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 Apr 21, 2021.
Experimental studies indicate a moderate antimicrobial effect of 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 of the Kunzea spp. extract at varying concentrations (40% to 100%) has shown moderate repellent activity comparable to that of pyrethrum 25% extract and citronella 40%.
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.
Data are limited; sensitivity to essential oils from cultivars of the Myrtaceae family.
Information regarding safety and efficacy in pregnancy and lactation is lacking.
None well documented.
Application of oxidized essential oils to the skin may cause skin sensitization.
K. ambigua is a shrub 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 (6.5 to 10 ft) 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 long and narrow-linear in shape are produced on short stalks.CANBR 1978, Thomas 2009, USDA 2015
K. ambigua was named for the German botanist Gustav Kunze (1793-1851) and from the Latin "ambigua," meaning doubtful or uncertain.2 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 2009
The essential oils from plants belonging to the Myrtaceae family (eg, tea tree oil) have inhibited production of tumor necrosis factor-alpha, PGE2, 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
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 2009, 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 2009 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
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, TGA 2015
Uses and Pharmacology
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 to 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
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 chemopreventative 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
A randomized, controlled-comparator clinical study conducted in horses (N = 37) 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%). The 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 2009
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 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
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 an 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
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 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 diethyltoluamide (DEET) than for the other products. The addition of vanillin to kunzea oil did not affect mean repellency.Thomas 2009
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 2009
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.
None well documented.
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
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