Chemical composition, antibacterial and antioxidant activities of leaf essential oil and extracts of Metasequioa glyptostroboides Miki ex Hu

Chemical compositions, antioxidant and antimicrobial properties of Ziziphora clinopodioides Lam. essential oils collected from different parts of Iran

The aims of the present study were to investigate chemical compositions, antioxidant and antimicrobial properties of Ziziphora clinopodioides essential oils (ZEOs) collected from four provinces in western Iran (Ilam, Lorestan, Kermanshah and Kurdestan). Carvacrol was the most abundant constituent in the flower, stem and leaf oil samples of Ilam, Lorestan and Kermanshah regions by 73.12-74.29%, 66.47-66.89% and 65.11-65.32%, respectively. The most abundant components in Kurdestan sample were thymol (55.32-55.60%), followed by γ-terpinene (24.45-24.56%), p-cymene (10.21-10.25%) and α-terpinene (2.75-2.77%). The ZEO inhibited the growth of Listeria monocytogenes, Salmonella typhimurium, Escherichia coli O157:H7, Bacillus subtilis, Bacillus cereus and Staphylococcus aureus at MIC values between 0.03 and 0.04%. Kermanshah oil sample had a higher 1,1-diphenyl-2-picrylhydrazyl radical scavenging (0.30-0.31 mg/ml), ability to prevent the bleaching of β-carotene (0.09-0.1 mg/ml), ferric reducing power (0.40-0.42 mg/ml) and thiobarbituric acid (0.004-0.006 Meq of malondialdehyde/g) values than that of ZEOs from Ilam, Kurdestan and Lorestan. The strong in vitro antimicrobial and antioxidant activities supports the traditional use of ZEO in the treatments of gastrointestinal diseases.

Chemical analysis and in vitro antimicrobial effects and mechanism of action of Trachyspermum copticum essential oil against Escherichia coli

OBJECTIVE

To find a natural plant essential oil (EO) with excellent antimicrobial effects on food-borne bacteria and to explore the mechanism of its antimicrobial function against Escherichia coli (E. coli).

METHODS

The antimicrobial activity of seven EOs against Gram-negative E. coli ATCC 8739 and Gram-positive Staphylococcus aureus ATCC 6538 was investigated using agar disk diffusion method, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each EO was determined using the broth dilution method. The chemical composition of the Trachyspermum copticum (T. copticum) EO was analyzed using gas chromatography-mass spectrometry (GC/MS). In order to explore the mechanism of the antimicrobial action, 1 MIC and 2 MIC of T. copticum EO was added to a suspension of E. coli, the growth curve and the scanning electron microscopy (SEM) analysis of E. coli, and the release of cell constituents and protein and potassium ions from the bacterial cell were measured.

RESULTS

The T. copticum EO had the best antimicrobial activity against the test bacteria, and 10 compounds accounting for 94.57% of the total oil were identified, with the major components being thymol (46.22%), p-cymene (19.03%), and γ-terpinene (22.41%). The addition of 1 MIC that T. copticum EO significantly inhibited the growth of E. coli and increased the release of cell constituents and protein and potassium ions from the bacterial cells. Scanning electron micrographs showed that T. copticum EO caused most of the E. coli cell membranes to collapse and rupture, leading to cell death.

CONCLUSIONS

These results indicate that T. copticum EO is a good natural antimicrobial agent for food-borne pathogens.

Efficacy of Eucalyptus cinerea as a Source of Bioactive Compounds for Curative Biocontrol of Crown Gall Caused by Agrobacterium tumefaciens Strain B6

This research investigated the Eucalyptus cinerea leaves efficiency in the Agrobacterium tumefaciens biocontrol, the causative agent of crown gall. GC-MS analysis of the essential oil (EO) showed that the main components were 1,8-cineole (61%) and camphene (15.13%). Thanks to its polyphenols, flavonoids, quinones, terpenoids, alkaloids, and tannins richness, the EtOAc-F exhibited the most potent antibacterial activity in vitro. Indeed, compared to the other fractions, it has the lowest MIC and MBC values of 0.312 mg/mL and 2.5 mg/mL, respectively. The GC-MS analysis of EtOAc-F confirmed its richness in antibacterial compounds including gallic acid (7.18%), shikimic acid (5.07%), and catechin (3.12%). The time-kill curve assay of EtOAc-F (2.5 mg/mL) showed a potent bactericidal effect after 20 min of direct contact with A. tumefaciens. In planta experiments, gall weights were significantly reduced when EtOAc-F was applied at 0.625 and 2.5 mg/wounds. Besides, the disease reduction rates in gall weight were 95% and 97.5%, respectively. Interestingly, no phytotoxic effect was observed since tomato seeds germinated in the presence of the different concentrations of EtOAc-F. These results suggest that EtOAc-F has a good potential to be a curative biocontrol agent for crown gall disease.

Oregano Essential Oil as an Antimicrobial and Antioxidant Additive in Food Products

Food consumers and industries urged the need of natural alternatives to assure food safety and quality. As a response, the use of natural compounds from herbs and spices is an alternative to synthetic additives associated with toxic problems. This review discusses the antimicrobial and antioxidant activity of oregano essential oil (OEO) and its potential as a food additive. Oregano is a plant that has been used as a food seasoning since ancient times. The common name of oregano is given to several species: Origanum (family: Lamiaceae) and Lippia (family: Verbenaceae), amongst others. The main compounds identified in the different OEOs are carvacrol and thymol, which are responsible for the characteristic odor, antimicrobial, and antioxidant activity; however, their content may vary according to the species, harvesting season, and geographical sources. These substances as antibacterial agents make the cell membrane permeable due to its impregnation in the hydrophobic domains, this effect is higher against gram positive bacteria. In addition, the OEO has antioxidant properties effective in retarding the process of lipid peroxidation in fatty foods, and scavenging free radicals. In this perspective, the present review analyzes and discusses the state of the art about the actual and potential uses of OEO as an antimicrobial and antioxidant food additives.

Fumigant toxicities of essential oils and two monoterpenes against potato tuber moth (Phthorimaea operculella Zeller)

Introduction: The potato tuber moth (PTM) is the major economic pest of potato. Different approaches were tried to prevent and control this pest including natural pesticides and synthetic fumigants.

Objectives: This study was conducted to evaluate the insecticidal activity of the essential oils of thyme and myrtle. In addition to evaluating the insecticidal activity of carvacrol and eucalyptol against the different life stages of potato tuber moth using a fumigation bioassays.

Methods: Thyme and myrtle oils were extracted from wild Thymus syriacus Boiss. and wild Myrtus communis L. by hydrodistillation. Fumigation experiments were conducted on potato tuber moth of different stages of development (eggs, larvae, pupae, and adults), using standard methods. The potato tuber moth was treated for different periods using different concentrations of the essential oils. One-way analysis of variance (ANOVA) was applied on the mortality percentages data to estimate the significance of differences between treatments at p<0.05. Probit analysis was used to estimate the LC50, LC90 and LT50.

Results: Adult stage was the most sensitive to essential oils vapours with LC50 value of 0.5 μl/l air. Whereas, pupal stages were the most tolerant. The essential oil of thyme possessed the strongest fumigant toxicity against eggs with a LC50 value of 6.1 μl/l air. The two monoterpens showed varied fumigant toxicity against adult stage. Carvacrol achieved 100% mortality at 0.125 μl/l air after 6 h, and 0.025 μl/l air after 48h exposure with LT50 period of 0.5 h.

Conclusion: The present work demonstrated that T. syriacus essential oil is a promising natural fumigant against the different developmental stages of PTM.

Antibacterial Activity and Mechanism of Action of Black Pepper Essential Oil on Meat-Borne Escherichia coli

The aim of this study was to investigate the antibacterial activity of black pepper essential oil (BPEO) on Escherichia coli, further evaluate the potential mechanism of action. Results showed that the minimum inhibition concentration (MIC) of BPEO was 1.0 μL/mL. The diameter of inhibition zone values were with range from 17.12 to 26.13 mm. 2 × MIC treatments had lower membrane potential and shorter kill-time than 1 × MIC, while control had the highest values. E. coli treated with BPEO became deformed, pitted, shriveled, adhesive, and broken. 2 × MIC exhibited the greatest electric conductivity at 1, 3, 5, 7, 9, 11, and 13 h, leaked DNA materials at 4, 8, 12, 16, 20, 24, and 28 h, proteins at 4, 6, 8, 10, 12, 14, and 16 h, potassium ion at 0, 0.5, 1, 1.5, and 2 h, phosphate ion at 0.5, 1, 1.5, and 2 h and ATP (P < 0.05); 1 × MIC had higher values than control. BPEO led to the leakage, disorder and death by breaking cell membrane. This study suggested that the BPEO has potential as the natural antibacterial agent in meat industry.

Chemical composition, antibacterial activity and related mechanism of the essential oil from the leaves of Juniperus rigida Sieb. et Zucc against Klebsiella pneumoniae

ETHNOPHARMACOLOGICAL RELEVANCE

Juniperus rigida is used as Tibetan and Mongolian medicine in China for the treatment of rheumatoid arthritis, nephritis, brucellosis and other various inflammatory diseases.

AIM OF THE STUDY

To evaluate antibacterial potential of essential oils from J. rigida leaves against Klebsiella pneumoniae and to examine its possible related mechanisms. The study was undertaken in order to scientifically validate the traditional use of J. rigida.

MATERIALS AND METHODS

The essential oil was extracted from the leaves of J. rigida by supercritical CO₂ fluid extraction technology. Chemical composition of essential oils was analyzed by gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was evaluated against 10 bacteria by the paper disc diffusion method. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of the essential oil were estimated by agar dilution method. The antibacterial mechanism was evaluated by growth curve, the integrity of cell membrane, the SDS-PAGE of protein patterns and scanning electron microscope (SEM).

RESULTS

61 components were identified from the essential oil. Caryophyllene (13.11%) and α-Caryophyllene (11.72%) were found to be the major components. The antibacterial activities of the essential oil were screened and compared against 10 bacteria. The essential oil showed good antibacterial activity against K. pneumoniae, with the biggest diameters of inhibition zones (DIZ) (16.00±0.25mm) and the lowest MIC and MBC values of 3.125mg/mL. The increase in proteins, 260nm absorbing materials of bacterial cells suspension indicated that the cytoplasmic membranes were broken by the essential oil. The SDS-PAGE of bacterial proteins demonstrated that the essential oil could damage bacterial cells through the destruction of cellular proteins. Scanning electron microscopy (SEM) showed that the essential oil damaged the morphology of cell wall and membrane.

CONCLUSIONS

The essential oil of J. rigida has potential antibacterial activities against K. pneumoniae. The antibacterial mechanism is the essential oil causing the irreversible damage to the cell wall and membrane, leading to the leakage of proteins and 260nm absorbing materials (DNA and RNA). Further phytochemical and pharmacological studies are required for proper scientific validation of the folk use of this plant species.

Antimicrobial activity and bioguided fractionation of Rumex tingitanus extracts for meat preservation

This study was undertaken to investigate the antibacterial and antifungal activities of Rumex tingitanus leaves extracts as well as the identification of bioactive components and their performance in meat preservation. Total phenolics and flavonoids showed the highest content of phenolics and flavonoids in the ethyl acetate fraction (Rt EtOAcF). For antimicrobial efficacy, leaves extract and derived fraction were tested for their capacity to inhibit bacterial and fungal proliferation in vitro and in vivo. The ethyl acetate fraction showed the most potent antibacterial and antifungal activities compared to the others extracts. Thus, the efficacy of this extract to inhibit the proliferation of Listeria monocytogenes in minced beef meat model was examined. This fraction eradicates the L. monocytogenes population in meat in a concentration- and time-dependent manner. A bio-guided purification of the Rt EtOAc fraction resulted in the isolation of the compound responsible for the observed antimicrobial activity. This compound was identified as luteolin by analysis of spectroscopic data.

CHEMICAL COMPOUNDS ISOLATED IN THIS ARTICLE

Luteolin (PubChem CID: 5280445); p-iodonitrotetrazolium chloride (PubChem CID: 64957); Amphotericin B (PubChem CID: 5280965); Gentamicin and (PubChem CID: 6419933); Hexane (PubChem CID: 8058); Methanol (PubChem CID: 887); Ethanol (PubChem CID: 702); Dimethylsulfoxide (PubChem CID: 679); Quercetin (PubChem CID: 5280343); Gallic acid (PubChem CID: 370).

Composition, in vitro Anti-inflammatory, Antioxidant and Antimicrobial Activities of the Leaf Essential Oil of Machilus konishii from Taiwan

The chemical composition and in vitro anti-inflammatory, antioxidant and antimicrobial activities of the leaf essential oil of Machilus konishii has been investigated. The essential oil was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC–FID and GC–MS. Sixty-six compounds were identified, representing 100% of the oil. The main components identified were α-pinene (33.9%), β-pinene (13.9%), and thymol (12.0%). The leaf oil was able to reduce nitric oxide production by lipopolysaccharide-activated murine macrophages RAW 264.7 without reducing the cell viability. In addition, the leaf oil showed strong antioxidant and antimicrobial activities. The major ingredient of the oil that was responsible for the anti-inflammatory, antioxidant and antimicrobial activities was thymol.

Anti-Listerial Activity of Four Seaweed Essential Oils Against Listeria monocytogenes

Background

Listeria monocytogenes is one of the most virulent types of bacteria and causes severe foodborne illness, such as listeriosis. Because this pathogen has become resistant to sanitizers and other disinfectants that are used to clean utensils and surfaces during food processing, it poses a serious threat to the food industry.

Objectives

The study was conducted to determine the anti-listerial potential of essential oils extracted from four edible seaweeds against L. monocytogenes.

Materials and Methods

Essential oil was extracted from four edible seaweeds (Enteromorpha linza, Undaria pinnatifida, Laminaria japonica, and Porphyra tenera) against L. monocytogenes using the microwave hydrodistillation method. The anti-listerial activity of the essential oil was determined using the standard disc diffusion method.

Results

Among the four essential oils, E. linza (ELEO) was most effective against all three strains of L. monocytogenes (11.3 - 16.0 mm). The other three essential oils were only effective against two strains, L. monocytogenes ATCC 19115 (10.0 - 10.5 mm) and L. monocytogenes ATCC 7644 (11.0 - 15.0 mm). The minimum inhibitory concentration and the minimum bactericidal concentration of all four essential oils varied from 12.5 - 25.0 mg/mL. Further, the mode of action of ELEO against L. monocytogenes was investigated by examining its effect on cell viability, the release of 260-nm absorbing materials, the number of K+ ions, the relative electrical conductivity, and the salt tolerance capacity. The results indicated that the essential oils exhibited strong anti-listerial activity against multiple strains of L. monocytogenes. It displayed potential inhibitory effects on the viability of bacterial cells and loss of integrity as indicated by an increase in the relative electrical conductivity, leakage of K+ ions and other 260-nm absorbing materials, and a loss of the salt tolerance capacity.

Conclusions

The results presented herein provided insight into a possible explanation for the modes of action of essential oils on L. monocytogenes. The outcome of the present study may aid the food industry in locating the most promising potential anti-listerial agents from edible seaweed sources to control L. monocytogenes and also in facilitating their application in food processing and preservation techniques in a nontoxic and environmental friendly manner.

Antibacterial Activity and Action Mechanism of the Essential Oil from Enteromorpha linza L. against Foodborne Pathogenic Bacteria

Foodborne illness and disease caused by foodborne pathogenic bacteria is continuing to increase day by day and it has become an important topic of concern among various food industries. Many types of synthetic antibacterial agents have been used in food processing and food preservation; however, they are not safe and have resulted in various health-related issues. Therefore, in the present study, essential oil from an edible seaweed, Enteromorpha linza (AEO), was evaluated for its antibacterial activity against foodborne pathogens, along with the mechanism of its antibacterial action. AEO at 25 mg/disc was highly active against Bacillus cereus (12.3-12.7 mm inhibition zone) and Staphylococcus aureus (12.7-13.3 mm inhibition zone). The minimum inhibitory concentration and minimum bactericidal concentration values of AEO ranged from 12.5-25 mg/mL. Further investigation of the mechanism of action of AEO revealed its strong impairing effect on the viability of bacterial cells and membrane permeability, as indicated by a significant increase in leakage of 260 nm absorbing materials and K⁺ ions from the cell membrane and loss of high salt tolerance. Taken together, these data suggest that AEO has the potential for use as an effective antibacterial agent that functions by impairing cell membrane permeability via morphological alternations, resulting in cellular lysis and cell death.

Antifungal Activity of Isoliquiritin and Its Inhibitory Effect against Peronophythora litchi Chen through a Membrane Damage Mechanism

This study investigated the antifungal activity and potential antifungal mechanism(s) of isoliquiritin against P. litchi Chen, one of the main litchi pathogens. The antifungal activity of isoliquiritin against P. litchi Chen had been proven in a dose-dependent manner through in vitro (mycelial growth and sporangia germination) and in vivo (detached leaf) tests. Results revealed that isoliquiritin exhibited significant antifungal activity against the tested pathogens, especially, P. litchi Chen, with a minimum inhibitory concentration of 27.33 mg/L. The morphology of P. litchi Chen was apparently changed by isoliquiritin through cytoplasm leakage and distortion of mycelia. The cell membrane permeability of the P. litchi Chen increased with the increasing concentration of isoliquiritin, as evidenced by a rise in relative electric conductivity and a decrease in reducing sugar contents. These results indicated that the antifungal effects of isoliquiritin could be explained by a membrane lesion mechanism causing damage to the cell membrane integrity leading to the death of mycelial cells. Taken together, isoliquiritin may be used as a natural alternative to commercial fungicides or a lead compound to develop new fungicides for the control of litchi downy blight.

Antibacterial mechanism of the action of Enteromorpha linza L. essential oil against Escherichia coli and Salmonella Typhimurium

BACKGROUND

Identification of natural antibacterial agents from various sources that can act effectively against disease causing foodborne bacteria is one of the major concerns throughout the world. However, the natural antibacterial agents identified to date are primarily effective against Gram positive bacteria, but less effective against Gram negative bacteria. In the present study, Enteromorpha linza L. essential oil (EEO) was evaluated for antibacterial activity against Escherichia coli and Salmonella Typhimurium along with the mode of their antibacterial action.

RESULTS

The chemical composition of EEO revealed high amounts of acids (54.6 %) and alkenes (21.1 %). EEO was effective against both E. coli and S. Typhimurium. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of EEO for both pathogens were 12.5 mg/ml and 25.0 mg/mL, respectively. EEO at the MIC acted on the loss in viability of E. coli ATCC 43890, which was used as the model system for evaluation of the antibacterial mode of action of EEO against Gram negative bacteria. Significant increase in relative electrical conductivity and K+ concentration were recorded with respect to time, indicating the disruption of tested E. coli cells owing to the controlling effect of EEO. Alternation of the morphology of the cell surface, increase in the release of 260 nm absorbing materials and loss of high salt tolerance were observed.

CONCLUSIONS

The results suggest that EEO induced a bactericidal effect via structural membrane damage caused by deposition of EEO in the cytosol or through enzymatic degradation of bacterial intracellular enzymes that resulted in cellular lysis. Accordingly, EEO can be used as a strong natural antibacterial agent against Gram negative foodborne pathogens such as E. coli and S. Typhimurium.

Composition, in Vitro Anti-inflammatory, Antioxidant and Antimicrobial Activities of Essential Oils from Leaf and Twig Parts of Cupressus Cashmeriana

The chemical composition and in vitro anti-inflammatory, antioxidant and antimicrobial activities of the essential oils isolated from the leaf and twig of Cupressus cashmeriana have been investigated. The essential oils were isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC–FID and GC–MS, respectively. The leaf oil mainly consisted of α-pinene (21.8%), epizonarene (8.0%), sabinene (7.9%), limonene (7.6%), γ-terpinene (7.0%), and allo-aromadendrene (7.0%); the twig oil was mostly carvacrol methyl ether (35.4%), manool (16.1%), carvacrol (14.2%), and (2 Z,6 E)-farnesol (6.9%). Twig oil, but not leaf oil, was able to reduce nitric oxide production by lipopolysaccharide-activated murine macrophages RAW 264.7 without reducing the cell viability. In addition, twig oil showed better antioxidant and antimicrobial activities than leaf oil. The major ingredient of the twig oil that was responsible for the anti-inflammatory, antioxidant and antimicrobial activities was carvacrol.

In vitro antibacterial and chemical properties of essential oils including native plants from Brazil against pathogenic and resistant bacteria

The antimicrobials products from plants have increased in importance due to the therapeutic potential in the treatment of infectious diseases. Therefore, we aimed to examine the chemical characterisation (GC-MS) of essential oils (EO) from seven plants and measure antibacterial activities against bacterial strains isolated from clinical human specimens (methicillin-resistant Staphylococcus aureus (MRSA) and sensitive (MSSA), Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium) and foods (Salmonella Enteritidis). Assays were performed using the minimal inhibitory concentration (MIC and MIC90%) (mg/mL) by agar dilution and time kill curve methods (log CFU/mL) to aiming synergism between EO. EO chemical analysis showed a predominance of terpenes and its derivatives. The highest antibacterial activities were with Cinnamomun zeylanicum (0.25 mg/mL on almost bacteria tested) and Caryophyllus aromaticus EO (2.40 mg/mL on Salmonella Enteritidis), and the lowest activity was with Eugenia uniflora (from 50.80 mg/mL against MSSA to 92.40 mg/mL against both Salmonella sources and P. aeruginosa) EO. The time kill curve assays revealed the occurrence of bactericide synergism in combinations of C. aromaticus and C. zeylanicum with Rosmarinus. officinalis. Thus, the antibacterial activities of the EO were large and this can also be explained by complex chemical composition of the oils tested in this study and the synergistic effect of these EO, yet requires further investigation because these interactions between the various chemical compounds can increase or reduce (antagonism effect) the inhibitory effect of essential oils against bacterial strains.

Antibacterial activity and kinetics of Litsea cubeba oil on Escherichia coli

Litsea cubeba oil is extracted from the fresh fruits of Litsea cubeba by distillation. In this study, its chemical constituents, antibacterial activity, kinetics and effects against Escherichia coli were studied. Its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were both 0.125% (v/v) by toxic food method. Moreover, the antibacterial kinetic curves indicated 0.0625% (v/v) of litsea cubeba oil was able to prolong the growth lag phase of E. coli cells to approximate 12 hours while 0.125% (v/v) of litsea cubeba oil was able to kill the cells completely. Furthermore, transmission electron microscope (TEM) observation showed most E. coli cells treated with 0.125% (v/v) of litsea cubeba oil were killed or destroyed severely within 2 hours. The litsea cubeba oil might penetrate and destroy the outer and inner membrane of E. coli cells. Thus many holes and gaps were observed on the damaged cells, which led to their death eventually. The antibacterial effects of litsea cubeba oil mainly attributed to the presence of aldehydes, which accounted for approximately 70% in its whole components analyzed by GC/MS. Based on the antimicrobial properties, litsea cubeba oil would have a broad application in the antimicrobial industry.

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

OBJECTIVE

To investigate the antioxidant efficacy of a biologically active diterpenoid 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 76.5% as compared to α-tocopherol (80.13%) and butylated hydroxyanisole (76.59%). In addition, the sugiol had significant scavenging activities of 1,1-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 α-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.

Antioxidant Capacity and Proanthocyanidin Composition of the Bark of Metasequoia glyptostroboides

Metasequoia glyptostroboides Hu et Cheng is the only living species in the genus Metasequoia Miki ex Hu et Cheng (Taxodiaceae), which is well known as a “living fossil” species. In the Chinese folk medicine, the leaves and bark of M. glyptostroboides are used as antimicrobic, analgesic, and anti-inflammatory drug for dermatic diseases. This study is the first to report the free radical scavenging capacity, antioxidant activity, and proanthocyanidin composition of the bark of M. glyptostroboides. We observed total of six extracts and fractions, which were easily obtained by water-ethanol extraction and followed by a further separation with D101 resin column chromatography, had significant DPPH radical, superoxide anion radical, and hydroxyl radical scavenging capacity, total antioxidative capacity (T-AOC), lipid peroxidation inhibitory activity, and metal ions chelating capacity. The fraction MGEB, which was obtained by 60% ethanol extraction and followed by a further separation with D101 resin column chromatograph, possessed the highest proanthocyanidin content and the highest free radical scavenging and antioxidant activities. Furthermore, MGEB could significantly protect against CCl₄ induced acute liver injury through inhibition of oxidative stress in mice. In addition, ten proanthocyanidins were isolated from MGEB, and six of them were firstly reported from this plant.

6-carboxydihydroresveratrol 3-O-β-glucopyranoside--a novel natural product from the Cretaceous relict Metasequoia glyptostroboides

Metasequoia glyptostroboides, a tree native to China, is described as a living fossil and has existed for millions of years. The oldest fossils recorded have been dated to the late Cretaceous era. During the time of its existence, the molecular defence system of the tree has apparently resisted millions of generations of pathogens, which encouraged search for novel natural product from this source. Eight compounds have been characterised from needles of M. glyptostroboides, including the novel natural product 6-carboxydihydroresveratrol 3-O-β-glucopyranoside. The structure determinations were based on extensive use of 2D NMR spectroscopic techniques and high-resolution mass spectrometry.

Antibacterial and Antioxidant Activities of Various Medicinal Plants Used in Oriental Medicine

The antibacterial activities of the ethanol extracts of 35 medicinal plants were screened against Escherichia coli, Bacillus cereus, and Staphylococcus aureus by following standard antimicrobial susceptibility testing procedures. The ethanol extracts of Coptis chinensis and Glycyrrhiza uralensis showed antibacterial activity against all three test bacterial species. The screened extracts were also tested for their antioxidant activities using the DPPH free radical scavenging activity assay, and for their cytotoxic and antioxidant activity in vitro using an assessment of cell viability on mouse embryonic fibroblast cells. The ethanol extracts of both C. chinensis and G. uralensis showed good radical scavenging antioxidant properties and attenuated the rate of cell death caused by oxidative damage. Our results showed that C. chinensis and G. uralensis are promising sources of natural products with good antibacterial and antioxidant activities.

Antimicrobial and antioxidant activities of Cichorium intybus root extract using orthogonal matrix design

Solvent, impregnation time, sonication repetitions, and ultrasonic power were important factors in the process of ultrasound-assisted extraction from chicory (Cichorium intybus) root, while there were no studies about optimizing these 4 factors for extract yield, total phenolic content (TPC), antioxidant, antibacterial, and antifungal activity of the extracts using orthogonal matrix design. The present research demonstrated that the solvent composition played a significant role in the improving extract yield, TPC, antioxidant, and antibacterial activities. The other 3 factors had inequable effect on different purposes, ultrasonic power could improve TPC and antioxidant activity, but long time of extraction lowered antioxidant activity. The TPC increased from 22.34 to 27.87 mg GAE (gallic acid equivalents)/100 g (dry extracts) with increasing solvent polarity. The half inhibition concentration (IC(50,) μg/mL) of the radical scavenging activity of the chicory extracts ranged from 281.00 to 983.33 μg/mL. The content of caffeoylquinic acids of root extract, which was extracted by the optimal combination was 0.104%. Several extracts displayed antibacterial activities against Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, Bacillus subtilis, and Salmonella typhi, while Penicillium sp. and Aspergillus sp. resisted against all the extracts. Combination of 70% ethanol v/v, 24-h impregnation time, 3 sonication rounds, and 300-W ultrasonic input power was found to be the optimal combination for the chicory extract yield, TPC, antioxidant activity, and antibacterial activity.

Composition, Anticancer, and Antimicrobial Activities in vitro of the Heartwood Essential Oil of Cunninghamia lanceolata var. konishii from Taiwan

This study investigated the chemical composition, anticancer, and antimicrobial activities in vitro of the essential oil isolated from the heartwood of Cunninghamia lanceolata var. konishii from Taiwan. The essential oil was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. Thirty-seven compounds were identified, representing 100% of the oil. The main components identified were cedrol (58.3%), α-cedrene (11.8%), α-terpineol (4.2%) and β-cedrene (3.5%). The oil exhibited cytotoxic activity against human lung, liver and oral cancer cells. The active source compound was cedrol. The antimicrobial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against ten microbial species. The oil exhibited strong growth suppression against Gram-positive bacteria and yeast with inhibition zones of 42~50 mm to MIC values of 31.25~62.5 μg/mL, respectively. For the antimicrobial activities of the oil, the active compound was determined to be cedrol.

Investigation of optimal extraction, antioxidant, and antimicrobial activities of Achillea biebersteinii and A. wilhelmsii

OBJECTIVE

Achillea species are endowed with multiple biological activities including antioxidant properties. However, no study has yet investigated the impact of extraction method and pH on the biological activities of these plants. The present study aimed to investigate the antioxidant and antimicrobial effects of methanol extracts from the aerial parts of the species Achillea biebersteinii Afan and Achillea wilhelmsii C. Koch (Asteraceae). In addition, the impact of extraction method and pH on these biological activities was evaluated.

MATERIALS AND METHODS

Methanol extracts of A. biebersteinii and A. wilhelmsii were prepared using classical maceration and high-intensity ultrasound methods. Ultrasound-assisted extraction was performed at three different pH values: 5.7, 6.3 and 6.9.

RESULTS

Total phenolic compounds (range: 20.16-108.54 vs. 17.18-59.61 mg gallic acid equivalent/g sample in A. biebersteinii and A. wilhelmsii, respectively), total flavonoids (range: 8.33-12.97 vs. 7.79-9.41 mg catechin equivalent/g sample), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (IC₅₀: 40.63-346.34 vs. 84.02-462.41) and reducing power (IC₅₀: 504.44-4406.67 vs. 1710.00-5501.67) were significantly higher in A. biebersteinii vs. A. wilhelmsii and ultrasound-assisted vs. classical maceration extracts of both species. The aforementioned items were higher at pH = 6.3, followed by pHs of 6.9 and 5.7, respectively. Overall, A. biebersteinii extracts were more active against all of the tested microorganisms than A. wilhelmsii. Sensitivities of Gram-positive bacteria were higher for both Achillea extracts than the Gram-negative bacteria. No observable inhibitory activity was found from different extracts against Aspergillus niger.

CONCLUSION

The findings of the present study suggest that methanol extracts of A. biebersteinii and A. wilhelmsii possess antioxidant and antimicrobial activity, being higher in the former. Ultrasound-assisted extraction and pH of 6.3 have significant augmenting impact on the total phenolic and flavonoid content as well as antioxidant activities of both species.

Volatiles of Curcuma mangga Val. & Zijp (Zingiberaceae) from Malaysia

Analysis by GC and GC/MS of the essential oil obtained from Malaysian Curcuma mangga Val. & Zijp (Zingiberaceae) rhizomes allowed the identification of 97 constituents, comprising 89.5% of the total oil composition. The major compounds were identified as myrcene (1; 46.5%) and β-pinene (2; 14.6%). The chemical composition of this and additional 13 oils obtained from selected Curcuma L. taxa were compared using multivariate statistical analyses (agglomerative hierarchical cluster analysis and principal component analysis). The results of the statistical analyses of this particular data set pointed out that 1 could be potentially used as a valuable infrageneric chemotaxonomical marker for C. mangga. Moreover, it seems that C. mangga, C. xanthorrhiza Roxb., and C. longa L. are, with respect to the volatile secondary metabolites, closely related. In addition, comparison of the essential oil profiles revealed a potential influence of the environmental (geographical) factors, alongside with the genetic ones, on the production of volatile secondary metabolites in Curcuma taxa.

Composition, Antioxidant, Antimicrobial and Anti-wood-decay Fungal Activities of the Twig Essential Oil of Taiwania cryptomerioides from Taiwan

This study investigated the chemical composition, antioxidant, antimicrobial and anti-wood-decay fungal activities of the essential oil isolated from the twigs of Taiwania cryptomerioides from Taiwan. The essential oil was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. A total of 35 compounds were identified, representing 100% of the oil. The main components identified were α-cadinol (45.9%), ferruginol (18.9%) and β-eudesmol (10.8%). The antioxidant activity of the oil was tested by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging capability test. The results showed an IC50 of 90.8 ± 0.2 μg/mL. The active source compound was ferruginol. The antimicrobial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against ten microbial species. The oil exhibited strong growth suppression against Gram-positive bacteria and yeast with inhibition zones of 45~52 mm and MIC values of 31.25~62.5 μg/mL, respectively. The anti-wood-decay fungal activity of the oil was also evaluated. The oil demonstrated excellent activity against four wood-decay-fungal species. For the antimicrobial and anti-wood-decay fungal activities of the oil, the active source compounds were determined to be α-cadinol, β-eudesmol and ferruginol.

Antibacterial abietane-type diterpenoid, taxodone from Metasequoia glyptostroboides Miki ex Hu

In an attempt to isolate bioactive constituents, ethyl acetate cone extract of Metasequoia glyptostroboides was subjected to a column chromatographic analysis that resulted in isolation of an abietane-type diterpenoid, taxodone. Its structure was elucidated by spectroscopic means. Further, taxodone showed potential antibacterial effect as diameters of zones of inhibition against foodborne pathogenic bacteria, such as Listeria monocytogenes ATCC 19166, Salmonella typhimurium KCTC 2515, S. enteritidis KCTC 2021, Escherichia coli ATCC 8739, E. coli O157:H7 ATCC 43888, Enterobacter aerogenes KCTC 2190, Staphylococcus aureus ATCC 6538 and S. aureus KCTC 1916, were found in the range of 9.4 to 14.2 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of taxodone against the employed bacterial pathogens were found in the range of 250 to 1000 and 250 to less than 2000 microg/ml, respectively. Also the compound had a strong antibacterial effect on the viable counts of the tested bacteria. These findings indicate that the bioactive compound taxodone present in M. glyptostroboides could be used as an antibacterial agent in food industry to inhibit the growth of certain important foodborne pathogens.

Optimization of antibacterial activity of Perilla frutescens var. acuta leaf against Staphylococcus aureus using evolutionary operation factorial design technique

This study was undertaken to optimize extraction using evolutionary operation-factorial (EVOP) design technique to elicit the antibacterial activity of Perilla frutescens var. acuta leaf against Staphylococcus aureus ATCC6538. Higher antibacterial activity was achieved at higher extraction temperature and over a longer extraction time. Antibacterial activity was not affected by differentiation of the ethanol concentration in the extraction solvent. The maximum antibacterial activity of ethanolic extract of P. frutescens leaf against S. aureus was obtained at 75 °C (R = −0.7904^**) extraction temperature, 24 h (R = −0.7273^**) extraction time, and 45% (R = −0.0635) ethanol concentration. The population of S. aureus was decreased from 7.535 log CFU/mL in the initial set to 4.865 log CFU/mL in the third set by EVOP factorial design technique, as well as to 2.600 log CFU/mL by extraction with ethyl acetate. Further, the ethyl acetate extract revealed the highest phenolic contents (111.3 ± 8.6 mg% of dry sample) as compared to the other extracts. Also, the scanning electronic microscopic study of the ethanolic extract of P. frutescens revealed potential detrimental effect on the morphology of S. aureus.