Kunzea Oil
Scientific Name(s): Kunzea ambigua
Common Name(s): Poverty bush, Southern spring flower, Tasmanian spring flower, Tick bush, White cloud, White kunzea
Medically reviewed by Drugs.com. Last updated on Mar 22, 2024.
Clinical Overview
Use
In vitro studies indicate a moderate antimicrobial effect of topical K. ambigua essential oil on common hospital-acquired pathogenic organisms of the oral cavity and skin (eg, methicillin-resistant Staphylococcus aureus [MRSA], other staphylococci and streptococcal spp., Candida krusei and other Candida spp.). Insecticidal activity has also been studied; Kunzea spp. extract at varying concentrations (40% to 100%) has shown moderate repellent activity comparable to that of pyrethrum 25% extract and citronella 40%.
Dosing
Clinical studies are lacking to provide kunzea oil dosing recommendations.
Contraindications
Data are limited; sensitivity to essential oils from cultivars of the Myrtaceae family may be considered a contraindication.
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Interactions
None well documented.
Adverse Reactions
Application of oxidized essential oils to the skin may cause skin sensitization.
Toxicology
No data.
Scientific Family
- Myrtaceae (myrtle)
Botany
K. ambigua and the related Kunzea ericoides species are shrubs in the Myrtaceae family native to the coastal strip and adjacent plateaus in the southeastern Australian states of Tasmania, Victoria, and New South Wales. It often forms dense thickets, and although closely identified with Leptospermum, it is easily distinguished by its long, protruding stamens. Its growth habit is variable on sandstone or granite-based soils, reaching a height of 2 to 3 m and consisting of stiff, upright, spreading branches with fibrous, furrowed bark. Masses of spreading stamens give the flowers a fluffy appearance. Small leaves approximately 1 cm in length and narrow-linear in shape are produced on short stalks.(CANBR 2015, Thomas 2009a, USDA 2021)
History
K. ambigua was named for the German botanist Gustav Kunze (1793-1851) and from the Latin ambigua, meaning doubtful or uncertain.(CANBR 2015) Commonly known as "tick bush," it has been described anecdotally as a bush under which animals sleep to seek refuge from biting insects. Essential oils have been used as insecticides and antiseptics, and as a treatment for wounds, diarrhea, cold, and inflammation.(Ito 2004, Kasajima 2008, Thomas 2009a)
Chemistry
Composition of essential oils varies based on the country of origin or cultivar. For example, 2 cultivars collected in November 2005 from the campus of the University of Tasmania contained variable concentrations of 1,8-cineole (5.6% vs 0%), viridiflorol (0.3% vs 3.9%), alpha-pinene (53.7% vs 7.3%), and spathulenol (1.3% vs 34.8%), among others.(Thomas 2009a, Thomas 2009b, Warnke 2009) Common chemical constituents with the highest, although variable, concentrations among K. ambigua essential oils from a commercial preparation and 2 cultivars from the campus of the University of Tasmania were alpha-pinene (7.3% to 53.7%), spathulenol (1.3% to 34.8%), globulol 2104 (7% to 15.3%), bicyclogermacrene 1758 (1.2% to 7.6%), viridiflorol 2112 (0.3% to 6.6%), and viridiflorene plus alpha-terpineol (2.3% to 5.1%). Other constituents common to all 3 sources but in lower amounts (0.1% to 4.5%) were limonene, alpha-gurjunene, linalool, caryophyllene, aromadendrene, alloaromadendrene, citronellol plus delta-cadinene, calamenene, palustrol, ledol, and rosifoliol.(Thomas 2009a, Thomas 2009b) Because essential oils containing alpha-pinene can auto-oxidize, storage in a dark, airtight container under refrigeration is recommended.(Kasajima 2008) A new flavonoid (kunzeagin A) and 6 new chromones (kunzeachromones A through F) were discovered from an extract of the dried leaves, as well as 6 phloroglucinol glucosides (kunzeaphlogins A through F) and a hydrolysable tannin (kunzeatannin A).(Ito 2004, Kasajima 2008)
Uses and Pharmacology
The essential oils from plants belonging to the Myrtaceae family (eg, tea tree oil) have inhibited production of tumor necrosis factor alpha, prostaglandin E2, interleukin 1 (IL-1), and IL-8. They have also exhibited antipruritic, anti-inflammatory, and possibly anti-infective effects for some dermatologic conditions, including psoriasis, eczema, pastern dermatitis in horses, and Malassezia spp. skin infections. Modulation of vasodilation and plasma extravasation has been demonstrated by components of tea tree essential oil, such as terpinen-4-ol.(Thomas 2015)
Ducane kunzea oil (1 mL per milliliter of K. ambigua liquid) for inhalation is listed by the Australian Therapeutic Goods Administration (TGA) as a therapeutic substance for treating symptoms of influenza/flu, arthritis pain, muscular aches and pains, rheumatic pain, nervous tension, stress, and mild anxiety.(Ducane 2015) K. ambigua is also available for topical application. Advisory statements by the Australian TGA for K. ambigua essential oil topical products note that undiluted oils should not be applied directly to the skin unless formulated in a cream base.(TGA 2012)
Antifungal activity
In vitro data
Activity against fungal pathogens has been reported for the related K. ericoides oil.(Chen 2016)
Antimicrobial activity
In vitro data
The antimicrobial activity of various essential oils, including kunzea oil (from Australia), were tested in vitro against 13 common hospital-acquired pathogenic organisms of the oral cavity and skin (eg, MRSA, other staphylococci and streptococcal spp., C. krusei and other Candida spp.), as well as against commercially available reference strains. Kunzea oil showed considerable efficacy with inhibition zones ranging from 9 to 18 mm on agar diffusion tests. The largest effective zones ranged from 16 to 50 mm for thyme white, lemon, lemongrass, and cinnamon oils compared with 0 to 12 mm for sandalwood, whereas controls ranged from 14 to 16 mm for povidone iodine, chlorhexidine, and hydrogen peroxide; ethanol concentrations of 70% reached a maximum of 9 mm in diameter.(Warnke 2009)
Antiviral activity
Clinical data
A group of researchers evaluated a honey preparation containing the related K. ericoides for antiviral activity.(Semprini 2017, Semprini 2019) In the single-blind, open-label study, no difference was reported regarding efficacy between the honey and the comparator (acyclovir 5%) in the treatment of herpes simplex labialis.(Semprini 2019)
Cancer
In vitro data
Of the 6 kunzeachromones (A through F) identified from an extract of dried leaves, 4 (A, B, D, and F) were the first examples of C-glucosylchromone digalloyl esters. Because other polyphenols with a galloyl unit (ie, epigallocatechin gallate [EGCG] from green tea) have possible chemopreventive effects against cancer, kunzeachromones A, B, D, and F were tested in vitro for possible anti–tumor-promoting activity via Epstein-Barr virus early antigen (EBV-EA) test. All 4 chromones inhibited EBV-EA activation at least as effectively as EGCG without exhibiting cytotoxicity.(Ito 2004)
Dermatological effects
Animal data
A randomized, controlled-comparator clinical study conducted in 37 horses with localized pastern dermatitis evaluated the effect of an ointment formulation containing kunzea oil 20% compared with that of the same ointment formulation containing a control (ketoconazole 2%). Each ointment formulation contained zinc oxide (5%), salicylic acid (5%), precipitated sulfur (5%), triethanolamine (1%), and cod liver oil (10%), and was applied twice daily for 7 to 28 days. Horses receiving kunzea oil experienced significantly better healing of total lesion area (P<0.01) and total lesion scores (P<0.05) by day 7, with 7 of the 11 (64%) in the kunzea group recovering fully, compared with 2 of 10 (20%) in the control group. Two of the remaining 4 horses in the intervention group recovered fully within 21 additional days of treatment. Of the 6 horses in the control group that crossed over to kunzea oil after day 7, five (83%) recovered fully within 28 total days (mean, 14 days).(Thomas 2009b)
Clinical data
In an 8-week, randomized, double-blind, comparator trial (N=30), adults with mild to moderate psoriasis (10% or less of body surface area) experienced no statistically significant differences in clinical efficacy scores (51% and 60%) or pruritus scores (77% and 72%) with a kunzea oil 20% formulation and active control, respectively, both of which contained liquor carbonis detergens 5% and salicylic acid 3%. No adverse events were reported.(Thomas 2015)
A group of researchers has published clinical studies evaluating a honey preparation containing the related K. ericoides in rosacea(Braithwaite 2015) and acne(Semprini 2016) (as well as for antiviral activity).(Semprini 2017, Semprini 2019) Positive findings were reported for kanuka-containing honey in reducing severity scores in rosacea and acne; however, both studies were single-blind, and attribution of efficacy to honey alone rather than kunzea chemical constituents cannot be ruled out.
Insecticide/Repellent
In vitro data
The insecticidal effects of an extract mixture from the leaves and stems of K. ambigua and Kunzea baxterii were compared with the effects of a natural pyrethrum 25% extract. Extracts from each Kunzea spp. provided similar proportions of the biologically active epimers and conformers of tetramethylcyclohexenedione. For the insecticidal Kunzea spp. extract mixture, median lethal dose (LD50) by topical application to mustard beetles, aphids, thrips, and houseflies was 1 mcg, 3.9 mcg, 15 mcg, and 10 mcg, respectively, per insect, compared with 0.3 mcg, 3.8 mcg, 7.9 mcg, and 0.01 mcg, respectively, per insect for pyrethrum. The insecticidal activity of the Kunzea spp. extract was moderate and comparable to that of pyrethrum extract.(Khambay 2002)
Clinical data
The potential mosquito repellent activity of kunzea oil was investigated by measuring the total number of landings (repellency) and bites (complete protection time) from female Aedes aegypti mosquitoes on treated and untreated forearms of volunteers (N=4). Kunzea oil (40%, 60%, and 100%) was tested against citronella (40% and 60%) and diethyltoluamide (DEET) (5.2%). Although there was significantly more repellent effect in the treatment group versus the untreated control (P<0.05), no significant difference was noted among the 3 kunzea oil concentrations, and mean repellency remained below 80%. All kunzea oil concentrations had similar repellency to citronella 40%, but significantly less activity than citronella 60% (P<0.05) and DEET (P<0.05). Complete protection time was approximately 5 times greater for DEET than for the other products. The addition of vanillin to kunzea oil did not affect mean repellency.(Thomas 2009a)
Dosing
Clinical studies are lacking to provide kunzea oil dosing recommendations.
In clinical trials, kunzea oil 20% in dermatological formulations demonstrated no effects on mild to moderate psoriasis in humans, but demonstrated efficacy on pastern dermatitis in equines.(Thomas 2015, Thomas 2009b)
Pregnancy / Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking. No data are available; pregnant or lactating women were excluded from clinical trials.
Interactions
None well documented.
Adverse Reactions
Auto-oxidation of alpha-pinene products can cause skin sensitization; avoidance of old or oxidized oils is recommended. To avoid oxidation, store in a dark, airtight container under refrigeration.(Tisserand 2014)
Toxicology
No data.
References
Disclaimer
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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