Chemical constituents essential oils

Wintergreen Oil. Water distillation of the leaves of Gaultheriaprocumbens L. yields an oil which consists of essentially one chemical constituent, methyl saUcylate. Because of this, the oil has been almost totally replaced by the synthetic chemical. Natural oil of wintergreen [68917-75-9] is a pale yellow to pinkish colored mobile Hquid of intensely sweet-aromatic odor and flavor. The oil or its synthetic replacement find extensive use in pharmaceutical preparations, candy, toothpaste, industrial products, and in rootbeer flavor. In perfumery, it is used in fougnre or forest-type fragrances. 

The different constituents present in the plant may belong to different chemical groups. For example, chamomile contains pharmacologically active essential oils, polyacetylenes, terpenoids, flavonoids, coumarins, and polysaccharides. 

About 120 chemical constituents have been identified in chamomile as secondary metabolites, including 28 terpenoids, 36 flavonoids and 52 additional compounds [4]. A substantial part of drag effects are determined by the essential oil content. Oil is collected from flower heads, either by steam distillation or solvent extraction, for yields of 0.24-1.90% of fresh or dry plant tissue. Among the essential oil constituents the most active are /-/-a-bisabolol and chamazulene. /-/-a-bisabolol has demonstrated anti-inflammatory, antispasmodic, antimicrobial, antiulcer, sedative and CNS activity. Chamazulene is also anti-inflammatory. Topical applications of chamomile preparation have shown benefit in the treatment of eczema, dermatitis and ulceration [5]. 

As everyone knows, plants have been used for centuries in herbalism, homeopathy, and aromatherapy because of their medicinal qualities. The long-term use of plants has led to recent observations about their antioxidant properties (1, 2). Many scientists have observed antioxidant activities in compounds derived from the volatile constituents (3, 4) and essential oil extracts - of plants. They have reported that ingestion of these volatile chemicals can prevent lipid peroxidation, which is associated with diseases such as cancer, leukemia, and arthritis. In the present study, analysis and antioxidative tests on the volatile extract isolated from a commercial beer were performed. Why did we choose beer We chose beer because... 

To ensure lot-to-lot consistency, standardization of extracts often relies on constituents as biomarkers for plant identity and potency. SJW Hypericum perforatum), a perennial shrub traditionally used as a mood enhancer and mild antidepressant, has been tested in dozens of clinical trials, with mixed results for efficacy. Some of its purported bioactive constituents include naphthodianthrones, including hypericin flavonoids phloroglucinols, including hyperforin and essential oils. For many years, hypericin was presumed to be the active component. As a result most extracts were standardized based on hypericin concentration. Recent data, however, support other components such as hyperforin and the flavanoids, that may also contribute to the therapeutic efficacy of the SJW extracts (33-35). Because these secondary components were previously unaccounted for in the standardization of the former clinical test articles, and because these constituents are chemically unrelated to and their content within the plant varies independently of hypericin, it has been argued that the potency of these constituents in any particular batch was unlikely to be similar to that of other batches. This variability between batches could explain the observed differences in the clinical trial results (36). 

Komai, K. and C. S. Tang. 1989. Chemical constituents and inhibitory activities of essential oils from Cyperus brevifolius and C. kyllingia. J. Chem. Ecol. 15 2171-2176. Hellion-Ibarrola, M. C., D. A. Ibarrola, Y. Montalbetti, D. Villalba, O. Heinichen, and E. A. Ferro. 1999. J. Ethnopharmacol. 66 271-276. 

Zhao, X., J. Wang, M. Yang, and X. Pan. 1996. Study on the chemical constituents of the essential oil of berries of Physalis pubescene. J. NorthEast Forestry Univ. 24 94-98. 

Terpenoid alcohols appeared early in the history of synthetic perfumery because several were readily available from inexpensive essential oils. Alpha-terpineol, citronellol and linalool shown in Figure 7 are important constituents of pine stump oil, citro-nella oil and rosewood oil, respectively. The fourth material listed, hydroxycitronellal, is a hydroxy aldehyde which perhaps has a questionable place in this discussion. It is included because it is one of the most important fragrance chemicals used today. "Hydroxy" is almost a perfume unto itself. Its soft flowery, linden blossom odor blends very well in many floral perfumes. 

Phytochemical studies of cinnamon and related species are restricted mainly to the volatile oil and its constituents. Recently, the chemical composition of the essential oils of a few rare species has been researched and new aroma sources have been identified. The chemistry of the genus Cinnamomum is interesting, as there exist several chemo-types within a species. So far, except for C. cassia, very little attention has been paid to the non-volatiles of the genus. This is an area worth exploring. 

Gil et al. (2002) made a study of the essential oil composition of coriander fruits in plants growing in environments differing in soil conditions and weediness level. The variation in the oil composition was related to the relative proportion of the constituents and not to the presence/absence of a particular component. Location, fertilization and weediness also affected the chemical profile. The European landrace showed a more stable concentration of the major components than the Argentinean landrace. 

The tissue of the fruits contains fatty oil with resin, mucilage and gum, malates and albuminous matter and, in the outer seed-coat, there are significant amounts of tannin. The yield of ash is about 8%. Dried cumin fruits contain essential oil with over 100 different chemical constituents, including abundant sources of the essential fatty acids, oleic acid (3%), linoleic acid (34%), flavonoid glycosides, tannins, resins and gum (Singh et al., 2006). 

Essential oils have properties that reflect their chemical composition and the range and amounts of constituents are used for evaluation of qualities such as criteria for purity, in determining extraction methods and in defining aspects such as chemotypes. 

As an aromatherapist you will encounter very few elements in their pure form as constituents of essential oils. However, the numbers of ways in which elements can join up chemically to form compounds is astonishing. 

In the following chapters we will apply what we have learnt concerning physical and chemical changes, molecules and bonding to explore the structures of the molecules that form the essential oils. The structure of the molecules in a compound and the constituent compounds in a chemical have a big impact on its properties and these will also be reflected in the essential oils containing them. 

The type of chemical constituent is quoted when explaining the influence of chemotype. This occurs when plants have the same botanical species and name but have significantly different chemical constituents in their oils, which then exhibit different therapeutic properties. Different types of alcohols are found in essential oils of thyme grown in different situations. For Thymus vulgaris the position, altitude and other environmental factors cause the formation of essential oils with differing types of alcohols. 

A pale olive green essential oil with a sharp, warm, woody spicy odour. Principal constituents are monoterpenes limonone (15-17%), sabinene (9-19%), (l-pinene (5-14%), a-pinene (2-11%), P-myrcene (1.5-2.5%), carene (0.2-14.0%), a-phellandrene (0.5-5.0%), sesquiterpenes P-caryphyllene (9-31%), P-bisabolene (0.1-5.1%) and p-farnescene (1-3%). Box 7.15 shows a chemical analysis and Box 7.16 is a material safety data sheet from a sup-... 

The method of extraction has an important influence on the composition of the final product. The fresh flower petals produce the essential oil after steam distillation and produce rose water as an important by-product. Solvent extraction produces a concrete or absolute. The chemical composition of rose oils is considered to be one of the most complex, with much still to be identified. A general list of principal constituents of distilled products would... 

The container must be sealed by a closure. If air is allowed to enter and interact with the essential oil, the chemical reaction of oxidation can occur. Oxidation in this case can be considered the addition of oxygen to an oil constituent to form a new compound. New compounds formed will alter the composition of the oil. Water vapour may also enter from the air. An open or incompletely sealed container will allow essential oil components to escape as vapours, and this will change the balance of constituents. The best choice of closure for a bottle is a screw cap fitted with a wad or washer. Ideally bottles are fitted with childproof tops and drop dispensers to control amounts dispensed. 

Essential oil from A. annua is another active research interest as it could be potentially used in perfume, cosmetics, and aromatherapy. Depending on its geographical origin, the oil yield in A. annua ranges from 0.02% to 0.49% on a fresh weight basis and from 0.04% to 1.9% on a dry weight basis. The major components in the oil were reported to be artemisia ketone (80), isoartemisia ketone (81), 1,8-cineole (82), and camphor (83) (Structure 5-5). GC/MS was employed to analyze the chemical composition in the essential oil more than 70 constituents have been identified. For more detailed information on the oil composition of essential oil from A. annua, the readers are referred to Refs. 65, 66 and 72-81. 

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