My family recently became transport vehicles for an unwanted microbe family this holiday season. One of the wellness tools that was used to send these little invaders out of our residence was a combination blend of different species of eucalyptus oils. I’ve written on eucalyptus oil recently and even highlighted Eucalyptus globulus in the past. However, with the recent wintery season upon us, I thought I’d look into some more of eucalyptus oils’ qualities.
(As usual, the full abstracts are made available for your information and due to FDA regulations.)
The Many Faces of Eucalyptus Oil
According to an introduction in a 2012 study in BMC Complementary and Alternative Medicine, there are approximately 900 species of Eucalyptus with about 300 species containing essential oil components in their leaves. 20 of these species have been reported to contain high amounts of 1, 8-cineole. (1)
This means that there are many species and chemotypes of eucalyptus oil, each with different proportions of constituents present. Furthermore, variations in extraction methods yield different ratios and presence of these specific compounds within each species. For example, this abstract below compared 13 species of the genus Eucalyptus and reported the identification of 142 components via analysis by GC (RI) and GC/MS . “The main compenents were 1,8-cineole (1), followed by cryptone, spathulenol (4), p-cymene (2), viridiflorol (6), globulol (7), beta-eudesmol, alpha-terpineol (5), limonene (8), D-piperitone, alpha-pinene (3), cuminal, and gamma-eudesmol.” (2)
Hydrodistillation of the dried leaves of 13 species of the genus Eucalyptus L’ Hér., viz., E. bicostata Maiden, Blakely & Simmonds, E. cinerea F. Muell. ex Benth., E. exerta F. Muell., E. gigantea Hook. f., E. gunnii Hook. f., E. macarthurii Deane & Maiden., E. macrorrhyncha F. Muell., E. maidenii F. Muell., E. odorata Behr., E. pauciflora Sieber ex Sprengel, E. sideroxylon A. Cunn. ex Woolls, E. tereticornis Sm., and E. viminalis Labill., harvested from Souinet arboreta (region of Ain Draaham, north of Tunisia) in June 2006, afforded essential oils in yields varying from 0.5+/-0.2 to 3.9+/-0.4%, dependent on the species. E. cinerea and E. exerta provided the highest and the lowest percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 142 components, representing 81.5 to 98.9% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8-cineole (1), followed by cryptone, spathulenol (4), p-cymene (2), viridiflorol (6), globulol (7), beta-eudesmol, alpha-terpineol (5), limonene (8), D-piperitone, alpha-pinene (3), cuminal, and gamma-eudesmol. The principal component and the hierarchical cluster analyses separated the 13 Eucalyptus leaf essential oils into three groups, each constituting a chemotype.(2)
Whereas this comparison of 11 eucalyptus oil species reported, “The main components were 1,8-cineole, followed by trans-pinocarveol (1), spathulenol (2), alpha-pinene, p-cymene, (E,E)-farnesol, cryptone, globulol (3), beta-phellandrene, alpha-terpineol, viridiflorol, and alpha-eudesmol.” (3)
Hydrodistillation of the dried leaves of eleven species of the genus Eucalyptus L’Hér., i.e., E. astringens Maiden, E. camaldulensis Dehnh., E. diversifolia Bonpl., E. falcata Turcz., E. ficifolia F. Muell., E. gomphocephala DC., E. lehmannii (Schauer) Benth., E. maculata Hook., E. platypus Hook., E. polyanthemos Schauer, and E. rudis Endl., harvested from Korbous arboreta (region of Nabeul, northeast of Tunisia) in April 2006, afforded essential oils in yields varying from 0.1+/-0.1 to 3.8+/-0.1%, dependent on the species. E. astringens and E. ficifolia showed the highest and the lowest mean percentage of essential oil amongst all the species examined, respectively. Analysis by GC (RI) and GC/MS allowed the identification of 138 components, representing 74.0 to 99.1% of the total oil. The contents of the different samples varied according to the species. The main components were 1,8-cineole, followed by trans-pinocarveol (1), spathulenol (2), alpha-pinene, p-cymene, (E,E)-farnesol, cryptone, globulol (3), beta-phellandrene, alpha-terpineol, viridiflorol, and alpha-eudesmol. The principal-component and the hierarchical-cluster analyses separated the eleven Eucalyptus leaf essential oils into seven groups, each constituting a chemotype.(3)
Another example of how constituent percentages vary in eucalyptus oils is based on the timing of distillation and growth stage of the plant:
The leaf-essential oil from Eucalyptus robusta and E. saligna, the latter in two phenologic stages, were analysed by gas chromatography coupled to mass spectrometry (GC-MS). The major constituent in E. robusta oil was the monoterpene alpha-pinene (73.0% of the total amount). The oil composition of the E. saligna was dependent of the phenologic stage. In the vegetative phase, the major constituents were p-cymene (54.2%) and gamma-terpinene (43.8%), while during the blossoming alpha-pinene became the major constituent followed by p-cymene (22.5%). Additionally, the antimicrobial activity for all three oils was evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. The E. robusta oil presented the highest growth inhibition for all the microorganisms tested. (4)
Therefore, similar to frankincense, the application and therapeutic use of various eucalyptus oils will be determined by the particular species, its chemotype (variations in the presence of plant secondary metabolites), and a company’s distillation processes (to what they deem the most therapeutic constituents). That is why, beyond assuring if a company uses GC/MS analysis of constituents present and/or uses European standardizations, you will want to verify what other types of testing they use for purity and assessment of quality. For example, Young Living has many different chemotypes and species available of eucalyptus which all exhibit different properties and can create synergism when combined in a blend.
For this blog, I’ll be focusing on various forms of eucalyptus and some of my favorite findings in the literature on the benefits of eucalyptus oil.
9 Reasons To Love Eucalyptus Oil
Studies On Eucalyptus Oil’s Inhibiting Unwanted Critters In Our Environment
This abstract reported on various eucalyptus species’ ability to kill adult and larva forms of the yellow fever mosquito. The authors verified chemical composition of the oils after distillation and believed that 1,8-cineole and p-cymene were the constituents mainly responsible to kill these critters based on their previous work. They study’s aim was to verify a biological model which predicated the kill rate of this oil based on constituents present.
The aim of this work is to validate the pre-existing models that relate the larvicidal and adulticidal activities of the Eucalyptus essential oils on Aedes aegypti. Previous works at our laboratory described that the larvicidal activity of Eucalyptus essential oils can be estimated from the relative concentration of two main components (p-cymene and 1,8-cineole) and that the adulticidal effectiveness can be explained, to a great extent, by the presence of large amounts of the component 1,8-cineole in it. In general, the results show that the higher adulticidal effect of essential oils the lower their larvicidal activity. Fresh leaves was harvested and distilled. Once the essential oil was obtained, the chemical composition was analysed, evaluating the biological activity of 15 species of the genus Eucalyptus (Eucalyptus badjensis Beuzev and Welch, Eucalyptus badjensis × nitens, Eucalyptus benthamii var Benthamii Maiden and Cambage, Eucalyptus benthamii var dorrigoensis Maiden and Cambage, Eucalyptus botryoides Smith, Eucalyptus dalrympleana Maiden, Eucalyptus fastigata Deane and Maiden, Eucalyptus nobilis L.A.S. Johnson and K.D.Hill, Eucalyptus polybractea R. Baker, Eucalyptus radiata ssp radiata Sieber ex Spreng, Eucalyptus resinifera Smith, Eucalyptus robertsonii Blakely, Eucalyptus robusta Smith, Eucalyptus rubida Deane and Maiden, Eucalyptus smithii R. Baker). Essential oils of these plant species were used for the validation of equations from preexistent models, in which observed and estimated values of the biological activity were compared. The regression analysis showed a strong validation of the models, re-stating the trends previously observed. The models were expressed as follows: A, fumigant activity [KT(50(min)) = 10.65-0.076 × 1,8-cineole (%)](p < 0.01; F, 397; R (2), 0.79); B, larval mortality (%)((40 ppm)) = 103.85 + 0.482 × p-cymene (%) – 0.363 × ?-pinene (%) – 1.07 × 1,8-cineole (%) (p < 0.01; F, 300; R (2), 0.90). These results confirmed the importance of the mayor components in the biological activity of Eucalyptus essential oils on A. aegypti. However, it is worth mentioning that two or three species differ in the data estimated by the models, and these biological activity results coincide with the presence of minor differential components in the essential oils. According to what was previously mentioned, it can be inferred that the model is able to estimate very closely the biological activity of essential oils of Eucalyptus on A. aegypti.(5)
Seems like the power of eucalyptus oil may be a good thing to consider if you have some unwanted houseflies. At least, this is what this in vitro study suggested. It showed that Eucalyptus polybractea had the highest killing affect. Correlation was found between the content of 1,8-cineole and toxic effect on the flies:
Oils extracted from various species of Eucalyptus (Eucalyptus badjensis Beuzev & Welch, Eucalyptus badjensis x Eucalyptus nitens, Eucalyptus benthamii variety dorrigoensis Maiden & Cambage, Eucalyptus botryoides Smith, Eucalyptus dalrympleana Maiden, Eucalyptus fastigata Deane & Maiden, Eucalyptus nobilis L.A.S. Johnson & K. D. Hill, Eucalyptus polybractea R. Baker, Eucalyptus radiata ssp. radiata Sieber ex Spreng, Eucalyptus resinifera Smith, Eucalyptus robertsonii Blakely, Eucalyptus rubida Deane & Maiden, Eucalyptus smithii R. Baker, Eucalyptus elata Dehnh, Eucalyptus fraxinoides Deane & Maiden, E. obliqua L’Hér) were obtained by hydrodistillation. The chemical composition of essential oils was determined by gas chromatography coupled to mass spectrometry. Essential oils were mainly composed of 1,8-cineole, alpha-pinene, alpha-terpineol, 4-terpineol, and p-cymene. Vapors from these essential oils and their major components were found to be toxic to Haematobia irritans (L.) (Diptera: Muscidae) adults. An aliquot of each oil was placed in a cylindrical test chamber, and the number of knocked down flies was recorded as a function of time. Knockdown time 50% was then calculated. Results showed that essential oil of E. polybractea had the highest knockdown activity of 3.44 min. A correlation was observed between the content of 1,8-cineole in the Eucalyptus essential oils and the corresponding toxic effect.(6)
The use of fourteen GC/MS verified essential oils and various isolated monoterpenes constituents were tested for their ability to decrease a major type of allergen found in the home, dust mites. The studies placed the poor little mites on prepared cell cultures then sought to count their little dead bodies at the end of various time intervals. According to the study (abstract below), “Clove, matrecary, chenopodium, rosemary, eucalyptus and caraway oils were shown to have high activity.”
The acaricidal activities of fourteen essential oils and fourteen of their major monoterpenoids were tested against house dust mites Dermatophagoides pteronyssinus. Five concentrations were used over two different time intervals 24 and 48 h under laboratory conditions. In general, it was noticed that the acaricidal effect based on LC 50 of either essential oils or monoterpenoids against the mite was time dependant. The LC 50 values were decreased by increasing of exposure time. Clove, matrecary, chenopodium, rosemary, eucalyptus and caraway oils were shown to have high activity. As for the monoterpenoids, cinnamaldehyde and chlorothymol were found to be the most effective followed by citronellol. This study suggests the use of the essential oils and their major constituents as ecofriendly biodegradable agents for the control of house dust mite, D. pteronyssinus. (7)
(This may be why some of your report less sneezing with diffusing. It seems the little air born critters may get killed by oil droplet dispersion. This would be an additional benefit, besides reducing mold.)
This recent abstract was a review of some of eucalyptus oil’s mechanisms. When I was on my plane ride back from training in November, I got lost in it awhile cross-referencing its sources. The review included mostly in vitro and in vivo trials, but also some human studies. It showed that eucalyptus oil may not only kill the unwanted critters in our environment, but may also help balance our immune response in various ways:
Eucalyptus oil (EO) and its major component, 1,8-cineole, have antimicrobial effects against many bacteria, including Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus (MRSA), viruses, and fungi (including Candida). Surprisingly for an antimicrobial substance, there are also immune-stimulatory, anti-inflammatory, antioxidant, analgesic, and spasmolytic effects. Of the white blood cells, monocytes and macrophages are most affected, especially with increased phagocytic activity. Application by either vapor inhalation or oral route provides benefit for both purulent and non-purulent respiratory problems, such as bronchitis, asthma, and chronic obstructive pulmonary disease (COPD). There is a long history of folk usage with a good safety record. More recently, the biochemical details behind these effects have been clarified. Although other plant oils may be more microbiologically active, the safety of moderate doses of EO and its broad-spectrum antimicrobial action make it an attractive alternative to pharmaceuticals. EO has also been shown to offset the myelotoxicity of one chemotherapy agent. Whether this is a general attribute that does not decrease the benefit of chemotherapy remains to be determined. This article also provides instruction on how to assemble inexpensive devices for vapor inhalation. (8)
In the past, I discussed how essential oils could modulate our microbiome and have listed studies that demonstrated their ability to inhibit microbial growth. (They also provide polyphenols to feed our good bugs.) This may be good news due to the rise of resistance to antibiotics from overuse of them in our livestock, unnecessary prescribing, and other lifestyle and environmental factors. (9-11)
Below was a recent study on inhibiting multi-and extensively drug resistant tuberculosis (TB) using Eucalyptus citriodora. In this study, a 3-D analytic approach with multi-channel counter-current chromatography (CCC), GC/MS analysis, bioactivity measurements, and chemometric analysis was used to verify the complexity of the essential oil (EO) components and its activity on TB. 32 airborne “anti-TB-active” compounds were revealed. Citronellol, by itself and in a mixture with another monoterpene, and eucalyptol (1,8 cineole) showed inhibition of greater than 90% to the TB:
The rapid emergence of multi- and extensively drug-resistant tuberculosis (MDR/XDR-TB) has created a pressing public health problem, which mostly affects regions with HIV/AIDS prevalence and represents a new constraint in the already challenging disease management of tuberculosis (TB). The present work responds to the need to reduce the number of contagious MDR/XRD-TB patients, protect their immediate environment, and interrupt the rapid spread by laying the groundwork for an inhalation therapy based on anti-TB-active constituents of the essential oil (EO) of Eucalyptus citriodora. In order to address the metabolomic complexity of EO constituents and active principles in botanicals, this study applied biochemometrics, a 3-D analytical approach that involves high-resolution CCC fractionation, GC-MS analysis, bioactivity measurements, and chemometric analysis. Thus, 32 airborne anti-TB-active compounds were identified in E. citriodora EO: the monoterpenes citronellol (1), linalool (3), isopulegol (5), and ?-terpineol (7) and the sesquiterpenoids spathulenol (11), ?-eudesmol (23), and ?-cadinol (25). The impact of the interaction of multiple components in EOs was studied using various artificial mixtures (AMxs) of the active monoterpenes 1, 2, and 5 and the inactive eucalyptol (33). Both neat 1 and the AMx containing 1, 2, and 33 showed airborne TB inhibition of >90%, while the major E. citriodora EO component, 2, was only weakly active, at 18% inhibition. (12)
Another study on infectious bugs of the respiratory system was done with Eucalyptus globulus. The study tested cytotoxicity and antibacterial activity. It demonstrated that that the following bacteria were most susceptible: H. influenza, parinfluenzae, and S. maltophila followed by S. puneumonia against clinical specimens of patients with upper respiratory infections. Eucalyptus globulus also had a mild inhibitory activity against a strain of the mumps virus:
The activity of Eucalyptus globulus essential oil was determined for 120 isolates of Streptococcus pyogenes, 20 isolates of S. pneumoniae, 40 isolates of S. agalactiae, 20 isolates of Staphylococcus aureus, 40 isolates of Haemophilus influenzae, 30 isolates of H. parainfluenzae, 10 isolates of Klebsiella pneumoniae, 10 isolates of Stenotrophomonas maltophilia and two viruses, a strain of adenovirus and a strain of mumps virus, all obtained from clinical specimens of patients with respiratory tract infections. The cytotoxicity was evaluated on VERO cells by the MTT test. The antibacterial activity was evaluated by the Kirby Bauer paper method, minimum inhibitory concentration, and minimum bactericidal concentration. H. influenzae, parainfluenzae, and S. maltophilia were the most susceptible, followed by S. pneumoniae. The antiviral activity, assessed by means of virus yield experiments titered by the end-point dilution method for adenovirus, and by plaque reduction assay for mumps virus, disclosed only a mild activity on mumps virus.(13)
Another study to demonstrate that eucalyptus oil showed an inhibition of bacteria also showed that it had additional antioxidant properties in vitro:
The chemical composition of the essential oil from the leaves of Eucalyptus camaldulensis, Eucalyptus camaldulensis var. obtusa and Eucalyptus gomphocephala grown in northern Egypt was analysed by using GC-FID and GC-MS techniques. The antibacterial (agar disc diffusion and minimum inhibitory concentration methods) and antioxidant activities (2,2′-diphenypicrylhydrazyl) were examined. The main oils constituents were 1,8-cineole (21.75%), ?-pinene (20.51%) and methyleugenol (6.10%) in E. camaldulensis; spathulenol (37.46%), p-cymene (17.20%) and crypton (8.88%) in E. gomphocephala; spathulenol (18.37%), p-cymene (19.38%) and crypton (16.91%) in E. camaldulensis var. obtusa. The essential oils from the leaves of Eucalyptus spp. exhibited considerable antibacterial activity against Gram-positive and Gram-negative bacteria. The values of total antioxidant activity were 70 ± 3.13%, 50 ± 3.34% and 84 ± 4.64% for E. camaldulensis, E. camaldulensis var. obtusa and E. gomphocephala, respectively. The highest antioxidant activity value of 84 ± 4.64% could be attributed to the high amount of spathulenol (37.46%). (14)
Finally, eucalyptus oil also showed an in vitro inhibition against the HSV1 and HSV2 (herpes virus) prior to infection and when adhering to the cell:
The antiviral effect of Australian tea tree oil (TTO) and eucalyptus oil (EUO) against herpes simplex virus was examined. Cytotoxicity of TTO and EUO was evaluated in a standard neutral red dye uptake assay. Toxicity of TTO and EUO was moderate for RC-37 cells and approached 50% (TC50) at concentrations of 0.006% and 0.03%, respectively. Antiviral activity of TTO and EUO against herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) was tested in vitro on RC-37 cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of TTO for herpes simplex virus plaque formation was 0.0009% and 0.0008% and the IC50 of EUO was determined at 0.009% and 0.008% for HSV-1 and HSV-2, respectively. Australian tea tree oil exhibited high levels of virucidal activity against HSV-1 and HSV-2 in viral suspension tests. At noncytotoxic concentrations of TTO plaque formation was reduced by 98.2% and 93.0% for HSV-1 and HSV-2, respectively. Noncytotoxic concentrations of EUO reduced virus titers by 57.9% for HSV-1 and 75.4% for HSV-2. Virus titers were reduced significantly with TTO, whereas EUO exhibited distinct but less antiviral activity. In order to determine the mode of antiviral action of both essential oils, either cells were pretreated before viral infection or viruses were incubated with TTO or EUO before infection, during adsorption or after penetration into the host cells. Plaque formation was clearly reduced, when herpes simplex virus was pretreated with the essential oils prior to adsorption. These results indicate that TTO and EUO affect the virus before or during adsorption, but not after penetration into the host cell. Thus TTO and EUO are capable to exert a direct antiviral effect on HSV. Although the active antiherpes components of Australian tea tree and eucalyptus oil are not yet known, their possible application as antiviral agents in recurrent herpes infection is promising.(15)
The ability of Eucalyptus globulus to inhibit 14 food spoilage microorganisms was studied. It showed various inhibitory concentrations, with the highest being in the vapor phase. (Anyone want some eucalyptus-spiced salmon?):
The antimicrobial activity of Eucalyptus globulus essential oil was evaluated against 14 food spoilage microorganisms in liquid and vapour phase using agar dilution/well diffusion method and disc volatilisation method, respectively. The minimum inhibitory concentration (MIC) varied from 2.25 to 9 mg/ml for bacterial and fungal strains, and from 1.13 to 2.25 mg/ml for yeast strains. Significantly higher antimicrobial activity was observed in the vapour phase. The chemical composition of E. globulus in liquid as well as in the vapour phase was determined by gas chromatography (GC), gas chromatography/mass spectrometry (GC-MS) and solid phase micro extraction-gas chromatography mass spectrometry (SPME GC-MS), respectively. The dominant compounds in E. globulus oil were 1,8-cineole (45.4%), limonene (17.8%), p-cymene (9.5%), ?-terpinene (8.8%), ?-pinene (4.2%) and ?-terpineol (3.4%), while in the vapour, 1,8-cineole (34.6%), limonene (29.9%), p-cymene (10.5%), ?-terpinene (7.4%), ?-pinene (4.0%) and ?-phellandrene (2.4%) were identified. (16)
A study using Eucalyptus species, clove, and 15 formulations of various concentrations of these oils alone was tested against the head louse as a contact fumigant and in a human hair wig. It was determined that eucalyptus applied in an 8% spray was effective protection:
The control efficacy of clove, Eugenia caryophyllata, and eucalyptus, Eucalyptus globulus, essential oils and 15 formulations containing these essential oils alone (8, 12, and 15% sprays) and their binary mixtures (7:3, 5:5, and 3:7 by weight) against adult females of insecticide-susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of head louse, Pediculus humanus capitis (De Geer), was examined by using contact plus fumigant and human hair wig (placed over the head of mannequin) mortality bioassays. In contact plus fumigant mortality bioassay, essential oils from eucalyptus (0.225 mg/cm2) and clove (1.149 mg/cm2) were less effective than either d-phenothrin (0.0029 mg/cm2) or pyrethrum (0.0025 mg/cm2) based on 6-h median lethal concentration values. However, the efficacies of eucalyptus and clove oils were almost identical against females fromn both strains, despite high levels of resistance of the BR-HL females to d-phenothrin (resistance ratio, 667) and pyrethrum (resistance ratio, 754). In human hair wig mortality bioassay, eucalyptus oil spray treatment gave better control efficacy than either spray treatment with clove oil alone or their binary mixtures. Thus, eucalyptus applied as 8% sprays (15 or 20 ml) appears to provide effective protection against pediculosis even to insecticide-resistant head louse populations. Once the safety issues resolved, covering the treated hair and scalp with bath shower cap or hat would ensure the fumigant action of the essential oil. (17)
The following study demonstrated Eucalyptus oil to modulate innate immune response in human monocyte derived macrophages and rate peripheral blood monocyte/granulocytes (immune cells).
(Note: the specifications on the purity of the oil weren’t reported in the study which could skew results.)
Background: Besides few data concerning the antiseptic properties against a range of microbial agents and the anti-inflammatory potential both in vitro and in vivo, little is known about the influence of Eucalyptus oil (EO) extract on the monocytic/macrophagic system, one of the primary cellular effectors of the immune response against pathogen attacks. The activities of this natural extract have mainly been recognized through clinical experience, but there have been relatively little scientific studies on its biological actions. Here we investigated whether EO extract is able to affect the phagocytic ability of human monocyte derived macrophages (MDMs) in vitro and of rat peripheral blood monocytes/granulocytes in vivo in absence or in presence of immuno-suppression induced by the chemotherapeutic agent 5-fluorouracil (5-FU).
Methods: Morphological activation of human MDMs was analysed by scanning electron microscopy. Phagocytic activity was tested: i) in vitro in EO treated and untreated MDMs, by confocal microscopy after fluorescent beads administration; ii) in vivo in monocytes/granulocytes from peripheral blood of immuno-competent or 5-FU immuno-suppressed rats, after EO oral administration, by flow cytometry using fluorescein-labelled E. coli. Cytokine release by MDMs was determined using the BD Cytometric Bead Array human Th1/Th2 cytokine kit.
Results: EO is able to induce activation of MDMs, dramatically stimulating their phagocytic response. EO-stimulated internalization is coupled to low release of pro-inflammatory cytokines and requires integrity of the microtubule network, suggesting that EO may act by means of complement receptor-mediated phagocytosis. Implementation of innate cell-mediated immune response was also observed in vivo after EO administration, mainly involving the peripheral blood monocytes/granulocytes. The 5-FU/EO combined treatment inhibited the 5-FU induced myelotoxicity and raised the phagocytic activity of the granulocytic/monocytic system, significantly decreased by the chemotherapic.
Conclusion: Our data, demonstrating that Eucalyptus oil extract is able to implement the innate cell-mediated immune response, provide scientific support for an additional use of this plant extract, besides those concerning its antiseptic and anti-inflammatory properties and stimulate further investigations also using single components of this essential oil. This might drive development of a possible new family of immuno-regulatory agents, useful as adjuvant in immuno-suppressive pathologies, in infectious disease and after tumour chemotherapy. (18)
1,8 cineole is a monoterpene oxide, known as eucalyptol, and is one of the most studied components in all eucalyptus oils. Below are some articles on its effect on wellness.
An in vitro study showed that 1,8 cineole, along with another monoterpene, alpha-pinene, was able to modulate oxidative stress by various means. This included raising glutathione production, a major antioxidant in the body used for detoxifying waste products and toxins:
Abstract Context: Salvia lavandulifolia has been employed in folk medicine for the treatment of memory and dementia problems. This specie contains numerous bioactive terpenes which may contribute to its effectiveness. Objective: To analyze the composition of essential oil of S. lavandulifolia and to investigate the potential in vitro cytoprotective and antioxidant activities of its major compounds, ?-pinene and 1,8-cineole, against H2O2-induced oxidative stress in the U373-MG cell line. Materials and methods: Chemical composition was analyzed by gas chromatography; antioxidant capacity was measured using the ORAC assay, and cytoprotective activity was evaluated using the MTT assay (for cell viability) (range of concentrations: 10-400??M), DCFH-DA assay (for intracellular ROS generation), thiobarbituric acid reactive substances (TBARS) method (for lipid peroxidation), and spectrofometric techniques and Western blot (for enzymatic activity and protein expression, respectively) at 10 and 25?µM. Results: ?-Pinene (18.39%) and 1,8-cineole (19.57%) were identified as major compounds in S. lavandulifolia essential oil. Pretreatments with these monoterpenes protected U373-MG cells against H2O2-induced oxidative injury by attenuating the loss of cell viability (IC50 : 79.70?µM to ?-pinene and 66.23?µM to 1,8-cineole) and cell morphology, inhibiting ROS production (the most active compound was 1,8-cineole by decreasing the ROS production over 30-45% at 10 and 25??M) and lipid peroxidation and increasing the endogenous antioxidant status (glutathione levels and CAT, SOD, GR, GPx, and HO-1 activity and protein expression). Conclusions: These findings demonstrate for the first time the effects of the monoterpenes 1,8-cineole and ?-pinene identified in S. lavandulifolia essential oil as regulators of cellular redox balance in astrocytes. (19)
This recent abstract reported on its potential use in those with respiratory issues by inhibiting inflammation and also due to its antioxidant properties:
1,8-cineole is a natural monoterpene, also known as eucalyptol. It is a major compound of many plant essential oils, mainly extracted from Eucalyptus globulus oil. As an isolated compound, 1,8-cineole is known for its mucolytic and spasmolytic action on the respiratory tract, with proven clinical efficacy. 1,8-cineole has also shown therapeutic benefits in inflammatory airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). This clinical evidence refers to its anti-inflammatory and anti-oxidant mode of action, which has been proven in numerous pre-clinical studies. In vitro studies found strong evidence that 1,8-cineole controls inflammatory processes and mediator production of infection- or inflammation-induced mucus hypersecretion by its action as anti-inflammatory modifier rather than a simple mucolytic agent. The aim of this review is to present these preclinical studies performed with the pure monoterpene, and to summarize the current knowledge on the mode of action of 1,8-cineole. The actual understanding of the pure 1,8-cineole compared to mixtures of natural volatile oils containing 1,8-cineole as a major compound and to mixtures of natural terpenes, known as essential oils, will be discussed. Based on the anti-oxidative and anti-inflammatory properties, recent clinical trials with 1,8-cineole have shown first evidence for the beneficial use of 1,8-cineole as long-term therapy in the prevention of COPD-exacerbations and to improve asthma control. (20)
Recently, 1, 8-cineole was also tested for its effect on mood. A randomized study compared the effect of inhalation of limonene, 1,8-cineole, or eucalyptus oil verses almond oil on anxiety in subjects before a selective nerve root block (SNRB). This study reported that 1,8 cineole helped to relieve their anxiety:
The aim of this study was to investigate the effect of inhalation of eucalyptus oil and its constituents on anxiety in patients before selective nerve root block (SNRB). This study was a randomized controlled trial carried out in 62 patients before SNRB. The patients were randomized to inhale limonene, 1,8-cineole, or eucalyptus oil, each at concentrations of 1% vol/vol in almond oil or almond oil (control). Anxiety-visual analog scale (A-VAS), state-trait anxiety inventory (STAI), profile of mood states (POMS), pain-visual analog scale (P-VAS), blood pressure, and pulse rate were measured before and after inhalation prior to SNRB. Measures of anxiety, including A-VAS ( ), STAI ( ), and POMS ( ), were significantly lower in 1,8-cineole than in the control group and significantly greater in 1,8-cineole than in the eucalyptus group in A-VAS. P-VAS was significantly lower after than before inhalation of limonene, 1,8-cineole, and eucalyptus, despite having no significant difference in the four groups compared with control group. 1,8-Cineole, a major constituent of eucalyptus, was effective in decreasing anxiety before SNRB. The present findings suggest that inhalation of 1,8-cineole may be used to relieve anxiety before, during, and after various operations, in addition to SNRB. (21)
In a randomized control study of 52 participants, the inhalation of a specific chemotype of eucalyptus oil verified by GC/MS was compared to inhaling almond oil. The study reported, “A total of 31 compounds were identified (Table 1). The major volatile flavor compounds of eucalyptus oil were 1,8-cienol (61.46%), limonene (13.68%), ?-cymene (8.55%), y-terpinene (5.87%), and a-pinene (4.95%).”
Serum measurements for inflammation and white blood cells along with measurements in blood pressure, heart rate, and pain perception were tested. There was a significant difference favoring the eucalyptus participants in blood pressure and pain perception:
Eucalyptus oil has been reported effective in reducing pain, swelling, and inflammation. This study aimed to investigate the effects of eucalyptus oil inhalation on pain and inflammatory responses after total knee replacement (TKR) surgery. Participants were randomized 1:1 to intervention group (eucalyptus inhalation group) or control group (almond oil inhalation group). Patients inhaled eucalyptus or almond oil for 30 min of continuous passive motion (CPM) on 3 consecutive days. Pain on a visual analog scale (VAS), blood pressure, heart rate, C-reactive protein (CRP) concentration, and white blood cell (WBC) count were measured before and after inhalation. Pain VAS on all three days ( ) and systolic ( ) and diastolic ( ) blood pressure on the second day were significantly lower in the group inhaling eucalyptus than that inhaling almond oil. Heart rate, CRP, and WBC, however, did not differ significantly in the two groups. In conclusion, inhalation of eucalyptus oil was effective in decreasing patient’s pain and blood pressure following TKR, suggesting that eucalyptus oil inhalation may be a nursing intervention for the relief of pain after TKR. (21)
An in-vivo study with rats with various Eucalyptus species demonstrated a benefit on pain perception after they were exposed to acetic-acid and hot plates. As opposed to the above the study, in this trial, the extracts of EOs did demonstrate some inhibition of inflammation. However, results were not able to be consistently reported “reflecting the complex nature of the oil extracts and/or the assay systems used.” This could provide some evidence that the constituent makeup of eucalyptus, as discussed above, was what effected results on inhibiting inflammation:
Many species of the genus Eucalyptus from the Myrtaceae family are used in Brazilian folk medicine for the treatment of various medical conditions such as cold, flue, fever, and bronchial infections. In the current investigation, we evaluated the analgesic and anti-inflammatory effects of essential oil extracts from three species of Eucalyptus employing various standard experimental test models. Using acetic acid-induced writhes in mice and hot plate thermal stimulation in rats, it was shown that the essential oils of Eucalyptus citriodora (EC), Eucalyptus tereticornis (ET), and Eucalyptus globulus (EG) induced analgesic effects in both models, suggesting peripheral and central actions. In addition, essential oil extracts from the three Eucalyptus species produced anti-inflammatory effects, as demonstrated by inhibition of rat paw edema induced by carrageenan and dextran, neutrophil migration into rat peritoneal cavities induced by carrageenan, and vascular permeability induced by carrageenan and histamine. However, no consistent results were observed for some of the parameters evaluated, both in terms of activities and dose-response relationships, reflecting the complex nature of the oil extracts and/or the assay systems used. Taken together, the data suggest that essential oil extracts of EC, ET, and EG possess central and peripheral analgesic effects as well as neutrophil-dependent and independent anti-inflammatory activities. These initial observations provide support for the reported use of the eucalyptus plant in Brazilian folk medicine. Further investigation is warranted for possible development of new classes of analgesic and anti-inflammatory drugs from components of the essential oils of the Eucalyptus species. (22)
Eucalyptus oils have been shown to inhibit a lot of unwanted critters in a lot of studies and in vitro. 1,8-cineole is the most studied constituent; however, various chemotypes all have different constituents that exert different responses in the body. For this reason, I like to keep a variety of eucalyptus oils on hand for diffusing and for applying to make critters unwelcome in my home and on or in my body.
You can find a review of safety considerations, including a reference to eucalyptus here.
(Note: use cautiously with little ones, in pregnancy, and in epilepsy because it’s pretty strong!)
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Disclaimer: This information is applicable ONLY for therapeutic, Grade A essential oils. This information DOES NOT apply to essential oils that have not been AFNOR and ISO standardized. There is no quality control in the United States and oils labeled as “100% pure” need only contain 5% of the actual oil. The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin.
This information is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness.
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