Essential Oils
Essences or essential oils are a complex mixture of aromatic substances responsible for the fragrances of flowers. They have numerous pharmacological actions, which is why they are the basis of aromatherapy, but they are also widely used in perfumery and cosmetics, in the pharmaceutical industry and in the food, liquor and confectionery industry.
Volatile oils, essential oils or simply essences, are the natural aromatic substances responsible for the fragrances of flowers and other plant organs. Currently, this definition is only used if they are obtained by steam entrainment or by expression of the pericarp in the case of citrus.
With the exception of some, such as bitter almonds, which are produced by heteroside hydrolysis, these essences are found as such in the plant. They are synthesized and secreted by certain specialized histological structures, frequently located on or near the plant surface: oil cells, secretory ducts or cavities, or glandular hairs.
They can also be deposited in specific tissues such as the pericarp of citrus fruits; in the petals of roses; in the bark, stem and leaves of cinnamon; in the woods of camphor and sandalwood; in the glandular hairs of mint leaves, stems, and flowers; in the roots of valerian, etc. They are often associated with other substances, such as gums and resins, and tend to resinify on exposure to air. In the plant world they are widespread in numerous botanical species. They are especially abundant in conifers, lamiaceae, apiaceae, myrtaceae, rutaceae and asteraceae. Various functions are attributed to it in plants, such as protection against insects and herbivores, adaptation to water stress, and they are of great importance in pollination, because they constitute elements of chemical communication due to their volatility and marked odor.
General characteristics
Essential oils, in general, constitute 0.1 to 1% of the dry weight of the plant. They are liquids with little solubility in water, soluble in alcohols and organic solvents. When they are fresh, at room temperature, they are colourless, since when they oxidize they become resinous and take on a dark yellowish color (which is prevented by depositing them in topaz-colored glass containers, completely filled and perfectly closed). Most oils are less dense than water (with exceptions such as the essential oils of cinnamon, sassafras, and clove) and have a high refractive index.
In terms of their chemical composition, with the exception of the essences derived from heterosides (such as that of bitter almonds and mustard), they are generally complex mixtures of highly variable constituents that belong, almost exclusively, to the group of terpenes and, in to a lesser extent, to the group of aromatic compounds derived from phenylpropane (cinnamic aldehyde, eugenol, anethole, anisic aldehyde and safrole, among others).
Terpene compounds are made up of isoprene units (5 carbons), which can be monoterpenes (10 carbons) and sesquiterpenes (15 carbons). These monoterpenes and sesquiterpenes can be, in turn, acyclic, monocyclic and bicyclic, and also oxygenated and non-oxygenated.
Some oils are almost monomolecular, since they have almost exclusively a single component, others are rich in 2-3 molecules. But most are polymolecular, containing 3-4 major molecules, a number of minor molecules, and sometimes hundreds of different molecules that are only present in trace amounts.
Obtaining methods
Essential oils can be obtained by different methods. The most common is extraction in a vapor stream (distillation). Other methods applicable in specific cases are the cold expression of the citrus fruit pericarp, the so-called enflowering with fats at room temperature to extract some delicate floral aromas (jasmine, orange blossom, rose) and extraction with organic solvents at room temperature.
Hydrolates
The water that is collected at the end of a distillation process is called hydrolate. A small amount of essential oil, as well as metals, mucilages and trace elements, are retained in it in a totally natural way. Due to this, some of these hydrolates have interesting therapeutic properties. Rose water and orange blossom water are the two hydrosols that have been most developed thanks to cosmetics and the food industry.
Rose water is an excellent tonic, soothing and regenerating skin, very suitable for dry skin, and orange blossom water tones the skin and, taken orally, is particularly suitable for nervous and stressed people.
Therapeutic properties
From the pharmacological point of view, the properties of essential oils are highly variable due to the heterogeneity of their components. Some of the molecules present in the essential oils of certain plants have great therapeutic interest, which has given rise to aromatherapy. Some of these actions, due to their effects on the skin, have also found their application in cosmetics.
On the other hand, from the toxicological point of view, essential oils are potentially toxic (despite being considered in the popular sphere as slightly dangerous natural products), since an overdose can easily occur, even with essential oils from plants that in themselves are very slightly toxic. In addition, some show a specific toxicity for having components that cross the blood-brain barrier and affect the central nervous system, as is the case with thujone, which abounds in the essences of wormwood, yours and sage.
Among the pharmacological actions of essential oils, the most notable are the following:
Antiseptic power
This antiseptic action, which is not antibiotic, is manifested against a large number of pathogenic bacteria and includes certain antibiotic-resistant strains. Some oils are also active against lower fungi responsible for mycoses and even against yeasts (Candida). Compounds such as citral, geraniol, linalool or thymol show a much higher antiseptic power than phenol.
Irritant properties
Used externally, products such as the essence of turpentine cause an increase in microcirculation, significant flushing, a sensation of heat and, in certain cases, a slight local anesthetic action. There are many different preparations for topical use that incorporate essential oils designed to relieve sprains, stiffness, strains and other joint or muscle pain.
Internally, they produce irritation at different levels: the essential oils of eucalyptus, niaulí and pine stimulate the mucus cells and increase the movements of the cilia of the bronchial tree. Similarly, some essential oils can, at the renal level, produce vasodilation and cause a diuretic effect (juniper).
Essential oils with anethole (those of many umbelliferae, those of mints or verbena) are effective in reducing or suppressing gastrointestinal spasms
Spasmolytic and sedative action
Essential oils with anethole (those of many umbelliferae, those of mints or verbena) are effective in reducing or suppressing gastrointestinal spasms. They frequently intensify gastric secretion, which is why they have been described as digestive and stomachic. Also, some essential oils exert a neurosedative action (lavender, lemon balm, valerian).
Other actions
Certain essential oils have a cholagogue and choleretic effect (turmeric), others have an antirheumatic, anti-inflammatory and antiphlogistic action (mustard and chamomile) and some have a healing effect (lavender).
Administration form
Essential oils can be used for therapeutic purposes in treatments lasting 1-3 weeks, applied in different ways that we will describe below.
Cutaneous route
* Body massage oil. It is obtained by incorporating a quantity of essential oil(s) into a vegetable oil that usually ranges between 1% and 10%. The therapeutic objectives of the lotion thus obtained are immediate because the massage favors an excellent absorption of the aromatic components. The direct use (without dissolving) of an essential oil on the body is inadvisable due to the strong irritations that in most cases originate. Ointments can be included in this section, despite the fact that vegetable oil is replaced by a mixture, generally of honey and beeswax. Its use is much more specific: very localized pain, burns, insect bites, etc.
* Aromatic bath. Enjoying an aromatic bath presents the problem of the insolubility of essential oils in water, so it is necessary to resort to the use of solubilizers.
The direct use (without dissolving) of an essential oil on the body is inadvisable due to the strong irritations that in most cases originate
Olfactory pathway
* Atmospheric diffusion. It is the most important way to take advantage of the therapeutic properties of essential oils. It is a simple and pleasant method, but for which it is necessary to have a suitable device: an electric micro-diffuser for essential oils that propels, through a vibrating mechanism, the aromatic molecules in a certain area. The use of phenolic essences (thyme, clove) is not recommended as they are irritating to the respiratory tract.
* Vapors. The vapors that are released from a pot of boiling water to which 20-25 drops of one or more essential oils have been added with decongestant effects on the respiratory tract are inhaled for a few minutes. It is an old procedure, but very effective in case of cold or sinusitis. The operation can be repeated several times a day.
Orally
Although it is not the most ideal way to apply them, essential oils can also be ingested orally. If there are no defined rules regarding the dosage to follow (in general, 1-2 drops per dose are sufficient), it must be taken into account that essential oils do not have a flavor that can be classified as pleasant and that, in addition, they You have to avoid the slightest burn to the digestive system that will absorb them. It is, therefore, advisable to incorporate them into a quantity of honey that will later dissolve in a glass of water or in a hot herbal tea.
Applications
Pharmacological
On the other hand, some essential oils are used in pharmacy to obtain various active ingredients (anethole, eugenol) or as excipients and flavorings in the preparation of syrups, suspensions, elixirs and other pharmaceutical forms. Also, in the food, liquor and confectionery industry they are often used as flavorings.
Cosmetics
In perfumery and cosmetics, essential oils are widely used. Its use in perfumery is very important, obviously due to the olfactory qualities of essential oils. This implies that they are incorporated into countless compositions: from perfumes for cologne to fragrances for laundry detergents. As for its use in cosmetics, it is also important and is based on the specific functions that some essences have on the skin, in addition to its use as a flavoring agent in different cosmetic preparations.
Aromatherapeutic
Directly related to essential oils, so-called aromatherapy has emerged, which is a discipline within natural medicine that basically uses essential oils in its treatments.
The term aromatherapy was first used by the French chemist René Maurice Gatefossé, who specialized in the cosmetic uses of essences.
A very important contribution of aromatherapy has been the deepening and development of anti-infective treatments from essential oils, with which comparable results are obtained, in many cases, to those of antibiotic therapy, but with fewer side effects and little appearance of resistors. In this sense, we must highlight the aromatogram technique, which experimentally confirms the antibacterial and fungicidal power of essential oils. This procedure is similar to the antibiogram (system used to define the power of an antibiotic), but the antibiotics are replaced by essential oils.
