Maria Lis-Balchin

Relationship between bioactivity and chemical composition of commercial essential oils

In order to establish the value of the use of biological activities as accessory criteria (in conjunction with gas chromatography, but in the absence of enantiomeric analysis) for establishing the authenticity of essential oils, the biological activities of 105 commercial essential oils were investigated against 25 species of bacteria, 20 strains of Listeria monocytogenes, and three filamentous fungi; their antioxidant action was also determined and all the results were related to the actual chemical composition of the oils as determined by gas chromatography. The results showed some relationship between the major components and some bioactivities. There was a negative correlation between 1,8-cineole content and antifungal activity. There was, however, great variability between the biological action of different samples of individual oils and groups of oils under the same general name, e.g. lavender, eucalyptus or chamomile, which was reflected in differences in chemical composition, The results suggest that, although the biological activities are not all related to the main components, any significant blending, rectification and adulteration of commercial oils can be monitored by their biological activities. The use of essential oils named simply as ‘chamomile’ or ‘eucalyptus’, or any commercial oil which has been adulterated, cannot be justifiably used in treating medical conditions unless it can be shown that the action is non-specific and independent of the chemical composition.

Studies on the mode of action of the essential oil of lavender (Lavandula angustifolia P. Miller)

Lavender (Lavandula angustifolia, P. Miller) is used in aromatherapy as a holistic relaxant and is said to have carminative, antiflatulence and anticolic properties. Its sedative nature, on inhalation, has been shown both in animals and man. Lavender has a spasmolytic activity on guineapig ileum and rat uterus in vitro and it also decreases the tone in the skeletal muscle preparation of the phrenic nerve–diaphragm of rats. As the mechanism of action has not been studied previously, the spasmolytic activity was studied in vitro using a guinea‐pig ileum smooth muscle preparation. The mechanism of action was postsynaptic and not atropine‐like. The spasmolytic effect of lavender oil was most likely to be mediated through cAMP, and not through cGMP. The mode of action of linalool, one of lavenders major components, reflected that of the whole oil. The mode of action of lavender oil resembled that of geranium and peppermint oils. Copyright

In-vitro activity of S. lavandulaefolia (Spanish sage) relevant to treatment of Alzheimer's disease

Salvia lavandulaefolia Vahl. (Spanish sage) essential oil and individual monoterpenoid constituents have been shown to inhibit the enzyme acetylcholinesterase in‐vitro and in‐vivo. This activity is relevant to the treatment of Alzheimers disease, since anticholinesterase drugs are currently the only drugs available to treat Alzheimers disease. Other activities relevant to Alzheimers disease include antioxidant, anti‐inflammatory and estrogenic effects. Results of in‐vitro tests for these activities are reported here for S. lavandulaefolia extracts, the essential oil and its major constituents. Antioxidant activity (inhibition of bovine brain liposome peroxidation) was found in the EtOH extract of the dried herb (5 mg mL−1) and the monoterpenoids (0.1 M) α‐ and β‐pinene and 1,8‐cineole. Thujone and geraniol had lower antioxidant effects, while camphor had no antioxidant effects. Possible anti‐inflammatory activity (eicosanoid inhibition in rat leucocytes) was found in the EtOH extract (50 μg mL−1) and was shown by the monoterpenoids α‐pinene and geraniol (0.2 mM), but not 1,8‐cineole, thujone or camphor. Possible estrogenic activity (via induction of β‐galactosidase activity in yeast cells) was found in the essential oil (0.01 mg mL−1) and the monoterpenoid geraniol (0.1–2 mM). 1,8‐Cineole, α‐ and β‐pinene and thujone did not exhibit estrogenic activity in this analysis. These results demonstrate that S. lavandulaefolia, its essential oil and some chemical constituents have properties relevant to the treatment of Alzheimers disease and provide further data supporting the value of carrying out clinical studies in patients with Alzheimers disease using this plant species.

Pharmacological and antimicrobial studies on different tea‐tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand

Three different species of Myrtaceae growing in Australia and New Zealand are known as ‘Tea‐tree’: the Australian Tea tree (Melaleuca alternifolia), the New Zealand Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides). All three essential oils are used by aromatherapists, although only Melaleuca has been tested for toxicity, and its antimicrobial effects studied. The pharmacology and antimicrobial activity of the three ‘tea‐tree’ oils was determined using guinea‐pig ileum, skeletal muscle (chick biventer muscle and the rat phrenic nerve diaphragm) and also rat uterus in vitro. Differences were shown between the three essential oils in their action on smooth muscle: Manuka had a spasmolytic action, while Kanuka and Melaleuca had an initial spasmogenic action. Using the diaphragm, Manuka and Melaleuca decreased the tension and caused a delayed contracture; Kanuka had no activity at the same concentration. The action on chick biventer muscle was, however, similar for all three oils, as was the action on the uterus, where they caused a decrease in the force of the spontaneous contractions. The latter action suggests caution in the use of these essential oils during childbirth, as cessation of contractions could put the baby, and mother, at risk. The comparative antimicrobial activity showed greater differences between different samples of Manuka and Kanuka than Melaleuca samples. The antifungal activity of Kanuka was inversely proportional to its strong antibacterial activity, whilst Manuka displayed a stronger antifungal effect, though not as potent as Melaleuca. The antioxidant activity of Manuka samples was more consistent than that of Kanuka, while Melaleuca showed no activity. The variability in the Manuka and Kanuka essential oils suggests caution in their usage, as does the fact that the oils have not been tested for toxicity.

Evaluation of massage with essential oils on childhood atopic eczema

Childhood atopic eczema is an increasingly common condition in young children. As well as being irritating to the child, it causes sleepless nights for both the child and the family and leads to difficulties in parental relationships and can have severe effects on employment. A group of eight children, born to professional working mothers were studied to test the hypothesis that massage with essential oils (aromatherapy) used as a complementary therapy in conjunction with normal medical treatment, would help to alleviate the symptoms of childhood atopic eczema. The children were randomly allocated to the massage with essential oils group and both counselled and massaged with a mixture of essential oils by the therapist once a week and the mother every day over a period of 8 weeks. The preferred essential oils, chosen by the mothers for their child, from 36 commonly used aromatherapy oils, were: sweet marjoram, frankinsence, German chamomile, myrrh, thyme, benzoin, spike lavender and Litsea cubeba. A control group of children received the counselling and massage without essential oils. The treatments were evaluated by means of daily day‐time irritation scores and night time disturbance scores, determined by the mother before and during the treatment, both over an 8 week period; finally general improvement scores were allocated 2 weeks after the treatment by the therapist, the general practitioner and the mother. The study employed a single case experimental design across subjects, such that there were both a within‐subject control and between‐subjects control, through the interventions being introduced at different times.

A preliminary study of the effect of essential oils on skeletal and smooth muscle in vitro

The pharmacological activity of nine commercial essential oils was studied on the rat isolated phrenic nerve diaphragm preparation and compared with activity on field-stimulated guinea-pig ileum preparations. The essential oils at final bath concentrations of 2 x 10(-5) and 2 x 10(-4) g/ml produced four different effects on skeletal muscle, whilst only a contracture with or without a decrease in response to field stimulation in smooth muscle. The first type of effect on skeletal muscle involved a contracture and inhibition of the twitch response to nerve stimulation shown by a sample of clary sage, dill, fennel, frankincense and nutmeg; a second, shown by thyme produced a contracture without a change in the twitch response; a third, shown by lavender reduced the twitch response alone and the fourth, shown by camphor, increased the size of the twitch response. Angelica root oil at the highest concentration studied showed no response on skeletal muscle.

Buchu (Agathosma betulina and A. crenulata, Rutaceae) essential oils: their pharmacological action on guinea-pig ileum and antimicrobial activity on microorganisms

The mode of action of essential oils from two buchu species (Agathosma betulina and A. crenulata, Rutaceae) from the Cape region of South Africa has been studied on smooth muscle in‐vitro using guinea‐pig ileum. At high concentration, the oils had an initial spasmogenic activity followed by spasmolysis. The spasmolytic action was post‐synaptic, not atropine‐like and did not involve adrenoceptor or guanylyl cyclase activation. In the presence of the phosphodiesterase inhibitor rolipram, the spasmolytic action of A. betulina was significantly increased whilst that due to A. crenulata was also increased but not to a significant level. These results suggested a mode of action for the oils involving cyclic adenosine monophosphate. In addition, A. betulina appeared to block calcium channels but this was not seen with A. crenulata, possibly because the initial spasmogenic activity complicated the study of its spasmolytic action. Neither essential oil (10 μL, undiluted) demonstrated antimicrobial action against Enterococcus hirae and Pseudomonas aeruginosa but very low activity was observed against Escherichia coli, Saccharomyces cerevisiae and Staphylococcus aureus, suggesting little potential for these oils as antimicrobial agents/preservatives.

Bioactivity of Geranium Oils from Different Commercial Sources

ABSTRACT Geranium oil is one of the most frequently used oils in aromatherapy. However, there is a large and diverse variation in the composition of commercial geranium oil, which depends only partly on its country of origin. The bioactivity of 16 commercial samples of geranium oils was assessed in vitro against 25 different bacteria, 20 Listeria monocytogenes strains and 3 filamentous fungi; the antioxidant and pharmacological effect was also studied and the results correlated against the chemical composition. The results show that the wide variability in bioactivity between samples cannot be directly correlated with the country of origin nor the main chemical components. This suggests that the many different paramedical effects of geranium oil, which are accredited to geranium oil regardless of its chemical composition, may be due to its action as an odor through the limbic system.

Parallel placebo-controlled clinical study of a mixture of herbs sold as a remedy for cellulite

Cellasene, a product containing Ginkgo biloba, sweet clover, sea‐weed, grape seed oil, lecithins and evening primrose oil, has been marketed all over the world as a miracle cure for cellulite. As the efficacy of the product was in doubt, a parallel placebo‐controlled clinical study was undertaken in a group of women to see whether the product had any effect on cellulite, or on the body weight, fat content, circumference of thighs, hips, etc. No significant changes were found in these parameters compared with the starting values, nor compared with the placebo control after a 2 month course of Cellasene, except for an increase in the cellulite, assessed by the author, compared with that initially. Seven of 11 women taking Cellasene gained weight, as did eight in the placebo control group, taking Colonease, where significance was achieved. The weight gain in both groups was apparent after the first 2 weeks, and all women had to reduce their food consumption. Only three of the women in the Cellasene group thought that their cellulite had slightly improved against two women in the control group. Copyright

Studies on the mode of action of essential oils of scented-leaf Pelargonium (Geraniaceae)

A selection of essential oils obtained by steam distillation from scented‐leaf Pelargonium species, hybrids and cultivars were assessed for their method of spasmolytic activity in vitro using an isolated smooth muscle preparation. Their mechanism of action was postsynaptic and not atropine‐like. The spasmolytic action was correlated with the chemical composition of the essential oils assessed by gas chromatography and mass spectroscopy. The spasmolytic effect of Pelargonium essential oils with a rose‐like odour was most likely mediated through cAMP, and not through cGMP; the action of all other essential oils with diverse odours was neither through cAMP, cGMP, nor via calcium channel blockade or potassium channel activation. The mechanism of action of the main components of the rose‐like pelargoniums, citronellol and geraniol, reflected that of the whole oils.