Medicinal and Aromatic Plants—Industrial Profiles


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part of The Gordon and Breach Publishing Group.

IAN SOUTHWELL
4
have, for economic reasons, meant that most plantations have been established from seed.
The establishment of seed orchards to facilitate cross pollination of selected genotypes is
important for producing high quality and high oil yielding strains. Investigations selecting
for these superior trees, although long term projects, are beginning to show yield gains
(Doran et al. 1997).
Steam distillation is the preferred method for processing tea tree leaf for oil production.
The cost of alternate processes like supercritical fluid extraction or the application of
microwave extraction methods is prohibitive for such a high volume—low value product.
Based on eucalyptus distillation technology (Davis and House 1991), tea tree is distilled
either by hydro or steam distillation in plants ranging from state-of-the-art gas or oil fired
boilers, stainless steel bins and tubular horizontal condensers, to the more primitive
hydrodistillation bins with “coiled-pipe-in-the-water-tank” type condensers.
Tea tree oil gained early popularity because of strong antimicrobial activity measured in
the 1920s. It has been established that this activity is caused chiefly by terpinen-4-ol, the
major component in tea tree oil (Southwell et al. 1993). Early uses however included flavoring
applications where it was added to citrus oil to enhance the terpinen-4-ol content. Antimicrobial
zones of inhibition (ZOI) and minimum inhibitory concentration (MIC) values have been
recorded for the oil and numerous oil constituents against many bacteria, fungi and plant
pathogens (Carson and Riley 1995; Southwell et al. 1997b; Bishop 1995; Bishop and Thornton
1997). Clinical trials have determined the activity in vivo for conditions such as acne, tinea
and vaginitis (Bassett et al. 1990; Tong et al. 1992; Bélaiche 1985) and confirmed the non-
irritant nature of the oil when applied topically at less than 25% concentration (Southwell et
al. 1997a). Investigations such as these have led to improved in vivo and in vitro testing
methods for tea tree oil (Carson and Riley 1995; Mann and Markham 1998) including cell-
line testing of cytotoxicity as an alternative to animal testing (Hayes et al. 1997).
Entrepreneurs have capitalised on this bioactivity by either selling the oil neat or
formulating it into a myriad of value added products where it acts as a simple preservative,
antiseptic or antibacterial soothing agent or as an active ingredient in medicinal products.
Such products include antiseptic creams, soaps, mouthwashes, toothpastes, bath oils, body
lotions, lip balms, acne creams and washes, tinea creams and vaginitis creams and douches.
Legislation governs how, where and in what concentration tea tree oil can be used, what
claims can be made about its activity and how bottles must be sealed, stored and labelled.
Use in medicinal products is legislated in Australia, for example by the Therapeutic Goods
Administration (TGA) which either “lists” or “registers” such therapeutic goods depending
on the testing that the product and ingredients have undergone. The TGA then controls the
claims that can then be made about the product. Basic toxicological and efficacy investigations
have established the safety and effectiveness of use by accumulating toxicological data and
measuring both in vitro and in vivo activity (Altman 1991; Tisserand and Balacs 1995).
Data on LD
50
 values, dermal toxicity, dermal irritation, mutagenicity etc. have been acquired
from animal testing and on skin irritation and allergy response from human panellists.
Although not a skin irritant, especially in formulations containing less than 25% of the oil,
a very small number of people react with allergy to the application of tea tree oil and tea tree
oil products (Southwell et al. 1997a). Investigations are determining which tea tree oil
constituents are the most allergenic and suggestions for their possible removal are being
made.
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

INTRODUCTION
5
Over a period of ten years, the volume of production at the farm gate has increased ten-
fold. This oil has, in most cases, been sold with only minor delays and a minimum of stock-
piling. The price has varied somewhat to reflect the supply and demand equilibrium. Prices
peaked in the late eighties when demand exceeded supply. More recently however the price
has fallen and stabilised gradually to reflect increasing production. The establishment of
more large-scale plantations, if successful, will increase production beyond demand and
consequently decrease the international price of the oil. An increasing quantity of the oil is
being sold in value-added products by the smaller producers rather than being sold in bulk
to commercial formulators. Some believe that markets will have to expand in existing buyer
countries, spread into new territories, and be formulated into a wider range of pharmaceutical
type products, for the world market to absorb the projected increase in oil volumes.
Although traditionally longer established on world markets, cajuput and niaouli oils from the
large leaved M. cajuputi and M. quinquenervia respectively (Brophy and Doran 1996) have not
enjoyed the surge in market popularity associated with the M. alternifolia group. These species
are still popular in their local producing regions of SE Asia and New Caledonia respectively,
with the latter also growing in Madagascar. The potential exists for many other Melaleuca species
to be distilled and their oils traded commercially. M. stipitata, for example, combines the
antimicrobially active ingredients of the M. alternifolia group with the pleasant aromatic notes
of lemon grass. Higher yielding varieties of these chemotypes would be needed for their
commercial production to be viable. Other large leaved varieties have potential as sources of
linalool, nerolidol and viridiflorol (M. quinquenervia), methyl cinnamate and ocimene (M.
viridiflora) and lemon oil (M. citrolens). Other small leaved species could also be used as sources
of eudesmol (M. uncinata), methyl eugenol and methyl isoeugenol (M. brarteata).
In this volume we attempt to review the wealth of information on the commercial and
potentially commercial Melaleuca species that exists in the scientific literature, in agricultural
bulletins, in government legislation and in the manuals of Melaleuca oil entrepreneurs.
REFERENCES
Aboriginal Communities of the Northern Territory. (1988) Traditional Bush Medicines. An Aboriginal
Pharmacopoeia. Greenhouse, Richmond, Victoria, pp. 160–165.
Altman, P. (1991) Assessment of the skin sensitivity and irritation potential of tea tree oil. Report for
Rural Industries Research and Development Corporation. Pharmaco Pty Ltd., Sydney, Australia.
Bassett, I.B., Pannowitz, D.L. and Barnetson, R.St-C. (1990) A comparative study of tea-tree oil versus
benzoylperoxide in the treatment of acne. Med. J. Aust., 153, 455–458.
Bélaiche, P. (1985) Traitement des infections vaginales a Candida albicans par l’huile essentielle de
Melaleuca alternifolia (Cheel). Phytotherapy, 15, 13–14.
Bishop, C.D. (1995) Antiviral activity of the essential oil of Melaleuca alternifolia (Maiden & Betche)
Cheel (Tea Tree) against tobacco mosaic virus. J. Essent. Oil Res., 7, 641–644.
Bishop, C.D. and Thornton, I.B. (1997) Evaluation of the antifungal activity of the essential oils of
Monarda citriodora var. citriodora and Melaleuca alternifolia on post-harvest pathogens. J. Essent.
Oil Res., 9, 77–82.
Blake, S.T. (1968) A revision of Melaleuca leucadendron and its allies (Myrtaceae) Contr. Queensland
Herb., 1,1–114.
Boland, D.J., Brooker, M.I.H., Chippendale, G.M., Hall, N., Hyland, B.P.M, Kleinig, D.A. and Turner,
J. (1984) Forest Trees of Australia, 4th edition, Nelson, Melbourne.
Brophy, J.J. and Doran, J.C. (1996) Essential Oils of Tropical Asteromyrtus, Callistemon and Melaleuca
Species. ACIAR Monograph No. 40, Canberra.
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

IAN SOUTHWELL
6
Campbell, A.J. and Maddox, C.D.A. (1997) Controlling insect pests in tea tree using pyrgo beetle as
the basis. RIRDC Research Paper Series, 97/62, Rural Industries Research and Development
Corporation, Canberra.
Carson, C.F. and Riley, T.V. (1995) Antimicrobial activity of the major components of the essential oil
of Melaleuca alternifolia. J. Appl. Bact., 78, 264–269.
Colton, R.T. and Murtagh, G.J. (1990) Tea-tree oil—plantation production. Agfact P6.4.6. NSW
Agriculture and Fisheries, Orange, Australia.
Cornwell, C.P., Leach, D.N. and Wyllie, S.G. (1995) Incorporation of oxygen-18 into terpinen-4-ol from
the H
2
18
O steam distillates of Melaleuca alternifolia (Tea Tree). J. Essent. Oil Res., 7, 613–620.
Davis, G.R. and House, A.P.N. (1991) Still design and distillation practice. In D.J.Boland, J.J.Brophy
and A.P.N.House (eds.), Eucalyptus Leaf Oils, Inkata Press, Sydney, pp. 187–194.
Doran, J.C. (1991) Commercial sources, uses, formation, and biology. In D.J.Boland, J.J.Brophy and
A.P.N.House (eds.), Eucalyptus Leaf Oils, Inkata Press, Sydney.
Doran, J.C., Baker, G.R., Murtagh, G.J. and Southwell, I.A. (1997) Improving tea tree yield and quality
through breeding and selection. RIRDC Research Paper Series, 97/53, Rural Industries Research
and Development Corporation, Canberra.
Geary, T.F. (1988) Melaleuca quinquenervia (Cav.) S.T.Blake. In R.M.Burns and M.Mosquera (eds.),
Useful Trees of Tropical North America. North American Forestry Commission Publ. No. 3,
Washington DC.
Guenther, E. (1950) The Essential Oils, Van Nostrand, New York, Vol. 4, pp. 526–548.
Hayes, A.J., Leach, D.N. and Markham, J.L. (1997) In vitro cytotoxicity of Australian tea tree oil
using human cell lines. J. Essent. Oil Res., 9, 575–582.
International Standards Organization (1996) Oil of Melaleuca, terpinen-4-ol type (Tea Tree Oil).
International Standard ISO 4730:1996(E), International Standards Organization, Geneva.
Lawrence, B.M. (1985) A review of the world production of essential oils (1984). Perfumer and
Flavorist, 10(5), 1–16.
Leach, D.N., Wyllie, S.G., Hall, J.G. and Kyratzis, I. (1993) The enantiomeric composition of the
principal components of the oil of Melaleuca alternifolia. J.Agric. Food Chem., 41, 1627–1632.
List, S., Brown, P.H. and Walsh, K.B. (1995) Functional anatomy of the oil glands of Melaleuca
alternifolia (Myrtaceae). Austral. J. Bot., 43, 629–641.
Mann, C.M. and Markham, J.L. (1998) A new method of determining the MIC of essential oils. J.
Appl. Microbiology, in press.
Motl, O., Hodacová, J. and Ubik, K. (1990) Composition of Vietnamese cajuput essential oil. Flavour
and Fragrance Journal, 5, 39–42.
Murtagh, G.J. (1991) Irrigation as a management tool for production of tea tree oil. RIRDC Research
Report DAN-19A. Rural Industries Research and Development Corporation, Canberra.
Murtagh, G.J, (1996) Month of harvest and yield components of tea tree. I. Biomass. Australian Journal
of Agricultural Research, 47, 801–815.
Murtagh, G.J. and Etherington, R.J. (1990) Variation in oil concentration and economic return from
tea tree (Melaleuca alternifolia Cheel) oil. Australian Journal of Experimental Agriculture, 30,
675–679.
Murtagh, G.J. and Smith, G.R. (1996) Month of harvest and yield components of tea tree. II Oil
concentration, composition and yield. Australian Journal of Agricultural Research, 47, 817–827.
Penfold, A.R. and Morrison, F.R. (1950) Tea tree oils. In Guenther, E. (ed.), The Essential Oils, Van
Nostrand Co. Inc., New York, Vol. 4, pp. 526–548.
Ramanoelina, P.A.R., Bianchini, J.P., Andriantsiferana, M., Viano, J. and Gaydou, E.M. (1992) Chemical
composition of niaouli essential oils from Madagascar. J. Essent. Oil Res., 4, 657–658.
Ramanoelina, P.A.R., Viano, J., Bianchini, J.P. and Gaydou, E.M. (1994) Occurrence of variance
chemotypes in niaouli (Melaleuca quinquenervia) essential oils from Madagascar using multivariate
statistical analysis. J. Agric. Food Chem., 42, 1177–1182.
Southwell, I.A., Hayes, A.J., Markham, J. and Leach, D.N. (1993) The search for optimally bioactive
Australian tea tree oil. Acta Horticulturae, 344, 256–265.
Southwell, I.A., Freeman, S. and Rubel, D. (1997a) Skin irritancy of tea tree oil. J. Essent. Oil Res., 9,
47–52.
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

INTRODUCTION
7
Southwell, I.A., Maddox, C.D.A. and Zalucki, M.P. (1995) Metabolism of 1,8-cineole in tea tree
(Melaleuca alternifolia and M.linariifolia) by pyrgo beetle (Paropsisterna tigrina). J. Chem. Ecol.,
21, 439–453.
Southwell, I.A., Markham, J. and Mann, C. (1997b) Why cineole is not detrimental to tea tree oil.
RIRDC Research Paper Series, 97/54, Rural Industries Research and Development Corporation,
Canberra.
Southwell, I.A. and Stiff, I.A. (1989) Ontogenetical changes in monoterpenoids of Melaleuca
alternifolia leaf. Phytochemistry, 28, 1047–1051.
Storrie, A., Cook, T., Virtue, J., Clarke, B. and McMillan, M. (1997) Weed Management in Tea Tree.
NSW Agriculture, Orange, Australia.
Tisserand, R. and Balacs, T. (1995) Essential Oil Safety—A Guide for Health Care Professionals.
Churchill Livingstone, Edinburgh, pp. 45–55, 80, 82, 150, 187, 204, 219.
Todorova, M. and Ognyanov, I. (1988) Composition of Vietnamese essential oil from Melaleuca
leucadendron L. Perfumer and Flavorist, 13, 17–18.
Tong, M.M., Altman, P.M. and Barnetson, R.St-C. (1992) Tea tree oil in the treatment of Tinea pedis.
Australasian J. Dermatol. 33, 145–149.
Virtue, J.G. (1997) Weed interference in the annual regrowth cycle of plantation tea tree (Melaleuca
alternifolia). PhD Thesis. The University of Sydney.
Weiss, E.A. (1997) Essential Oil Crops, CAB International, Oxford, pp. 302–319.
Whish, J.P.M. and Williams, R.R. (1996) Effects of post harvest drying on the yield of tea tree oil
(Melaleuca alternifolia). J. Essent. Oil Res., 8, 47–51.
Wrigley, J.W. and Fagg, M. (1993) Bottlebrushes, Paperbarks and Tea Trees and all other Plants in
the Leptospermum Alliance, Angus and Robertson, Sydney.
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

Plate 1 Tea tree plantation in New South Wales, Australia (R.Colton)
Plate 3 Melaleuca alternifolia flower
(I.Holliday)
Plate 2 Mature Melaleuca alternifolia tree in a
natural stand (I.Southwell)
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

Plate 4 Melaleuca cajuputi subsp. cajuputi flower (J.Brock)
Plate 5 Melaleuca quinquenervia flower (B.Trilles)
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

Other volumes in preparation in Medicinal and Aromatic Plants—Industrial Profiles
Ginkgo, edited by T.van Beek
Ginseng, edited by W.Court
Hypericum, edited by K.Berger Büter and B.Büter
Illicium and Pimpinella, edited by M.Miró Jodral
Kava, edited by Y.N.Singh
Licorice, edited by L.E.Craker, L.Kapoor and N.Mamedov
Piper Nigrum, edited by P.N.Ravindran
Plantago, edited by C.Andary and S.Nishibe
Salvia, edited by S.E.Kintzios
Stevia, edited by A.D.Kinghorn
Tea, edited by Y.S.Zhen
Tilia, edited by K.P.Svoboda and J.Collins
Thymus, edited by W.Letchamo, E.Stahl-Biskup and F.Saez
Trigonella, edited by G.A.Petropoulos
Urtica, edited by G.Kavalali
This book is part of a series. The publisher will accept continuation orders which may be
cancelled at any time and which provide for automatic billing and shipping of each title in
the series upon publication. Please write for details.
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

11
1. BEHIND THE NAMES: THE BOTANY OF TEA TREE,
CAJUPUT AND NIAOULI
LYN A.CRAVEN
Australian National Herbarium, CSIRO Division of Plant Industry,
Canberra, Australia
INTRODUCTION
“We know what plant X is. Why should we have to worry about its scientific name?” Well,
sometimes calling a plant X is neither sufficiently precise to enable us to communicate
unambiguously nor to find the information that we seek in the ever-burgeoning literature
with which we must cope. Australians use the name tea tree to refer to many indigenous
species of Leptospermum, Melaleuca and Neofabricia (Wrigley and Fagg 1993). These
three genera belong to the family Myrtaceae so they do have something in common. Clearly
though, the use of tea tree by itself will not suffice as the only name for the subject of this
book and we must use its scientific nameMelaleuca alternifolia, to distinguish it
unambiguously from all the other tea trees.
Apart from being a label, the scientific name of a plant can be considered a concise
definition as to what the plant actually is, as the name can be related to a particular
morphological circumscription. Similarly with the many ecological and chemical attributes
that species possess. Melaleuca leucadendra sensu Bentham taxonomically, and ecologically,
geographically and chemically, is very different to M. leucadendra sensu Blake. Unless the
name is qualified such as in the previous sentence, it is not easy to determine which of the
potentially several taxonomic concepts a particular author is using.
In itself a name is not especially useful as an indication to the position occupied by a
species in taxonomic classifications, other than informing us of the genus to which the
species belongs. The binomial nomenclatural system, i.e. the combination of a generic with
a specific epithet (such as Melaleuca alternifolia), does not cater for taxa between the ranks
of genus and species, such as section or series. This is unfortunate in large genera such as
Melaleuca in which we need to know in which part of the genus our taxon or taxa of interest
are classified. Notwithstanding this, the scientific name is our only sure password to the
information that is available in the literature.
This contribution provides a brief outline of the genus Melaleuca and of the species
groups to which tea tree, cajuput and niaouli belong.
THE GENUS MELALEUCA
Melaleuca was established as a genus by Linnaeus in 1767 with M. leucadendra as its only,
and hence type, species. Linnaeus based his genus on the pre-Linnaean Arbor alba that was
described by Rumphius from plants growing on Ambon in present day Indonesia (Rumphius
Copyright © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint,
part of The Gordon and Breach Publishing Group.

LYN A.CRAVEN
12
1741). From 1767 until the mid-1800s, several further species were added to the genus but
it was not until 1867 that the first comprehensive treatment of Melaleuca was published in
Bentham’s account of Myrtaceae in his classic flora of Australia, Flora Australiensis
(Bentham 1867). Within Melaleuca, Bentham recognised 97 species in 7 series. His series
include some groupings of undoubtedly closely related species but overall the classification
is artificial. This is not a reflection upon the general quality of Bentham’s treatment but is
an indication of the difficulty inherent in classifying a large group of species that, while
differing considerably in gestalt, is remarkably similar in essential structural details. To the
present day, Bentham’s work has remained the most monographic account of Melaleuca
available.
Since 1867, many other species have been described in Melaleuca by botanists. These
usually have been published as isolated descriptions of novelties or in accounts of flora
collected by large expeditions; it has only been in recent decades that studies of Melaleuca
within large regions have been undertaken and published. These more comprehensive studies
include a revision of the broad-leaved paperbarks (Blake 1968), a revision of Melaleuca in
South Australia (Carrick and Chorney 1979), a treatment of the northern and eastern
Australian species (Byrnes 1984, 1985, 1986), treatments of several largely southwestern
and eastern Australian species groups (Barlow 1987; Barlow and Cowley 1988; Cowley et
al. 1990), and a revisionary level treatment of the New Caledonian species (Dawson 1992).
The genus Asteromyrtus, included in Melaleuca by Bentham (1867) and Byrnes (1984,
1985) was resurrected by Craven (1989) to accommodate a constellation of species most of
which had been treated under Melaleuca but of which one had been placed in the monotypic
genus Sinoga by Blake (1958). Asteromyrtus is not closely related to Melaleuca; its
relationships lie with Agonis in the Leptospermum group of genera. In passing it may be
noted that at least one species of Asteromyrtus, A. symphyocarpa, has potential as a viable
source of essential oil (
Chapter 16
, this volume). Preparatory work towards an account of
Melaleuca for Flora of Australia is in train and a precursory paper enumerating all the
Australian species and providing identification keys currently is being completed by
L.A.Craven and B.J.Lepschi.
According to the classification of Briggs and Johnson (1979), the genera most closely
related to Melaleuca are Callistemon, Conothamnus and Lamarchea while Beaufortia,
Calothamnus, Eremaea, Phymatocarpus and Regelia are more distantly related. It seems
that there is no especially close relationship with the genera clustered around Leptospermum,
i.e.  Agonis, Angasomyrtus, Asteromyrtus, Homalospermum, Kunzea, Neofahrma and
Pericalymma. The conventional circumscription of Melaleuca given below may require
amendment when research in progress by the author into the relationships of Callistemon
and Conothamnus to Melaleuca is concluded. At least two species of Australian Callistemon.,
C. glaucus and C. viminalis, have their stamens grouped into 5 basally fused groups, one of
the key generic characters of Melaleuca. Indeed, this was the basis for Byrnes’ transfer of
the eastern Australian species, C. viminalis, to Melaleuca (Byrnes 1984, 1986). Similarly,
the endemic New Caledonian species of Callistemon are very close to the endemic New
Caledonian Melaleuca, several of them having stamens fused into groups, and they may be
transferred to Melaleuca as a result of research in progress.
As it is presently circumscribed, Melaleuca consists of about 230 species (Craven
1997). The great majority of the species, about 220, is endemic to Australia and Tasmania
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