Aromatherapy is the therapeutic use of essential oils to cure, mitigate, or prevent diseases, infections, and indispositions mainly by inhalation, but also by the skin (Buchbauer et al., 1993; Lee et al., 2012). In recent years there has been increasing attention to screening plants to study the biological activities of their essential oils from the chemical and pharmacological points of view. Essential oils are complex mixtures made up of many compounds whose contents can be influenced by several factors. Each of these constituents contributes to the beneficial or adverse effects of these oils. Therefore, a deep knowledge of the essential oil composition is necessary for their therapeutic application (Lahlou, 2004). The presence, yield, and composition of secondary metabolites in plants, and specifically in essential oils, can be affected in a number of ways, from their formation in the plant to their isolation. Several of the factors of influence have been studied, in particular for commercially important crops, to optimize the cultivation conditions and time of harvest and to obtain higher yields of high-quality essential oils. The factors that determine the chemical variability and yield of essential oils include (1) physiological variations, (2) environmental conditions, (3) geographic variations, (4) genetic factors and evolution, and (5) political and social conditions (Figueiredo et al., 2008). The quality of plant raw materials can also be influenced by human adulterations due to dishonesty or unscrupulous operators. Probable errors could be accidental botanical substitution or intentional botanical substitution. The variability in the content and concentrations of the constituents of plant material, along with the range of extraction techniques and processing steps used by different manufacturers, results in marked variability in the content and quality of commercially available herbal products. Thus, the quality control of essential oils is necessary to ensure the genuineness of the product, the shelf life, and the storage conditions (Bonaccorsi et al., 1999). In the specific case of essential oils used for aromatherapy, the quality control is an important issue because it guarantees purity, safety, and efficacy. There is a specific term used in this context, therapeutic grade, but it is not a label from the Food and Drug Administration (FDA); it is only a market certification. Recently, European Medicinal Agency published “Reflection Paper on Quality of Essential Oils as Active Substances in Herbal Medicinal Products/Traditional Herbal Medicinal Products,” which discusses the importance of and the way to gain quality for essential oils used as active pharmaceutical ingredients or herbal medicinal products. The conclusion, however, is that there is a need for specific guidance, because the current guidance does not fully address the question of essential oils (EMA/HMCP/84789/2013). Essential oils are complex mixtures that act directly on the gustatory and olfactory receptors in the mouth and nose, leading to taste and aroma responses. Interacting with the human senses, essential oils have applications in food, preservatives, medicines, symbolic articles in religious and social ceremonies, and remedies to modify behavior. In most cases, essential oils gain widespread acceptance as multifunctional agents due to their strong stimulation of the human gustatory (taste) and olfactory (smell) senses. Based on histories of use of selected plants and plant products that strongly impact the senses, it is not unexpected that society would bestow powers to heal, cure diseases, and spur desirable emotions in the effort to improve the human condition, often with only a limited understanding or acknowledgment of the toxic effects associated with high doses of these plant products. The natural origin of these products and their long history of use by humans have, in part, mitigated concerns as to whether these products work or are safe under conditions of intended use. The adverse effects resulting from the use of these products are often unknown. In the absence of information concerning efficacy and safety, recommendations for the quantity and quality of natural product to be consumed remain ambiguous. However, when the intended use is as a flavor or fragrance that is subject to governmental regulation, effective and safe levels of use are defined by fundamental biological limits and careful risk assessment. The safety control of an essential oil is performed in the context of all available data for groups of known constituents and the group of unknown constituents, and any potential interactions that may occur by the essential oil when used in combination with other essential oils, or other natural substances. Adams and Taylor proposed in 2010 a chemically based approach to the safety evaluation of an essential oil. The approach depends on a quantitative analysis of the chemical constituents in the essential oil. The chemical constituents are assigned to well-defined congeneric groups that are established based on biochemical and toxicologic information, and this is evaluated in the context of intake of the congeneric group resulting from consumption (by olfactory or gustative sense) of the essential oil. The overall objective in safety of essential oils is the knowledge of their chemical composition (Adams and Taylor, 2010). Sometimes, during the extraction processes, well-known contaminants of synthetic or artificial origin (e.g., plasticizers, chemicals used for solvent stabilization, and butylated hydroxytoluene) are identified as constituents of essential oils and considered to be native plant metabolites. The importance of this problem should be considered since such compounds are still repeatedly being reported as natural products (Radulovic and Blagojevic, 2012). Radulovic investigated some of the most common semivolatile contaminants that could originate from the solvents used during the isolation procedures and analyses of essential oils (Radulovic and Blagojevic, 2012).
|Titolo:||Extraction, sample preparation, and analytical methods for quality issues of essential oils|
|Data di pubblicazione:||2016|
|Appare nelle tipologie:||2.1.2 Articolo su libro con ISBN|