceptible to the mechanisms of resistance shared among bacteria is imperative. We recently showed that tomatidine (TO), a steroidal alkaloid from solanaceous plants, possesses potent antibacterial activity against S. aureus small-colony variants (SCVs), the notoriously persistent form of this bacterium that has been associated with recurrence of infections. Here, using genomic analysis of in vitro-generated TO-resistant S. aureus strains to identify mutations in genes involved in resistance, we identified the bacterial ATP synthase as the cellular target. Sequence alignments were performed to highlight the modified sequences, and the structural consequences of the mutations were evaluated in structural models. Overexpression of the atpE gene in S. aureus SCVs or introducing the mutation found in the atpE gene of one of the high-level TO-resistant S. aureus mutants into the Bacillus subtilis atpE gene provided resistance to TO and further validated the identity of the cellular target. FC04-100, a TO derivative which also possesses activity against non-SCV strains, prevents high-level resistance development in prototypic strains and limits the level of resistance observed in SCVs. An ATP synthesis assay allowed the observation of a correlation between antibiotic potency and ATP synthase inhibition. The selectivity index (inhibition of ATP production by mitochondria versus that of bacterial ATP synthase) is estimated to be >105-fold for FC04-100.

Comparative Evaluation of Antibacterial Effect of Dental Luting Cements on Streptococcus mutans and Lactobacillus acidophilus: An in vitro Study

This study aimed at evaluating and comparing the antibacterial activity of six types of dental luting cements on Streptococcus mutans and Lactobacillus acidophilus using the agar diffusion test (ADT) and the direct-contact test (DCT). The antibacterial activity in ADT was measured based on the diameter of the zone of inhibition formed, whereas in DCT the density of the bacterial suspension was measured. The lower the density of the suspension, the more antibacterial activity the cement possesses. Agar diffusion test was carried out on the bacteria. After an incubation period of 24 hours, the plates were checked for the presence of zone of inhibition. In DCT the cement was mixed and applied. Once the cement was set, bacterial suspension and brain-heart infusion medium was poured and incubated for 24 hours. After 24 hours, the plate was placed in the enzyme-linked immunosorbent assay plate reader, which measured the optical density of the fluid. The first set of data was recorded approximately 1 hour after incubation. Overall, three sets of data were recorded. Additional experiments were performed on set test materials that were allowed to age for 24 hours, 1 week, 1, 3, and 6 months. When using ADT only two cements zinc oxide eugenol (ZOE) and zinc polycarboxylate (ZPC) cement showed antibacterial activity against the test organisms. When using DCT, all cements showed some amount of antibacterial activity. Zinc oxide eugenol and ZPC cement showed highest amount of antibacterial activity against S. mutans and L. acidophilus respectively. Within the limitations of study, ZOE cement and ZPC cement were most effective against the tested microorganisms followed by the newer resin cement. The glass ionomer cement was the weakest of all. Patients with high caries index can be treated more effectively using the abovementioned cements.

Composition Analysis and Inhibitory Effect of Sterculia lychnophora against Biofilm Formation by Streptococcus mutans.

Pangdahai is a traditional Chinese drug, specifically described in the Chinese Pharmacopoeia as the seeds of Sterculia lychnophora Hance. Here, we separated S. lychnophora husk and kernel, analyzed the nutrient contents, and investigated the inhibitory effects of S. lychnophora ethanol extracts on cariogenic properties of Streptococcus mutans, important bacteria in dental caries and plaque formation. Ethanol extracts of S. lychnophora showed dose-dependent antibacterial activity against S. mutans with significant inhibition at concentrations higher than 0.01 mg/mL compared with the control group (p < 0.05). Furthermore, biofilm formation was decreased by S. lychnophora at concentrations > 0.03 mg/mL, while bacterial viability was decreased dose-dependently at high concentrations (0.04, 0.08, 0.16, and 0.32 mg/mL). Preliminary phytochemical analysis of the ethanol extract revealed a strong presence of alkaloid, phenolics, glycosides, and peptides while the presence of steroids, terpenoids, flavonoids, and organic acids was low. The S. lychnophora husk had higher moisture and ash content than the kernel, while the protein and fat content of the husk were lower (p < 0.05) than those of the kernel. These results indicate that S. lychnophora may have antibacterial effects against S. mutans, which are likely related to the alkaloid, phenolics, glycosides, and peptides, the major components of S. lychnophora.

Synthesis andIn VitroEvaluation of New Thiosemicarbazone Derivatives as Potential Antimicrobial Agents

In an effort to develop potent antimicrobial agents, new thiosemicarbazone derivatives were synthesizedviathe reaction of 4-[4-(trifluoromethyl)phenyl]thiosemicarbazide with aromatic aldehydes. The compounds were evaluated for their inhibitory effects on pathogenic bacteria and yeasts using the CLSI broth microdilution method. Microplate Alamar Blue Assay was also carried out to determine the antimycobacterial activities of the compounds againstMycobacterium tuberculosisH37Rv. Among these derivatives, compounds5and11were more effective againstEnterococcus faecalis(ATCC 29212) than chloramphenicol, whereas compounds1,2, and12and chloramphenicol showed the same level of antibacterial activity againstE. faecalis. Moreover, compound2and chloramphenicol exhibited the same level of antibacterial activity againstStaphylococcus aureus. On the other hand, the most potent anticandidal derivatives were found as compounds2and5. These derivatives and ketoconazole exhibited the same level of antifungal activity againstCandida glabrata. According to the Microplate Alamar Blue Assay, the tested compounds showed weak to moderate antitubercular activity.

Antioxidant Activity and Antibacterial Effects on Clinical IsolatedStreptococcus suisandStaphylococcus intermediusof Extracts from Several Parts ofCladogynos orientalisand Their Phytochemical Screenings

The in vitro antioxidant and antibacterial assays against clinically isolated Streptococcus suis and Staphylococcus intermedius of the extracts prepared by decoction and ethanolic reflux of different parts of Chettaphangki (Cladogynos orientalis Zipp. ex Span), including the leaves, roots, and stems, using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay and disc diffusion method were conducted. Quantitative analysis of total phenolic and total flavonoid contents in the extracts using spectrophotometric methods was also performed. Finally, phytochemical screening by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) was conducted. Leaf ethanolic reflux extract (100 g) contained the highest total phenolic and total flavonoid contents of 7.21 ± 0.28 μg gallic acid equivalent (GAE) and 11.51 ± 2.02 μg rutin equivalent (RE), respectively. Chettaphangki extracts promoted low antioxidant activity with EC50 values in the range of 0.27–0.48 mg/mL. Extracts and fractions from the roots and stems of this plant promoted low to intermediate antibacterial activity against S. intermedius with the inhibition zones between 7 and 14 mm. The chromatographic data suggested that the leaf extracts of C. orientalis contained rutin while the root and stem extracts contained scopoletin and chettaphanin I. Rutin promoted strong antioxidant activity while chettaphanin I showed low antibacterial activity against Staphylococcus intermedius.

In Vitro Effect of Zingiber officinale Extract on Growth of Streptococcus mutans and Streptococcus sanguinis.

Background and Objectives. Tooth decay is an infectious disease of microbial origin. Considering the increasing prevalence of antibiotic resistance due to their overuse and also their side effects, medicinal plants are now considered for use against bacterial infections. This study aimed to assess the effects of different concentrations of Zingiber officinale extract on proliferation of Streptococcus mutans and Streptococcus sanguinis in vitro. Materials and Methods. In this experimental study, serial dilutions of the extract were prepared in two sets of 10 test tubes for each bacterium (total of 20). Standard amounts of bacterial suspension were added; 100ƛ of each tube was cultured on prepared solid agar plates and incubated at 37°C for 24 hours. Serial dilutions of the extract were prepared in another 20 tubes and 100ƛ of each tube was added to blood agar culture medium while being prepared. The mixture was transferred to the plates. The bacteria were inoculated on plates and incubated as described. Results. The minimum inhibitory concentration (MIC) was 0.02 mg/mL for S. mutans and 0.3 mg/mL for S. sanguinis. The minimum bactericidal concentration (MBC) was 0.04 mg for S. mutans and 0.6 mg for S. sanguinis. Conclusion. Zingiber officinale extract has significant antibacterial activity against S. mutans and S. sanguinis cariogenic microorganisms.

The use of zinc oxide nanoparticles to enhance the antibacterial properties of light-activated polydimethylsiloxane containing crystal violet

Crystal violet–ZnO mixtures were incorporated into PDMS by a simple two step method. The modified polymer demonstrated significant antibacterial activity againstE. coliandS. aureus, showing possibly the most potent light-induced antibacterial polymer reported to date.

Cotton Fabric Finished by WPU/LPAA Modified Nano-ZnO for Antibacterial Applications

An antibacterial agent (ZPU) was prepared by surface modification of nanoZnO with aliphatic aqueous polyurethane (WPU) and polyacrylates sodium of lower molecular weight (LPAA). Then two kinds of cotton fabrics were dipped in ZPU and finally finished by paking-baking process. ZPU and the finished cotton fabrics were characterized by SEM, TEM and DLS. The antimicrobial properties of the cotton fabrics were investigated. The results indicated that ZnO retained nanosize with little aggregation on the fabric surface. The finished cotton fabrics showed obviously antibacterial activity againstS. aureusandE. coliwith the 24 h antibacterial rate of 99%.

Evaluation of Benzophenone-N-ethyl Morpholine Ethers as Antibacterial and Antifungal Activities

Microorganisms are closely associated with the health and welfare of human beings. Whereas some microorganisms are beneficial, others are detrimental. Bacterial infections often produce inflammation and pains and in some instances, infections result in high mortality. Any subtle change in the drug molecule, which may not be detected by chemical methods, can be revealed by a change in the antimicrobial activity and hence microbiological assays are very useful. A series of substituted hydroxy benzophenones and benzophenone-N-ethyl morpholine ethers were screened for their antibacterial and antifungal activities. Antibacterial activity againstS. aureus,E. aerogenes,M. luteus,K. pneumonia, andS. typhimurium,S. paratyphi-BandP. vulgarisbacterial strains and antifungal activity againstC. albicans,B. cinerea,M. pachydermatis,C. kruseifungal strains were carried out. The bioassays indicated that most of the synthesized compounds showed potential antibacterial and antifungal agents.

Characterization and Biocompatibility of Chitosan Gels with Silver and Gold Nanoparticles

The presence of bacterial resistance to antibiotics is a very important issue and the search of new alternatives is necessary. In this work, a combination of chitosan gel with silver or gold nanoparticles was prepared and characterized using thermal, rheology, bactericide, and biocompatibility analyses. ESEM images were also taken to visualize the incorporation of the nanoparticles into the gel matrix. Thermal analysis showed a better thermal stability in the chitosan‐gold nanoparticles gels compared to the chitosan‐silver nanoparticles gels. Rheology analyses showed that the viscosity of the gels decreased when velocity increased and there were differences in viscosity when silver and gold nanoparticles concentrations change. ESEM images showed the presence of agglomerates of silver and gold nanoparticles into the gel matrix with a good distribution; in some cases the formation of microstructures was found. Bactericide results show that these materials present an antibacterial activity against S. aureus, S. mutans, and E. coli. The biocompatibility test showed neither negative reaction nor wound healing delay after the application of the gels in an in vivo test. The gels with silver and gold nanoparticles could be used to treat wound infections in oral or skin applications.

Antioxidant and Antimicrobial Properties of Chitosan-PE Bi-Layer Films by Incorporating Oregano Essential Oil

Chitosan-PE bi-layer films exhibit antimicrobial activity but poor antioxidant activity. Oregano essential oil (100μL/100mL) was incorporated into chitosan solution to improve films antioxidant and antimicrobial behaviors. The present work investigated the scavenging of O2·, ·OH, DPPH radical and reducing power of film, antimicrobial activity was also evaluated. The results showed that the scavenging effect of film solution on O2·, ·OH, and DPPH was 80.87%, 85.56%, and 87.24%, respectively. Reducing power of film increased with the improvement of oregano essential oil. The antibacterial activity againstE. ColiandB. Subtilisincreased from 80.77% to 96.15% and from 93.02% to 98.10%, respectively. The preservation experiments showed that chitosan-PE film incorporated with oregano essential oil could extend the shelf life of pork to 810 days at 4°C.

English

Antibacterial properties of&nbsp;Lactobacillus&nbsp;strains isolated from traditional fermented mustard were investigated. Among the strains tested, strain B0105 was found to produce bacteriocin-like compounds against&nbsp;Streptococcus mutans&nbsp;BCRC 10793. Strain B0105 was identified as&nbsp;Lactobacillus plantarum&nbsp;by phenotypical and physiological tests as well as16S rDNA identification. The molecular weight of bacteriocin-like compounds was 3.5 and 4.7 kDa by Tris-Tricine SDS-PAGE. In addition, this bacteriocin-like exhibited a strong antibacterial activity, heat stability (15 min at 121&deg;C) and pH stability (pH 2.0&ndash;4.0) againstS. mutans&nbsp;BCRC 10793, however, it was sensitive to proteolytic enzyme. Overall, the results obtained, demonstrate that strain B0105 is able to produce bacteriocin-like compounds inhibiting&nbsp;S. mutans&nbsp;BCRC 10793, making it potential candidate for antibacterial agents. &nbsp; Key words:&nbsp;Lactobacillus plantarum, bacteriocin,&nbsp;Streptococcus mutans.

Effects ofMesua ferreaLeaf and Fruit Extracts on Growth and Morphology ofStaphylococcus aureus

Mesua ferrea is traditionally used for treating bleeding piles, fever, and renal diseases. It has been reported to have antimircobial activity. In the present study, antibacterial efficacy of leaf and fruit extracts on the growth and morphology of Staphylococcus aureus is evaluated. Both extracts display good antibacterial activity against S. aureus with a minimum inhibition concentration of 0.048 mg/mL. Both extracts are bacteriostatic at a minimum bacteriostatic concentration of 0.39 mg/mL. The bacteriostatic activity lasts for 24 h, and then cells start to grow as normal as shown in time-kill analysis. Scanning electron microscopy study indicated potential detrimental effect of the extracts of leaf and fruits of M. ferrea on the morphology of S. aureus. The treatment with the extracts caused extensive lysis of the cells, leakage of intracellular constituents, and aggregation of cytoplasmic contents forming an open meshwork of the matrix.

Synthesis Characterization and Antimicrobial Activity Studies of Some Transition Metal Complexes Derived from 3-Chloro-N′-[(1E)-(2-hydroxy phenyl)methylene]-6-methoxy-1-benzothiophene-2-carbohydrazide

A series of new coordination complexes of Cu(II), Co(II), Ni(II), Zn(II), Hg(II), Mn(II), and Fe(III) with the Schiff base 3-chloro-N′-[(1E)-(2-hydroxy phenyl)methylene]-6-methoxy-1-benzothiophene-2-carbohydrazide (HL) have been synthesized and characterized by elemental analysis, electrical conductivity measurements, IR spectra, 1H NMR, mass spectral data, electronic spectra, magnetic susceptibility, ESR spectra, TGA, and Powder XRD data. The Schiff base behaves as tridentate ONO donor ligand and forms the complexes of the type ML2 (metal-ligand) stoichiometry for Cu(II), Co(II), Ni(II), and Mn(II) complexes and ML stoichiometry for Zn(II), Hg(II), and Fe(III) complexes. All the complexes are colored and nonelectrolytes. It is found that Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) complexes have exhibited octahedral geometry whereas Zn(II) and Hg(II) complexes exhibited tetrahedral geometry. The ligand and its metal complexes have been screened for their antibacterial activity against E. coli and S. aureus and antifungal activity against A. niger and A. flavus.

In VitroAntibacterial Activity of Essential Oils againstStreptococcus pyogenes

Streptococcus pyogenes plays an important role in the pathogenesis of tonsillitis. The present study was conducted to evaluate the in vitro antibacterial activities of 18 essential oils chemotypes from aromatic medicinal plants against S. pyogenes. Antibacterial activity of essential oils was investigated using disc diffusion method. Minimum Inhibitory Concentration of essential oils showing an important antibacterial activity was measured using broth dilution method. Out of 18 essential oils tested, 14 showed antibacterial activity against S. pyogenes. Among them Cinnamomum verum, Cymbopogon citratus, Thymus vulgaris CT thymol, Origanum compactum, and Satureja montana essential oils exhibited significant antibacterial activity. The in vitro results reported here suggest that, for patients suffering from bacterial throat infections, if aromatherapy is used, these essential oils, considered as potential antimicrobial agents, should be preferred.