Edited By: Dr. Asha Jyoti Bharati
Eucalyptus oil: Introduction
Eucalyptus oil is derived from the leaves of various eucalyptus species (family Myrtaceae) by steam distillation.
Distribution: Eucalyptus species are distributed throughout the world. Australia, the United States, the Middle East, India, and South America are the main growers of this species.
Common name: Eucalyptus (Latin), Eucalypt (English), Neelgiri (Hindi), Sugandh Patra (Sanskrit), Gum Tree, etc (1).
Main plants for eucalyptus oil: Lemonor lemon-scented eucalyptus (E. citriodora)
Tasmanian blue gum (E. globulus)
Blue mallee (E. polybractea)
River red gum (E. camaldulensis)
Constituents of Eucalyptus oil
More than 300 species of this genus contains predominantly volatile terpenes and aromatic compounds, the most abundant typically being the monoterpenoid 1,8-cineole. According to British and European pharmacopeias, Eucalyptus oil must contain at least 70% 1,8-cineole when the oil is used commercially in pharmaceutical and cosmetic industries (2).
Eucalyptus oil is widely used in traditional medicine for the treatment of colds, asthma, cough, diarrhea and dysentery, hemorrhage, laryngalgia, laryngitis, sore throat, spasm, trachea, and vermifuge (3).
Eucalyptus oil is a natural pest and disease control and can be useful in sensitive areas such as schools, restaurants, hospitals, and homes.
The medical significance of Eucalyptus oil
Eucalyptus oil and cineole, are very important ingredients of many proprietary drugs in the form of syrups, lozenges, nasal drops and preparations for inhalation. Owing medicinal significance, the essential oil of several species of Eucalyptus is widely used for aroma-therapy in Europe and Japan (4).
Health benefits of eucalyptus oil
Eucalyptus oil exhibits various pharmacological effects, which include antiseptic, antioxidant, anticancer, respiratory and gastrointestinal effect, wound healing, and insecticidal/insect repellent, herbicidal, acaricidal, nematicidal, antihyperglycemic, anti-inflammatory and flavoring properties (5).
1. The antioxidant property of Eucalyptus oil
The essential oil of eucalyptus possesses hydroxyl radical scavenging activity greater than synthetic antioxidants like butylated hydroxytoluene and curcumin. Thus this oil may be the potential scavengers of superoxide anions to prevent lipid oxidation (6).
2. Antimicrobial properties of Eucalyptus oil
A various bioactive compound such as 1,8-cineole, citronellal, citronellol, citronellyl acetate, p-cymene, eucamalol, limonene, linalool, β- pinene, α-pinene, γ-terpinene, α- terpinol, alloocimene and aromadendrene which act as a natural antibiotic for the treatment of several infectious diseases caused by different multidrug-resistant bacteria such as Staphylococcus. aureus, Haemophilus influenzae, S. agalactiae, S. pyogenes, S. pneumoniae Mycobacterium tuberculosis and Escherichia coli Listeria ivanovii, Bacillus cereus and P. aeruginosa (7, 8).
Virucidal activity against herpes simplex virus (HSV-1 and HSV-2) and Influenza virus (9). This oil reduces plaque formation and virus replication before or during adsorption into the host cell. Therefore, eucalyptus oil may be useful to prevent virus transmission through direct contact among children and passengers (10).
4. Reduce joint pain
Eucalyptus oil contains 1,8-cineole which play an important role in the reduction in pain (somatic, inflammatory, and visceral pain), swelling, inflammation and blood pressure after total knee replacement (TKR) surgery via modulating central nervous system and autonomic nervous system. Thus, eucalyptus oil inhalation has a wonderful effect on reducing pain (11).
5. Analgesic and Anti-inflammatory properties of Eucalyptus oil
It possesses central and peripheral analgesic effects as well as neutrophil-dependent and independent anti-inflammatory activities by inhibiting edema (swelling) induced by different chemical agents (12).
6. Insect repellents
Eucalyptus oils contain PMD (p-menthane-3,8-diol), citronellol, limonene, and linalool which proven safe to human health and more effective against mosquito larvae at a lower concentration as compared to neem oil (13). Therefore eucalyptus oil can be used as an insect repellent and are registered by the EPA which show wonderful activity against mosquito (Aedes aegypti Culex quinquefasciatus, Anopheles stephensi and Aedes albopictus), flies (Musca domestica and Haemotobia irritans) and tick with Lyme disease and Rocky Mountain spotted fever (14, 15).
7. Enhance immunity
Eucalyptus oil possesses the ability to activate the immune response and stimulate phagocytic activity against pathogen attacks. Thus this oil act as an immunoregulatory agent, useful as an adjuvant in immuno-suppressive pathologies, in infectious disease and after tumor chemotherapy boosts the immune system (16).
8. Treat Headache
Eucalyptus oil and peppermint oil combination increased cognitive performance and had a muscle-relaxing and mentally relaxing effect which further reduces the sensitivity to headache. Thus this combination shows the neurophysiological effect and reduces headache frequency and intensity (17).
9. Treat sinusitis and asthma
Eucalyptus oil is a rich source of 1,8-cineol, also known as eucalyptol. It has anti-inflammatory properties for the treatment of upper and lower airway diseases. It also promoted lung repair at a higher dose (10 mg/ml) and reduce collagen deposit around the peribronchiolar area (18). Thus this oil plays an important role in the treatment of chronic sinusitis and bronchitis, and bronchial asthma (19).
10. Anti-Fatigue properties
Eucalyptus oil aromatherapy increases swimming performance and decreases oxidative damage and inflammatory reactions in tissues, indicating good anti-fatigue, antioxidant, and anti-inflammatory effects after high-intensity endurance exercise (20).
11. Wound healing properties of Eucalyptus oil
This oil helps in the formation of granulation tissue, promoting collagen synthesis thus non-irritant and higher wound contraction rate with respect to control and neomycin treated rats. therefore, favorable for topical application in pharmaceutical industries (21).
12. Manage psychosis
Psychosis is a chronic recurrent psychiatric disorder affecting patient thoughts, emotions, perceptions, behavior, and memory.
Eucalyptus oil (500, 1000 mg/kg) contains neuroprotective and therapeutic compounds, which acts by facilitating the neurotransmission of GABA and blockade of dopamine and AChE activity thus protect from neuropsychiatric disorders (22).
13. Antifungal properties of Eucalyptus oil
Antifungal actions against different pathogenic fungi such as Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, T. mentagrophytes, Candida albicans, and Trichophyton rubrum. Therefore, this oil acts as a natural therapeutic agent for the treatment of dermatophytosis (23).
14. Treat Giardiasis
Giardiasis is a type of small intestine infection caused by a parasite known as Giardia lamblia through contaminated food or water. However, eucalyptus oil is good source of 1,8-eucalyptol, α-pinene and α-terpineol acetate which act as an anti giardia agent and thus kills giardia cysts (24).
15. Antiproliferative and cytotoxic effects against different types of cancer
Presence of 1,8-cineole, a-pinene, terpinen-4-ol, and g-terpinene antioxidants in eucalyptus oil exhibit antiproliferative and cytotoxic effects against different types of cancer cells such as colon, liver, ovary, prostate, cervix, neuroblastoma, lung breast and gastric cells (25).
16. Treat Cough and Cold
Eucalyptus oil may be useful as a cold and flu remedies and may be applied directly as a decongestant and/or expectorant (26).
Eucalyptus oil contains citronellal (64.7%) and citronellol which suppress seed germination and seedlings growth of weeds. Thus this oil act as a bioherbicide agent which show a negative allelopathic effect on weed (27).
18. Kill hair lice and promote hair growth
Eucalyptus oil and Leptospermum petersonii solution thrice a week is safe and effective in eliminating head lice (28). Moreover, eucalyptus oil (15 or 20 ml) spray treatment proved better against pediculosis even to insecticide-resistant head louse populations than clove oil (29).
Eucalyptus extract is very beneficial for hair growth. It increases amount and hair fiber properties thus improve hair luster and bounce in the root part of the hair (30).
19. Healthy skin
Chlorhexidine (CHG) is an antimicrobial agent widely used for skin:: antisepsis and eucalyptus oil in the combination of CHG enhance the ability to penetrate skin thus this combination may be used as an improve biocide contact with additional microorganisms present in the skin, thereby enhancing:: antisepsis (32).
Side effects of Eucalyptus oil
1. Risk of allergy
The person who is allergic to eucalyptus oil shows side effects like a burning pain in the mouth, nausea, vomiting, diarrhea, abdominal pain, bronchospasm, tachypnea, chemical pneumonitis, respiratory depression, headache, vertigo, drowsiness, slurred speech, ataxia, convulsions, and coma. Breath and urine may smell of eucalyptus oil (32).
2. Risk of seizure
Exposure of eucalyptus oil in patients with epilepsy induce a seizure, which symptoms are central nervous system depression within 30 minutes however this oil is easily available in almost every home (33).
Therefore, the person who has epilepsy in history consuming, applying, or inhaling eucalyptus oil in any form should be avoided (34).
3. Should not be consumed directly
A research study suggested that 10 ml of eucalyptus oil oral consumption results in a burning sensation in the mouth and throat, abdominal pain, vomiting, central nervous system depression, ataxia, and disorientation followed by loss of consciousness occurring in 10–15 min. Thus, small amounts of eucalyptus oil can be fatal, it should never be given orally (35).
4. Risk of prolonged coma
Eucalyptus oil injections can cause a rapid onset of the central nervous system (CNS) depression, seizures, pneumonitis, and cardiac dysrhythmias. Other than this overdose (1000 ml) of eucalyptus oil can cause prolonged coma which occurs elevated serum levels, heart failure, and brain injury thus precaution should be needed (36).
5. Should not apply more than a concentration of 25%
A research study suggested that according to Canada Cosmetic Ingredient Hotlist eucalyptus oil should be used at no more than 25% in cosmetic products. Eucalyptus oil is also classed as a ‘Schedule 6’ poison in Australia. Therefore, strong warnings and safety directions on the label is needed.
6. The risk to disturb human skin integrity
Low concentration of eucalyptus oil is beneficial for skin penetration while a higher concentration of this oil may decrease the integrity of the dermal barrier thus precautions should be needed before application (37).
How to use Eucalyptus oil
1. Application of eucalyptus oil may vary with its applicability what you want to treat For asthma – 7 drop of eucalyptus oil with fry sesame oil with beeswax is used (38).
2. Essential oil/vapor as beverages
The use of the combination of eucalyptus essential oil with thermal treatment successfully inhibited the development of yeast (S. cerevisiae SPA) in fresh fruit juices thus this oil can be used as an antimicrobial agent and suggest its potential application for beverages preservation. (39)