Activity Of Essential Oil Components Research Articles

Antibacterial Activity and Synergistic Interaction of Various Essential Oil Components and Antibiotics

Inappropriate and uncontrolled use of antibiotics in humans and animals leads to the emergence of multi-resistant bacteria. Before the discovery of antibiotics, plant extracts and essential oils were used for therapeutic purposes. Today, due to increasing antibiotic resistance, many studies are frequently carried out on the antimicrobial activities of natural active substances that can be a source for new drug candidates. The aim of this study was to investigate the antibacterial activity of components such as α-pinene (α-PN), p-cymene (p-CYM), carvacrol (CAR), thymol (TY) and eugenol (EG) found in the essential oils of many plants and their synergistic interaction with antibiotics. In this study, the antibacterial activity of these essential oil components and antibiotics in clinical use such as gentamicin (GEN), tetracycline (TET), tigecycline (TGC) and linezolid (LZD), against Staphylococcus aureus [methicillin resistant S.aureus (MRSA), and methicillin sensitive S.aureus (MSSA)], Escherichia coli and Pseudomonas aeruginosa strains were determined by disc diffusion and microdilution method. In addition, the interaction between the essential oil components and antibiotics was also determined by the checkerboard method. While CAR, TY and EG components showed strong antibacterial activity, the antibacterial activity of αPN and p-CYM was found to be weak. Combinations of α-pinene, carvacrol, thymol and eugenol with gentamicin and tetracycline mostly showed synergistic interactions against all bacteria. In αPN, CAR, TY and EG with GEN and TET, synergistic/partial synergistic interaction was observed against S.aureus strains, while indifferent interaction was detected in E.coli and P.aeruginosa strains. The combination of αPN and p-CYM with TGC showed synergistic interaction against E.coli and P.aeruginosa strains, and additive and indifferent interaction against S.aureus strains. On the other hand, synergistic interaction was observed against all bacterial strains in combinations of TGC and CAR, TY and EG components. Antagonistic interaction was not detected in any of the tested component-antibiotic combinations against the bacteria used in our study. A synergistic interaction between natural bioactive components and commonly used antibiotics may contribute to the effectiveness of antibiotics and components at lower doses, minimizing their potential toxic side effects and reducing treatment costs. However, more research is needed in terms of their pharmacokinetic and toxic properties to evaluate the therapeutic application potential of phytochemicals.

Potentially Effective and Safe Anti-Helicobacter pylori Natural Products: Chemometric Study

The susceptibility of Helicobacter pylori to three essential oils (EOs), 12 naturally occurring monoterpene hydrocarbons, oxygenated and phenolic monoterpenes and three reference antibiotics were studied. Classification and comparison of essential oils and monoterpenes on the basis of their chemical composition and antibacterial activity were made by the utilization of principal component analyses (PCA) and agglomerative hierarchical clustering (AHC). The most abundant compound in the Thymus glabrescens Willd. and Thymus pulegioides L. EOs is geraniol (33.8% and 52.5%), while the main constituent in Satureja kitaibelii Wierzb. ex Heuff. EO is limonene (16,1%). The compound that was the most active against H. pylori was carvacrol. EOs of T. glabrescens and S. kitaibelii exhibit higher antibacterial ability in comparison with all monoterpenes, except carvacrol, probably based on the concept of synergistic activity of essential oil components. PCA separated essential oils based on chemical composition and explain 96.5% of the total variance in the first two principal components. Essential oils, phenolic monoterpenes and two antibiotics were classified in the same sub-cluster within AHC analyses. EOs of T. glabrescens and S. kitaibelii can be used to treat infections caused by H. pylori, as a potentially effective, cheap and safe natural products. Further research of antibacterial activity of selected monoterpenes, essential oils and standard antibiotic combinations, as well as clinical study are required.

Study of the potential synergistic antibacterial activity of essential oil components using the thiazolyl blue tetrazolium bromide (MTT) assay

The thiazolyl blue tetrazolium bromide (MTT) assay was used to study the potential interactions between several active compounds from plant essential oils (carvacrol, eugenol, cinnamaldehyde, thymol and eucalyptol) when used as antibacterial agents against Escherichia coli and Listeria innocua. The minimum inhibitory concentration (MIC) of each active compound and the fractional inhibitory concentration (FIC) index for the binary combinations of essential oil compounds were determined. According to FIC index values, some of the compound binary combinations showed an additive effect, but others, such as carvacrol-eugenol and carvacrol-cinnamaldehyde exhibited a synergistic effect against L. innocua and E. coli, which was affected by the compound ratios. Some eugenol-cinnamaldehyde ratios exhibit an antagonistic effect against E. coli, but a synergistic effect against L. innocua. The most remarkable synergistic effect was observed for carvacrol-cinnamaldehyde blends for both E. coli and L. innocua, but using different compound ratios (1:0.1 and 0.5:4 respectively for each bacteria).

Enhanced antimicrobial activity of essential oil components immobilized on silica particles

The antimicrobial activity of essential oils components (EOCs) is well-known. However, their high volatility and powerful aroma limit their application in the formulation of a wide range of food products. In this context, the antimicrobial activity of carvacrol, eugenol, thymol and vanillin grafted onto the surface of three silica supports with different morphologies, textural properties and chemical reactivities (fumed silica, amorphous silica and MCM-41) was evaluated herein. Materials characterization revealed a good immobilization yield and all the devices showed a micro-scale particle size. Sensory evaluation revealed that sensory perception of EOCs decreases after covalent immobilization. Moreover, immobilization greatly enhanced the antimicrobial activity of the essential oil components against Listeria innocua and Escherichia coli compared to free components. The incorporation of EOCs immobilized on silica particles into pasteurized milk inoculated with L. innocua demonstrated their effectiveness not only for in vitro conditions, but also in a real food system.

Antimicrobial Efficacy of Emulsified Essential Oil Components against Weak Acid-Adapted Spoilage Yeasts in Clear and Cloudy Apple Juice

The antimicrobial activity of oil-in-water emulsions containing dual combinations of the essential oil components cinnamaldehyde, perillaldehyde, and citral was examined against two acid-resistant yeast strains (Zygosaccharomyces bailii) in beverage systems composed of diluted clear or cloudy apple juice and in a Sabouraud dextrose broth model. Antimicrobial properties of an encapsulated oil-in-water emulsion and of essential oil components dissolved in 10% dimethyl sulfoxide were compared using plate counts and turbidity measurements. Growth curves were modulated to qualitatively assess differences in antimicrobial efficacy. The impact of the presence of a beverage emulsion without essential oils (unloaded; 5% oil and 1% modified starch, pH 3.0) on the antimicrobial efficacy also was investigated. Dual combinations of essential oil components were sufficient to completely inhibit and/or kill yeast cells in diluted apple juice and Sabouraud dextrose broth systems at very low concentrations (100 to 200 μg/ml). However, the combination of perillaldehyde and citral had the weakest antimicrobial effect; a concentration of 400 μg/ml was necessary to prevent yeast growth in beverages, and up to 800 μg/ml was required in systems to which an unloaded emulsion had been added. The antimicrobial activity of essential oil components did not differ in diluted clear and cloudy apple juices and was not affected by being added in emulsified form or dissolved in dimethyl sulfoxide as long as there was no unloaded emulsion also present. These results indicate that formulations of essential oil combinations encapsulated together in emulsions are highly effective for inhibiting and/or killing microorganisms in real beverage systems.

Physiological effect of olfactory stimuli inhalation in humans: an overview

The importance of odorants in human life has long been recognized. Literature contains different approaches of physiological and psychological effects of odorant compounds, fragrances and essential oils. This work discusses odorants inhalation effect, based on an overview of major studies in humans. Beneficial effect of fragrances is mainly related to human behaviour. Studies document odorants influence in sympathetic and parasympathetic nervous systems, and neurophysiological brain activity. Moreover, odours compounds can act on the neuroendocrine system, neurotransmitters and neuromodulators, influencing psychological behaviour as well as body function. Odorant inhalation modulates physiological pathways, and in some cases, results in skin function regulation. The mechanism is incompletely elucidated. These findings suggest that olfactory system plays a role in central nervous system function beyond that of smell. In this overview, it was observed that odour compounds influenced stress biomarkers, dehydroepiandrosterone, oxidative stress, estradiol, dopamine, cutaneous barrier, sebum secretion and cutaneous immune system in humans. Some can be related with skin function. As the skin is associated with an extensive biochemical cascade and has complex mechanisms, studies have far to go, as there are processes not yet investigated related to skin that may be affected through olfaction. Future researches are needed to further understand and describe the mechanisms of action of physiological effects in fragrance compounds.

Chemical composition and antibacterial activity of Pinus halepensis Miller growing in West Northern of Algeria

ObjectiveTo find new bioactive natural products, the chemical composition and to sudy the antibacterial activity of essential oil components extracted from the aerial parts of the Algerian aromatic plant Pinus halepensis Miller (P. halepensis) (needles, twigs and buds). MethodsThe essential oil used in this study was isolated by hydrodistillation using a Clevenger-type apparatus according to the European Pharmacopoeia. The chemical composition was investigated using GC-retention indices (RI) and GC-MS. ResultsForty-nine compounds, representing 97.9% of the total collective oil, were identified. Essential oil was dominated by hydrocarbon compounds (80.6%) especially monoterpenes (65.5%). The major compounds from ten oils stations were: myrcene (15.2%–32.0%), α-pinene (12.2%–24.5%), E-β-caryophyllene (7.0%–17.1%), terpinolene (1.8%–13.3%), 2-phenyl ethyl isovalerate (4.8%–10.9%), terpinene-4-ol (1.0%–8.2 %) and sabinene (1.5%–6.3%). The intra-species variations of the chemical compositions of P. halepensis aerial parts essential oils from ten Algerian sample locations were investigated using statistical analysis. Essential oil samples were clustered in 2 groups by hierarchical cluster analysis, according to their chemical composition. The essential oil revealed an interesting antimicrobial effect against Lysteria monocytogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Acinetobacter baumanii, Citrobacter freundii and Klebsiella pneumoniae. ConclusionsThese results suggest that the essential oil from P. halepensis may be a new potential source as natural antimicrobial applied in pharmaceutical and food industries.

Detection of antibacterial activity of essential oil components by TLC-bioautography using luminescent bacteria

The aim of the present study was the chemical characterization of some medically relevant essential oils (tea tree, clove, cinnamon bark, thyme, and eucalyptus) and the investigation of antibacterial effect of the components of these oils by use of a direct bioautographic method. Thin-layer chromatography (TLC) was combined with biological detection in this process. The chemical composition of the oils was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Eucalyptol (84.2%) was the main component of the essential oil of eucalyptus, eugenol (83.7%) of clove oil, and trans-cinnamic aldehyde (73.2%), thymol (49.9%), and terpinen-4-ol (45.8%) of cinnamon bark, thyme and tea tree oils, respectively. Antibacterial activity of the separated components of these oils as well as of their pure main components (eucalyptol, eugenol, trans-cinnamic aldehyde and thymol) was observed against the Gram-negative luminescence gene-tagged plant pathogenic bacterium Pseudomonas syringae pv...

Investigation of the chemical composition–antibacterial activity relationship of essential oils by chemometric methods

The antibacterial effects of Thymus vulgaris (Lamiaceae), Lavandula angustifolia (Lamiaceae), and Calamintha nepeta (Lamiaceae) Savi subsp. nepeta var. subisodonda (Borb.) Hayek essential oils on five different bacteria were estimated. Laboratory control strain and clinical isolates from different pathogenic media were researched by broth microdilution method, with an emphasis on a chemical composition-antibacterial activity relationship. The main constituents of thyme oil were thymol (59.95%) and p-cymene (18.34%). Linalool acetate (38.23%) and β-linalool (35.01%) were main compounds in lavender oil. C. nepeta essential oil was characterized by a high percentage of piperitone oxide (59.07%) and limonene (9.05%). Essential oils have been found to have antimicrobial activity against all tested microorganisms. Classification and comparison of essential oils on the basis of their chemical composition and antibacterial activity were made by utilization of appropriate chemometric methods. The chemical principal component analysis (PCA) and hierachical cluster analysis (HCA) separated essential oils into two groups and two sub-groups. Thyme essential oil forms separate chemical HCA group and exhibits highest antibacterial activity, similar to tetracycline. Essential oils of lavender and C. nepeta in the same chemical HCA group were classified in different groups, within antibacterial PCA and HCA analyses. Lavender oil exhibits higher antibacterial ability in comparison with C. nepeta essential oil, probably based on the concept of synergistic activity of essential oil components.

Antibacterial Activity of Essential Oil Components and Their Potential Use in Seed Disinfection

Among the main (> or = 0.7%) components of some essential oils, considerable antibacterial activity was shown by terpenoid and phenylpropanoid derivatives containing phenol and alcohol functionalities. A reduced or no activity was shown by those derivatives containing ketones, aldehydes, ethers, and ester functionalities as well as the remaining terpenoids. Eugenol emulsion treatments (1-8 mg/mL) of bean seeds bearing about 2.6 x 10(6) cfu/seed of strain ICMP239 of Xanthomonas campestris pv. phaseoli var. fuscans determined a highly significant reduction of the bacteria on seeds. In particular, eugenol at 4 mg/mL disinfect seeds bearing about 7.0 x 10(2) cfu/seed and lower densities. However, after 72 h, incubation treatments with 2, 4, and 8 mg/mL of eugenol caused germination reduction of 3%, 7%, and 16%, respectively, which was significantly different from the controls. No effect on germination was observed with 1 mg/mL eugenol emulsion treatment. These data indicate eugenol as potentially useful for bean seed disinfection from X. campestris pv. phaseoli var. fuscans. Further studies on the effects on seed vitality and on formulation of essential oils are needed.

The antibacterial mechanism of carvacrol and thymol againstEscherichia coli

To investigate the antibacterial mechanism of carvacrol and thymol against Escherichia coli. The time-kill curve results showed that carvacrol and thymol at 200 mg l(-1) could inhibit the growth of E. coli. Flow cytometry and fluorescent dyes were used to explore the effect of two components on membrane permeability and membrane potential. In membrane permeability experiment, the mean fluorescence intensity of cells treated with 200 mg l(-1) carvacrol or thymol were lower than nonexposed cells. The ratio of red to green fluorescence intensity of DiOC2(3) reflected the change of membrane potential. Carvacrol and thymol at 200 mg l(-1) caused the ratio of red/green decreasing from 0.42 of control to 0.08 and 0.07, respectively. Carvacrol and thymol had desired antimicrobial effect on E. coli. The antibacterial effects were attributed to their ability to permeabilize and depolarize the cytoplasmic membrane. This study showed the potential use of flow cytometry as a suitable method to investigate the mode of antibacterial action of essential oil components.

Fumigant Antifungal Activity of Essential Oil Components from Acorus gramineus against Three Phytopathogenic Fungi

Analysis by gas chromatography-mass spectrometry led to the identification of 26 compounds in Acorus gramineus essential oil. The antifungal activity of the identified compounds was tested singularly by using standard compounds. Allyl isothiocyanate and cis-asarone showed inhibition rates of 100% against P. cactorum at 28 mg/l air. In a test with C. parasitica and E. circinatum, allyl isothiocyante and cis-asarone showed moderate activity at 28 mg/l air.

Use of Novel Compounds for Pest Control: Insecticidal and Acaricidal Activity of Essential Oil Components from Heartwood of Alaska Yellow Cedar

Laboratory bioassays were conducted to determine the activity of 15 natural products isolated from essential oil components extracted from the heartwood of Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach., against Ixodes scapularis Say nymphs, Xenopsylla cheopis (Rothchild), and Aedes aegypti (L.) adults. Four of the compounds from the essential oil have been identified as monoterpenes, five as eremophilane sesquiterpenes, five as eremophilane sesquiterpene derivatives from valencene and nootkatone, and one as a sesquiterpene outside the eremophilane parent group. Carvacrol was the only monoterpene that demonstrated biocidal activity against ticks, fleas, and mosquitoes with LC50 values after 24 h of 0.0068, 0.0059, and 0.0051% (wt:vol), respectively. Nootkatone from Alaska yellow cedar was the most effective of the eremophilane sesquiterpenes against ticks (LC50 = 0.0029%), whereas the nootkatone grapefruit extract exhibited the greatest biocidal activity against fleas (LC50 = 0.0029%). Mosquitoes were most susceptible to one of the derivatives of valencene, valencene-13-aldehyde (LC50 = 0.0024%), after 24 h. Bioassays to determine residual activity of the most effective products were conducted at 1, 2, 4, and 6 wk after initial treatment. Residual LC50 values for nootkatone did not differ significantly at 4 wk posttreatment from the observations made at the initial 24-h treatment. The ability of these natural products to kill arthropods at relatively low concentrations represents an alternative to the use of synthetic pesticides for control of disease vectors.

Nematicidal activity of essential oil components against the root-knot nematode Meloidogyne javanica

AbstractNematicidal activity of eight essential oil components; trans -anethole, anis alcohol, p-anisaldehyde, benzaldehyde, 4-methoxyphenol, trans-cinnamaldehyde, (R)-(+)-pulegone, 2-furaldehyde, and a non-essential oil component anisole, was tested against the root-knot nematode Meloidogyne javanica in solutions in 200-ml and 3-l pots and in microplots. Among the anisole derivatives, p-anisaldehyde showed the highest nematicidal activity in solutions and in soil. However, trans-cinnamaldehyde, 2-furaldehyde and benzaldehyde showed higher nematicidal activity than p-anisaldehyde in the 3-l pot experiments. EC50 values of trans-cinnamaldehyde for juvenile immobilisation and hatching inhibition in vitro were as low as 15 and 11.3 μl/l, respectively. In the 3-l pot experiments, trans-cinnamaldehyde, 2-furaldehyde, benzaldehyde and carvacrol at a concentration of 100 mg/kg greatly reduced the root galling of tomato, whereas trans-anethole was not effective. In a microplot experiment, soil treatment with trans-cinnamaldehyde (50 ml/m2) reduced the galling index and increased the shoot weight of tomato plants. Although further experiments, such as development of formulations and application methods, are needed, some essential oil components, especially aldehydes, can be developed into lowtoxicity nematicides.

Antibacterial activity of essential oil components

Antibacterial activity of fifteen essential oil components towards food borne Staphylococcus sp., Micrococcus sp., Bacillus sp. and Enterobacter sp. was studied by an agar plate technique. Cinnamic aldehyde was the most active compound followed by citral, geraniol, eugenol and menthol. At 500 μg/ml, cinnamic aldehyde completely inhibited the bacterial growth for more than 30 days at 30°C that was comparable to 200 μg/ml of butylated hydroxy anisole (BHA). At lower temperatures, 25 and 20°C, antibacterial activity of the five essential oil components increased. Addition of sodium chloride at 4% level (w/v) in the medium had no effect on the inhibitory activity of cinnamic aldehyde. In mixtures of cinnamic aldehyde and eugenol or BHA an additive effect was observed.

Fungitoxic Activity of Essential Oil Components on Food Storage Fungi

Click to increase image sizeClick to decrease image sizeKey Words: anetholcarvacrolcinnamaldehydeeugenolsafroleRhizopusMucorAspergillus

Fungitoxic Activity of Essential Oil Components on Food Storage Fungi

Click to increase image sizeClick to decrease image sizeKey Words: anetholcarvacrolcinnamaldehydeeugenolsafroleRhizopusMucorAspergillus