Cubeba Oil Research Articles

Excess Gibbs Energies and Isothermal Vapor–Liquid Equilibrium for Citral + Linalool, Citral + α-Pinene, and Linalool + α-Pinene Systems Using Headspace Gas Chromatography

Isothermal vapor–liquid equilibrium (VLE) data for expensive and thermosensitive Litsea cubeba oil systems, citral + linalool, citral + α-pinene, and linalool + α-pinene, were measured at 333.15, 3...

The Fumigating Activity of Litsea cubeba oil and Citral on Solenopsis invicta

This paper studied the fumigating activity of Litsea cubeba oil and citral on Solenopsis invicta, identified and analyzed the chemical constituents and volatile components of L. cubeba oil via solid-phase microextraction which were then identified via gas chromatography-mass spectrometry. The results showed that citral and (z)-3,7-dimethylocta-2,6-diena were the main components of L. cubeba oil, as well as its volatile compounds. According to the experimental results, L. cubeba oil and citral had good fumigating activity on workers, and also had significant inhibition on the walking ability and climbing ability of workers. At the same time, the effects of the two agentia on the fumigating activity and behavioral inhibition of microergate were stronger than those of macroergate. After treating with L. cubeba oil and citral for 24 hours, the walking rate and grasping rate of microergate were both 0 %. The results showed that L. cubeba oil and citral had good control effect on S. invicta.

Optimization of Process Conditions for Extracting Litsea cubeba Kernel Oil by Microwave-Assisted Water Method

Litsea cubeba is a rich woody oil plant resource in China. The economic value of Litsea cubeba oil is high. In order to improve the resource utilization rate of Litsea cubeba, this study used microwave-assisted water method to extract Litsea cubeba kernel oil from the seeds of Litsea cubeba. The optimum process conditions were as follows: microwave time 60 min, extraction temperature 80.18 °C, liquid-to-liquid ratio 11.46:1, microwave power 587.44 W. Under this optimized condition, the extraction rate of Litsea cubeba kernel oil was 37.54%. It can be seen that the microwave assisted water generation method for extracting Litsea cubeba nucleolus oil is reliable and has certain utilization value.

Antibacterial activity of essential oils against Stenotrophomonas maltophilia and the effect of citral on cell membrane

Stenotrophomonas maltophilia has both the pathogenic potential and the ability to cause food spoilage, and is characterized by multi-resistance to many antibiotics. Essential oils (EOs) have been reported as good antimicrobial agents. In this study, seven EOs were selected to evaluate the antibacterial effect against foodborne spoilage S. maltophilia 4–1 by disk diffusion method, broth dilution method, and fumigation treatment. The chemical compositions of EOs were analyzed via gas chromatography–mass spectrometry injecting with both gas and liquid, hoping to reveal the relationship between active compounds and antibacterial activity. The results indicated that litsea cubeba oil (LCO) exhibited a strong inhibitory effect with minimum bactericidal concentration (MBC) value of 0.125% (v/v), and only LCO showed bacteriostatic effect in fumigation treatment within the tested range. Its key active component, citral, was responsible for the antibacterial property by causing damage and rupture of cell membrane determined using fluorescent dyes and field emission scanning electron microscope. The minimum inhibitory concentration and MBC of citral against S. maltophilia 4–1 was determined to be 0.25% (v/v) and 0.5% (v/v), respectively. This study reveals the high efficiency of EOs to inhibit bacteria in terms of key active component, and provides an alternative to reduce the resistant bacteria.

Effect of some plant essential oils on the orientation and predation capacity of the predatory spider Pardosa pesudoannulata

Abstract Investigating the potential side-effects of plant essential oils to natural enemies is necessary before applying them in the field to control insect pests. In the present laboratory study, the attractancy/repellency of two plant oils to the spider Pardosa pseudoannulata was evaluated using a paired choice method. An individual spider was allowed to choose between the odors of essential oils extracted from Piper nigrum, Litsea cubeba, or their mixture and the control within 10 min. The predation deterrent was evaluated by observing the predation of caged spiders supplied with 20 nymphs or adults of Nephotettix cincticeps pre-treated with essential oils in 24 h. Results revealed that P. nigrum and L. cubeba oil had no significant influence on the orientation of the predator in all tested concentrations. However, the mixture of P. nigrum and L. cubeba triggered significant attraction to P. pseudoannulata at 100 and 1000 ppm. Significant reduction of predation was observed with increasing concentration of the mixture and P. nigrum alone. The predation rate in the L. cubeba assay was not significantly different among the tested concentrations. In all cases, predation was higher on nymphs than on adult stages. We did not observe any interaction effect between the life stages and concentrations. To our knowledge, this is the first study discussing the potential influence of plant essential oils on orientation and predation of P. pseudoannulata. Based on these results, some essential oils and their combinations may influence the orientation of P. pseudoannulata and might affect its predation capacity. Further field studies are needed, but these findings suggest caution regarding the selection and application of plant extracts used for biological control in rice fields.

Wound healing evaluation of self-nanoemulsifying drug delivery system containing Piper cubeba essential oil.

The objective of this work was to characterize and evaluate wound healing potential of Piper cubeba oil (PO) via self-nanoemulsifying drug delivery system (SNEDDS) in comparison with standard gentamycin. PO loaded SNEDDS was prepared by low energy emulsification technique and characterized for thermodynamic stability, self-emulsification power and various physico-chemical parameters. An optimal formula of PO SNEDDS was subjected to wound healing evaluation, collagen determination and histomorphological examination in female Wistar rats as compared with pure PO and standard antibiotic/gentamycin. An optimal formula of PO SNEDDS showed significant wound healing effects in Wistar female rats in comparison with pure PO. However, wound healing effects of optimized SNEDDS were comparable with standard gentamycin. An optimized formulation also indicated significant enhancement in collagen content (0.82mg/g) in comparison with pure PO (0.53mg/g) and negative control (0.33mg/g). While, the collagen content of SNEDDS (0.82mg/g) treated rats were comparable with standard gentamycin treated animals (0.98mg/g). Histopathological examinations of optimized SNEDDS treated animals showed no signs of inflammatory cells which indicated that prepared SNEDDS was safe and nontoxic to rats. The results obtained in this work showed the potential application of SNEDDS in enhancement of the wound healing activity of PO upon oral administration.

Effect of high temperature with Litsea cubeba Pers. to control mold growth on bamboo food packaging and its possible modes of action

This study examined the effect of high temperature and Litsea cubeba oil with its main components against molds (Aspergillus niger, Aspergillus flavus, Penicillium sp., Penicillium cyclopium, Rhizopus sp., Fusarium sp., and Cladosporium sp.) on bamboo food packaging. Response surface methodology (RSM) with X1 (concentration of L. cubeba oil at 100, 300, and 500 mg g-1), X2 (temperature at 60, 80, and 100 °C), and X3 (time at 12, 14, and 16 h) was used to find the inhibitory periods of natural mold on packaging plates. The physical properties and the change of chemical components on the bamboo packaging plate before and after temperature treatment were determined to find the mode of action using gas chromatography–mass spectrometry (GC-MS). High temperature (at 100 °C) was a good inhibitor of all mold growth with the MIC (minimum inhibitory concentration) of 300 mg g-1; without heat treatment, no MIC was found. In addition, it was found that by using 300 mg g-1 of L. cubeba oil at 100 °C with an exposure time of 12 h, spore germination on the bamboo surfaces was completely inhibited for at least 290 days. After using high temperature, citral was detected on the surface of the packaging plates. Therefore, these components could be the key factors for inhibiting molds.

Repellent activity screening of 12 essential oils against Aedes albopictus Skuse: Repellent liquid preparation of Mentha arvensis and Litsea cubeba oils and bioassay on hand skin

The repellent activities of 12 selected essential oils against Aedes albopictus were evaluated using a Y-tube olfactometer. Mentha arvensis oil showed the best repellent activity among the selected oils, with 91.66% percentage repellency at 20 min, followed by Litsea cubeba oil (73.94%) and Laurus nobilis oil (67.12%). The repellent activities of nine designed and prepared repellent liquid formulas were tested against Ae. albopictus using the arm-in-cage method. The optimal formula of the repellent liquid was defined as “10% Litsea cubeba oil + 10% Mentha arvensis oil + 5% Tween 80 + 5% vanillin +70% absolute ethyl alcohol.” The effective hand skin protection time of this liquid formula is 4 h, indicating its potential product development value. L. cubeba and M. arvensis oils can be used as green repellents for mosquito control because of their low toxicity and environmental friendliness.

Physical, antibacterial and antioxidant properties of chitosan films containing hardleaf oatchestnut starch and Litsea cubeba oil

More and more attention was attached to food safety, it is necessary to endow food packaging films with good antibacterial and antioxidant properties Edible films based on chitosan (CH), hardleaf oatchestnut starch (HOS) and Litsea cubeba oil (LEO) were prepared by solution casting. The properties and structures of the blend film with different proportion (xCH/yHOS) were evaluated. The CH-HOS films were firstly prepared by blending CH solution with HOS paste. The tensile strength (TS) and DPPH radical scavenging ability of CH-HOS films increased from 27.33 MPa to 33.54 MPa and 20.67% to 52.34%, respectively, and water vapor permeability (WVP) decreased from 1.531 × 10−11 g m−1 pa−1 s−1 to 1.491 × 10−11 g m−1 pa−1 s−1, with the HOS content increased from the ratio of 1:0 to 1:1. Then, the LEO was added to 1CH-1HOS films. Tensile strength (TS), water vapor permeability, moisture absorption and total soluble matter (TSM) of the 1CH-1HOS film were remarkably decreased with 16%LEO. Meanwhile, the static contact angle and antimicrobial activity of 1CH-1HOS-16LEO film increased significantly. Hence, this blend film system has great potential for food packaging in the future.

Chemical Composition and Acaricidal Activities of Essential Oils of Litsea cubeba Fruits and Mentha arvensis Leaves Against House Dust and Stored Food Mites

This study assessed the acaricidal activities of the essential oils of Litsea cubeba fruits and Mentha arvensis leaves against house dust mites, Dermatophagoides farinae and D. pteronyssinus, and stored food mite, Tyrophagus putrescentiae. The essential oil of L. cubeba fruits consisted mainly of citral (64.43%) and limonene (10.54%). In the essential oil of M. arvensis leaves, the main compounds were menthol (59.75%) and (-)-menthone (20.04%). The acaricidal activities of L. cubeba and M. arvensis oils against three types of mites were determined by a fumigant bioassay. The LD50 values of L. cubeba oil were respectively 1.54, 1.83 and 3.90 μg/cm2 and were circa 6.39, 5.01 and 3.08-fold more effective than benzyl benzoate (9.84, 9.16 and 12.01 μg/cm2) against D. farinae, D. pteronyssinus and T. putrescentiae. The LD50 values of M. arvensis oil were respectively 1.46, 1.83 and 3.41 μg/cm2 and were about 6.74, 5.01 and 3.52-fold more active than benzyl benzoate against D. farinae, D. pteronyssinus and T. putrescentiae, respectively. These results suggest that L. cubeba and M. arvensis oils may be valuable as eco-friendly acaricides for mites.

Adverse Phototoxic Effect of Essential Plant Oils on NIH 3T3 Cell Line after UV Light Exposure.

Natural or artificial substances have become an inseparable part of our lives. It is questionable whether adequate testing has been performed in order to ensure these substances do not pose a serious health risk. The principal aim of our research was to clarify the potential risk of adding essential oils to food, beverages and cosmetic products. The toxicity of substances frequently employed in cosmetics, aromatherapy and food industry (bergamot oil, Litsea cubeba oil, orange oil, citral) were investigated using cell line NIH3T3 (mouse fibroblasts) with/without UV irradiation. The MTT assay was used to estimate the cell viability. Reactive oxygen species (ROS) which are products of a number of natural cellular processes such as oxygen metabolism and inflammation were measured to determine the extent of cellular stress. DNA damage caused by strand breaks was examined by comet assay. MTT test determined EC50 values for all tested substances, varying from 0.0023% v/v for bergamot oil to 0.018% v/v for citral. ROS production measurement showed that UV radiation induces oxidative stress to the cell resulting in higher ROS production compared to the control and non-irradiated samples. Comet assay revealed that both groups (UV, without UV) exert irreversible DNA damage resulting in a cell death. Our findings suggest that even low concentrations (lower than 0.0464% v/v) of orange oil can be considered as phototoxic (PIF value 8.2) and probably phototoxic for bergamot oil (PIF value 4.6). We also found significant changes in the cell viability, the ROS production and the DNA after the cells were exposed to the tested chemicals. Even though these substances are widely used as antioxidants it should be noted that they present a risk factor and their use in cosmetic and food products should be minimized.

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.

Study on Extraction Process of Technics of Litsea Cubeba Oil

Litsea cubeba fruit as raw material in this experiment, the use of ultrasonic-assisted method of litsea cubeba oil extraction process are discussed. The effects of several ultrasonic processing parameters, such as ratio of liquid to solid, extraction temperature, ultrasonic power and extraction time on the extraction of litsea cubeba oil were investigated assisted by ultrasonic wave. And the L9 (34) orthogonal test was used to research this four factors, the result from the visual analysis indicated that the optimal extraction process was gotten when ratio of liquid to solid was 14:1 , ultrasonic time was 50min, ultrasonic power is 320W, ultrasonic temperature is 60 °C.Those experimental results showed that ultrasonic-assisted extraction of the Litsea cubeba oil is practicable, and this method is simple and efficient. With the preliminary investigation of the ultrasonic-assisted extraction of Litsea Cubeba oil, the oil yield reached up to 41.35%, this value is the highest of all the oil yields from the current oil extraction methods, and it is worthy of further exploration .

Growth inhibition and morphological alterations of Fusarium verticillioides by cinnamon oil and cinnamaldehyde

Fusarium verticillioides is a filamentous fungus and a widely distributed pathogen having the ability to infect and cause destruction in economically important crops and grains by producing fumonisin mycotoxins. In the present study, the inhibitory effect of cinnamon, citral, Litsea cubeba oil, clove, eucalyptus, anise, spearmint and camphor oils on F. verticillioides was investigated, and cinnamon oil proves to be the most effective in inhibition. The antifungal effect of cinnamon oil was studied with special reference to its mechanism of inhibition of F. verticillioides growth at the morphological and ultrastructural levels. For F. verticillioides, the minimal inhibitory concentrations (MICs) of cinnamon oil (85% cinnamaldehyde), natural cinnamaldehyde (95%), and synthetic cinnamaldehyde (99%) were 60, 50, and 45 μL/L, respectively. The antifungal activity of cinnamon oil was proportional to its cinnamaldehyde concentration. Scanning electron microscopy and transmission electron microscopy of F. verticillioides exposed to MIC of cinnamaldehyde showed irreversible deleterious morphological and ultrastructural alterations, such as lack of cytoplasmic contents, loss of integrity and rigidity of the cell wall, plasma membrane disruption, mitochondrial destruction, folding of the cell. These modifications induced by cinnamaldehyde may be due to its interference with enzymatic reactions of cell wall synthesis, thus affecting the morphogenesis and growth of the fungus. These results further emphasized the toxicity of cinnamon oil against F. verticillioides attacking grains, and that cinnamon oil could be safely used as an alternative to chemical fungicides during grain storage and in the field.

Fumigant, Contact, and Repellent Activities of Essential Oils Against the Darkling Beetle,Alphitobius diaperinus

The fumigant, contact, and repellent activities of four essential oils extracted from Citrus limonum (Sapindales: Rutaceae), Litsea cubeba (Laurales: Lauraceae), Cinnamomum cassia, and Allium sativum L. (Asparagales: Alliaceae) against 6th instars and adults of the darkling beetle, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), one of the main pests of materials and products of Juncus effuses L. (Poales: Juncaceae) during the storage period, were assayed, and chemical ingredients were analyzed with gas chromatography-mass spectrometry in this study. While the major ingredients found in C. limonum and C. cassia were limonene and (E)-cinnamaldehyde, the main constituents of L. cubea were D-limonene, (E)-3,7-dimethyl-,2,6-octadienal, (Z)-3,7-dimethyl,2 ,6-octadienal, and diallyl disulphide (18.20%), while the main constituents of and A. sativum were di-2-propenyl trisulfide and di-2-propenyl tetrasulfide. The fumigation activities of A. sativum and C. limonum on A. diaperinus adults were better than those of the other two essential oilss. The toxicities of A. sativum and C. limonum were almost equitoxic at 96 hr after treatment. Essential oils from Allium sativum and L. cubeba also showed good contact activities from 24 hr to 48 hr, and toxicities were almost equitoxic 48 hr posttreatment. The repellent activities of A. sativum and L. cubeba oils on 6th instars were also observed, showing repellence indexes of 90.4% and 88.9% at 12 hr after treatment, respectively. The effects of A. sativum on AChE activity of 6th instars of A. diaperinus were strongest compared to the other essential oils, followed by C. limonum, L. cubeba, and C. cassia. These results suggest that the essential oils of C. limonum and A. sativum could serve as effective control agents of A. diaperinus.

Degradation of fumonisin B1 by cinnamon essential oil

Fumonisins are group of mycotoxins produced mainly by Fusarium verticillioides and Fusarium proliferatum. They frequently contaminate corn and corn based products, and cause several diseases in humans and animals. Fumonisin B1 (FB1) is the most prevalent fumonisin and is highly toxic to human and animal. The essential oils from plants offer a hope in the prevention and detoxification of these mycotoxins. The present study investigates the degradation effect of cinnamon, citral, Litsea cubeba, clove, eucalyptus, anise, spearmint and camphor oils on FB1. The degradation level of FB1 was determined by ELISA. Cinnamon oil proves to be effective essential oil in reducing FB1, followed by citral, eugenol oil, eucalyptus oil, anise oil and camphor oil. The effects of incubation time, and temperature with respect to the concentration of cinnamon oil on their degradation effect on FB1 by cinnamon oil were investigated. Results showed that at 120 h time with the 280 μg/ml concentration of cinnamon oil, under 30 °C is optimal for FB1 reduction. Under optimal condition, FB1 was reduced from 15.03 to 0.89 μg/ml (94.06%). Cinnamon oil could be a promising candidate in the detoxification and control of FB1 in corn based products.

Determination of Seven Active Ingredients in Three Plant Essential Oils by Using Micellar Electrokinetic Chromatography

A simple micellar electrokinetic chromatography (MEKC) method was developed for determination of citronellal, citral (Z; E), α-pinene, limonene, linalool, and eugenol in plant essential oils (EOs). A buffer consisting of 20 mM Na2B4O7, 50 mM SDS, 20% (v:v) methanol adjusted to pH 9.5 was found to provide a very efficient and stable electrophoretic system for the analysis. The validation of the method included linearity, LODs, LOQs, precision (intra - and inter - day variation of migration time and peak area), and recovery. Seven terpenoids presented good linearity (R 2 > 0.9960) within the test ranges; LODs (S/N = 3) and LOQs (S/N = 10) were 0.2–1.8 µg/mL and 0.8–5.9 µg/mL, respectively. The precision and accuracy were satisfactory, with the overall intra- and inter-day variation (for migration time and peak area, RSD%) being less than 7.0%, and recoveries of this method were greater than 91% at spiked levels. The proposed method was successfully applied to the determination of seven terpenoids in clove oil, litsea cubeba oil, and citronella oil, respectively.

Neuropharmacological activities of fruit essential oil from Litsea cubeba Persoon

Litsea cubeba (Lauraceae) is woody plant endemic to Taiwan that is traditionally used as a spice. In the current study, several behavioral analyses were performed to evaluate the neuropharmacological activity of the essential fruit oil of L. cubeba in ICR mice. Oral administration of 100, 300 and 500 mg/kg of L. cubeba fruit oil significantly prolonged pentobarbitone-induced mouse sleeping time by 20.0, 110.8, and 159.6 %, respectively. In addition, after administration of L. cubeba oil, mice significantly increased the time spent in the open arms and number of entries into the open arms of an elevated plus maze compared to saline-treated mice suggesting that L. cubeba oil has anxiolytic activity. A tail-flick test conducted after treatment of mice with 500 mg/kg L. cubeba fruit oil also suggested that this oil has potent analgetic activity. According to GC/MS analyses, the essential fruit oil of L. cubeba oil consists of 23 compounds. The main components are geranial (37.16 %), neral (28.29 %), and d-limonene (22.90 %). We conclude that L. cubeba oil has a potent effect on the central nervous system of mice.

Insecticidal and feeding deterrent activities of essential oils in the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae)

AbstractTen essential oils were tested against the cabbage looper, Trichoplusia ni larvae for contact, residual and fumigant toxicities and feeding deterrent effects. Against third instar T. ni, Syzygium aromaticum (LD50 = 47.8 μg/larva), Thymus vulgaris (LD50 = 52.0 μg/larva) (the two positive controls) and Cinnamomum glanduliferum (LD50 = 76.0 μg/larva) were the most toxic via topical application. Litsea pungens (LD50 = 87.1 μg/larva), Ilex purpurea (LD50 = 94.0 μg/larva), Cinnamomum cassia (LD50 = 101.5 μg/larva) and Litsea cubeba (LD50 = 112.4 μg/larva) oils were equitoxic. Thymus vulgaris (LC50 = 4.8 mg/ml) and S. aromaticum (LC50 = 6.0 mg/ml) oils were the most toxic in residual bioassays. Cymbopogon citratus (LC50 = 7.7 mg/ml) and C. cassia (LC50 = 8.5 mg/ml) oils were equitoxic followed by Cymbopogon nardus (LC50 = 10.1 mg/ml) in this bioassay. The remaining five oils showed little or no residual effects. In a fumigation bioassay, L. cubeba (LC50 = 16.5 μl/l) and I. purpurea (LC50 = 22.2 μl/l) oils were the most toxic. Cinnamomum glanduliferum (LC50 = 29.7 μl/l) and Sabina vulgaris (LC50 = 31.2 μl/l) oils were equitoxic. Interestingly, S. aromaticum did not exhibit any fumigant toxicity. Cymbopogon citratus, C. nardus and C. cassia strongly deterred feeding by third instar T. ni (DC50s = 26.9, 33.8 and 39.6 μg/cm2, respectively) in a leaf disc choice bioassay. The different responses of T. ni larvae to the oils in different bioassays suggest that these essential oils exhibit different modes of action. Based on their comparable efficacy with essential oils already used as active ingredients in many commercial insecticides (i.e. clove oil and thyme oil), some of these essential oils may have potential as botanical insecticides against T. ni.

Investigation of the dermal sensitization potential of various essential oils in the local lymph node assay

Essential oils are commonly used fragrance ingredients. The oils themselves are complex mixtures, which may contain naturally occurring contact sensitizers. The local lymph node assay was used to evaluate the dermal sensitization potential of basil, citronella, clove leaf, geranium, litsea cubeba, lemongrass, and palmarosa oils. Three of the major components—citral, eugenol, and geraniol—were included to investigate any difference in sensitization potential arising from their exposure in a mixture. Each fragrance material was tested at five concentration ranging from 2.5% to 50% w/v in 1:3 ethanol:diethyl phthalate. The stimulation index (SI) values were calculated for each dose level, an SI ⩾ 3 was considered a positive response. The estimated concentration (EC3) required to elicit a positive was calculated and taken as a measure of relative potency. The EC3 values and potency classification for basil, clove leaf, litsea cubeba, lemongrass and palmarosa oils were calculated to be <2.5% (⩾moderate), 7.1% (weak), 8.4% (weak), 6.5% (weak) and 9.6% (weak), respectively. Citronella and geranium oils were negative. The individual components citral, eugenol and geraniol resulted in EC3 values of 6.3%, 5.4% and 11.4%, respectively. In general, the potency of each essential oil did not differ significantly from that observed for its main individual component.