Essential oils from Leptospermums of the Sunshine Coast and Northern Rivers Regions
Chemistry Central Journal
Essential oils from Leptospermums of the Sunshine Coast and Northern Rivers Regions
Sarah Alison Michelle Windsor 0
Peter Brooks 0
0 School of Science, Education and Engineering, University of the Sunshine Coast , Maroochydore DC Qld 4558 , Australia
Background: Around the turn of this century, the oil yield and chemical composition of Australian Leptospermum species was analysed. Since that time, research has been focused on their use as phytomedicines. The oil yield and composition of essential oils from Australian Leptospermum species directly impacts their commercialisation for medicinal use. Results: The essential oils from Leptospermum (L.) juniperinum, L. laevigatum, L. liversidgei, L. polygalifolium, L. semibaccatum, L. speciosum, L. trinervium and L. whitei have been examined from specimens in the Sunshine Coast (Queensland) and Northern Rivers (New South Wales) Regions. Both chemotypes of L. liversidgei were observed. However, only chemotype II of L. semibaccatum and chemotype I of L. trinervium were identified. The only subspecies observed of L. polygalifolium was L. polygalifolium wallum. Conclusions: L. liversidgei chemotypes I and II have the potential for phytomedical use as antibacterial or anti-inflammatory agents. Chemotype I has the potential for use as an insect repellent and chemotype II may provide antifungal activity.
Leptospermum; Laevigatum; Liversidgei; Polygalifolium; Semibaccatum; Trinervium; Whitei; Essential oils; GC-MS
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Background
Between 1998 and 2000 Brophy and co-workers published
a series of seven papers on the oil yield and chemical
composition of Australian Leptospermum species. The three
principal components in Leptospermum (L.) juniperinum
essential oils (yield 0.1–0.2%) collected in South East
Queensland (SEQ) and the Southern Highlands New South
Wales (NSW) were α-pinene, 1,8-cineole and
caryophyllene E, but with significant variation in the proportions
of these components [1]. The principal components in
L. laevigatum essential oils (yield 0.1%) from the Mid-North
Coast NSW were caryophyllene E or (E,E)-farnesol [2].
L. liversidgei essential oil samples from SEQ, Northern
Rivers Region NSW and Yarra Valley and Dandenong
Ranges Region Victoria showed a range of oil yield from
0.3–2.7% and identified two extremes in chemical
composition (high in isopulegol and citronellal and high in neral
and geranial) [3]. L. polygalifolium wallum essential oil
samples from SEQ showed a range of oil yield from 0.2–0.8%
and was composed primarily of the monoterpenes:
αpinene, β-pinene and 1,8-cineole; but the sesquiterpene
alcohols did not contribute much to this oil [4].
Monoterpenes (α-pinene and β-pinene) predominated in L.
semibaccatum chemotype II essential oils (yield 0.04–0.2%)
collected in SEQ, but the sesquiterpenes: caryophyllene E,
bicyclogermacrene and δ-cadinene; and the alcohols:
globulol, spathulenol, cadinol and muurolol; were also
present in significant amounts [2]. The principal
component of L. speciosum essential oils (yield 0.5–1.3%)
collected from SEQ and Northern Rivers Region NSW was
α-pinene [5]. L. trinervium chemotype I essential oil
samples from SEQ and the Southern Highlands NSW showed
a range of oil yield from 0.1–0.4% and contained significant
quantities of α-pinene, sabinene, 1,8-cineole, p-cymene,
pcymen-8-ol, caryophyllene E, viridiflorene, germacrene D,
bicycolgermacrene, globulol, viridiflorol and spathulenol
[2]. The main monoterpene hydrocarbon, sesquiterpene
hydrocarbon and oxygenated terpene found in L. whitei
essential oils (yield 0.2–0.3%) collected in SEQ were
αpinene, caryophyllene E and spathulenol, respectively [5].
Intra species variation has been proposed to be dependent
on location or collecting season or both [6]. Locational
and seasonal variation of essential oils from individual
species have been examined in this work. The
widespread occurrence of multiple antibiotic-resistant
organisms in hospital and community settings suggests new
antimicrobial agents, preferable with novel mechanisms
of action, are required and it seemed prudent to
reexamine previously superseded products such as
phytomedicines [7]. As opposed to most antimicrobial agents
currently used for air disinfection, essential oils are low
in toxicity and could be used in different environments,
while people are present. They possess high volatility
that is not seen in other non-toxic antimicrobial agents.
Essential oils are complex mixtures which often are
superior for reducing bacterial viable counts than a single
active compound in both the absolute effect and in the
speed of action. This is probably caused by the presence
of minor compounds, like p-cymene, which can cause
swelling of the bacterial cytoplasmic membrane and makes
it more permeable for active compounds [8]. Essential
oils have been found to provide high zones of inhibition
against methicillin-resistant Staphylococcus aureus in disc
diffusion assays. Lemon grass single ess (...truncated)