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.

Antioxidant,lipid peroxidation inhibition and free radical scavenging efficacy of a diterpenoid compound sugiol isolated from Metasequoia glyptostroboides

Objective:To investigate the antioxidant enicacy of a biologically active dilerpenoid compound sugiol isolated from Metasequoia glyptostroboides(M.glyptostroboides)in various antioxidant models.Methods:An abietane type diterpenoid sugiol,isolated from ethyl acetate extract of M.glyptostroboides cones,was analyzed for its antioxidant efficacy as reducing power ability and lipid peroxidation inhibition as well as its ability to scavenge free radicals such as 1,1-diphenyl-2-picryl hydrazyl,nitric oxide,superoxide and hydroxyl radicals.Results:The sugiol showed significant and concentration-dependent antioxidant and free radical scavenging activities.Consequently,the sugiol exerted lipid peroxidation inhibitory effect by 76.3%as compared to a-tocopherol(80.13%)and butylaled hydroxyanisole(76.59%).In addition,the sugiol had significant scavenging activities of l,l-diphenyl-2-picryl hydrazyl,nitric oxide,superoxide and hydroxyl free radicals in a concentration-dependent manner by 78.83%,72.42%,72.99%and 85.04%,when compared to the standard compound ascorbic acid(81.69%,74.62%,73.00%and 73.79%)and a-tocopherol/butylated hydroxyanisole(84.09%,78.61%,74.45%and 70.02%),respectively.Conclusions:These findings justify the biological and traditional uses of M.glyptostroboides or its secondary metabolites as confirmed by its promising antioxidant efficacy.

Anti-listerial synergism of leaf essential oil of Metasequoia glyptostroboides with nisin in whole,low and skim milks

Objective:To examine the individual and synergistic anti-listcrial effect of nisin and leaf essential oil of Metasequoia glyptostroboides(M.glyptostroboides) against one of the leading foodhorne pathogens Listeria monocytogenes(L.monocytogenes) ATCC 19116 in milk samples.Methods:The whole(8%),low(1%) and skim(no fat content) milk samples were inoculated with L.monocytogenes ATCC 19116 along with leaf essential oil of M.glyptostroboides or nisin alone as well in eomhinations.Results:In this study,the leaf essential oil at the concentrations of 2% and 5% revealed strong anti-listerial effect against L.monocytogenes ATCC 19116 in all categories of milk samples.Nisin at the concentrations of 250 and 500 IU/mL displayed a strong inhibitory effect against ATCC 19116 as compared to the control group.Additionally,synergistic combinations of leaf essential oil(1%) and nisin(62.5,125.250 and 500 IU/mL) also had a remarkable anti-listerial synergism in all the tested milk samples including whole,low and skim milk after 14 days.Conclusions:As a major finding,the leaf essential oil of M.glyptostroboides might he a useful candidate for using in food industry to control the growth of foodhorne pathogenic bacteria as confirmed by its potent anti-listerial Synergistic effect with nisin against L.monocytogenes ATCC 19116 in different milk samples.

Chemical composition, antioxidant and antibacterial activities of essential oil from Korean Citrus unshiu peel

The chemical composition, antioxidant and antibacterial activities of essential oil from peel of Citrus unshiuwhich cultivated in South Korea were investigated. Eight compounds were identified as l-limonene (88.11%), γ-terpinene (4.66%), cyclohexane, 2,4-diisopropenyl-1-methyl-1-vinyl (1.82%), diethyl phthalate (1.02%), β-linalool (0.97%), β-myrcene (0.91%), α-farnesene (0.91%) and o-cymene (0.85%) by GC-MS. The SC50values of this essential oil on DPPH and superoxide anion were 0.21 and 0.22% (v/v), respectively. The results of zone of inhibition, MIC, MBC and cell viability demonstrated the essential oil of-Citrus unshiupeel displayed antibacterial effect against B. cereus KCTC 14042, B. subtilis ATCC 6633 and S. aureusATCC 6538. The release of cell material and potassium ion from the B. subtilis ATCC 6633 cells treated with essential oil was further investigated. SEM observation also revealed the damaging effect of the essential oil on the morphology of B. subtilisATCC 6633 cells at minimum inhibitory concentration.

In vivo control of perilla rust disease by oak pyroligneous liquor

Leaves of Perilla frutescens, commonly known as perilla are widely used in Korea, due to their medicinal properties. The rust disease of perilla interrupts its wide use every year. The present study was carried out to evaluate the control of perilla rust disease by using oak pyroligneous liquor having various biological properties. The rust disease infected perilla leaves were applied with 100 μl of oak pyroligneous liquor at different concentrations such as 6.25, 12.5, 25 and 50 μg/ml. Then the leaf samples were observed for the abortion of active rust pustules (yellow color) after 48 hours of incubation at 26?C. Further, inhibition of rust pustules development by oak pyroligneous liquor was evaluated on the leaves of artificially induced perilla rust disease. The best abortion of rust pustules by oak pyroligneous liquor was noticed at the concentration of 50 μg/ml, where 74.4% of the pustules were aborted. Discoloration of rust pustules was also observed in the treated leaves from yellow to white when compared with the untreated control. In addition, oak pyroligneous liquor completely inhibited the development of rust pustules in artificially induced leaves even at low concentration (6.25 μg/ml). The results clearly indicated that oak pyroligneous liquor is a good candidate for the management of Perilla rust disease.

<i>In vitro</i>antagonistic potential of <i>Streptomyces</i>sp. AM-S1 against plant and human pathogens

In the present investigation, a total number of 132 different actinomycetes strains were isolated from the humus soil samples. Out of 132 isolates, 52 showed inhibitory activity against the fungal pathogen Rhizoctonia solani. Among the antagonists, the isolate designated as AM-S1 exhibited maximum inhibitory activity against the test pathogen R. solani (41 mm). Further, the light microscopic observations of the co-cultures showed severe structural alterations in the mycelia of R. solani near the zone of inhibition. The isolate AM-S1 was identified as Streptomyces sp. by morphological and 16S rDNA sequence analysis. The color of the aerial and substrate mycelia produced by the Streptomyces sp. AM-S1 varied with different media. The isolate Streptomyces sp. AM-S1 also effectively inhibited the growth of various plant and human pathogens. Further works are needed on optimization of this strain’s antagonistic activity, isolation and characterization of the antimicrobial metabolite.