Introduction
Essential oils are aromatic essences extracted from plants, flowers, trees, fruit, bark, grasses and seeds. They are high aromatic substances made in plant by special cells, but at this stage are known as essence, it becomes essential oil after it has been extracted. They are called essential oil because they were thought to represent the very essence of odour and vapour.
Although essential oils contain the word “oil”, essential oil do not necessarily feel oily; they are called oil because they contain the oil soluble chemicals in plant. This complex chemistry of multiple compounds content of essential oils gives them their therapeutic property and explains why different essential oil may have overlapping effects.
Essential oils isolated and identified from the vast number of plant species amount over 3000, and of these, several hundred have been produced commercially. These oils have distinctive therapeutic, psychological and physiological properties that can improve health and prevent illnesses. All essential oils have unique healing and valuable antiseptic properties. Some oils are antiviral, anti-inflammatory, pain relieving, antidepressant, stimulating, relaxing, expectorating, support digestion and have diuretic properties too.
Essential oil gets absorbed into our body and exerts an influence on it. The residue gets dispersed from the body naturally. They can also affect our mind and emotions.
Essential oils are secondary metabolites of plants whose constituents are basically a complex mixture of terpenic hydrocarbons especially monoterpenes and sesquiterpenes and oxygenated derivatives such as aldehyde, ketones, epoxides, alcohol and esters.
Essential oils greatly differ in their composition. Essential oils extracted from plants of same species differ in different geographic locations.
Composition also depends on the maturity of the plant from which the essential oils are extracted.
Essential oils function to attract pollinators, defend plants against predators, warn out plants and healing
Essential oil considered the chemical weapons of the plant world as their compounds may deter insects or protect the plant against bacterial or fungal attacks.
They act as plant pheromones in an effect to attract and seduce their pollinators.
The oxygenated molecules of essential oils, which serve as chemical messengers to the cells bringing life to the plant destroying infestations, aiding growth and stimulating healings.
Essential oils are regarded as plants’ soul because of their ethereal nature concentrated as scents through which plants communicate with their surrounding world.
Some essential oils were believed to embody plants spiritually by ancient people through to medieval time. They believed in the spiritual power of plants, rather than just chemical breakdown of its healing components. Each plant had spiritual healing elements. For example, the plant rosemary (Rosmarinus officinalis) was used in medieval times to drive out evil spirits. A sprig ( small stem with leaves on it which has been picked from a bush or plant, especially so that it can be used in cooking or as a decoration) of rosemary and other such plants were often hung or plant near the door of the home to protect its inhabitants.
Essential oils enter the body in three ways: inhalation, absorption and consumption.
Examples of Essential Oilsils and their Uses
Essential oils include:
- Lavender (Lavandula angustifolia)
- Peppermint (Mentha piperita)
- Lemon (Citrus limon)
- Tea Tree (Melaleuca alternifolia)
- Bergamot (Citrus bergamia)
- Eucalyptus (Eucalyptus globulus)
- Geranium (Pelargonium graveolens)
- Rosemary (Rosmarinus officinalis)
- Ginger (Zingiber officinale)
- Mandarin (Citrus reticulata)
1. Lavender (Lavandula angustifolia)
Lavender is noted for its floral scent and woody undertones and is one of the most commonly used essential oils in the world today. This refreshing and balancing aroma is frequently used for relaxation. Other common uses include management of anxiety, insomnia, burns, infections, wounds, candida and insect bites.
Therapeutic properties:
Analgesic, antibacterial, antidepressant, anti-inflammatory, antifungal, antiviral, antispasmodic
Applications:
Inhalation, diffusion, compress, bath, massage, direct application to skin
2. Peppermint (Mentha piperita)
Enjoy this refreshing and mentally stimulating essential oil. Its minty fresh scent is easy to recognize and is frequently an ingredient in gum, candy and herbal teas.
Therapeutic properties:
Analgesic, expectorant, antispasmodic and anti-nausea
Applications:
Inhalation, diffusion, bath, massage. Always mix with a carrier oil if applying directly to the skin. Avoid internal use, especially for those with G6PD deficiency, atrial fibrillation, post-cardiac surgery and on 5-FU chemotherapy.
3. Lemon (Citrus limon)
Lemon is often selected for its pleasant, crisp and clean scent. Mental alertness may be increased with the diffusion of lemon into the environment. It is also uplifting and sharpens our focus with decision-making. Use this oil in the morning or afternoon to promote energy levels. Additionally, lemon has antiseptic properties.
Therapeutic properties:
Antiviral, antibacterial, astringent, tonic, antispasmodic, antiseptic, diuretic
Applications:
Massage, bath, inhalation, diffusion. Always mix with a carrier oil if applying directly to the skin. Avoid sun exposure after topical application, as this oil is phototoxic
4. Tea Tree (Melaleuca alternifolia)
Tea tree oil is highly regarded and one the world’s most researched essential oils for its medicinal properties. The pungent odor associated with tea tree oil is similar to eucalyptus and camphor. Tea tree oil is commonly used to treat skin infections, wounds, ringworm, cold sores, acne, mouth/throat infections, toenail fungus, athlete’s foot, psoriasis, dandruff and head lice.
Therapeutic properties:
Antifungal, antibacterial, antiviral, wound-healing
Applications:
Inhalation, diffusion, compress, direct application to the skin. Do not apply to skin undiluted without a patch test to check for allergies and skin sensitivities. May use undiluted on skin if no allergic response is present.
5. Bergamot (Citrus bergamia)
Try this fresh citrus scent with slightly spicy undertones to lift your mood and stimulate your immune system. You may recognize this scent if you like Earl Grey tea. Bergamot mixes well with other citrus scents providing a fragrant, mellow sensory experience. It is beneficial for reducing symptoms of stress, anxiety, depression and acne.
Therapeutic properties;
Antispasmodic, sedative, analgesic, antidepressant, tonic, antifungal
Applications:
Inhalation, diffusion, compress, bath and massage. Avoid sun exposure after topical application, as this oil is phototoxic.
6. Eucalyptus (Eucalyptus globulus)
The familiar, sharp and somewhat pungent scent of eucalyptus is easily recognized and found in many over-the-counter drug store products. Eucalyptus oil is effective for symptom relief from the common cold and sinus congestion by acting as a decongestant. This oil is cooling and increases mental concentration and alertness.
Therapeutic properties:
Antibacterial, antiviral, analgesic
Applications:
Inhalation, diffusion, steam bath, compress and massage. Always mix with a carrier oil if applying directly to the skin.
7. Geranium (Pelargonium graveolens)
Enjoy this herb-like fragrance that features a subtle combination of rose, citrus and woody undertones. Geranium’s scent is physically and emotionally balancing, and helps to reduce stress and anxiety. This oil is popular among women for hormonal-related problems such as PMS, fluid retention and menopausal symptoms. Geranium is also helpful for dermatitis, wound healing, inflammation, eczema, burns, ringworm and insomnia.
Therapeutic properties:
Sedative, antibacterial, antiviral, anti-inflammatory, antifungal
Application:
Inhalation, diffusion, baths, massage and direct application to the skin with a carrier oil.
8. Rosemary (Rosmarinus officinalis)
The sharp woody scent of rosemary conveys a feeling of warmth. This stimulating oil is used to increase energy, improve mental clarity and offer an alert state. Rosemary is helpful in relieving respiratory congestion and muscular aches and pain.
Therapeutic properties:
Mild stimulant, analgesic, anti-inflammatory
Applications:
Inhalation, diffusion, massage, compress, bath and direct application to the skin with a carrier oil. Avoid with hypertension and seizure disorders.
9. Ginger (Zingiber officinale)
When you think of ginger, you may think about food. Indeed, ginger is often used in cooking and baking. The essential oil of ginger offers a peppery, sharp and yet warm aromatic scent. The warmth associated with ginger is good for reducing symptoms such as joint swelling associated with arthritis. Ginger settles the digestive system and relieves nausea, including morning sickness.
Therapeutic properties:
Anti-emetic, anti-inflammatory, analgesic, antispasmodic
Applications:
Inhalation, bath, massage, compress and direct application to the skin with a carrier oil.
10. Mandarin (Citrus reticulata)
This is one of the gentlest and safest essential oils impacting the body, mind and spirit. Mandarin offers a calming influence that promotes restful sleep, and is especially good for children and the elderly. This oil brings out joy, lifts moods and reduces irritability.
Therapeutic properties:
Anti-nausea, astringent, digestive, diuretic, relaxant, sedative.
Applications:
Inhalation, dilution, bath, massage, compress and direct application to the skin with a carrier oil. Avoid sun exposure after topical application, as this oil may be mildly phototoxic.
How Essential oils work
You’ve probably noticed that when we humans cut ourselves a red fluid (blood) oozes out! No great news there. Similarly, when you break or injure the parts of plants they ”bleed,” too.
Unlike blood, this fluid is clear. It is, in fact, an oil or resin and within it can be found trace elements of nutrients, hormones, enzymes, vitamins, minerals and anti-bodies. It has a whole range of different properties such as anti-fungal, anti-bacterial, anti-infectious, antiseptic and can stimulate the immune system as well. Oxygen is also found in this resin, bound chemically within other molecules such as alcohols, phenols, esters and many other organic molecules, which together make up the essential oil.
This oil is released by the plant to clean the wound, kill the bacteria and start the regeneration or healing process, and in fact has the same function as blood in humans (and other animals). Like blood, this fluid/oil in plants transports the basic nutrients necessary to feed and support the cells.
What’s more, the essential oil has the ability to permeate or penetrate the plant’s cell walls and transport oxygen and nutrients into the cells themselves to support and help their immune system. Research has shown that, because of these immune stimulating properties, essential oils can support the immune system. So that, for instance, whether applied topically (rubbed on) or inhaled, 70% of people who get a cold or flu will recover faster using essential oils!
Essential oils have many special properties which give them the ability to help us deal with odors and bacteria.
They act in several ways.
- They are able to increase atmospheric oxygen in a closed space as they release oxygenating molecules into the atmosphere. Oils increase ozone and negative ions in the home, which inhibits the growth of bacteria. This prevents and destroys existing odors of cigarettes, mold, animals, etc.
- They are able to break up the molecular chains of some chemicals in the air, making them non-toxic to us because of their particular electromagnetic attraction to these chemicals.
- Essential Oils will bond to metals and chemicals within the body and carry them out of the body, working as natural chelators (they bond organically, forming new compounds called chelates), so that these toxic substances can’t remain in the tissues.
- Essential Oils remove dust particles from the air, acting as an air filtration system.
- Essential Oils are recognized as having a very marked ability to increase cellular oxygen through their normal functioning. When applied to the body by rubbing the feet, they will travel through the body and affect every cell, including the hair, within 20 minutes!
In orthodox medicine, one compound, such as aspirin, is made and its properties are tested and known. However, in nature, in each essential oil, there can be many, many different compounds, all with different therapeutic effects. They act synergistically to give the body what it needs. Sometimes it can have opposing effects so it can act as a relaxant or stimulant depending on what’s needed.
According to Dr Alan Huch, a neurologist, psychiatrist and also the director of Smell and Taste Research Centre in Chicago says, ‘Smell acts directly on the brain, like a drug’. Our nose has the capacity to distinguish 1,00,000 different smells, many of which affect us without our knowledge regarding the same.
The aroma enters our nose and connects with cilia, the fine hair inside the nose lining. The receptors in the cilia are linked to the olfactory lobe which is at the end of the smell tract. The end of the tract is in turn connected to the brain itself. Smells are converted by cilia into electrical impulses that are transmitted to the brain through olfactory system. All the impulses reach the limbic system. Limbic system is that part of the brain, which is associated with our moods, emotions, memory and learning. All the smell that reaches the limbic system has a direct chemical effect on our moods.
The molecular sizes of the essential oils are very tiny and they can easily penetrate through the skin and get into the blood stream. It takes anything between a few seconds to two hours for the essential oils to enter the skin, and within four hours, the toxins get out of the body through urine, perspiration and excreta.
Aroma oils work like magic for stress-related prob-lems, psychosomatic disorders, skin infections, hair loss, inflammations and pains arising from muscular or skeletal disorders.
Essential oils are safe to use. The only caution being they should never be used directly because some oils may irritate sensitive skin or cause photosensitivity. They should be blended in adequate proportion with the carrier oils. A patch test is necessary to rule out any reactions
Essential Oils Application Methods
Essential oils can be utilized in a myriad of ways, such as topically, ingesting or internal and the most common inhalations.
1. Topical Applications:
When using natural products, only your body knows how it is going to respond; therefore, watch for any signs of skin irritation or side effects. Essential oils are soluble with the lipids found in the skin and can penetrate the skin surface and be absorbed into the lymph and circulatory systems. They may be worn as perfumes, ointments, cologne, and can be applied undiluted or diluted using a carrier oil or other base. As a rule, due to the con-centrated and potency of pure essential oils, dilution in a carrier is highly recommended for beginners or for those people with sensitive, fair skin, or applications of the face, neck and other sensitive areas and also if you are trying a new oil or blend of oils. Please be careful with children or infants as the dilution’s necessary are very minute. When in doubt, always consult.
Baths: Seven to eight drops of essential oil in 30 ml of carrier oil or honey. Add this to running water and mix well before getting in. Be sure to check the safety info for the essential oils that you choose.
Foot baths: Up to six drops in a bowl or footbath of warm water. Soak for approx. 10 minutes. This is great for varicose veins, swollen ankle or tired aching legs.
Compresses: Hot or cold. Five to eight drops of essential oil in a basin filled with either hot or cold water. Agitate the water and place a cotton cloth on top of the water to collect the floating oil. Gently squeeze excess water out and apply directly and immediately to affected area. Wrap another towel over the compress and leave until it reaches body temperature. This can be repeated over and over for relief of pain, headache or to reduce inflammation.
Massage: Add 15–22 drops of essential oil to a 30 ml of carrier oil for a full body massage. Always massage in an upward motion and towards the heart for best effect.
2. Inhalation Applications:
This is one of the simplest and effective methods of dispersing essential oils into the air. Inhalations are a method of introducing essential oils to the lungs via the nose and throat. This can have great benefit for respiratory problems, sinus congestion, flu, coughs, colds, catarrh and sore throats. Use this method once or twice a day.
Facial Steams: Two to three drops of oil into a bowel of boiled water. Drape a towel over your head and lean over the bowl to inhale the steam deeply while keeping eyes shut. Inhale slowly at first, then breathe deeper and deeper. Breathe through your mouth for throat problems, and inhale through your nose for sinus congestion.
Atomizers: Add 12–20 drops of essential oils to distilled water in a spray bottle. Shake well before using and mist on face or into the air.
Vaporizers: 10–12 drops in the top of the vaporizer for a normal size room.
Nebulizers: This electrical unit is designed to disperse the essential oils in a micro-fine mist. This means that the molecules of oil will hang in the air for much longer due to the minuscule weight of the particles. Research has shown that diffusing in this way may help to reduce bacteria, fungus, mold and unpleasant odours. It not only makes the air fresh, but it also helps you to relax, relieves tension and creates an atmosphere of harmony and peace-ful tranquillity.
Direct Inhalation: Put 3 drops of essential oil into the palm of your hand and rub hands together briefly, and then quickly inhale deeply for greater inhalation. Relieves sinus congestion and is quite invigorating.
Essential oils have being used by the people for thou-sand years; it has great potential to use in modern days. Appropriate method of cultivation and distillation certainly yield good quality essential oil. The more an essential oil is interfered physically or chemically, the less clinical value it will have. This can be overcome by means of suitable evaluation technique.
Extraction of Essential Oils
Essential oils are valuable plant products, generally of complex composition comprising the volatile principles contained in the plant and the more or less modified during the preparation process (Bruneton, 1995). The oil droplets being stored in the oil glands or sacs can be removed by either accelerate diffusion through the cell wall or crush the cell wall. The adopted techniques depend on the part of the plants where the oil is to be extracted, the stability of the oil to heat and susceptibility of the oil constituents to chemical reactions. Common techniques used for the extraction of essential oils are
Hydrodistillation/Water distillation
The technique involves distillation of water that is in direct contact with fresh or sometimes dried macerated plant materials. Plant material is grinded and weighed, then transferred into the Clevenger set up. Plant material is heated in two to three times its weight of water with direct steam. The distillation vessel is heated over heating mantle and the water vapour and oil are removed through a water cool condenser.
Hydrodiffusion
Hydrodiffusion is a method of extracting essential oils in which steam at atmospheric pressure (low-pressure steam <0-1 bar) is passed through the plant material from the top of the extraction chamber, thus resulting in the oils that retain the original aroma of the plants (Buchbauer, 2000).
Enfleurage
This process is applicable to flowers such as jasmine or tuberose, that have low content of essential oil and so delicate that heating would destroy the blossoms before releasing the essential oils. Flower petals are placed on trays of odourless vegetable or animal fat which will absorb the flowers essential oil. Every day or every few hours after the vegetable or fat has absorbed as much essential oil as possible; the depleted petals are removed and replaced with fresh ones. This procedure continues until the fat or oil becomes saturated with the essential oil. This is called Enfleurage mixture. Addition of alcohol helps to separate the essential oil from the fatty substances. The alcohol then evaporates leaving behind only the essential oil, hence enfleurage method is the best method when the source from the oil is to be extracted from flower or petals.
Cold pressing
Another method of extracting essential oil that has not found high application in scientific research is cold pressing. It is used to obtain citrus fruits oils such as bergamot, grape fruit, lemon, lime, etc. The fruits to be extracted are rolled over a trough with sharp projections that penetrate the peels, this pierce the tiny pouches containing the essential oil. The whole fruit is pressed to squeeze the juice and is separated from the juice by centrifugation.
Solvent extraction
This method involves the extraction of the oils from the oil bearing materials with the use of solvent. Solvent used depends on the part of the plant to be used for extraction. For instance, leaves, roots, fruits are extracted with benzene with or without mixture of acetone or petroleum ether, in the cold or at boiling point while flowers are extracted with ethers. The solvent enters the plant to dissolve the oil waxes and colour. After the extraction, the solvent is removed by distillation under reduced pressure leaving behind the semisolid concentrate, this concentrate are extracted with absolute ethanol. The second extract is cooled to precipitate the waxes and then filtered. This wax free alcoholic solution is distilled under reduced pressure to remove alcohol and finally the essential oil.
Microwave assisted process (MAP)
The MAP process uses microwave to excite water molecules in plant tissue causing the cells to rupture and release the essential oil trapped in the extra cellular tissue of the plants (Belanger et al., 1995). This technique has been developed and reported by many authors as a technique for extraction of essential oils in order to obtain a good yield of the essence and to reduce the time of extraction (Pare et al., 1989, Collin et al., 1991, Bouzid et al., 1997, Chiasson et al., 2001, Ghoulami et al., 2001). This technique has also been applied for the extraction of saponins from some medicinal plants (Safir et al., 1998).
Carbondioxide extraction
In this technique, plant material is placed in a high pressure vessel and carbon dioxide is passed through the vessel. The carbon dioxide turns into liquid and acts as a solvent to extract the essential oil from the plant material. When the pressure is decreased, the carbon dioxide returns to a gaseous state leaving no residue behind.
Qualities of essential oil extracted with any of the techniques described above depend on the chemical composition of the oil.
ANALYSIS OF ESSENTIAL OILS
The two main purposes of analysing essential oils are:
(і) To identify and quantify as many constituents as possible.
(іі) To evaluate the quality of the oils and detect any possible adulteration that may affect their usage. Analysis of essential oils is generally performed using Gas chromatography (qualitative analysis) and Gas chromatography-mass spectroscopy (qualitative analysis)(Keravis, 1997). Gas chromatography analysis is a common confirmation test