Evaluation of extracts and essential oil from Callistemon viminalis leaves:Antibacterial and antioxidant activities,total phenolic and flavonoid contents

Objective:To investigate antioxidant and antibacterial activities of Callistemon viminalis(C.viminalis)leaves.Methods:The essential oil of C.viminalis leaves obtained by hydrodistillation was analyzed by GC/MS.Different extracts were tested for total phenolic and flavonoid contents and in vitro antioxidant(DPPH assay)and antibacterial(agar disc diffusion and 96-well micro-plates methods)actives.Results:Fourteen components were identified in the essential oil,representing 98.94%of the total oil.The major components were 1,8-cineole(64.53%)andα-pinene(9.69%).Leaf essential oil exhibited the highest antioxidant activity of(88.60±1.51)%comparable to gallic acid,a standard compound[(80.00±2.12)%].Additionally,the biggest zone of inhibitions against the studied bacterial strains was observed by the essential oil when compared to the standard antibiotic(tetracycline).The crude methanol extract and ethyl acetate fraction had a significant antibacterial activity against the tested bacterial strains.Conclusions:It can be suggested that C.viminalis is a great potential source of antibacterial and antioxidant compounds useful for new antimicrobial drugs from the natural basis.The present study revealed that the essential oil as well as the methanol extracts and ethyl acetate fraction of C.viminalis leaves exhibited highly significant antibacterial activity against the tested bacterial strains.

Recent advances in essential oils and their nanoformulations for poultry feed

Antibiotics in poultry feed to boost growth performance are becoming increasingly contentious due to concerns over antimicrobial resistance development.Essential oils(EOs),as natural,plant-derived compounds,have demonstrated antimicrobial and antioxidant properties.EOs may potentially improve poultry health and growth performance when included in poultry feed.Nevertheless,the incorporation of EOs as nutritional additives is hindered by their high volatility,low water solubility,poor intestinal absorption,and sensitivity to environmental conditions.Recently,nanoencapsulation strategies using nanoformulations have emerged as a potential solution to these challenges,improving the stability and bioavailability of EOs,and enabling targeted delivery in poultry feed.This review provides an overview of the antioxidant and antibacterial properties of EOs,the current limitations of their applications in poultry feed,and the recent advancements in nano-engineering to overcome these limitations.Furthermore,we outline the potential future research direction on EO nanoformulations,emphasizing their promising role in advancing sustainable poultry nutrition.

Chemical composition of Mentha suaveolens and Pinus halepensis essential oils and their antibacterial and antioxidant activities

Objective: To determin the chemical compounds of Mentha suaveolens(M. suaveolens) and Pinus halepensis(P. halepensis) essential oils(Eos) and evaluate their antioxidant and antibacterial activities. Methods: The chemical composition of P. halepensis and M. suaveolens EOs was determined by GC-MS analysis. The antioxidant activity was evaluated using DPPH,ABTS and FRAP assays. The antibacterial effect was tested against 6 bacterial strains using the well diffusion method and micro-dilution assay. Results: The major components of P. halepensis EOs were β-caryophyllene(28.04%),myrcene(23.81%) and α-pinene(12.02%). However,piperitenone oxid(56.28%),piperitenone(11.64%) and pulegone(6.16%) were the major components of M. suaveolens EOs. M. suaveolens EOs showed remarkable antioxidant activities compared with P. halepensis EOs,showing antioxidant capacity values of IC50=(64.76±2.24) μg/mL,IC50=(82.73±3.34) μg/mL,and IC50=(93.35±4.45) μg/mL,revealed by DPPH,ABTS and FRAP assays,respectively. However,P. halepensis EOs showed interesting antibacterial effects against all bacterial strains. The most sensible strains to P. halepensis EOs were Staphylococcus aureus [(34.00±0.50) mm],Listeria monocytogenes [(31.00±1.50)] mm and Proteus mirabilis [(29.00±2.25)mm]. Furthermore,the lowest minimal inhibitory concentration(MIC) and minimal bactericidal concentration(MBC) values were revealed by P. halepensis EOs against Staphylococcus aureus [MIC=MBC=0.125%(v/v)] and Listeria monocytogenes [MIC=MBC=0.25%(v/v)]. Conclusions: P. halepensis and M. suaveolens EOs contain bioactive compounds that could have potential applications against bacterial infections and oxidative stress related diseases as well as for food conservation. However,further investigations are necessary to isolate and investigate the action mechanisms of these bioactive compounds.

Evaluation and comparison of antibacterial activities of edible vegetable oils in China

To evaluate antibacterial activities of edible vegetable oils in China for healthy consumption, we investigated the antibacterial activities of extracts from 6 edible vegetable oils and rapeseed oils at different refining levels on 4 bactria (Staphylococcus aureus,Bacillus subtilis, Escherichia coli and Pseudomonas strains) by disc diffusion test. Results showed that camellia oil had considerable antibacterial activity against E. coli with antibacterial rate of 108.3%. Perilla oil, sunflower seed oil, and flaxseed oil showed the highest antibacterial activities against B. subtilis with the antibacterial rates of 108.3%, 102.8%and94.4%respectively. Moreover, the extracts of rapeseed oils obtained by different processing technologies showed significantly different antibacterial effects. Two crude oils and grade4 rapeseed oil showed antibacterial rates of more than 40%, whereas grade 1 and 2 rapeseed oils showed antibacterial rates of less than 20%. Therefore, it was recommended to use rapeseed oil rather than refined rapeseed oil because of higher antibacterial activities. It was suggested that proper refining processes should be taken to obtain the edible oils with higher antibacterial activities.

Chemical Compositions and Antibacterial Activity of Essential Oil from Thymus Seedlings of Tissue Culture

[Objective] This study aimed to compare and analyze the chemical compositions, the relative contents and the antibacterial activity of the essential oils extracted from the tissue culture seedlings, the aseptic seedlings and the common seedlings from seeds of Thymus vulgaris. [Method] The essential oil was extracted by steam distillation; the chemical compositions and their relative contents were analyzed by gas chromatography-mass spectrometry （GC/MS） and peak area normalization method; and the antimicrobial activity was tested by filter paper method. [Result] A total of 54 compositions were identified from these three samples, they had similar main compositions： thymol, m-Cymene, terpinene and so on, and these compositions were slightly different in contents. In addition, the essential oils from these three samples exhibited obvious antibacterial effect against Escherichia coli and Staphylococcus aureus, in which the antibacterial activity against S. aureus was stronger than against E. coli. [Conclusion] It is possible to produce essential oil by tissue culture technology; the main compositions and antibacterial activity of the oils remained almost the same.

Chemical composition, mechanism of antibacterial action and antioxidant activity of leaf essential oil of Forsythia koreana deciduous shrub

Objective: To identify the chemical constituents of leaf essential oil of Forsythia koreana(F. koreana) and evaluate its ef ects on bacterial strains. Methods: The essential oil of leaf of F. koreana was extracted by using hydrodistillation process and the volatile components investigated with the help of gas chromatography coupled with mass spectrometry. The antibacterial study was carried out with the help of agar disc dif usion method, MIC, MBC and viable count. The mode of action was determined with help of potassium ion l ux, cellular material release and scanning electron microscopy. The antioxidant activity was determined with the help of 2, 3-diphenyl-2-picrylhydrazyl method, nitric oxide scavenging activity and superoxide anion radical scavenging assay. Results: Total ten compounds were identii ed as trans-phytol(42.73%), cis-3-hexenol(12.95%), 毬-linalool(10.68%), trans-2-hexenal(8.86%), trans-2-hexenol(8.86%), myrcenol(3.86%), 4-vinylphenyl acetate(3.86%),(4Z)-4,6-heptadien-1-ol(3.18%), lemonol(2.73%) and benzeneacetaldehyde(2.27%) by gas chromatography coupled with mass spectrometry. The antibacterial study was demonstrated that leaf essential oil of F. koreana act against foodborne and other pathogenic bacteria. The mode of action revealed that this essential oil acted on the cytoplasmic membrane, resulting in loss of integrity and increased permeability. In addition, leaf essential oil of F. koreana was shown to be rich in linalool, which contributes to improved antioxidant activity. Conclusions: These results show that leaf essential oil of F. koreana has great potential as a natural food preservative, antibacterial and antioxidant agent.

Antibacterial activity of lemongrass(Cymbopogon citratus) oil against some selected pathogenic bacterias

Objective:To find the effectiveness of essential oil of lemongrass for the treatment of pathogenic organisms.Methods:Lemongrass oil was investigated for activity against Staphylococcus aureus (S.aureus),Bacillus cereus(B.cereus),Bacillus subtilis(B.subtilis),Escherichia coli(E.coli), Klebsiella pneumoniae(K.pneumoniae) and Pseudomonas aeruginosa(P.aeruginosa),using Agar Diffusion Method and Broth Dilution Method.Minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) were determined by the Broth Dilution Method. The antibiotic susceptibility test against the test organisms was performed by Disc Diffusion Method.Results:Lemongrass was found effective against all the test organisms except P. aeruginosa.Gram positive organisms were found more sensitive to lemon grass oil as compared to gram negative organisms.The test organisms were found inhibited by Lemon grass oil at lower concentrations in Broth Dilution Method as compared to Agar Diffusion Method.Conclusions: The tested organisms,particularly gram-negative organisms had shown high resistance towards different antibiotics whereas they were found to be inhibited by lemongrass oil even at lower concentration.Thus lemongrass oil is effective against drug resistant organisms.It can be suggested that use of lemongrass oil would be helpful in the treatment of infections caused by multidrug resistant organisms.

In vitro antibacterial activity and major bioactive components of Cinnamomum verum essential oils against cariogenic bacteria,Streptococcus mutans and Streptococcus sobrinus

Objective:To evaluate the antibacterial activity of Cinnamomum verum(C.verum) from32 different essential oils against cariogenic bacteria,Streptococcus mutans(S.mutans)and Streptococcus sobrinus(S.sobrinus).Methods:The antibacterial activities of each essential oil were individually investigated against S.mutans and S.sobrinus.The essential oil of C.verum was selected for further evaluation against S.mutans and S.sobrinus.Gas chromatography mass spectrometry was used to determine the major constituents of C.verum essential oil.In addition,the minimum inhibitory concentration(MIC) and minimum bactericidal concentration of the most effective constituent was investigated.Results:The essential oil from C.verum exhibited the greatest antibacterial activity.Gas chromatography mass spectrometry analysis revealed that the major components of C.verum essential oil were cinnamaldehyde(56.3%),cinnamyl acetate(7.1%) and bphellandrene(6.3%).The MIC of cinnamaldehyde was measured using broth dilution assays.The MIC of cinnamaldehyde was 0.02%(v/v) against both bacterial strains tested.The minimum bactericidal concentration of cinnamaldehyde against S.mutans and S.sobrinus were 0.2% and 0.1%(v/v),respectively.Conclusions:The essential oil of C.verum and its major component cinnamaldehyde possessed considerable in vitro antibacterial activities against cariogenic bacteria,S.mutans and S.sobrinus strains.These results showed that the essential oil of C.verum and its bioactive component,cinnamaldehyde,have potential for application as natural agents for the prevention and treatment of dental caries.

Chemical compositions and biological activities of essential oils obtained from some Apiaceous and Lamiaceous plants collected in Thailand

Objective: To determine the chemical composition, as well as the antioxidant, antityrosinase and antibacterial activities of essential oils obtained from some Apiaceous and Lamiaceous plants collected in Thailand. Methods: The essential oils of the specified spices and aromatic herbs were obtained by hydro-distillation, and their chemical constituents were analyzed by gas chromatography/mass spectrometry. Antioxidant assays were based on the scavenging effects of 2,2-Diphenyl-1-picrylhydrazyl(DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS) free radicals as well as the lipid oxidation inhibition of β-carotene bleaching by linoleic acid. Tyrosinase enzyme inhibition was evaluated by the dopachrome method. Broth microdilution technique was performed for the purposes of studying microbial growth inhibition against the isolated bacterial strains. Results: The essential oils of Elsholtzia stachyodes, Coleus amboinicus(I) and Trachyspermum ammi presented a high degree of potency in DPPH, ABTS and β-carotene bleaching assays. The Trachyspermum ammi oil, which mainly contained thymol(49.04%) and p-cymene(22.06%), proved to be the most effective in terms of antibacterial activity. The major compositions of Coleus amboinicus(I) were carvacrol(51.57%), γ-terpinene(18.04%) and p-cymene(7.81%); while thymol(43.76%) and γ-terpinene(24.61%) were identified as the major components of Elsholtzia stachyodes oil, with p-cymene(6.73%) being identified as a minor constituent. Moreover, Cuminum cyminum oil containing cuminaldehyde(49.07%) and Elsholtzia communis oil composed with geranial(44.74%) and neral(35.27%) as the major components displayed a specific ability for the inhibition of the mushroom tyrosinase enzyme. Conclusions: The results indicated that these bioactive essential oils obtained from indigenous herbs are of significant interest as alternative raw materials in food, cosmetic and medicinal products.

Gas chromatography mass spectrometry analysis and in vitro antibacterial activity of essential oil from Trigonella foenum-graecum

Objective:To evaluate the antibacterial activity of essential oil from Trigonella foenumgraecum seeds powder,and identify the compounds from the extracted oil.Methods:The seeds powder of Trigonella foenum-graecum was subjected to Clevenger extractor.Seven strains of bacteria were used to test antibacterial activity of the extract.The activity against bacteria was tested by disk diffusion method using Whatman No.1filter paper.Gas chromatography mass spectrometry analysis was performed with an Agilent7890/5975B-gas chromatography/mass selective detector.Results:The hydrodistillation of seeds powder yielded 0.285%(v/w)of oil.Disk diffusion of the oil showed bactericidal activity against both Gram negative and Gram positive bacteria of tasted strains.The inhibition zone ranged from(8±0)mm to(15.0±0.7)mm depending on microbial strains.Gas chromatography mass spectrometry analysis showed14 different compounds.The total compounds represented 80.96%of the oil.Conclusions:The antibacterial activity is due to the effects of different biological active compounds present in the extract.Identification of the compounds may help to develop new effective antimicrobial agent(s).Further researches on purification,characterization and toxicology of the active compounds are needed.

Chemical Composition, Antibacterial Activity of the Essential Oil from Roots of <i>Radix aucklandiae</i>against Selected Food-Borne Pathogens

Radix aucklandiae from Yunnan Province in China is a significant medicinal plant. In the present study, the essential oil composition from?Radix aucklandiae roots was investigated by gas chromatography-mass spectrometry (GC-MS). A total of 23 compounds representing 57.95% of the essential oil were tentatively identified. The main constituents were eremanthin (12.74%), d-Guaiene (6.26%), ζ-Himachalene (6.16%) and l-Caryophyllene (4.84%). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the essential oil from R. aucklandiae were evaluated against three Gram-positive bacteria (Staphylococcus aureus, Staphylococcus albus and Bacillus subtilis) three Gram-negative bacteria (Salmonella typhimurium, Escherichia coli and Shigella dysenteriae). Results revealed that the essential oil exhibited significant in vitro antimicrobial property. Among all the tested microorganisms, the essential oil showed the strongest inhibitory effect against S. typhimurium. The data of this study suggests that the essential oil from Radix aucklandiae has great potential for application as a natural antimicrobial agent to preserve food.

Balanites aegyptiaca Oil Synthesized Iron Oxide Nanoparticles: Characterization and Antibacterial Activity

Antibacterial activity of iron oxide nanoparticles, an employing B. aegyptiaca oil (L.) Del., was used as natural stabilizer by modifying a co-precipitation method. In this work, we chose B. aegyptiaca oil as the new surfactant coating agent, and synthesized B. aegyptiaca oil coating with iron oxide nanoparticles which were characterized with a variety of methods, including Gas Chromatography (GC) to determine the fatty acids composition of the seeds oil, Fourier Transform-Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) equipped with Energy Dispersive Spectroscopy (EDS), X-ray Powder Diffractometer (XRD) and Vibrating Sample Magnetometer (VSM). In antibacterial studies, disk diffusion susceptibility test was used to measure efficacy of iron oxide nanoparticles against Gram-positive bacteria Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis) and Gram-negative bacteria Escherichia coli (E. coli) in terms of zone inhibition. The B. aegyptiaca coated on the surface of iron oxide nanoparticles;its particle size was found to be nanoscale below 50 nm, and the magnetization (δs) was 16.975 emu g-1. Antibacterial activity was measured. Efficacy of iron oxide nanoparticles against bacterial strains was found in Escherichia coli (E. coli). All these findings suggest that the nanoparticles synthesized from B. aegyptiaca oil may be a promising reagent for a wide variety of applications in biological fields as well as in nanomedicine.

Chemical Composition and Antibacterial Activity of Essential Oils from <i>Struchium sparganophora</i>Linn. Ktze Asteraceae

Struchium sparganophora Linn. Ktze Asteraceae is a culinary herb that is consumed in the Western part of Nigeria and has wide medicinal uses in traditional medicine. The present study was carried out to determine the chemical composition of the oils from its leaf and stem and their antibacterial activity. Essential oils were collected from the leaf and stem of Struchium sparganophora by hydrodistillation and analysed by GC and GC-MS. The antimicrobial activity was tested against Gram negative (G-ve) and Gram positive (G + ve) microorganisms obtained from the Medical Microbiology Unit, University College Hospital (UCH), Ibadan, Nigeria. Forty-six compounds were identified in the leaf representing 95.3% of the total oil while fifty-five compounds were identified in the stem representing 93.5% of the oil. β-caryophyllene, Germacrene A, a-humulene and Germacrene D represented the major components in both oils. Antibacterial activity of the oils against certain strains of bacteria showed that the different concentrations of the oils (100 – 10,000 ppm) from the leaf had activity ranging from 9.0 ± 1.0 to 14.3 ± 2.55 mm while that from the stem had activity ranging from 18.5 ± 2.2 to 20.0 ± 0.0 mm for both G-ve.and G + ve microorganisms respectively.

Phytochemical Screening, Antibacterial Effect, and Essential Oil Extract from the Leaf of Artemisia afra against on Selected Pathogens

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.

Chemical Variability and Antibacterial Activity of Eucalyptus camaldulensis Essential Oils from Senegal

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.

GC-MS Analysis and Antibacterial Activity Study of Volatile Oil from 11 Kinds of Aurantii Fructus Immaturus Processed Products

[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.

Chemical Composition and in Vitro Antibacterial Activity of the Leaf Essential Oil of Mentha officinalis from Rwanda

The search for new prototype drugs to combat infection is an absolute necessity and in this regard plant essential oils may offer great potential and hope. In this investigation, the essential oil of the leaves ofMentha officinalis grown in Rwanda was extracted by hydrodistillation method and analyzed by gas chromatography （GC） and gas chromatography coupled with mass spectrometry （GC-MS）. The disc diffusion method was used to evaluate in vitro the zone of bacterial growth inhibition at various concentrations of the oil for five bacterial strains： Escherichia coli, Bacillus aureus, Streptococcus lactis, Staphylococcus aureus and Salmonella typhimurium. The results of this study revealed many components among which the major components were menthol （80.79%）, menthone （4.906%）, isomenthone （3.5%）, piperitone （2.56%）, and methyl acetate （2.2%）. After 7 days of incubation on PCA medium, the growth of Escherichia coli, Bacillus aureus, Streptococcus lactis and Staphylococcus aureus was totally inhibited at an average diameter of 19 mm, 32 mm, 50 mm and 30 mm respectively by a medium concentration of 30 μm/disc ofM. officinalis oil. Quite the reverse, this investigation by a bioassay showed that the essential oil ofM. officinalis has no effect on Salmonella typhimurium. The obtained results in the present study indicate the possibility of exploiting the essential oil ofM. officinalis to combat so many infectious human diseases in Rwanda. However, further investigations are required to make the medical exploitation of this plant successful.

Comparison of Distillation Methods of Mentha cordifolia Opiz, Essential Oil on Antibacterial Activity for Application Use in Animal Feeds

This study was conducted to evaluate the effect of different distillation methods of Mentha cordifolia Opiz. essential oil on antibacterial activity. The essential oils were isolated by water and steam, hydro, ethanol, and 3methanol： lethanol distillations. Moreover, we also compared the efficacy of these various distillations with commercial peppermint oil. Essential oils were tested in vitro against three pathogen bacteria species by sensitivity test include disc diffusion assay （DD）, minimal inhibition concentration （MIC） and maximal bactericidal concentration （MBC）. Escherichia coli, Staphylococcus aureus and Salmonella typhimurium were used in this investigation. The results showed that the water and steam distillation and 3methanol： lethanol under tested by DD assay was found to be effective against all the pathogenic bacteria, in which the zone of inhibition exhibited E. coil S. aureus and S. typhimurium were 9.67 ± 0.35, 11.67 ± 0.66, 18.0± 1.15 and 9.00 ± 0.05, 8.3 ± 0.35, 19.0 ± 0.00 ram, respectively. While the hydro and ethanol distillations did action to against only E. coli which the inhibition zones were 8.67 ± 0.66 and 8.67 ± 0.35 mm, respectively. However, the commercial oil was more effective against tested pathogenic bacteria than all M. cordifolia essential oil. In case of MIC and MBC assays, the results showed that all essential oil distillation methods posed antibacterial potential in which the water and steam distillation showed the lowest MIC and MBC values against E. coli, S. aureus and S. typhimurium. It is suggested that among all M. cordifolia essential oil extractions, water and steam distillation was found to be highly bactericidal as it has shown in lowest MIC and MBC values and high in growth inhibition zone diameter.

Incorporation of Essential Oils from Cymbopogon Citratus and Ceasalpinia Decapitala Leaves, Citrus Lemon and Citrus Sinensis Peels into HPC （HydroxyPropyl Cellulose） Films and Assessment of Their Antibacterial Activity

In this study, essential oils from Cymbopogon citratus and Ceasalpinia decapitala leaves, Citrus lemon and Citrus sinens＆ peels, were extracted, chemically characterized and evaluated on both Gram positive and Gram negative bacteria, Salmonella Typhimurium, Escherichia coli, Listeria innocua, Staphylococcus aureus, Klebsiella pneumonia and Streptococcus pyogenes. Essential oil of C. citratus was found to be rich in geranial （33.0%） and neral （49.7%）, that from C. decapitala in 13-pinene （8.4%）, ct-pinene （25.5%）, 13-ocymene （31.6%）, 15-phellandrene （8.4%）, caryophyllene （7.5%） and geranial （5.9%）. The essential oil from C. lemon and C. sinensis where mainly composed by limonene with percentages of 77.5% and 83.3% respectively, and 13-phellandrene with percentages of 8.1% and 10.8% for the essential oil of C. lemon and C. sinensis, respectively. The antibacterial activity assessment realized on different microorganisms contaminating food showed that essential oil from C. citratus was shah more effective against all tested bacteria while that from C. sinensis was the less active essential oil. The incorporation of essential oils in HPC （hydroxy-propyl cellulose） films showed that those essential oils, especially essential oils from C. citratus, maintained their antibacterial activities against targeted microorganisms and therefore can be applied in food packing.

香芹酚对肠炎沙门氏菌的抗菌活性及机制研究

为探讨香芹酚对肠炎沙门氏菌的抗菌活性及抗菌机制,试验以天然植物精油香芹酚为研究对象,以肠炎沙门氏菌作为指示菌,通过测定肠炎沙门氏菌的抑菌圈直径、最小抑菌浓度(MIC)、最小杀菌浓度(MBC)和生长情况以评价香芹酚的抗菌活性;研究不同浓度香芹酚对肠炎沙门氏菌菌液电导率、胞外蛋白质和核酸浓度、碱性磷酸酶(AKP)活性及细菌结构变化的影响。结果表明:香芹酚对肠炎沙门氏菌的抑菌圈直径、MIC、MBC分别为(22.5±2.6)mm、0.125μg/mL、0.25μg/mL,肠炎沙门氏菌在1 MIC和2 MIC香芹酚作用下生长受到了明显抑制;随着香芹酚浓度增大,菌液电导率呈现增长的趋势;培养至第3,6小时时,胞外蛋白质和核酸浓度随香芹酚浓度升高显著升高(P<0.05);培养至第6小时时,AKP活性随香芹酚浓度升高显著升高(P<0.05);0.5MIC~2MIC香芹酚能够破坏菌体结构,使菌体出现形态改变、皱缩、溶解等结构变化。说明香芹酚可以通过破坏肠炎沙门氏菌菌体细胞壁或细胞膜通透性及完整性,致使菌体内容物泄露,对肠炎沙门氏菌表现出良好的抗菌活性。