Due to the large-scale adulteration of commercial lavender oils, new ways of authentification have had to be developed. The tests which can be usefully employed have been studied by
Charles (2000) and include:
Refractive index (RI)
Optical rotation (OP)
Specific gravity (SG)
Gas chromatography (GC)
Using different columns: DB-5, DB-WAX Chiral columns RT-S-DEXse with Mass spectroscopy (MS) or with FID Radioactive (14C) Stable isotope ratio (S13C and SD)
The chiral analyses are especially good in the case of synthetic linalool and linalyl acetate adulteration and this is easily confirmed by the radioactive analyses. Most of the initial, ISO testing is now obsolete (RI, OP and SG), with ordinary GC of limited benefit unless gross adulteration has occurred with unusual components or solvents.
Pharmacological studies Effect on lipid peroxidation in vivo
Lavender oil and a variety of other essential oils were tested for effects on the lipid-peroxidation-antioxidase defence system and lipid metabolism in 150 patients with chronic bronchitis (Siurin, 1997). There was a lowering of plasma levels of dienic conjugates and ketones, activation of catalase in red blood cells which the author stated was characteristic of an antioxidant effect on exposure to essential oils of rosemary, basil, fir and eucalyptus. However, lavender had a normalizing effect on the level of total lipids and the ratio of cholesterol to its alpha fraction.
Aqueous methanolic extracts of L. angustifolia; rosmarinic acid, caffeic acid, luteolin 7-O-glucoside, methyl carnosoate investigated in two different biological systems of lipid peroxidation (LPO). All the extracts and individual components were active. More effect was found on the enzyme-dependent system than the enzyme-independent system. This suggests that there is a direct effect on the enzyme, acting as an inhibitor (Hohmann et al, 1999).
Anaesthetic activity of L. angustifolia essential oil was evaluated in vivo in the rabbit conjunctival reflex test and in vitro using the rat phrenic nerve-hemidiaphragm preparation (Ghelardini et al, 1999) against two citrus fruit essential oils (Citrus reticulata 'Blanco' and Citrus limon), with no medical uses. L. angustifolia and its components, linalool and linalyl acetate were able to drastically reduce contractions in the rat phrenic nerve diaphragm and in the eye, there was a dose-dependent increase in the number of stimuli necessary to provoke the reflex, apparently confirming in vivo the local anaesthetic activity observed in vitro. The activity in the rat diaphragm however, does not seem to be indicative to the present author of an anaesthetic action.
Nagai et al. (2000) studied the effect of pleasant odour inhalation using lavender, rose and jasmine on diastolic blood pressure during exercise and found that it was decreased by 24 per cent. In contrast, the blood pressure increase during static handgrips, where a power of 30-40 per cent of maximum was maintained was not affected by the odours. The authors concluded that as the blood pressure increase during the static handgrip is a lower brainstem reflex, the results indicated that the inhalation of these odours suppresses the muscle sympathetic vasoconstrictor activity and attenuates the blood pressure increase by affecting the CNS higher than the midbrain.
L. latifolia is used in Paraquay for treating bronchitis, asthma, rheumatism and has also been applied topically for swellings. The aerial parts of L. latifolia (650g) were extracted with hot 70 per cent ethanol and then concentrated to give a 70 per cent extract (164 g). The extract was then partitioned between water and chloroform to give a chloroform-soluble and water-soluble fraction and a precipitate (Shimizu et al, 1990). The chloroform fraction was then further partitioned to yield coumarin, 7-methoxy-coumarin, trans-phytol and caryophyllene oxide. Coumarin in the chloroform fraction as well as the fraction itself was shown to have a weak effect on carageenin-induced paw edema in rats on topical application. The authors also reported that caryophyllene oxide showed an inhibitory effect on histamine-induced contractions in guinea-pig ileum, but did no further tests with acetylcholine or atropine therefore these are not very meaningful results.
'Hypoglycaemic effect of Lavandula species, but not in diabetes
Gamez et al. (1987, 1988) studied the effects of water-soluble extracts of L. dentata, L. latifolia, L. stoechas and L. multifida on hypoglycaemic rats. Tests in normal rats, that is, normaglycaemic showed that both the 10 per cent and 20 per cent infusion and 10 per cent suspension administered orally decreased the blood glucose, that is, had a hypoglycaemic effect. L. stoechas was more active as an infusion while the other species as a suspension. L. dentata and L. stoechas both showed an hypoglycaemic effect on glucose-induced hyperglycaemic rats. However, there was no hypoglycaemic effect on alloxan-induced diabetic rats. This indicates that the hypoglycaemic effect can only occur if the pancreas is intact and is therefore absolutely useless in diabetes.
Perillyl alcohol is found in small amounts in lavender, peppermint, spearmint, cherries and celery seeds. Many experiments using perillyl alcohol in animals have shown a positive effect on regression of various tumours including: pancreatic, mammary, and liver tumours (Belanger, 1998). It is also a chemopreventative agent for colon, skin and lung cancer. It is also a chemotherapeutic agent for treating neuroblastoma and prostate and colon cancer. Preliminary trials in human cancers have not been successful as remission has not occurred and there are gastrointestinal and other side effects.
In order to optimize the environment in which flight controllers work, several essential oils and and aromas were used including lavender, anise and brandy mint. After 20 days of exposure the health condition of the flight controllers improved (Leshchinskaia et al, 1983). They felt less tired at the end of the day. When no photocides were used, the REG-wave amplitude decreased and also the tonic tension of cerebral vessels increased indicative of fatigue; when the aromas were employed the changes were in the opposite direction.
The autonomic nervous system (ANS) responses were studied with regard to emotional factors induced by odorants which included lavender, ethyl acetoacetate, camphor, acetic acid and butyric acid (Vernet-Maury, 1999). Fifteen subjects inhaled these five odorants at different times and their various ANS parametres were monitored. These included: skin potential and resistance, skin blood flow, and temperature, instantaneous respiratory frequency and instantaneous heart rate. The subjects also evaluated their feelings after inhalation, which ranged from pleasant to unpleasant on an 11 point hedonic scale. Analysis of variance showed that lavender elicited happiness as did ethyl acetoacetate, camphor elicited either happiness, surprise or sadness, based on past association with the odour. Butyric and acetic brought unhappiness with negative emotions like anger and disgust expressed. More than sixty subjects in three similar experiments, showed similar autonomic responses which were correlated with basic emotions; therefore a multiparametric autonomic analysis could identify a type of basic emotion and its intensity.
Four odours were studied on the EEG of four men and two women at rest while sitting (Lee et al., 1994). The odours were: lavender, citrus and floral and were released for 10 min from a duct to fill the room completely. Subjective estimation, at the lower concentration, indicated that citrus was the most comfortable, but this was not significant. The rate of alpha wave (Oz) in the period of giving the citrus was significantly higher than for lavender. The rate of beta wave (Oz) during floral exposure was significantly higher than that of lavender. At the higher concentration, the regression coefficient of the power of the spectra of frequency-fluctuation of alpha wave for lavender was significantly higher than for the other two odours and at the lower concentration it was higher during the dosing than at other periods. This measurement is therefore suggested to be useful for evaluating psychophysiological responses.
Thirteen female subjects were assessed under four odour conditions using lavender, chamomile, sandalwood and eugenol applied respectively to each person (Masago et al., 2000). Both EEG
and sensory evaluation by the subjects were evaluated. The factor of a 'comfortable feeling' was highest for lavender and descended in order of eugenol, chamomile and sandalwood. The alpha-1 (8-10 Hz) of EEG at the parietal and posterior temporal regions decreased significantly after the onset of inhalation of lavender. Some smaller changes occurred with eugenol and chamomile but not with sandalwood. Therefore the authors concluded that alpha-1 activity decreased significantly only when the subject felt comfortable. There seems therefore to be a correlation between alpha-1 activity and subjective evaluation.
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