Lysozyme(EC3.2.1.17)plays an important role in the immune response;as a nonspecific immune factor,it can resist causative agents.Lysozyme can be divided into c-type and g-type in fish.In a previous study,through genom...Lysozyme(EC3.2.1.17)plays an important role in the immune response;as a nonspecific immune factor,it can resist causative agents.Lysozyme can be divided into c-type and g-type in fish.In a previous study,through genome-wide association analysis,the g-type lysozyme gene,which is named NaLyg in yellow drum(Nibea albiflora),was found to be a key candidate gene for disease resistance in response to Vibrio harveyi infection.The cDNA of NaLyg was 1025 bp,including four exons and three introns,and its open reading frame(ORF)had a full-length of 582 bp,encoding 193 amino acids.NaLyg was found to be conserved during evolution through bioinformatic analyses.The NaLyg protein possessed a sugar binding domain and three catalytic sites,including Glu71,Asp84 and Asp101.Quantitative qRT-PCR results confirmed that NaLyg gene mRNA was visibly increased after V.harveyi infection.The NaLyg protein purified by prokaryotic expression killed some gram-negative bacterial pathogens by inducing cell wall destruction,including V.harveyi,Aeromonas hydrophila and Edwardsiella tarda.Moreover,the NaLyg protein killed two gram-positive bacteria,Bacillus subtilis and Staphylococcus aureus.Taken together,the experimental results suggested that the NaLyg protein of N.albiflora played an important role in fighting bacterial infections.展开更多
Carboxymethyl starch/silver oxide nanocomposites(CMS-Ag_(2)O NCs)were successfully fabricated by modifying carboxymethyl starch(CMS)with Ag_(2)O obtained from an aqueous AgNO_(3)solution as silver source.Ag_(2)O nanop...Carboxymethyl starch/silver oxide nanocomposites(CMS-Ag_(2)O NCs)were successfully fabricated by modifying carboxymethyl starch(CMS)with Ag_(2)O obtained from an aqueous AgNO_(3)solution as silver source.Ag_(2)O nanoparticles(NPs)formed on the surface of CMS by ion exchange.Based on SEM images,the diameters of Ag_(2)O NPs were determined to be between 50 and 100 nm.From the XRD spectra of CMS-Ag_(2)O NCs,the new diffraction peaks appeared at 33.88°and 38.08°,which were attributed to the Ag_(2)O NPs.According to the XPS analysis,Ag 3d_(5/2)and Ag 3d_(3/2)peaks in CMS-Ag_(2)O NCs were fitted into two main peaks centered at 367.6 eV and 373.6 eV,which were attributed to Ag^(+).The antibacterial efficiencies of CMS-Ag_(2)O NCs against Escherichia coli,Staphylococcus aureus,Pseudoalteromonas tetraodonis,Micrococcus luteus,and Shewanella putrefaciens were determined to be 99.6%,99.7%,99.4%,99.5%,and 99.6%,respectively.The antibacterial efficiencies of CMS-Ag_(2)O NCs against the bacterial species were all greater than 99%.Therefore,these results indicated that CMS-Ag_(2)O NCs was highly effective as a bactericidal agent against multiple bacterial species.CMS-Ag_(2)O NCs can be further applied to antifouling coating.展开更多
Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many micro...Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. Zn O-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. Zn O is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered Zn O-NPs antibacterial activity including testing methods, impact of UV illumination, Zn O particle properties(size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species(ROS) including hydrogen peroxide(H2O2), OH-(hydroxyl radicals), and O2-2(peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to Zn O-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions.These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on Zn O abrasive surface texture. One functional application of the Zn O antibacterial bioactivity was discussed in food packaging industry where Zn O-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of Zn O-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.展开更多
A pair of new enantiomeric furoquinoline alkaloids,(±)-zanthonitidine A(1),together with nine known ones(2-10)were isolated from the radix of Zanthoxylum nitidum.Their chemical structures were elucidated based on...A pair of new enantiomeric furoquinoline alkaloids,(±)-zanthonitidine A(1),together with nine known ones(2-10)were isolated from the radix of Zanthoxylum nitidum.Their chemical structures were elucidated based on the extensive spectroscopic analysis.The racemic mixture of 1 was separated by chiral column chromatography,and the absolute configurations of (+)-1 and(-)-1 were determined by the comparison of experimental and calculated electronic circular dichroism spectra.Antibacterial activities of compounds 1-9 were evaluated,and compounds(+)-1,(-)-1,3,7 and 8 showed antibacterial activities against Bacillus subtilis,Enterococcus faecalis or Staphylococcus aureus.展开更多
A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susc...A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.展开更多
Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide mon...Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.展开更多
Filamentous microalgae from genus Tribonema are promising sustainable sources of omega-7 palmitoleic acid,but their ability to accumulate this compound varies among species and depends on the initial nitrogen concentr...Filamentous microalgae from genus Tribonema are promising sustainable sources of omega-7 palmitoleic acid,but their ability to accumulate this compound varies among species and depends on the initial nitrogen concentration(INC)supply.In this study,the palmitoleic acid accumulation capacities of five Tribonema species were examined under three different INCs to select the alga species with the highest production.Results showed that a high INC was associated with increased palmitoleic acid accumulation but led to decreased biomass concentration in all tested species.In particular,T.minus grown at 18 mmol L^(−1)INC had the highest palmitoleic acid content(20.72%of dry weight)and productivity(90.88 mg L^(−1)d−1).The combination of alkali metal freezing precipitation(AMFP)and urea complexation successfully isolated and enriched palmitoleic acid from T.minus and obtained a purity of 80.11%and a yield of 7.39 g(100 g)^(−1) of algal powder.The compound was identified as(9Z)-hexadecenoic acid(C16:1ω-7).Antibacterial activity evaluation for the highly concentrated palmitoleic acid(10 mg mL^(−1))against Streptococcus agalactiae revealed the formation of a 12.10 mm-diameter inhibition zone and the minimum inhibitory concentration of 31.25μg mL^(−1),indicating that palmitoleic acid is an effective antibacterial agent.This study is the first to report that palmitoleic acid derived from T.minus can antagonize S.agalactiae,which further broadens the potential application of Tribonema biomass in green aquaculture.展开更多
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...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.展开更多
To synthesize three different grafting ratios of gallic acid(GA)-chitosan(CS)copolymer by a free radical mediated grafting method,which is further applied to the field of antibacterial materials,crosslinking structure...To synthesize three different grafting ratios of gallic acid(GA)-chitosan(CS)copolymer by a free radical mediated grafting method,which is further applied to the field of antibacterial materials,crosslinking structures of the compound GA-CS copolymer were characterized,fully indicating that gallic acid is resoundingly grafted onto chitosan.The grafting ratios of three copolymers GA-CS are 45.71%(Ⅰ),36.12%(Ⅱ),and 18.96%(Ⅲ)were determined by UV-Vis spectrophotometer.The minimum inhibitory concentrations of three GA-CS copolymers are 30μg/mL against Escherichia coli and are ranged from 250 to 550μg/mL against Staphylococcus aureus.By counting viable bacterial colonies,it can be found that antibacterial property is preferable by increasing the grafting ratio of GA-CS copolymers.Findings of investigation on aforementioned bacteria experiment indicate that the CFU/mL values of GA-CS(Ⅰ,Ⅱ,Ⅲ)are 2.04×10^(6),7.56×10^(6),1.48×10^(7) to Staphylococcus aureus,and 2.96×10^(6),1.01×10^(7),2.14×10^(7) to Escherichia coli after 12 h treatment.In addition,the interaction process between GA-CS copolymer and bacteria can be observed through a transmission electron microscope.The specific manifestation is that the bacterial cell membranes are ruptured after being treated with the copolymer,which causes the cell contents to flow out,and the cell morphology is shrunk and out ofshape.展开更多
<b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Traditional medicine h...<b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Traditional medicine has employed </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> to treat a variety of ailments. However, there is little information on the use of this </span><span><span style="font-family:Verdana;">plant in Zambia. </span><b><span style="font-family:Verdana;">Objective:</span></b><span style="font-family:Verdana;"> To evaluate the phytochemicals and antibacterial</span></span><span style="font-family:Verdana;"> activity of </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaf extracts against </span><i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">coli.</span></i> <b><span style="font-family:Verdana;">Materials and Methods:</span></b><span style="font-family:Verdana;"> 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 </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> aqueous and ethanolic extracts </span><span><span style="font-family:Verdana;">were used to test the antibacterial activity of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i> <i><span style="font-family:Verdana;">against</span></i> <i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">co</span></i></span><i><span style="font-family:Verdana;">li</span></i><span style="font-family:Verdana;">. The sensitivity of the tested microorganisms to aqueous and ethanolic </span><span><span style="font-family:Verdana;">leaf extracts was shown by zones of inhibition after incubation. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The</span></span><span style="font-family:Verdana;"> phytochemical screening of the </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> 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 </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaves extract was determined by zones of inhibition which showed that both aqueous and ethanol extracts had activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;">. 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. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">The extracts of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> displayed antibacterial activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> in a dose-dependent manner. Comparatively, the aqueous extract produced better antibacterial properties against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> than the ethanolic extract.展开更多
Magnesium(Mg) has attracted wide interest in orthopedic applications as they exhibit great biodegradability and strong biocompatibility,while corrosion is the main concern for Mg that should be addressed prior to biom...Magnesium(Mg) has attracted wide interest in orthopedic applications as they exhibit great biodegradability and strong biocompatibility,while corrosion is the main concern for Mg that should be addressed prior to biomedical applications. In this work, ZM31(Mg-3Zn-1Mn)/x RGO(x = 0, 0.5, 1 and 1.5 wt%) biocomposites were synthesized by semi-powder metallurgy method. The results showed that the RGO acting as an effective reinforcing filler to prevent deformation and showed better compressive strength(282.3 ± 9 MPa) and revealed enhancement in failure Strain(7.8 ± 2.1%) at 1 wt% RGO concentration compared to Mg alloy(244.5 ± 9 MPa and 7.1 ± 1.5%respectively). Moreover, fracture analysis indicated a more ductile fracture of the nanocomposites after the incorporation of RGO. Crack bridging, crack deflection and crack branching are dominant mechanisms for reinforcement of Mg-based containing RGO. Mg composites containing 0.5 wt% RGO showed a low corrosion rate(2.75 mm/year), while more incorporation of RGO resulted in an increased corrosion rate(4.38 mm/year). In addition, the degradation rate of ZM31 alloy(2.57 mg·cm-2·d-1) obviously decreased with the addition of 0.5 wt%RGO(1.84 mg·cm-2·d-1) in the SBF. Besides, continuous apatite layers were created on the composites in the SBF solution. Also, the cell culture examinations showed good cell viability and adhesion on composites with 0.5 and 1 wt% RGO, which was demonstrated by the SEM and MTT assay The alkaline phosphatase(ALP) activity of the ZM3–0.5RGO composite was considerably higher than that of ZM31matrix alloy in 24 h and 48 h, implying higher osteoblastic differentiation. The antibacterial behavior toward both bacteria(E. coli and S.aureus) exhibited that escalating RGO concentration in Mg-matrix composites leads to further inhibition of bacteria growth. These findings suggested that ZM31–0.5RGO biocomposite could be a more promising candidate for orthopedic implants.展开更多
Objective:To explore secondary metabolite of bacteria-associated Xestospongia testudinaria from Tanjung Kasuari,Sorong,Papua.Methods:The antimicrobial activities of extracts against two Gram-positive bacteria(Staphylo...Objective:To explore secondary metabolite of bacteria-associated Xestospongia testudinaria from Tanjung Kasuari,Sorong,Papua.Methods:The antimicrobial activities of extracts against two Gram-positive bacteria(Staphylococcus aureus) and three Gram-negative bacteria(Pseudomonas aeruginosa,Eschericia coli and Salmonella typhi) were determined by disk diffusion dilution method.Results:The test showed that of 15 isolates of symbiont bacteria,6 isolates were successfully isolated and coded,namely,Xp 4.1,Xp 4.2,Xp 4.3,Xp 4.4,Xp 4.5 and Xp 4.6.Of the six bacterial isolates,isolated Xp 4.2 was found to have more powerful antibacterial activity than any other isolates of symbiont bacteria.Antibacterial activity assay for the n-hexane soluble fractions,ethyl-acetate soluble fractions,and n-buthanol soluble fractions revealed more powerful anti-bacterial activity than any other soluble fractions.Phytochemical screening showed alkaloid and steroid/triterpenoid,while identification for isolate of Xp 4.2 bacterial showed bacteria.Conclusions:Metabolites of bacterial associated with marine sponge Xestospongia testudinaria promise to be developed into antibacterial agents.展开更多
Objective:To assess the antibacterial activity of 5 selected plants against 4 pathogenic bacteria.Methods:Three solvents with different polarities were used to extract antimicrobial agents from the plants via macerati...Objective:To assess the antibacterial activity of 5 selected plants against 4 pathogenic bacteria.Methods:Three solvents with different polarities were used to extract antimicrobial agents from the plants via maceration technique.The agar-disc diffusion technique was adopted to primarily screen antibacterial activities.Broth-dilution assay was employed to determine the minimum inhibitory concentration(MIC)and the minimum bactericidal concentration(MBC).Results:Among all extracts,the ethanol extract of Piper betle Linn showed the highest antibacterial activity against Gram-positive and the negative bacteria.MIC and MBC of the ethanol extract of Piper betle Linn against Salmonella typhimurium were the same(1?562.50 mg/L);while it showed the highest MIC and MBC against Pseudomonas aeruginosa of 6?250 mg/L and 12?500 mg/L,respectively.Conclusions:Salmonella typhimurium is the most susceptible bacteria while Pseudomonas aeruginosa is the most resistant bacteria towards the ethanol extract of Piper betle Linn.Piper betle possesses compounds with potential antibacterial activity and might be useful as an alternative to control infectious diseases.展开更多
Bacterial cellulose(BC) is a type of nanoscale cellulose produced by microorganisms.In this work,BC films were utilized as a template to in situ synthesize silver nanoparticles(AgNPs) by a variety of simple chemical s...Bacterial cellulose(BC) is a type of nanoscale cellulose produced by microorganisms.In this work,BC films were utilized as a template to in situ synthesize silver nanoparticles(AgNPs) by a variety of simple chemical strategies,including chemical reduction with NaBH4 or vitamin C,hydrothermal treatment and UV radiation.A comparative study of the formation of AgNPs such as the silver particle size and silver content,as well as the antibacterial activity of the BC-AgNPs nanocomposites by different preparation methods and reaction conditions was investigated.A beneficial support was provided for future applications of AgNPs contained BC composites with antibacterial properties.展开更多
[Objectives]To study the volatile components and antibacterial effects of 11 kinds of Aurantii Fructus Immaturus processed products.[Methods]11 kinds of Aurantii Fructus Immaturus processed products were obtained acco...[Objectives]To study the volatile components and antibacterial effects of 11 kinds of Aurantii Fructus Immaturus processed products.[Methods]11 kinds of Aurantii Fructus Immaturus processed products were obtained according to the traditional processing method,the volatile oil was extracted by steam distillation,and the composition of volatile oil in the 11 kinds of processed products was analyzed by gas chromatography-mass spectrometry(GC-MS).the relative percentage content of each component in these 11 kinds of processed products was determined using the peak area normalization.The drug sensitivity activity of the volatile oil of these 11 kinds of processed products was tested using the K-B paper diffusion method and the minimum inhibition volume fraction of volatile oil of these 11 kinds of processed products was tested using the microdilution method.[Results]The highest yield of volatile oil of 11 kinds of these processed products was baking(5.193%),and the lowest was stir-bake to scorch(1.998%).A total of 36 chemical components were identified from the volatile oils of these 11 kinds of processed products.The components with the most volatile oil were stir-bake to scorch(24 kinds),and the components with the least volatile oil were the method of processing with rice-washed water(15 kinds).They contain 8 kinds of common chemical components,such as limonene,linalool,myrcene,α-pinene.The highest content of limonene came from processing with honey(60.93%),the lowest came from processing with rice-washed water(55.25%);the highest content of linalool came from processing with rice-washed water(7.139%),the lowest came from processing with honey(5.436%);the highest content of myrcene came from processing with honey(1.899%),the lowest came from stir-bake to scorch(1.632%);the highest content ofα-pinene came from raw Aurantii Fructus Immaturus(2.355%),and the lowest came from stir-bake to scorch(1.618%).The volatile oil of these 11 kinds of Aurantii Fructus Immaturus processed products has good antibacterial effect on Escherichia coli and Staphylococcus aureus.[Conclusions]The oil yields of volatile oils of 11 kinds of Aurantii Fructus Immaturus processed products are different,the content of limonene is significantly different,and the changes of other chemical components and their contents are not significantly different.The volatile oil of 11 kinds of Aurantii Fructus Immaturus processed products has certain antibacterial effect.展开更多
<span style="font-family:Verdana;">Due to the continuous emergence and rapid spread of drug-resistant strains of bacteria, there is an urgent need for the development of novel antimicrobials. Along thi...<span style="font-family:Verdana;">Due to the continuous emergence and rapid spread of drug-resistant strains of bacteria, there is an urgent need for the development of novel antimicrobials. Along this line, the synthesis and antibacterial activity of 4,5-diphenylimidazol-2-thiol derivatives <strong>2a-g</strong> and <strong>6a-e</strong> are reported. The structures of the synthesized compounds were confirmed by Nuclear Magnetic Resonance (NMR) and High Resolution Mass Spectrometry (HRMS). All compounds were screened <em>in vitro</em> for their antibacterial activity against <em>Pseudomonas aeruginosa</em> and <em>Escherichia coli</em> (Gram-negative bacteria) and also against <em>Staphyloccocus aureus</em> and <em>Enterococcus faecalis</em> (Gram-positive bacteria). The results showed most of the synthesized compounds have no antibacterial activity. However compound <strong>6d</strong> was two-fold potent than ciprofloxacin against <em>Staphylococcus aureus</em> with Minimum Inhibitory Concentration (MIC) of 4 μg/mL and <strong>6c</strong> showed moderate biological activity against <em>Staphylococcus aureus</em> (16 μg/mL) and <em>Enterococcus faecalis</em> (16 μg/mL).</span>展开更多
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 J...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.展开更多
1,8-cineole, also known as eucalyptol, is the main constituent and the most important of the leaf oils of many species of the genus Eucalyptus. In present study, the essential oils isolated by hydrodistillation from t...1,8-cineole, also known as eucalyptol, is the main constituent and the most important of the leaf oils of many species of the genus Eucalyptus. In present study, the essential oils isolated by hydrodistillation from the leaves of Eucalyptus camaldulensis from six different locations were analyzed by GC-FID and GC-MS. Essential oil yields ranged from 0.33% to 4.35%. In total, 34 constituents were identified, accounting for 94.0% to 99.8% of the total compositions. 1,8-cineole (46.4% - 84.4%) was the main constituent of all the essential oil samples, except for one sample collected in the Fatick region, which had p-cymene (46.4%) and 1,8-cineole (26.0%) as major compounds. The essential oil showed excellent activity against S. aureus, E. coli and E. faecalis (IZ = 25.3 ± 1.2 mm;18.7 ± 0.6 mm;17.8 ± 0.3 mm, respectively) and moderate activity against P. aeruginosa (IZ = 10.8 ± 0.8 mm). They may have potential applications in food and pharmaceutical products.展开更多
This investigation was undertaken to enhance the solubility and consequent antibacterial activity of cefuroxime axetil (CA), a </span><i><span style="font-family:Verdana;">β</span>&l...This investigation was undertaken to enhance the solubility and consequent antibacterial activity of cefuroxime axetil (CA), a </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-lactamase-stable broad spectrum second generation cephalosporin through solid dispersion (SD) technique. For this purpose, CA loaded SDs (CSDs) were prepared by solvent evaporation method using different concentrations of microcrystalline cellulose (MCC) as carrier. The CSDs were characterized by </span><i><span style="font-family:Verdana;">in-vitro</span></i><span style="font-family:Verdana;"> dissolution study, thermal analysis (DSC), crystallinity (PXRD), interactions (FTIR) and morphology (SEM). Among the formulations, CSD-2 showed the highest dissolution rate which was 2.59-fold higher than pure CA with a drug-carrier (CA: MCC) ratio of 1:3. Enhanced dissolution rate was attributed to conversion of drug from crystalline to amorphous state during preparation of SDs, which was validated by DSC, PXRD, FTIR and SEM analyses. Antibacterial activity of CSD-2 against </span><i><span style="font-family:Verdana;">Staphylococcus aureus</span></i><span style="font-family:Verdana;"> (ATCC 25923) and </span><i><span style="font-family:Verdana;">Escherichia coli</span></i><span style="font-family:Verdana;"> (ATCC 25922) showed 1.94- and 6.75-fold higher relative zone of inhibition (RZOI), respectively than pure CA. CSD-2 has been found to be the most effective optimized formulation in terms of both enhanced dissolution rate and antibacterial activity. Thus, it can be an effective alternative to conventional dosage forms of CA. However, further investigations are needed to validate its pharmacokinetic properties, </span><i><span style="font-family:Verdana;">in-vivo </span></i><span style="font-family:Verdana;">antibacterial efficacy and safety before recommending as a novel展开更多
One of the serious problems the world is facing today is the antimicrobial resistance on available antibiotics by most bacterial pathogens and the rising cost of finding effective antimicrobial agents. In recent years...One of the serious problems the world is facing today is the antimicrobial resistance on available antibiotics by most bacterial pathogens and the rising cost of finding effective antimicrobial agents. In recent years, efforts to find new drugs especially from natural sources have been boosted by the demand for an effective cure for infectious diseases. Only the antibacterial activity of <em>apis mellifera</em> honey and not stingless bee honey from western Kenya has been reported. This study was therefore carried out to determine the effect of <em>Plebenia hylderbrandii </em>and <em>Meliponula bocandei </em>honey samples on the growth of control;sensitive cases of Escherichia coli (ATCC 25922) and <em>Staphylococcus aureus</em> (ATCC 25923). Different honey concentrations (1.18% - 17.65% v/v) of the two samples were tested against the two micro-organisms. The samples were screened for their antibacterial potential against <em>Escherichia coli </em>and <em>Staphylococcus aureus</em> by agar well dilution method. The Partial inhibitory concentration (PIC), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined by in vitro method. The inhibitory effect of <em>Plebenia hylderbrandii</em> honey on <em>E. coli</em> and <em>S. aureus</em> growth was apparent at concentrations 3.53% and 1.76% (v/v) respectively. On the other hand, the inhibitory effect of <em>Meliponula bocandei </em>honey on <em>S. aureus</em> growth was at concentration 16.47% (v/v). <em>Plebenia hylderbrandii</em> honey had bactericidal effect on both <em>E. coli </em>and <em>S. aureus</em> at concentrations 4.71% and 2.35% (v/v) respectively. However, <em>Meliponula bocandei</em> honey exerted bactericidal effect on <em>S. aureus </em>only at 16.47% (v/v) concentration. <em>Plebenia hylderbrandii </em>honey had higher antibacterial potency and can be a potential source of antibacterial substances. Moreover, the honeys tested in this study showed great antibacterial potential for <em>S. aureus</em>.展开更多
基金supported by the National Natural Science Foundation of China(No.32072969)the National Key R&D Program of China(No.2022YFD2401002)+1 种基金the Natural Science Foundation of Fujian Province(No.2022 J01325)the Open Research Fund Program of Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment(No.Z822280).
文摘Lysozyme(EC3.2.1.17)plays an important role in the immune response;as a nonspecific immune factor,it can resist causative agents.Lysozyme can be divided into c-type and g-type in fish.In a previous study,through genome-wide association analysis,the g-type lysozyme gene,which is named NaLyg in yellow drum(Nibea albiflora),was found to be a key candidate gene for disease resistance in response to Vibrio harveyi infection.The cDNA of NaLyg was 1025 bp,including four exons and three introns,and its open reading frame(ORF)had a full-length of 582 bp,encoding 193 amino acids.NaLyg was found to be conserved during evolution through bioinformatic analyses.The NaLyg protein possessed a sugar binding domain and three catalytic sites,including Glu71,Asp84 and Asp101.Quantitative qRT-PCR results confirmed that NaLyg gene mRNA was visibly increased after V.harveyi infection.The NaLyg protein purified by prokaryotic expression killed some gram-negative bacterial pathogens by inducing cell wall destruction,including V.harveyi,Aeromonas hydrophila and Edwardsiella tarda.Moreover,the NaLyg protein killed two gram-positive bacteria,Bacillus subtilis and Staphylococcus aureus.Taken together,the experimental results suggested that the NaLyg protein of N.albiflora played an important role in fighting bacterial infections.
基金supported by the National Key Research and Development Project(No.2019YFC0312103)the Open Fund of Shandong Key Laboratory of Corrosion Science(No.KLCS201905)。
文摘Carboxymethyl starch/silver oxide nanocomposites(CMS-Ag_(2)O NCs)were successfully fabricated by modifying carboxymethyl starch(CMS)with Ag_(2)O obtained from an aqueous AgNO_(3)solution as silver source.Ag_(2)O nanoparticles(NPs)formed on the surface of CMS by ion exchange.Based on SEM images,the diameters of Ag_(2)O NPs were determined to be between 50 and 100 nm.From the XRD spectra of CMS-Ag_(2)O NCs,the new diffraction peaks appeared at 33.88°and 38.08°,which were attributed to the Ag_(2)O NPs.According to the XPS analysis,Ag 3d_(5/2)and Ag 3d_(3/2)peaks in CMS-Ag_(2)O NCs were fitted into two main peaks centered at 367.6 eV and 373.6 eV,which were attributed to Ag^(+).The antibacterial efficiencies of CMS-Ag_(2)O NCs against Escherichia coli,Staphylococcus aureus,Pseudoalteromonas tetraodonis,Micrococcus luteus,and Shewanella putrefaciens were determined to be 99.6%,99.7%,99.4%,99.5%,and 99.6%,respectively.The antibacterial efficiencies of CMS-Ag_(2)O NCs against the bacterial species were all greater than 99%.Therefore,these results indicated that CMS-Ag_(2)O NCs was highly effective as a bactericidal agent against multiple bacterial species.CMS-Ag_(2)O NCs can be further applied to antifouling coating.
基金support from a research university Grant number 1001/PFIZIK/814174 of Universiti Sains Malaysia(USM)
文摘Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. Zn O-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. Zn O is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered Zn O-NPs antibacterial activity including testing methods, impact of UV illumination, Zn O particle properties(size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species(ROS) including hydrogen peroxide(H2O2), OH-(hydroxyl radicals), and O2-2(peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to Zn O-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions.These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on Zn O abrasive surface texture. One functional application of the Zn O antibacterial bioactivity was discussed in food packaging industry where Zn O-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of Zn O-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.
基金supported by the National Natural Science Foundation of China(31470428,21702231)the National New Drug Innovation Major Project of China(2017ZX09309027)the Program for Jiangsu Province Innovative Research Team,the Fund for Introduction of High-level Talents from China Pharmaceu-tical University and the Fundamental Research Funds for the Central Universities(2632017PY19).
文摘A pair of new enantiomeric furoquinoline alkaloids,(±)-zanthonitidine A(1),together with nine known ones(2-10)were isolated from the radix of Zanthoxylum nitidum.Their chemical structures were elucidated based on the extensive spectroscopic analysis.The racemic mixture of 1 was separated by chiral column chromatography,and the absolute configurations of (+)-1 and(-)-1 were determined by the comparison of experimental and calculated electronic circular dichroism spectra.Antibacterial activities of compounds 1-9 were evaluated,and compounds(+)-1,(-)-1,3,7 and 8 showed antibacterial activities against Bacillus subtilis,Enterococcus faecalis or Staphylococcus aureus.
基金supported by Major R&D Program of New Drugs-National S&T Key Special Subject of China (No.2009ZX09103-115)National Natural Science Foundation of China(No.20872081)Natural Science Foundation of Shandong(No.Y2006C31)
文摘A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.
基金financial support from the International S&T Cooperation Program of China (No.2015DFG31860)the National Science Foundation of China for the Key Projects (Nos.31430092 and 31110103902)
文摘Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.
基金supported by the Jiangsu Provincial Natural Science Foundation(No.BK20200734)the Hubei Provincial Natural Science Foundation(No.2021CFB224)+3 种基金the Engineering Research Center for Tropical and Subtropical Aquatic Ecological Engineering,Ministry of Education,Jinan University,P.R.China(No.2021A0401)the Research and Innovation Initiatives of Wuhan Polytechnic University(WHPU)(No.2021Y06)the Hubei Key Laboratory for Processing and Transformation of Agricultural Products(WHPU,China)(No.2020HBSQGDKFB17)the Sinopec Joint Program of China Petroleum and Chemical Corporation(No.ST18005-2).
文摘Filamentous microalgae from genus Tribonema are promising sustainable sources of omega-7 palmitoleic acid,but their ability to accumulate this compound varies among species and depends on the initial nitrogen concentration(INC)supply.In this study,the palmitoleic acid accumulation capacities of five Tribonema species were examined under three different INCs to select the alga species with the highest production.Results showed that a high INC was associated with increased palmitoleic acid accumulation but led to decreased biomass concentration in all tested species.In particular,T.minus grown at 18 mmol L^(−1)INC had the highest palmitoleic acid content(20.72%of dry weight)and productivity(90.88 mg L^(−1)d−1).The combination of alkali metal freezing precipitation(AMFP)and urea complexation successfully isolated and enriched palmitoleic acid from T.minus and obtained a purity of 80.11%and a yield of 7.39 g(100 g)^(−1) of algal powder.The compound was identified as(9Z)-hexadecenoic acid(C16:1ω-7).Antibacterial activity evaluation for the highly concentrated palmitoleic acid(10 mg mL^(−1))against Streptococcus agalactiae revealed the formation of a 12.10 mm-diameter inhibition zone and the minimum inhibitory concentration of 31.25μg mL^(−1),indicating that palmitoleic acid is an effective antibacterial agent.This study is the first to report that palmitoleic acid derived from T.minus can antagonize S.agalactiae,which further broadens the potential application of Tribonema biomass in green aquaculture.
文摘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.
基金Funded by the Health Commission of Hubei Province Scientific Research Project(No.WJ2019H275)。
文摘To synthesize three different grafting ratios of gallic acid(GA)-chitosan(CS)copolymer by a free radical mediated grafting method,which is further applied to the field of antibacterial materials,crosslinking structures of the compound GA-CS copolymer were characterized,fully indicating that gallic acid is resoundingly grafted onto chitosan.The grafting ratios of three copolymers GA-CS are 45.71%(Ⅰ),36.12%(Ⅱ),and 18.96%(Ⅲ)were determined by UV-Vis spectrophotometer.The minimum inhibitory concentrations of three GA-CS copolymers are 30μg/mL against Escherichia coli and are ranged from 250 to 550μg/mL against Staphylococcus aureus.By counting viable bacterial colonies,it can be found that antibacterial property is preferable by increasing the grafting ratio of GA-CS copolymers.Findings of investigation on aforementioned bacteria experiment indicate that the CFU/mL values of GA-CS(Ⅰ,Ⅱ,Ⅲ)are 2.04×10^(6),7.56×10^(6),1.48×10^(7) to Staphylococcus aureus,and 2.96×10^(6),1.01×10^(7),2.14×10^(7) to Escherichia coli after 12 h treatment.In addition,the interaction process between GA-CS copolymer and bacteria can be observed through a transmission electron microscope.The specific manifestation is that the bacterial cell membranes are ruptured after being treated with the copolymer,which causes the cell contents to flow out,and the cell morphology is shrunk and out ofshape.
文摘<b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Traditional medicine has employed </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> to treat a variety of ailments. However, there is little information on the use of this </span><span><span style="font-family:Verdana;">plant in Zambia. </span><b><span style="font-family:Verdana;">Objective:</span></b><span style="font-family:Verdana;"> To evaluate the phytochemicals and antibacterial</span></span><span style="font-family:Verdana;"> activity of </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaf extracts against </span><i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">coli.</span></i> <b><span style="font-family:Verdana;">Materials and Methods:</span></b><span style="font-family:Verdana;"> 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 </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> aqueous and ethanolic extracts </span><span><span style="font-family:Verdana;">were used to test the antibacterial activity of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i> <i><span style="font-family:Verdana;">against</span></i> <i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">co</span></i></span><i><span style="font-family:Verdana;">li</span></i><span style="font-family:Verdana;">. The sensitivity of the tested microorganisms to aqueous and ethanolic </span><span><span style="font-family:Verdana;">leaf extracts was shown by zones of inhibition after incubation. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The</span></span><span style="font-family:Verdana;"> phytochemical screening of the </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> 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 </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaves extract was determined by zones of inhibition which showed that both aqueous and ethanol extracts had activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;">. 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. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">The extracts of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> displayed antibacterial activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> in a dose-dependent manner. Comparatively, the aqueous extract produced better antibacterial properties against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> than the ethanolic extract.
文摘Magnesium(Mg) has attracted wide interest in orthopedic applications as they exhibit great biodegradability and strong biocompatibility,while corrosion is the main concern for Mg that should be addressed prior to biomedical applications. In this work, ZM31(Mg-3Zn-1Mn)/x RGO(x = 0, 0.5, 1 and 1.5 wt%) biocomposites were synthesized by semi-powder metallurgy method. The results showed that the RGO acting as an effective reinforcing filler to prevent deformation and showed better compressive strength(282.3 ± 9 MPa) and revealed enhancement in failure Strain(7.8 ± 2.1%) at 1 wt% RGO concentration compared to Mg alloy(244.5 ± 9 MPa and 7.1 ± 1.5%respectively). Moreover, fracture analysis indicated a more ductile fracture of the nanocomposites after the incorporation of RGO. Crack bridging, crack deflection and crack branching are dominant mechanisms for reinforcement of Mg-based containing RGO. Mg composites containing 0.5 wt% RGO showed a low corrosion rate(2.75 mm/year), while more incorporation of RGO resulted in an increased corrosion rate(4.38 mm/year). In addition, the degradation rate of ZM31 alloy(2.57 mg·cm-2·d-1) obviously decreased with the addition of 0.5 wt%RGO(1.84 mg·cm-2·d-1) in the SBF. Besides, continuous apatite layers were created on the composites in the SBF solution. Also, the cell culture examinations showed good cell viability and adhesion on composites with 0.5 and 1 wt% RGO, which was demonstrated by the SEM and MTT assay The alkaline phosphatase(ALP) activity of the ZM3–0.5RGO composite was considerably higher than that of ZM31matrix alloy in 24 h and 48 h, implying higher osteoblastic differentiation. The antibacterial behavior toward both bacteria(E. coli and S.aureus) exhibited that escalating RGO concentration in Mg-matrix composites leads to further inhibition of bacteria growth. These findings suggested that ZM31–0.5RGO biocomposite could be a more promising candidate for orthopedic implants.
文摘Objective:To explore secondary metabolite of bacteria-associated Xestospongia testudinaria from Tanjung Kasuari,Sorong,Papua.Methods:The antimicrobial activities of extracts against two Gram-positive bacteria(Staphylococcus aureus) and three Gram-negative bacteria(Pseudomonas aeruginosa,Eschericia coli and Salmonella typhi) were determined by disk diffusion dilution method.Results:The test showed that of 15 isolates of symbiont bacteria,6 isolates were successfully isolated and coded,namely,Xp 4.1,Xp 4.2,Xp 4.3,Xp 4.4,Xp 4.5 and Xp 4.6.Of the six bacterial isolates,isolated Xp 4.2 was found to have more powerful antibacterial activity than any other isolates of symbiont bacteria.Antibacterial activity assay for the n-hexane soluble fractions,ethyl-acetate soluble fractions,and n-buthanol soluble fractions revealed more powerful anti-bacterial activity than any other soluble fractions.Phytochemical screening showed alkaloid and steroid/triterpenoid,while identification for isolate of Xp 4.2 bacterial showed bacteria.Conclusions:Metabolites of bacterial associated with marine sponge Xestospongia testudinaria promise to be developed into antibacterial agents.
基金This research was financially supported by the National Research Council of Thailand,Thailand and Kalasin University,Thailand.The authors also thanks the Department of Science and Mathematics,Faculty of Science and Health Technology and the Department of Biotechnology,Faculty of Agricultural Technology,Kalasin University for providing instruments.
文摘Objective:To assess the antibacterial activity of 5 selected plants against 4 pathogenic bacteria.Methods:Three solvents with different polarities were used to extract antimicrobial agents from the plants via maceration technique.The agar-disc diffusion technique was adopted to primarily screen antibacterial activities.Broth-dilution assay was employed to determine the minimum inhibitory concentration(MIC)and the minimum bactericidal concentration(MBC).Results:Among all extracts,the ethanol extract of Piper betle Linn showed the highest antibacterial activity against Gram-positive and the negative bacteria.MIC and MBC of the ethanol extract of Piper betle Linn against Salmonella typhimurium were the same(1?562.50 mg/L);while it showed the highest MIC and MBC against Pseudomonas aeruginosa of 6?250 mg/L and 12?500 mg/L,respectively.Conclusions:Salmonella typhimurium is the most susceptible bacteria while Pseudomonas aeruginosa is the most resistant bacteria towards the ethanol extract of Piper betle Linn.Piper betle possesses compounds with potential antibacterial activity and might be useful as an alternative to control infectious diseases.
基金“111 Project” Biomedical Textile Materials Science and Technology,China(No.B07024)Natural Science Foundation of Shanghai,China(No.15ZR1401000)the Fundamental Research Funds for the Central Universities,China
文摘Bacterial cellulose(BC) is a type of nanoscale cellulose produced by microorganisms.In this work,BC films were utilized as a template to in situ synthesize silver nanoparticles(AgNPs) by a variety of simple chemical strategies,including chemical reduction with NaBH4 or vitamin C,hydrothermal treatment and UV radiation.A comparative study of the formation of AgNPs such as the silver particle size and silver content,as well as the antibacterial activity of the BC-AgNPs nanocomposites by different preparation methods and reaction conditions was investigated.A beneficial support was provided for future applications of AgNPs contained BC composites with antibacterial properties.
基金the First Phase of Teaching Ability Training Program for Young Backbone Teachers of Guangxi University of Chinese Medicine(04B1805815)Program of Key Laboratory for Extraction and Purification and Quality Analysis of TCM in 2014(Gui Jiao Ke Yan[2014]No.6)。
文摘[Objectives]To study the volatile components and antibacterial effects of 11 kinds of Aurantii Fructus Immaturus processed products.[Methods]11 kinds of Aurantii Fructus Immaturus processed products were obtained according to the traditional processing method,the volatile oil was extracted by steam distillation,and the composition of volatile oil in the 11 kinds of processed products was analyzed by gas chromatography-mass spectrometry(GC-MS).the relative percentage content of each component in these 11 kinds of processed products was determined using the peak area normalization.The drug sensitivity activity of the volatile oil of these 11 kinds of processed products was tested using the K-B paper diffusion method and the minimum inhibition volume fraction of volatile oil of these 11 kinds of processed products was tested using the microdilution method.[Results]The highest yield of volatile oil of 11 kinds of these processed products was baking(5.193%),and the lowest was stir-bake to scorch(1.998%).A total of 36 chemical components were identified from the volatile oils of these 11 kinds of processed products.The components with the most volatile oil were stir-bake to scorch(24 kinds),and the components with the least volatile oil were the method of processing with rice-washed water(15 kinds).They contain 8 kinds of common chemical components,such as limonene,linalool,myrcene,α-pinene.The highest content of limonene came from processing with honey(60.93%),the lowest came from processing with rice-washed water(55.25%);the highest content of linalool came from processing with rice-washed water(7.139%),the lowest came from processing with honey(5.436%);the highest content of myrcene came from processing with honey(1.899%),the lowest came from stir-bake to scorch(1.632%);the highest content ofα-pinene came from raw Aurantii Fructus Immaturus(2.355%),and the lowest came from stir-bake to scorch(1.618%).The volatile oil of these 11 kinds of Aurantii Fructus Immaturus processed products has good antibacterial effect on Escherichia coli and Staphylococcus aureus.[Conclusions]The oil yields of volatile oils of 11 kinds of Aurantii Fructus Immaturus processed products are different,the content of limonene is significantly different,and the changes of other chemical components and their contents are not significantly different.The volatile oil of 11 kinds of Aurantii Fructus Immaturus processed products has certain antibacterial effect.
文摘<span style="font-family:Verdana;">Due to the continuous emergence and rapid spread of drug-resistant strains of bacteria, there is an urgent need for the development of novel antimicrobials. Along this line, the synthesis and antibacterial activity of 4,5-diphenylimidazol-2-thiol derivatives <strong>2a-g</strong> and <strong>6a-e</strong> are reported. The structures of the synthesized compounds were confirmed by Nuclear Magnetic Resonance (NMR) and High Resolution Mass Spectrometry (HRMS). All compounds were screened <em>in vitro</em> for their antibacterial activity against <em>Pseudomonas aeruginosa</em> and <em>Escherichia coli</em> (Gram-negative bacteria) and also against <em>Staphyloccocus aureus</em> and <em>Enterococcus faecalis</em> (Gram-positive bacteria). The results showed most of the synthesized compounds have no antibacterial activity. However compound <strong>6d</strong> was two-fold potent than ciprofloxacin against <em>Staphylococcus aureus</em> with Minimum Inhibitory Concentration (MIC) of 4 μg/mL and <strong>6c</strong> showed moderate biological activity against <em>Staphylococcus aureus</em> (16 μg/mL) and <em>Enterococcus faecalis</em> (16 μg/mL).</span>
文摘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.
文摘1,8-cineole, also known as eucalyptol, is the main constituent and the most important of the leaf oils of many species of the genus Eucalyptus. In present study, the essential oils isolated by hydrodistillation from the leaves of Eucalyptus camaldulensis from six different locations were analyzed by GC-FID and GC-MS. Essential oil yields ranged from 0.33% to 4.35%. In total, 34 constituents were identified, accounting for 94.0% to 99.8% of the total compositions. 1,8-cineole (46.4% - 84.4%) was the main constituent of all the essential oil samples, except for one sample collected in the Fatick region, which had p-cymene (46.4%) and 1,8-cineole (26.0%) as major compounds. The essential oil showed excellent activity against S. aureus, E. coli and E. faecalis (IZ = 25.3 ± 1.2 mm;18.7 ± 0.6 mm;17.8 ± 0.3 mm, respectively) and moderate activity against P. aeruginosa (IZ = 10.8 ± 0.8 mm). They may have potential applications in food and pharmaceutical products.
文摘This investigation was undertaken to enhance the solubility and consequent antibacterial activity of cefuroxime axetil (CA), a </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-lactamase-stable broad spectrum second generation cephalosporin through solid dispersion (SD) technique. For this purpose, CA loaded SDs (CSDs) were prepared by solvent evaporation method using different concentrations of microcrystalline cellulose (MCC) as carrier. The CSDs were characterized by </span><i><span style="font-family:Verdana;">in-vitro</span></i><span style="font-family:Verdana;"> dissolution study, thermal analysis (DSC), crystallinity (PXRD), interactions (FTIR) and morphology (SEM). Among the formulations, CSD-2 showed the highest dissolution rate which was 2.59-fold higher than pure CA with a drug-carrier (CA: MCC) ratio of 1:3. Enhanced dissolution rate was attributed to conversion of drug from crystalline to amorphous state during preparation of SDs, which was validated by DSC, PXRD, FTIR and SEM analyses. Antibacterial activity of CSD-2 against </span><i><span style="font-family:Verdana;">Staphylococcus aureus</span></i><span style="font-family:Verdana;"> (ATCC 25923) and </span><i><span style="font-family:Verdana;">Escherichia coli</span></i><span style="font-family:Verdana;"> (ATCC 25922) showed 1.94- and 6.75-fold higher relative zone of inhibition (RZOI), respectively than pure CA. CSD-2 has been found to be the most effective optimized formulation in terms of both enhanced dissolution rate and antibacterial activity. Thus, it can be an effective alternative to conventional dosage forms of CA. However, further investigations are needed to validate its pharmacokinetic properties, </span><i><span style="font-family:Verdana;">in-vivo </span></i><span style="font-family:Verdana;">antibacterial efficacy and safety before recommending as a novel
文摘One of the serious problems the world is facing today is the antimicrobial resistance on available antibiotics by most bacterial pathogens and the rising cost of finding effective antimicrobial agents. In recent years, efforts to find new drugs especially from natural sources have been boosted by the demand for an effective cure for infectious diseases. Only the antibacterial activity of <em>apis mellifera</em> honey and not stingless bee honey from western Kenya has been reported. This study was therefore carried out to determine the effect of <em>Plebenia hylderbrandii </em>and <em>Meliponula bocandei </em>honey samples on the growth of control;sensitive cases of Escherichia coli (ATCC 25922) and <em>Staphylococcus aureus</em> (ATCC 25923). Different honey concentrations (1.18% - 17.65% v/v) of the two samples were tested against the two micro-organisms. The samples were screened for their antibacterial potential against <em>Escherichia coli </em>and <em>Staphylococcus aureus</em> by agar well dilution method. The Partial inhibitory concentration (PIC), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined by in vitro method. The inhibitory effect of <em>Plebenia hylderbrandii</em> honey on <em>E. coli</em> and <em>S. aureus</em> growth was apparent at concentrations 3.53% and 1.76% (v/v) respectively. On the other hand, the inhibitory effect of <em>Meliponula bocandei </em>honey on <em>S. aureus</em> growth was at concentration 16.47% (v/v). <em>Plebenia hylderbrandii</em> honey had bactericidal effect on both <em>E. coli </em>and <em>S. aureus</em> at concentrations 4.71% and 2.35% (v/v) respectively. However, <em>Meliponula bocandei</em> honey exerted bactericidal effect on <em>S. aureus </em>only at 16.47% (v/v) concentration. <em>Plebenia hylderbrandii </em>honey had higher antibacterial potency and can be a potential source of antibacterial substances. Moreover, the honeys tested in this study showed great antibacterial potential for <em>S. aureus</em>.
