Composition chemotypes

Differences in alkaloid composition between samples of Z dipetalum from different islands have also been reported (Arslanian et al., 1990). These workers found that a tree from Oahu (anethole/estragole chemotype) lacked thalicitrine [546] (see Fig. 6.5), whereas a tree from Kauai and one from Hawaii (both 2-undecanone/2-tridecanone chemotype) possessed the compound. 

The composition of living cells is related to the availability and usefulness of 15-20 elements (see Figure 4.3) and, as we shall see, changes in availability profoundly influenced evolution of chemotypes. However, it is probable that the collection of elements in life at any one time is a unique set. 

The use of enantiomers as additional markers for taxonomic characterization of aromatic plants may be very helpful. The differences in the enantiomeric distribution of trans- and cis- sabinene hydrates in two Origanum species enable the species to be distinguished in spite of their similar essential oil compositions. A further study on the natural variation of the enantiomeric composition within a wild population may be carried out in order to examine the stability in a taxon (including the possible presence of chemotypes). The enantiomeric ratio of essential oil components is a reliable parameter for assessing quality because it may be indicative of adulteration, contamination, aging, shelf life, technological process and the botanical source of a specific chiral compound. ... 

The major components of artemisia oil are the ketones camphor (15-40%) and a- and /3-thujone (see p. 217) (together 70-25%) [267-270]. Since Artemisia herba-alba exists as various chemotypes, the composition of the oil may vary widely. 

The variable responses observed are probably the main drawback for the practical use of essential oil as miticides. It must be pointed out that the same plant species often produces essential oils with variable composition because of environmental and/or genetic factors many species have varieties, the so called chemotypes for instance at least seven chemotypes are known for Thymus vulgaris [88,89]. Also the extraction process influences the composition of the essential oils. For these reasons, it is advisable that authors report the composition of the essential oils used in the biological investigations. Unfortunately, only one paper reported this important information [64]. 

Indonesian cassia of commerce is the dried bark of C. burmannii. Most of the bark produced is exported and domestic consumption is very small. The main importing countries are the USA, Germany and the Netherlands. The chemical composition of Indonesian cassia was thought to be similar to that of Chinese cassia, but later studies showed the existence of various chemotypes. 

Ahmed et al, 2000). The physico-chemical properties of C. cassia leaf oil are indicated in Table 7.6. The chemical composition of tejpat oil was studied by several workers and the results exhibited variations. Several chemotypes of tejpat oil have been identified based on the leaf oil composition. 

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. 

Essential oils are mixtures of different chemical compounds and the composition will vary according to factors such as source, age, storage conditions and chemotypes of those compounds. Mixtures have properties that reflect all of their components, so by looking at the different compounds in an oil we can see how they not only have effects on different physiological systems in the body but can also complement each other. The fact that they are mixtures allows us to identify their components and analyze them with techniques such as chromatography. 

Analysis of an essential oil will tell us what compounds are present (qualitative analysis) and in what amounts (quantitative analysis). However, when considering the composition of any named oil it is difficult to lay down precise criteria. As with all products of natural origin, there will be variations according to growing conditions and how they are harvested, extracted and stored. Even if the species of plant is defined and the parts used for oil production are carefully controlled, variation in composition will occur. This has previously been explained in terms of chemotypes and will be examined in more detail for other essential oils later in this chapter. Even when examining a particular chemotype there will be differences in the amounts of constituents, although these are usually within a fairly narrow range. 

The composition of essential oils depends upon species and chemotypes. 

Tea tree is a misleading name. Tea tree is the general name given to all melaleuca trees (of the family Myrtaceae), usually associated with Australia. The species Melaleuca alternifolia is the one producing the essential oil. Many chemotypes exist and standards set for composition may encourage adulteration. 

The Australian standard for Melaleuca alternifolia tea tree oil sets levels for 1,8-cineole that should not exceed 15% and for terpineol-4 that should not be less than 30%. The components of this type of tea tree oil vary considerably owing to the existence of different varieties of the same plant species there are also many chemotypes and it has been shown that even trees growing next to each other can produce oils with differing composition. Imposing chemical standards can encourage adulteration commonly oils of various cultivars and species are blended and terpineol-4 is often added. 

Chemotype Plants from a given botanical species whose chemical composition varies from the average due to environmental growing conditions. 

Composition As a member of the Lamiaceae family the genus Ocimum is characterised by chemical polymorphism. For O. basilicum several chemotypes are reported in the literature [22, 23] hut only two types are of commercial interest. 

Composition Parsley seeds contain 2-8% essential oil with myristicin, apiol, elemicin and 2,3,4,5-tetramethoxyallylbenzene as main components. ISO specifies the oil as follows a-pinene (10-22%), P-pinene (7-15%), elemicin (1-12%), myristicin (25-50%), apiol (5-35%), l,2,3,4-tetramethoxy-5-allylbenzene (1-12%) [201], Also chemotypes with one main component of the latter three constituents do exist. 

Composition Up to 55% 1,8-cineole, camphor, bomeol and its acetate, a-terpineol, terpinene-4-ol, linalool, verbenone, 3-octanone and terpene hydrocarbons. For detailed analyses see e.g. [254, 255, 256[. Even if different chemotypes of rosemary exist, only two qualities are of commercial interest (ISO and European Pharmacopoeia give almost identical specifications) ... 

Composition of the essential oil Mainly a- and P-thujone, thujyl alcohol and thujyl acetate respectively [301 ]. Some chemotypes contain cis- and trans-epoxyocimene, sabinyl and chrysanthenyl acetate, chrysanthenol as main components [302]. For latest literature see [303]. 

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