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Manuka Oil

Scientific Name(s): Leptospermum scoparium J.R. Forst. et G. Forst.
Common Name(s): Manuka oil, Red manuka, Tea tree, Teatree

Clinical Overview

Use

Manuka oil has selective antibacterial activity against Gram-positive organisms particularly S. aureus. Limited studies in wound healing and for anti-inflammatory effect have been conducted.

Dosing

Clinical trials are lacking on which to base dosing guidance.

Contraindications

Avoid use during pregnancy because of reported spasmolytic activity.

Pregnancy/Lactation

Documented adverse effects. Avoid use during pregnancy because of reported spasmolytic activity.

Interactions

None well documented.

Adverse Reactions

L. scoparium contains a lipophilic flavonoid that specifically interacts with benzodiazepine receptors (GABA-A receptor-chloride channel complex).

Toxicology

There are limited clinical toxicological data on manuka oil in the scientific literature.

Botany

L. scoparium is the only Leptospermum species native to New Zealand. Its size ranges from a creeping plant to a small tree (of 8 m in height) and it is widely distributed in various climatic and altitudinal zones in New Zealand. The physical characteristics, such as flower and leaf color, leaf size and shape, branching habit, and foliage density vary considerably among populations. Manuka oil should not be confused with Melaleuca alternifolia (see Tea Tree Oil monograph). (USDA)1, 2, 3, 4

History

Early New Zealand records indicate that the plant's bark, leaves, sap, and seed capsules were used in beverages and medicinal preparations.4 The plant was valued for its medicinal properties and wood by the indigenous Maori people; the wood was utilized for gardening tools, fishing, housing structures, and weapons.2, 5

Captain James Cook used the leaves of the plant as a tea to combat scurvy during long explorations of the southern hemisphere; early European settlers of New Zealand adopted Captain Cook's use of the plant as a tea.2

Commercial development of the essential oils has led to a range of OTC products marketed in New Zealand and exported to European and Asian markets. These products are used for topical treatment of various conditions including the following: Fungal and bacterial skin infections; inflammation from sunburn, insect bites, or joint pain; eczema or psoriasis. The oils also are used in perfumes and soaps.2

Chemistry

The L. scoparium populations of New Zealand are highly variable in oil chemical composition and activity.6, 7 Standardized steam distillation and gas chromatography-mass spectrometry of the essential oils of 15 New Zealand L. scoparium populations identified the following in various quantities per species: alpha-pinene, beta-pinene, myrcene, rho-cymene, 1,8-cineole, linalol, methylcinnamate, alpha-farnesine, isoleptospermone, leptospermone, sesquiterpenes such as cadina-3,5-diene and delta-amorphene, and triketones.3, 4, 6

Triterpenoids and flavonoids (including methylated and methoxylated flavonoids such as 5,7-dimethoxyflavone, 5-hydroxy-7-methoxy-6-methylflavone, and 5-hydroxy-7-methoxy-6,8-dimethylflavan-3-one) have been identified in a dichloromethane extract of L. scoparium.8, 9 Oligosaccharide components include maltose (the major component), isomaltose (or maltulose), kojibiose, turanose (or gentiobiose), and nigerose.10

The average content of total flavonoids in New Zealand manuka (L. scoparium) honey was 3.06 mg per 100 g honey; the main flavonoids consisted of quercetin, isorhamnetin, chrysin, and luteolin.11 The potentially active methylglyoxal, derived from the precursor dihydroxyacetone, has been identified in the flowers of certain species of Leptospermum native to New Zealand and Australia, and is found in Manuka honey.12, 13

Uses and Pharmacology

Antimicrobial

Animal data

Manuka oil has selective antibacterial activity against gram positive organisms14 such as Staphylococcus aureus and Micrococcus luteus.15 Manuka oil has little to no activity against gram-negative organisms such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Proteus vulgaris.14, 15, 16

Some studies document the activity of L. scoparium against fungi and yeast;14, 16 however, there are limited data to support these claims for L. scoparium as compared with other species of Myrtaceae (eg, kanuka or Kunzea ericoides ).17

Studies have been conducted on wound healing in animals, especially in horses.12

Clinical data

Studies have evaluated the efficacy of Manuka honey in healing infected wounds. In neuropathic diabetic foot ulcers, Manuka honey-impregnated dressings increased healing rates and reduced the need for antibiotics in a clinical study of 63 patients versus saline dressings. However, the percentage of healed ulcers was not affected.18 While the role of honey as an anti-infective agent has been described, the additive efficacy of Manuka in the honey has not been established in robust clinical trials.12, 13

Anti-inflammatory effects

Animal data

Anti-inflammatory and immunomodulatory effects have been described in published reviews.13

Clinical data

A small clinical trial (n=19) evaluated Manuka with Kanuka essential oils as a gargle for benefit on radiotherapy-induced mucositis and symptoms. Mucositis reportedly developed significantly later in patients with the active gargle. The small sample size of most variables prevented further statistical comparisons. Mean pain scores gradually increased over treatment time with fewer patients in the active gargle group experiencing scores of 3 or higher and going the longest until that level of pain was reached; this was also reflected in the use of daily analgesics. Interestingly, patients with more family members present during treatment tended to report more frequent and more severe pain than those without family members present.19

Manuka, as the honey, has been studied in radiotherapy-induced mucositis in limited clinical trials finding no improvement on mucositis, and some effect on bacterial infection.20, 21( Bardy, Hawley) A study conducted in patients with rhinosinusitis, using mankua honey nasal spray, found no endoscopically validated improvement in symptoms.22

Other uses

The pharmacological action of manuka oil for treating diarrhea, colds, and inflammation was studied on a field-stimulated guinea pig ileum. Manuka oil induced a spasmolytic effect17, 23; the mechanism of action is likely to be the result of a postsynaptic mechanism and associated with cAMP.23

L. scoparium contains a lipophilic flavonoid that specifically interacts with benzodiazepine receptors in the GABA-A receptor-chloride channel complex. A sedating and potentially anxiolytic effect was recorded in a locomotion study with rats.24, 25

Dosing

There are no reported clinical studies of manuka oil on which dosage recommendations can be based.

Manuka honey has been used anecdotally as a prebiotic. A study evaluated the safety of consuming 20 g of honey daily for 4 weeks found no adverse effects on GI flora.26 20 mL of the honey taken 4 times daily for 6 weeks was evaluated in oral mucositis.20

Pregnancy / Lactation

Documented adverse effects. Avoid use during pregnancy because of reported spasmolytic activity.17, 23

Interactions

None well documented.

Adverse Reactions

Clinical studies of Manuka honey in mucositis found tolerability of dosage regimens to be poor. (Bardy, Hawley)

L. scoparium contains a lipophilic flavonoid that specifically interacts with benzodiazepine receptors (GABA-A receptor-chloride channel complex).20, 21

Toxicology

There are limited clinical toxicological data on manuka oil in the scientific literature. Anecdotal information from OTC use of topical manuka oil products suggests good potential for its future use as an antimicrobial agent.2 Avoid use during pregnancy because of reported spasmolytic activity.17, 23

References

1. Leptospermum scoparium. USDA, NRCS. 2016. The PLANTS Database (http://plants.usda.gov, January 2017). National Plant Data Team, Greensboro, NC 27401-4901 USA.
2. Porter N. Manuka: The good oil from New Zealand. HerbalGram. 2001;53:26-30.
3. Melching S, Bülow N, Wihstutz K, Jung S, König WA. Natural occurrence of both enantiomers of cadina-3,5-diene and δ-amorphene. Phytochemistry. 1997;44:1291-1296.
4. Porter NG, Wilkins AL. Chemical, physical and antimicrobial properties of essential oils of Leptospermum scoparium and Kunzea ericoides. Phytochemistry. 1999;50:407-415.9933953
5. Riley M. Maori Healing and Herbal: New Zealand Ethnobotanical Sourcebook. Paraparaumu, NZ: Viking Sevenseas NZ; 1994.
6. Perry NB, Brennan NJ, Van Klink JW, et al. Essential oils from New Zealand manuka and kanuka: Chemotaxonomy of Leptospermum. Phytochemistry. 1997;44:1485-1494.
7. Priest D. Natural antimicrobials for personal care. Chimicaoggi. 2002;20:43-46.12416030
8. Häberlein H, Tschiersch KP. Triterpenoids and flavonoids from Leptospermum scoparium. Phytochemistry. 1994;35:765-768.
9. Häberlein H, Tschiersch KP. On the occurrence of methylated and methoxylated flavonoids in Leptospermum scoparium. Biochem Syst Ecol. 1998;26:97-103.
10. Weston RJ, Brocklebank LK. The oligosaccharide composition of some New Zealand honeys. Food Chem. 1999;64:33-37.
11. Yao L, Datta N, Tomas-Barberan FA, Ferreres F, Martos I, Singanusong R. Flavonoids, phenolic acids and abscisic acid in Australian and New Zealand Leptospermum honeys. Food Chem. 2003;81:159-168.
12. Carter DA, Blair SE, Cokcetin NN, et al. Therapeutic Manuka honey: no longer so alternative. Front Microbiol. 2016;7:569.27148246
13. White R. Manuka honey in wound management: greater than the sum of its parts? J Wound Care. 2016;25(9):539-543.27608515
14. Harkenthal M, Reichling J, Geiss HK, Saller R. Comparative study on the in vitro antibacterial activity of Australian tea tree oil, cajuput oil, niaouli oil, manuka oil, kanuka oil, and eucalyptus oil. Pharmazie. 1999;54:460-463.10399193
15. Rhee GJ, Chung KS, Kim EH, Suh HJ, Hong ND. Antimicrobial activities of a steam distillate of Leptospermum scoparium. Yakhakhoe Chi. 1997;41:132-138.
16. Kim EH, Rhee GJ. Activities of ketonic fraction from Leptospermum scoparium alone and synergism in combination with some antibiotics against various bacterial strains and fungi. Yakhakhoe Chi. 1999;43:716-728.
17. Lis-Balchin M, Hart SL, Deans SG. Pharmacological and antimicrobial studies on different tea-tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand. J Phytother Res. 2000;14:623-629.11114000
18. Kamaratos AV, Tzirogiannis KN, Iraklianou SA, Panoutsopoulos GI, Kanellos IE, Melidonis AI. Manuka honey-impregnated dressings in the treatment of neuropathic diabetic foot ulcers. Int Wound J. 2014;11(3):259-263.22985336
19. Maddocks-Jennings W, Wilkinson JM, Cavanagh HM, Shillington D. Evaluating the effects of the essential oils Leptospermum scoparium (manuka) and Kunzea ericoides (kanuka) on radiotherapy induced mucositis: a randomized, placebo controlled feasibility study. Euro J Oncol Nurs. 2009;13(2):87-93.19297246
20. Bardy J, Molassiotis A, Ryder WD, et al. A double-blind, placebo-controlled, randomised trial of active Manuka honey and standard oral care for radiation-induced oral mucositis. Br J Oral Maxillofac Surg. 2012;50(3):221-226.21636188
21. Hawley P, Hovan A, McGahan CE, Saunders D. A randomized placebo-controlled trial of manuka honey for radiation-induced oral mucositis. Support Care Cancer. 2014;22(3):751-761.24221577
22. Thamboo A, Thamboo A, Philpott C, Javer A, Clark A. Single-blind study of manuka honey in allergic fungal rhinosinusitis. J Otolaryngol Head Neck Surg. 2011;40(3):238-243.21518647
23. Lis-Balchin M, Hart SL. An investigation of the actions of the essential oils of Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides), Myrtaceae on guinea-pig smooth muscle. Pharm Pharmacol. 1998;50:809-811.9720632
24. Häberlein H, Tschiersch KP. 2,5-Dihydroxy-7-methoxy-6,8-dimethylflavan-3-one a novel flavonoid from Leptospermum scoparium: in vitro affinity to the benzodiazepine binding site of the GABA-A receptor-chloride channel complex. Pharmazie. 1994;49:860.7838874
25. Häberlein H, Tschiersch KP, Schafer HL. Flavonoids from Leptospermum scoparium with affinity to the benzodiazepine receptor characterized by structure activity relationships and in vivo studies of a plant extract. Pharmazie. 1994;49:912-922.7838881
26. Wallace A, Eady S, Miles M, at al. Demonstrating the safety of manuka honey UMF 20+in a human clinical trial with healthy individuals. Br J Nutr. 2010;103(7):1023-1028.20064284

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This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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