Articles

Melaleuca alternifolia

Synonyms

Melaleuca linariifolia

Vernacular Names:

Malaysia: Gelam Wangi [1]
English:  Australian Tea Tree, Narrow-leaved Paperbark, Snake oil

General Information

Description

Melaleuca alternifolia is a hardwood tree of the Myrtaceae family. It is a tree that is indigenous to the coastal areas of Australia. The tree can grow up to 8m high. The bark is flaky. The leaves are alternate, needle-like with spicy, strong and pungent aroma. The flowers are in loose, white to cream coloured terminal spikes which appear from October to November. The stamens of these flowers are prominent more than 12mm long, united at the bases to form 5 bundles. The petals are small and inconspicuous. The capsules persisting within fruiting hypanthium. [40]

Plant Part Used

Leaves [1]

Chemical Constituents

1,4-cineole, 1,8-cineole, allo-aromadendrene, a-bulnesene, a-copaene, a-cubebene, a-gurjunene, a-muurolene, a-p-dimethyl-styrene, a-phellandrene, a-pinene, a-terpinene, a-terpinolene, a-thujene, aromadendrene, b-elemene, b-phellandrene, b-pinene, calamenene, camphene, caryophyllene, cymenene, g-terpinene, humulene, limonene, menthatrienes, myrcene, p-cymene, sabinene, terpinolene, viridiflorene, a-terpineol, hexanol, linalol, nerol, p-cymen-8-ol, piperitol, terpinen-1-ol, terpinen-4-ol, allyl-hexanoate, alpha-cadinine, camphor leaf, piperitone leaf. [1] 

Traditional Used:

Bundjalung Aborigines of New South Wales made used of the leaves to treat cuts, abrasions and skin infections. They use the infusion of the leaves for treatment of skin diseases which are mainly injuries and infections. It is also useful in the treatment of burns. The essential oil can be used to relieve itching and redness and scaling of psoriasis, seborrhoea, and eczema. [1][2]

Poultice of the leaves are used to treat cough and colds. It relieves the symptoms of asthma, bronchitis, laryngitis, sinusitis and even whooping cough. [1][2]

It has found use in treatment of reproductive and urinary tract infection like vaginitis and cystitis. [2]

M. alternifolia improves oral hygiene and relieves gingivitis, mouth ulcers, periodontal disease and toothaches. This is in the form of decoction of the leaves used as mouth washes. 

Poultice of the leaves are used to treat cough and colds. It relieves the symptoms of asthma, bronchitis, laryngitis, sinusitis and even whooping cough. [1][2]

It has found use in treatment of reproductive and urinary tract infection like vaginitis and cystitis.

M. alternifolia improves oral hygiene and relieves gingivitis, mouth ulcers, periodontal disease and toothaches. This is in the form of decoction of the leaves used as mouth washes. [2]

Pre-Clinical Data

Pharmacology

Cytotoxic activity 

The potential of anti-tumour activity of M. alternifolia was done against human melanoma cells and their drug-resistant counterpart. It was reported that both cell line grown in the presence of tea tree oil were inhibited but more so with the drug-resistant variant cell population. This effects was found to be mediated by their interaction with plasma membrane and subsequent reorganization of membrane lipids. A more recent study done reported that the effect exerted on these drug-resistant variant human melanoma cells, is mediated by the interaction with the fluid DPPC phase, rather than with the more organized “rafts” and that this interactions preferentially influences the ATP-dependent antiapoptopic activity of P-gp likely localized outside “rafts” [3][4] 

In another study it was reported that M. alternifolia and its major active terpene component terpinen-4-ol significantly inhibit the growth of two murine tumour cell lines (AE17 mesothelioma and B16 melanoma) in a dose and time-dependent manner. M. alternifolia induced necrotic cell death coupled with low level apoptotic cell death in both tumour cell lines. However, M. alternifolia does not seem to affect non-tumour fibroblast cells. [5] 

Anti-oxidant and Anti-inflammaotory activity 

Studies found that the essential oil of M. alternifolia at a concentration of 0.1% directly stimulated ROS production by polymorphnuclear neutrophils (x8.7 vs. 0% EO, p>0.05) and increased the intracellular ROS produced by monocytes. Regardless of the stimulating agent used the (Phorbol ester, Formly-methionyl-leucyl-phenylalanine or opsonised zymosan) tea tree oil decrease the intracellular ROS production at the dilution of 0.1% by PMNs and monocytes, more so with PMNs. This shows that M. alternifolia also protects organism from an excess ROS through an anti-oxidant and radical scavenging activity apar from being a direct active mediator of batericidal action of circulating leucocytes. In another study, that M. alternifolia does not only act as an anti-inflammatory mediator through its antioxidant activity but also effectively protect the organism by reducing the proliferation of inflammatory cells without affecting their capacity to secrete anti-inflammatory cytokines. Study reported that the water soluble component of M. alternifolia did not affect the agonis-stimulated superoxide production by neutrophils but significantly and in a dose-dependent manner suppressed the agonist-stimulated superoxide production by monocytes and this suppression was not due to cell death. The water soluble component contains the following terpinen-4-ol, alpha-terpineol and 1,8-cineol. It was found that alpha-terpineol could siginficantly suppress fMLP, LPS and PMA-stimulated superoxider production while 1,8-cineole had no effect. [6][7][8] 

Acaricidal activity 

At a dose of 8 microl M. alternifolia was lethal to more than 70% of ticks (Ixodes ricinus) which increased with increase concentration and duration of exposure. The effects of tea tree oil on Sarcoptes scabiei var. hominis was investigated and reported that M. alternifolia and its active component terpinen-4-ol were highly effective in reducing mites survival times at 5% concentration. These effects on ticks and mites and also its effects on lice could be mediated through inhibition of acetylcholinesterase. [9] 

Antimicrobial activity 

Antiviral 

The antiviral activity of M. alternifolia essential oil and its main components, terpinen-4-ol, alpha-terpinene, gamma-terpinene, p-cymene, terpinolene and alpha-terpineol was evaluated against polio type 1, ECHO 9, Coxsackie B1, adeno type 2, herpes simplex (HSV) type 1 and 2 viruses by 50% plaque reduction assay and anti-influenza virus assay by inhibition of the virus-induced cytopathogenicity. Study reported that M. alternifolia and its main components was effective in inhibiting influenza A/PR/8 virus subtype H1N1 replication at dose below the cytotoxic dose. However, they were ineffective against the other tested viruses. [10] 

Antibacterial 

M. alternifolia and its major components had been found to effectively inhibit the growth of a wide range of bacteria which includes Escherichia coli, Staphylococcus aureus, MRSA, transient skin flora, oral pathogens. Carson et al. seem to have done a lot of studies on the effectiveness of tea tree oil on various micro-organism and had concluded that the most probable mechanism of action was its ability to disrupt the permeability barrier of cell membrane structure and accompanying loss of chemiosmosis control. The exception with Pseudomonas aeruginosa was probably due to its more resistant outer membrane which was not easily distrupted. It was recently identified that the MexAB-OprM efflux pump was the contributing factor to this special tolerance. [1][11-23] 

Antifungal 

Another notable effect of tea tree oil as an effective antimicrobial is its ability to inhibit the growth of a number of fungal infection. This property had made it relevant as an addition to anti-seborrhoeic preparations. Either alone or in combination with other anti-fungal drugs it has proven its efficacy in arresting the growth some of the well known fungi especially Candida albicans making it useful in the treatment of vaginal candidiasis. The susceptibility of Malassezia furfur to the effects of tea tree oil was demonstrated by Hammer et.al can render it useful in the treatment of skin conditions involving this fungus. Amongst other fungi which could be inhibited by tea tree oil are Trichophyton rubrum , Trichophyton mentagrophytes, Trichophyton tonsurans , Aspergillus niger, Penicillium species, Epidermophyton floccosum, and Microsporum gypsum. [24-29] 

With regard to the components of the essential oil which shows effects on fungal growth, it was found that all components (terpinen-4-ol, alpha-terpineol, linaool, alpha-pinene and 1,8-cineol) were effective except for beta-myrcene. [30]

Toxicities

Ingestion of the pure M. alternifolia of a magnitude of more than 10ml had been associated with diorientation and ataxia which is resolved spontaneously within 5 hours. It had been reported that the ingestion of an estimated amount of about 10ml by a 4 year old child had resulted in ataxia and respiratory depression requiring intubation. The child was susequently discharged after 24 hours with no sequelae. The ingestion of an estimated amount of 0.5-1ml/kg by an adult would result in coma for 12 hours followed by hallucination and persistent, colicky diarrhoea. [1]

Clinical Data

Clinical Trials

A number of clinical trials had been done for M. alternifolia

Treatment of tinea pedis – 104 patients completed a randomized, double blind trial to evaluate the efficacy of 10% w/w tea tree oil cream compared to 1% tolnaftate and placebo creams in the treatment of tinea pedis. It was found that tea tree oil is not able to out perform tolnaftate in its antifungal activity, however it was able to improve of the symptoms i.e. scaling, inflammation, itching and burning. [31] 

Treatment of toenail onychomycosis – 60 patients underwnt a randomized, double-blind, placebo-controlled study to examine the clinical efficacy and tolerability of 2% butenafine hydrochloride and 5% M. alternifolia oil incorporated in a cream to manage toenail onychomycosis. At the end of 16 weeks, 80% of the patients using the medicated cream were cured. No relapse was seen during follow up in the cured patients. [32] 

Treatment of hand wart. – Topical application of tea tree oil in a dose of once daily for 12 days had a successful outcome with disappearance of the wart and re-epithelization. [33] 

Determination of susceptability of organisms causing otitis externa to tea tree oil – 57 swabs were taken from ears of 52 patients with otitis externa. 51% of the swabs showe presence of pathogenic organism and of this 71% contained both bacteria and yeast which were susceptible oft tea tree oit at 2 % or less. The only organism showing resistance was Pseudomonas aeruginosa; however 25% of this bacteria was sensitive. [34] 

M. alternifolia reduces histamine-induced skin inflammation – 27 volunteers were injected intradermally in each formarm with histamine diphospate to investigate the anti-inflammatory properties of tea tree oil on histamine-induced weal and flare. It was found that the mean weal volume was significantly decreased after tea tree oil application (10 minutes). [35] 

Adverse Effects in Human:

M. alternifolia can cause irritant and allergic contact contact dermatitis, systemic hypersensitivity reactions and erythema multiforme-like eruptions particularly after the use of improperly stored oil on damaged skin. The typical lesion seen contact dermatitis of tea tree oil is an eczematous plaque in the area of topical application but bullous lesions and erythema multiforme-like reaction can also occur. Microscopical studies of areas distal to the contact dermatitis showed spongiotic dermatitis rather than the histological features of erythema multiforme. [1]

Used in Certain Conditions

Pregnancy / Breastfeeding

No documentation

Age Limitations

Neonates / Adolescents

No documentation

Geriatrics

No documentation

Chronic Disease Conditions

No documentation

Interactions

Interactions with drugs

No documentation

Interactions with Other Herbs / Herbal Constituents

No documentation

Contraindications

Contraindications

No documentation

Case Reports

Dermatological Adverse Reaction 

Four cases of allergic contact dermatitis due to tea tree oil was reported in the Netherlands. van der Valk et al. attribute this to the presence of eucalyptol which is probably the most important allergen. [36] Khanna et al. reported a case of contact dermatitis due to tea tree oil which presented with an extensive erythrema multiforme-like sik reaction. [37] 

Effects of Ingestion 

The first report on tea tree oil poisoning due to ingestion was in 1994 where a 23-month old boy developed confusion and inability to walk after 30 minutes of ingesting less than 10ml of T36-C7, a commercial product containing 100% melaleuca oil. He became asymptomatic within 5 hours of ingestion. [38] In 1995 another child was reported to have ingested less than 10 ml of tea tree oil and developed ataxia and drowsiness. This time the child was a 17-month old male. [39] A more recent report a 4-year old boy ingested a small quantity of tea tree oil and within 30 minutes developed ataxia which shortly progressed to unresponsiveness requireing endotracheal intubation. His neurological status improved gradually over 10 hours. Health care providers should be made aware of the potential toxicity of tea tree oil as this is becoming a commonly used disinfectant today.

Read more

  1) Cultivation

  2) Medicinal Herbs

  3) Essential Oil

References

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