Key References

New Zealand Institute for Crop & Food Research Ltd A Crown Research Institute. (2000). Essential oil production from manuka & kanuka (Crop & Food Research [BROAD sheet] No. Number 116) (p. 4).

Manuka and kanuka belong to the family Myrtaceae, a family rich in leaf oils, which also includes the Eucalypts. Essential oil can be extracted from both manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides) leaves by steam distillation. These oils are very different in their chemical composition, aroma, and biological activity. The characteristics of manuka and kanuka oils from different areas of New Zealand also vary and it is important to recognise the differences. Essential oils from both plants are used in cosmetics, hygiene and aromatherapy products, and herbal medicines.

Douglas, M., Anderson1, R., van Klink, J., Perry, N., & Smallfield, B. (2001). Defining North Island manuka chemotype resources (Crop & Food Research Report No. 447) (p. 15). New Zealand Crop & Food Research Limited.


A survey of the essential oil content and chemical composition of North Island Manuka (Leptospermum scoparium) was conducted to determine the range and variability of essential oil compounds. The purpose of the survey was to complete the resource knowledge base for New Zealand Manuka oil and provide a basis for the expansion of the Manuka oil industry. Foliage from 44 sites and 132 individual plants was collected during February–March 2001. The drying, distillation and chemical analysis of the 132 foliage samples was completed in April–June 2001. The average yield of steam distilled Manuka oil, based on a standard dried sample, was 0.3% but ranged from <0.1 to 1.1%. The levels of 48 chemical compounds were measured in each oil sample by gas chromatography. Broad plant to plant and/or site to site variations were found. Four major chemical types (chemotypes) and one minor chemotype can be identified.

Perry, N. B., Brennan, N. J., Van Klink, J. W., Harris, W., Douglas, M. H., McGimpsey, J. A., … Anderson, R. E. (1997). Essential oils from New Zealand manuka and kanuka: Chemotaxonomy of Leptospermum. Phytochemistry, 44(8), 1485–1494.


Standardized steam distillation and GC analytical methods for oils from manuka, Leptospermum scoparium, are described. These methods were used to analyse two oils from each of 15 L. scoparium populations derived from all around New Zealand, seven Australian Leptospermum populations and one population of Kunzea sinclairii. These populations were all grown from seed at a single site. Principal component analyses of the levels of 50 GC peaks in these 46 oils revealed compositional patterns. Kunzea sinclairii oils were distinguished from Leptospermum oils by higher α-pinene levels (mean 76%). Australian Leptospermum oils had significantly higher 1,8-cineole (mean 20%) and total monoterpene levels (mean 51%) than New Zealand L. scoparium oils (1,8-cineole mean 0.9%, total monoterpene mean 14%). This indicates the need for further taxonomic study of plants currently included in L. scoparium in Australia and New Zealand. There is evidence for three chemotypes of L. scoparium in New Zealand, conforming in part to morphological types: a high-pinene chemotype in the far north, a high-triketone (especially leptospermone) chemotype on the East Cape, and a type containing a complex of sesquiterpenes found over the rest of the country. An oil from the East Cape chemotype showed the strongest antimicrobial activity.

Douglas, M. H., van Klink, J. W., Smallfield, B. M., Perry, N. B., Anderson, R. E., Johnstone, P., & Weavers, R. T. (2004). Essential oils from New Zealand manuka: triketone and other chemotypes of Leptospermum scoparium. Phytochemistry, 65(9), 1255–1264.


The triketone chemotype of manuka, Leptospermum scoparium (Myrtaceae), is commercially important because of its antimicrobial activity. Oils from 36 individual plants on the East Cape of New Zealand all showed similar high triketone contents (> 20% total triketones) with little seasonal variation. Analyses of oils from 261 individual manuka plants collected from 87 sites throughout New Zealand showed that the high triketone chemotype was localised on the East Cape, although oils with triketone levels up to 20% were found in the Marlborough Sounds area of the South Island. Cluster analysis revealed other chemotypes localised on other areas. Ten further chemotypes are described: α-pinene; sesquiterpene-rich with high myrcene; sesquiterpene-rich with elevated caryophyllene and humulene; sesquiterpene-rich with an unidentified sesquiterpene hydrocarbon; high geranyl acetate; sesquiterpene-rich with high γ-ylangene + α-copaene and elevated triketones; sesquiterpene-rich with no distinctive components; sesquiterpene-rich with high trans-methyl cinnamate; high linalol; and sesquiterpene-rich with elevated elemene and selinene. Some of the chemotypes contained aroma compounds at relatively high levels, with a geranyl acetate-rich oil being most notable. Possible origins for this complex array of chemotypes are proposed.

Jonathan McD C Stephens. (2006). The factors responsible for the varing levels of UMF in manuka (Leptospermum scoparium) honey. (PhD). University of Waikato, New Zealand.


The variability in the level of the non-peroxide antibacterial component (UMF®) of mānuka honey produced in New Zealand was studied. A field analysis confirmed considerable variability existed in the honeys, and a number of hypotheses to explain this variability were proposed and examined. Nectar derived from Leptospermum scoparium (mānuka), was confirmed to be the source of UMF®. The dilution of mānuka honey with nectar derived from other floral sources was found to proportionally reduce the UMF® in monofloral mānuka honey. The utilisation of the thixotropic properties of mānuka honey allowed the degree of dilution in the field samples to be established, and an adjustment of the field results to account for the dilution of UMF® by other honey types revealed all monofloral mānuka honey contains UMF®. However, in the monofloral mānuka honey, significantly different levels of UMF® activity were found to come from reasonably well-defined geographic regions. The cause of the variable levels of UMF® activity in mānuka honey would appear to be the different varieties of L. scoparium being harvested by the honeybees, and the environmental parameters influencing nectar production or another species interacting with L. scoparium do not appear to influence UMF® activity. Three methods were used to establish genetic variability within regions of the North Island of New Zealand that gave rise to the various levels of UMF® activity. Analyses of morphological characteristics, chemotaxonomic essential oil profiles, and population genetics of L. scoparium populations were conducted, and the conclusions that were drawn from each of these were very similar. Two major divisions were identified, each divided into two varieties. The northern division, which contained the core populations from Northland and Waikato, represented the previously described L. scoparium var. incanum and L. scoparium var. linifolium. This division yielded mānuka honey with high UMF® activity. The southern division, which contained the core populations from the Central North Island and East Coast, represented the previously described L. scoparium var. myrtifolium and an unnamed variety. The latter, growing principally on the East Coast, uniquely contains triketones essential oils. The southern division yielded mānuka honey with low UMF® activity. Hybridisation between these varieties will occur, leading to a continuum of UMF® activity in mānuka honey. The data indicated multiple dispersions of L. scoparium to New Zealand from the evolutionary centre of the persistent-capsule Leptospermum group in south-east Australia, and later regional dispersal in New Zealand. From this study two hypotheses were accepted: the variability in the UMF® activity of mānuka honey is due to both the dilution of mānuka honey by other honey types and the variety of L. scoparium harvested.

Mahima J. Senanayake. (2006). A Chemical Investigation of New Zealand Unifloral Honeys. (PhD). University of Waikato, New Zealand, New Zealand.


The diethyl ether-extracted organic compounds of 155 samples of unifloral grade New Zealand kamahi and honeydew honeys, and New Zealand and Norwegian erica honeys, together with a series of active and inactive manuka honeys were analysed using combined gas chromatography/mass spectrometry. It was found that Kamahi honey is characterized by the presence of 2,6-dimethylocta-3,7-diene-2,6-diol, meliracemoic acid, and kamahines A-C and these compounds were typically present at average levels of 31, 14, and 73 mg/kg of honey, respectively. 2,6-Dimethylocta-3,7-diene-2,6-diol was isolated and the structure of this compound was defined using one- and two-dimensional NMR analyses. The only recognizably distinct peak present in the honeydew honey profile was indole acetic acid. In this honey, a relatively low to moderate level of indole acetic acid, ranging from 0.9 to 9.1 mg/kg honey was detected. In the New Zealand erica honey samples, ericinic acid, isoericinic acid isomers (average levels 363 and 34 mg/kg respectively), trans,cis and trans,trans abscisic acid isomers (average levels 302 and 224 mg/kg respectively) and benzoic acid (average level 6950 mg/kg) were identified as floral marker compounds. Ericinic acid was isolated and the structure of this acid was defined using one-and two dimensional NMR analyses. Low levels of ericinic and isoericinic acids (average levels of 1.1 and 0.32mg/kg respectively) were detected in the Norwegian erica-rich honeys. The results presented here indicate that ericinic and isoericinic acids are likely to be universally present in erica honeys at levels which may range from as low as 1 mg/kg or less, as found in some Norwegian samples, to more than 100 mg/kg in some New Zealand samples. Two groups, namely a fingerprint pattern which characterized active Manuka honeys, and a fingerprint pattern that characterized inactive manuka honeys were identified. Some substances contributing to the GC/MS profile were found as marker compounds for the presence of unidentified substances responsible for the UMF activity. A statistically significant correlation was found between a small set of marker compounds (i.e. phenylacetic acid, 2-methoxyacetophenone, 2-methoxybenzoic, phenyllactic, octanedioic, cis-cinnamic, trans-cinnamic, nonanedioic, 4-methoxyphenyllactic and decanedioic acids and methyl syringate) and UMF activity of manuka honey. The best-fit marker compound regression equation (R= 0.92) was obtained for a set of pooled 30 moderate to high activity (UMF > 14.1) samples. It was shown that the marker compound regression equation is capable of predicting the approximate UMF activity in both active and inactive manuka and kanuka honey samples. The leaf oil profiles of manuka (L. scoparium) plants that yielded active and inactive manuka honeys were characterized using an adaption of the micro-scale extraction and GC/FID or GC/MS, technique developed by Brophy et al. (1989). Six major groups of volatile (steam distillable) compounds (monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes [excluding eudesmols], eudesmols, triketones, and nor-triketones) and 3 groups of non-volatile or semi-volatile compounds (flavonoids, grandiflorone and nor-grandiflorone) were recognized in the leaf oil components. The active manuka honeys do not appear to be derived uniquely, or predominantly, from a single leaf oil chemotype.

Lis-Balchin, M., Hart, S. L., & Deans, S. G. (2000). 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. Phytotherapy Research: PTR, 14(8), 623–629.;2-Z/abstract;jsessionid=1AA7CB6EC9CE904F757D92DF4354D480.f03t04


Three different species of Myrtaceae growing in Australia and New Zealand are known as “Tea-tree”: the Australian Tea tree (Melaleuca alternifolia), the New Zealand Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides). All three essential oils are used by aromatherapists, although only Melaleuca has been tested for toxicity, and its antimicrobial effects studied. The pharmacology and antimicrobial activity of the three “tea-tree” oils was determined using guinea-pig ileum, skeletal muscle (chick biventer muscle and the rat phrenic nerve diaphragm) and also rat uterus in vitro. Differences were shown between the three essential oils in their action on smooth muscle: Manuka had a spasmolytic action, while Kanuka and Melaleuca had an initial spasmogenic action. Using the diaphragm, Manuka and Melaleuca decreased the tension and caused a delayed contracture; Kanuka had no activity at the same concentration. The action on chick biventer muscle was, however, similar for all three oils, as was the action on the uterus, where they caused a decrease in the force of the spontaneous contractions. The latter action suggests caution in the use of these essential oils during childbirth, as cessation of contractions could put the baby, and mother, at risk. The comparative antimicrobial activity showed greater differences between different samples of Manuka and Kanuka than Melaleuca samples. The antifungal activity of Kanuka was inversely proportional to its strong antibacterial activity, whilst Manuka displayed a stronger antifungal effect, though not as potent as Melaleuca. The antioxidant activity of Manuka samples was more consistent than that of Kanuka, while Melaleuca showed no activity. The variability in the Manuka and Kanuka essential oils suggests caution in their usage, as does the fact that the oils have not been tested for toxicity.

Porter, N. G., Smale, P. E., Nelson, M. A., Hay, A. J., Van Klink, J. W., & Dean, C. M. (1998). Variability in essential oil chemistry and plant morphology within a Leptospermum scoparium population. New Zealand Journal of Botany, 36(1), 125–133.


Abstract Essential oil composition and plant morphology were observed over four years in individual plants raised from seed of a wild population of Leptospermum scoparium (Myrtaceae) collected at a single site in New Zealand. Principal component analyses of data from young and mature plants showed no significant grouping of plants on the basis of oil composition, but identified differences between the essential oil components contributing most to variation in oil composition in both young and mature plants. The dominant variables were six sesquiterpene components in young plants, and three monoterpenes and two sesquiterpenes in mature plants. Levels of these components differed significantly at the population level between young and mature plants and also within and between seasons. Levels of all these components varied markedly within and between individual plants at all sample times. The habit, leaf size and density, and stem and foliage colour also varied markedly between individual plants. The variation observed indicates the need for more extensive sampling and statistical analysis over more than one growing season if sufficiently reliable data on essential oil compositions in individual plants or populations are to be obtained for chemotaxonomic or plant selection purposes.

Porter, N. G., & Wilkins, A. L. (1999). Chemical, physical and antimicrobial properties of essential oils of Leptospermum scoparium and Kunzea ericoides. Phytochemistry, 50(3), 407–415.


The major components of commercial New Zealand essential oils of Leptospermum scoparium (manuka) and Kunzea ericoides (kanuka) are identified. In the manuka oil, monoterpenes are present at low levels (≤3%). Sesquiterpene hydrocarbons are predominant (≥60%) and include groups possessing cubebene/copaene, elemene, gurjunene/aromadendrene, farnesene/caryophyllene, selinene, calamenene and cadinene skeletons. Oxygenated sesquiterpenes and triketones are present (≤30%). The antimicrobial activity of the manuka oil was associated with a fraction containing three major and three trace triketones, two of the latter were previously unreported. Kanuka oil was characterized by high levels of α-pinene (>50%) and lower levels (<10%) of viridiflorol and viridiflorene. GC-MS and GC-FID detector responses to the same components were noticeably different for some major components, including the triketones. Non-commercial manuka oils from different sites differed widely in composition and could be separated into four groups by the presence and levels of distinctive components. The density and refractive index of manuka and kanuka oils were closely correlated with the total sesquiterpene levels. The density of the commercial manuka oil was closely correlated with the level of the triketones. Simple density measurements enabled discrimination between the commercial oil and oils from other sites, and prediction of antimicrobial activity.