antibacterial activity

摘要： Silver nanoparticles(Ag NPs)are an effective antibacterial agent,but their application in food packaging is limited due to their easy agglomeration and oxidation.In this study,antibacterial microcapsules were fabricated using Ginkgo biloba essential oil(GBEO)as core material and chitosan and type B gelatin biopolymer as capsule mate-rials.These antibacterial microcapsules were then modified with green-synthesized Ag NPs,blended into the bio-polymer polylactic acid(PLA),and finally formed as films.Physicochemical properties and antibacterial activity against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were evaluated.Results showed that the prepared antibacterial PLA films exhibited excellent antibacterial activity against foodborne pathogens.Its TVC exceeded the limit value of 7 log CFU/g at 7 days compared with the 5 days of pure PLA films.Therefore,these films can extend the shelf life of grass carp fillets by 2–3 days under refrigeration.

摘要： The current study aimed to optimize a green synthesis procedure for fabricating biogenic silver nanoparticles (AgNPs) using an aqueous extract of Catha edulis (Qat;khat) leaves. The final product was characterized using various analytical techniques. Parameters’ optimization including pH, contact time, temperature, and amount of leaf extract were carried out. AgNPs formation was confirmed by UV-vis spectra at 403 nm, FT-IR, and XRD peaks. FTIR spectra showed the presence of various biochemical metabolites which played a critical role in the bio-reduction, capping, and stabilization of AgNPs. The biogenic AgNPs were spherical in shape with an average size between 27 and 32 nm as estimated from XRD and SEM images. Biogenic AgNPs showed significant activities against sensitive and multi-drug resistance Escherichia coli and Staphylococcus aureus strains. In addition, the experimental results proved that AgNPs have higher efficacy than antifungal drugs that are commonly used to treat Candida albicans oral infections.

摘要： Multifunctional fillers are greatly required for dental resin composites(DRCs).In this work,a spray dryer with a three-fluid nozzle was applied for the first time to construct high-performance complex nanoparticle clusters(CNCs)consisting of different functional nanofillers for dental restoration.The application of a three-fluid nozzle can effectively avoid the aggregation of different nanoparticles with opposite zeta potentials before the spray drying process in order to construct regularly shaped CNCs.For a SiO_(2)–ZrO_(2) binary system,the SiO_(2)–ZrO_(2) CNCs constructed using a three-fluid nozzle maintained their excellent mechanical properties((133.3±4.7)MPa,(8.8±0.5)GPa,(371.1±13.3)MPa,and(64.5±0.7)HV for flexural strength,flexural modulus,compressive strength,and hardness of DRCs,respectively),despite the introduction of ZrO_(2) nanoparticles,whereas their counterparts constructed using a two-fluid nozzle showed significantly decreased mechanical properties.Furthermore,heat treatment of the SiO_(2)-ZrO_(2) CNCs significantly improved the mechanical properties and radiopacity of the DRCs.The DRCs containing over 10%mass fraction ZrO_(2) nanoparticles can meet the requirement for radiopaque fillers.More importantly,this method can be expanded to ternary or quaternary systems.DRCs filled with SiO_(2)-ZrO_(2)-ZnO CNCs with a ratio of 56:10:4 displayed high antibacterial activity(antibacterial ratio>99%)in addition to excellent mechanical properties and radiopacity.Thus,the three-fluid nozzle spray drying technique holds great potential for the efficient construction of multifunctional cluster fillers for DRCs.

摘要： This study investigates the effect of graphene oxide(GO)on the mechanical and corrosion behavior,antibacterial performance,and cell response of Mg–Zn–Mn(MZM)nanocomposite.MZM/GO nanocomposites with different amounts of GO(i.e.,0.5 wt%,1.0 wt%,and1.5 wt%)were fabricated by the semi-powder metallurgy method.The influence of GO on the MZM nanocomposite was analyzed through the hardness,compressive,corrosion,antibacterial,and cytotoxicity tests.The experimental results showed that,with the increase in the amount of GO(0.5 wt%and 1.5 wt%),the hardness value,compressive strength,and antibacterial performance of the MZM nanocomposite increased,whereas the cell viability and osteogenesis level decreased after the addition of 1.5 wt%GO.Moreover,the electrochemical examination results showed that the corrosion behavior of the MZM alloy was significantly enhanced after encapsulation in 0.5 wt%GO.In summary,MZM nanocomposites reinforced with GO can be used for implant applications because of their antibacterial performance and mechanical property.

摘要： Background: Traditional medicine has employed Azadirachta indica to treat a variety of ailments. However, there is little information on the use of this plant in Zambia. Objective: To evaluate the phytochemicals and antibacterial activity of Azadirachta indica leaf extracts against Escherichia coli. Materials and Methods: This was a laboratory-based experimental study in which ethanol and water were used for extraction by maceration. Phytochemical analysis was then done on the leaf extract. Using the disc diffusion method, varying concentrations of A. indica aqueous and ethanolic extracts were used to test the antibacterial activity of A. indica against Escherichia coli. The sensitivity of the tested microorganisms to aqueous and ethanolic leaf extracts was shown by zones of inhibition after incubation. Results: The phytochemical screening of the A. indica leaves revealed the presence of phenolics and tannins in both the ethanol and aqueous extract. Saponins, flavonoids and alkaloids were only present in the aqueous extract. While steroids were only present in the ethanol extract. The antibacterial activity of A. indica leaves extract was determined by zones of inhibition which showed that both aqueous and ethanol extracts had activity against E. coli. The Minimum Inhibitory Concentration was determined at 10 mg/mL for the aqueous extract and 20 mg/mL for the ethanol extract. The zones of inhibition increased with concentration. Conclusion: The extracts of A. indica displayed antibacterial activity against E. coli in a dose-dependent manner. Comparatively, the aqueous extract produced better antibacterial properties against E. coli than the ethanolic extract.

摘要： Antimicrobial peptides (AMPs) are bioactive peptides with antibacterial activity, generally composed of 10-60 amino acid residues, and are cationic peptides with amphiphilic structures. It has broad-spectrum antibacterial properties, and also has antiviral, antitumor, antifungal and other effects, and is recognized as the most potential antibiotic alternative. This paper mainly takes the defensin Acipensins1 as an example to introduce the molecular structure of antimicrobial peptides, expounds and analyzes the mechanism of action of antimicrobial peptides that have been discovered, and summarizes the experiments of O. V. Shamova. The antimicrobial activity and safety of Acipensins1 are analyzed and compared, and the antimicrobial peptides are listed. Many applications of peptides, and finally put forward the prospect of designing and constructing hybrid antimicrobial peptides, hoping to provide some theoretical support for the research and application of antimicrobial peptides in the future.

摘要： Background: Artemisia afra is an indigenous plant used in Africa. It is used in traditional medicine to treat a variety of diseases caused by bacterial infections. As a result, developing innovative therapeutic methods using natural ingredients to combat pathogenic germs is critical. Methodology: Artemisia afra leaves were extracted using maceration extraction utilizing three solvents (petroleum ether, ethanol, and dichloromethane). Fresh leaves were extracted using hydrodistillation. The agar well diffusion method was used to test the crude extract and essential oil leaves of Artemisia afra against different human pathogenic bacteria strains (E. coli, S. aureus, E. faecalis, and K. pneumonia) at different concentrations in the presence of a positive (ciprofloxacin 5.0 μg) and negative (DMSO) control. Results: Artemisia afra revealed the presence of alkaloids, flavonoids, tannins, saponins, anthraquinones, terpenoids, coumarins, phenolic quinones, cardiac glycosides, and steroids. It showed that the highest antibacterial activity given by the ethanol extract had highly inhibition zones against gram-positive and gram-negative bacteria. The essential oil extract was effective against all tested bacteria. Conclusion: Plant crude extracts and essential oils may have antibacterial properties due to the synergistic activity of two or more active secondary metabolites.

摘要： Introduction: Jatropha multifida Lin was a plant of traditional Beninese medicine used as an antibiotic. This study aimed to evaluate the antibacterial activity and the toxicity of the sap and the aqueous extract of Jatropha multifida leaves. Methods: Phytochemical screening of Jatropha multifida leaves was carried out. The extract was obtained by maceration. The antimicrobial activity of sap and leaves was evaluated on the five strains of hospital germs. Acute oral toxicity by forced gavage in a single dose of 2000 mg/kg body weight was performed on female Wistar rats. Biochemical and hematological parameters were determined. Results: The presence of flavonoids, tannins, alkaloids, anthocyanins, mucilages, leuco-anthocyanins and saponosides was noted in the leaves of Jatropha multifida. The aqueous extracts of the leaves inhibited two strains of Staphylococcus aureus out of three, while the sap of Jatropha multifida was 100% bactericidal against the strains of Staphylococcus aureus and Streptococcus D. The sap and aqueous leaf extract were not bactericidal on strains of Escherichia coli, Klebsiella oxytoca and Pseudomonas aeruginosa. For the toxicity, there was no death of rats and the aqueous extract of the leaves did not significantly vary the weight of the rats, the creatinine, the ALAT transaminase, the hemoglobin level, the number of white blood cells and blood platelets. Conclusion: The sap of Jatropha multifida exerted a more effective antibacterial activity than the aqueous extract of its leaves. The leaves were not acutely toxic.

摘要： Mg and its alloys are suitable choices for implant materials due to their biodegradability and biocompatibility features. However, the high electrochemical activity of this family of biomaterials results in their fast degradation and severe corrosion in the physiological environment,producing hydrogen(H;) gas, and therefore increasing the p H of the environment. To meet the clinical requirements, the degradation rate of Mg biomaterials needs to be reduced. Nevertheless, higher corrosion resistance of Mg results in a low alkaline p H, weakening the antibacterial activity. Therefore, while the rapid degradation problem of Mg-based biomaterials needs to be addressed, good antibacterial properties are also necessary. By using the plasma electrolytic oxidation(PEO) surface modification technique, the antibacterial activity of Mg and its alloys can be enhanced while maintaining their corrosion protection properties at a high level. Throughout the PEO process, introducing antibacterial agents into solutions results in a major increase in antibacterial activity of the coatings. Moreover, post-or pre-processing on PEO coatings can provide better protection against bacteria. In this review, the antibacterial activity of PEO coatings applied on Mg and also its alloys will be discussed in more detail.

摘要： A series of 4-thioflavonols compounds were synthesized by treating flavonols with lawsons reagent with variable substituent groups at A, B, and AB rings. All the synthesized compounds were checked for antibacterial and antifungal activity. We report that many compounds were found active against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, bacterial strains and, C. albicans, C. parapsilosisstrains and C. krusei fungal strains. Most of the synthesized 4-thioflavonols compounds were found to show enhanced antimicrobial activity than respective flavonol compounds.

摘要： The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli(E．coli)in vitro and in vivo．E．coli was co-cultured in vitro with each probiotic strain individually and a mixture of the four strains and its population was counted at various time points．We also collected a cell-free culture supernatant(CFCS)of each probiotic strain and the four-strain mixed to examine their antibacterial activity using the cylinder plate method．Results demonstrated that co-culture with probiotics significantly reduced the number of E.coli．The different sizes of the inhibition zones made by each CFCS proved that E.coli was inhibited by the metabolites of the probiotics．In vivo，Kunming mice were allocated into different groups supplemented with selenium-enriched and other probiotics．After 28 days，the mice were inoculated with pathogenic E．coli to compare mortality and inspect other indexes of each treatment．The mortality of the group with selenium-enriched probiotics was the lowest．In addition，the organic antioxidant status improved，immunity was fortified，and the intemal environment of the intestinal tract was enhanced with selenium-enriched probiotic supplementation．In conclusion,selenium-enriched probiotics can strongly antagonize pathogenic E．coli in vitro and vivo．

摘要： The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli(E．coli)in vitro and in vivo．E．coli was co-cultured in vitro with each probiotic strain individually and a mixture of the four strains and its population was counted at various time points．We also collected a cell-free culture supernatant(CFCS)of each probiotic strain and the four-strain mixed to examine their antibacterial activity using the cylinder plate method．Results demonstrated that co-culture with probiotics significantly reduced the number of E.coli．The different sizes of the inhibition zones made by each CFCS proved that E.coli was inhibited by the metabolites of the probiotics．In vivo，Kunming mice were allocated into different groups supplemented with selenium-enriched and other probiotics．After 28 days，the mice were inoculated with pathogenic E．coli to compare mortality and inspect other indexes of each treatment．The mortality of the group with selenium-enriched probiotics was the lowest．In addition，the organic antioxidant status improved，immunity was fortified，and the intemal environment of the intestinal tract was enhanced with selenium-enriched probiotic supplementation．In conclusion,selenium-enriched probiotics can strongly antagonize pathogenic E．coli in vitro and vivo．

摘要： The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli(E．coli)in vitro and in vivo．E．coli was co-cultured in vitro with each probiotic strain individually and a mixture of the four strains and its population was counted at various time points．We also collected a cell-free culture supernatant(CFCS)of each probiotic strain and the four-strain mixed to examine their antibacterial activity using the cylinder plate method．Results demonstrated that co-culture with probiotics significantly reduced the number of E.coli．The different sizes of the inhibition zones made by each CFCS proved that E.coli was inhibited by the metabolites of the probiotics．In vivo，Kunming mice were allocated into different groups supplemented with selenium-enriched and other probiotics．After 28 days，the mice were inoculated with pathogenic E．coli to compare mortality and inspect other indexes of each treatment．The mortality of the group with selenium-enriched probiotics was the lowest．In addition，the organic antioxidant status improved，immunity was fortified，and the intemal environment of the intestinal tract was enhanced with selenium-enriched probiotic supplementation．In conclusion,selenium-enriched probiotics can strongly antagonize pathogenic E．coli in vitro and vivo．

摘要： The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli(E．coli)in vitro and in vivo．E．coli was co-cultured in vitro with each probiotic strain individually and a mixture of the four strains and its population was counted at various time points．We also collected a cell-free culture supernatant(CFCS)of each probiotic strain and the four-strain mixed to examine their antibacterial activity using the cylinder plate method．Results demonstrated that co-culture with probiotics significantly reduced the number of E.coli．The different sizes of the inhibition zones made by each CFCS proved that E.coli was inhibited by the metabolites of the probiotics．In vivo，Kunming mice were allocated into different groups supplemented with selenium-enriched and other probiotics．After 28 days，the mice were inoculated with pathogenic E．coli to compare mortality and inspect other indexes of each treatment．The mortality of the group with selenium-enriched probiotics was the lowest．In addition，the organic antioxidant status improved，immunity was fortified，and the intemal environment of the intestinal tract was enhanced with selenium-enriched probiotic supplementation．In conclusion,selenium-enriched probiotics can strongly antagonize pathogenic E．coli in vitro and vivo．