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Lemon Myrtle - Exciting Discoveries
Lemon Myrtle essential oil is the volatile essential oil steam distilled from the leaves and young branchlets of the native Australian Lemon Myrtle tree (Backhousia citriodora). This somewhat rare rainforest tree species is indigenous to moist, isolated locations along the subtropical and tropical east coast of Australia.
The Backhousia citriodora tree developed its natural defences to various plant pathogens and leaf eating bugs, by the evolution of tiny round oil sacs throughout the entire leaf. These ‘pin prick’ size oil sacs can be seen in the leaf, when the leaf is faced toward the sun or any good light source.
Lemon Myrtle essential oil was first distilled in 1888 and reported back to Germany as an essential oil extremely rich in citral.2 Further distillations occurred around Gympie in southeast Queensland, Australia throughout the 1900’s, with further reports back to London and Germany, again confirming the high citral quality of the essential oil of Lemon Myrtle. World War I brought about the winding down of wild bush harvesting of Lemon Myrtle from its indigenous locations.
In 1925 leading N.S.W. Government Chemist, Arthur Penfold revisited Lemon Myrtle and discovered that the oil of Lemon Myrtle, on the Rideal-Walker test, had a coefficient of 16 (16 times stronger in bacterial action than the then standard – carbolic acid) and was 25% stronger than Tea Tree oil, which had a coefficient of between 11 and 13. 3
During World War II a national drinks company, Tarax, used the essence of Lemon Myrtle to flavour drinks when natural lemon essence was in short supply. With the cessation of the war, supplies of lemon essences were restored and Lemon Myrtle was again neglected, and production subsequently declined – only to be revived again in the late 1980s.
In the late 1980’s and through the 90’s, a small number of committed Australian pioneers located in the sub tropical north east
coastal Byron Bay region of N.S.W. set about rediscovering a number of native Australian plants for potential food, herb and tea production.
Lemon Myrtle emerged as the most promising food flavouring, both as an essential oil and herb, for use in food, cosmetics and possibly therapeutics.
Anti-microbial Properties
“The antimicrobial activity of Backhousia citriodora (Lemon Myrtle) essential oil, was found to be greater than that of citral alone, and often superior to Melaleuca alternifolia (Tea Tree) essential oil.”
Research conducted by The School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia, demonstrated Lemon Myrtle essential oil to have greater antimicrobial activity than Tea Tree against Alcaligenes faecilis, Mycobacterium phlei, Staphylococcus aureus, Fusearium graminearum, Microsporum gypsium, Trichophyton mentrgrophytes and Trichophyton rubrum.
Also demonstrated by the research was the significant control of Trichphyton mentagrophytes, Trichophyton trichrubrum, Trichophyton tonsurans, at 100% concentration where no growth was observed. At 0.1% concentration of Lemon Myrtle essential oil, growth was inhibited for Trichphyton tonsurans. At 10% concentration of Lemon Myrtle essential oil, Trichophyton
mentagrophytes and Trichophyton trichrubrum growth was restricted.
“The results of this study show that Backhousia citriodora essential oil is an effective antibacterial and an excellent antifungal……. The data generated, however, would indicate that Backhousia citriodora essential oil has potential as an antiseptic or surface disinfectant”.4
“Lemon Myrtle (essential) oil was shown to possess significant antimicrobial activity against organisms Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, methicillin resistant Staphylococcus aureus (MRSA), Aspergillus niger, Klebsiella pneumoniae and propionibacterium acnes comparable to its major component-citral”.
“The results of the microbiological tests indicate that Lemon Myrtle oil was significantly more active than Tea Tree oil against the broad range of micro organisms tested”.
“Overall results indicate that Lemon Myrtle oil has potential usage as an antiseptic or antimicrobial agent in the treatment of skin micro organisms associated with cuts, bites, acne and tinea.
For Lemon Myrtle oil to be used as an effective topical antimicrobial, a toxicity-safety assessment is required. Skin sensitisation has been reported for the topical application of 100% citral at concentrations greater than 1%. However, researchers have shown that the addition of terpenes such as α-pinene and d-limonene to citral in the ratio of 1:4 prevents a sensitisation reaction occurring (Opdyke, 1976)”.5
Thirty one children (mean age 4.6 ± 2.1 years) with the diagnosis of Molluscum contagiosum (mean length of time with condition 8.6± 5.3 months) were treated with daily topical application of a 10% solution (v/v) of essential oil Australian Lemon Myrtle (Backhousia citriodora) or vehicle (olive oil). At the end of 21 days, there was greater than 90% reduction in the number of lesions in 9/16 children treated with lemon myrtle oil, whole 0/16 children met the same criteria for improvement in the vehicle group (P<0.05) no adverse effects were reported.6
1. Hayes A.J., Markovic B., Toxicity of Australian essential oil Backhousia citriodora (Lemon Myrtle). Part 1. Antimicrobial activity and in vitro Cytotoxicity, Food and Chemical Technology 40 (2002) 535-543.
2. Schimmel and Co. Apr 1888, pg 20, Oct 1888 p17.
3. Penfold A.R., Grant, R., 1925. The Germicidal values of some Australian Essential oils and their pure constituents. Journals and Proceedings of the Royal Society of New South Wales 59, 346-350.
4. Wilkinson J.M., Tipwell M., Ryan T., Cavanagh H.M.A., Bioactivity of Backhousia citriodora: Antibacterial and Antifungal Activity, Journal of Agriculture and Food Chemistry 2003, (51, 76-81)
5. Hayes A.J., Markovic B, Toxicity of Australian essential oil Backhousia citriodora (Lemon myrtle). Part 1. Antimicrobial activity
and in vitro cytotoxicity, Food and Chemical Toxicology 2002, (40, 535-543)
6. Burke B.E., Baillie J., Olson R.D., Biomedicine & Pharmacotherapy volume 58, issue 4, May 2004, Pages 245-247
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