Emu Oil(s): A Source of NonToxic
Transdermal Anti-Inflammatory
Agents
In Aboriginal Medicine
By:
Michael W. Whitehouse & Athol G. Turner,
Dept. of Medicine, University of Queensland, Princess
Alexandra Hospital, Brisbane Qld 4102, Australia, and Dept. of Biological
Sciences, Sydney, Institute of Technology, Ultimo NSW 2007, Australia
The
emu (bush chook) is a free-roving large flightless bird indigenous
to Australia, now farmed in Australia, Canada, Europe, and the U.S.A.
The native Aboriginals and early white settlers in Australia
rubbed on the liquid fat to facilitate wound healing and to alleviate
pain and disability form various musculoskeletal disorders.
An
adult bird (15 months old) weighing 45 kg carries up to 10 kg of
body fat, from which 7-8 litres of a thick oil is obtained by rendering
at temperatures up to 90 degrees C.
Filtering this semisolid fat at 25 degrees C yields 20-80%
v/v of a clear oil (CO); the proportion varying with conditions
of nurture and other factors (genetic stock, stress, ect.).
The
CO varies greatly in content of a) natural antioxidants (e.g., carotenoids,
flavones), and b) skin permeation-enhancing (PE) factors e.g. unesterified
oleic acid, sesquiterpenes.
The content of alpha-linolenic acid (18:3) in total triglyceride
fraction varies notably from almost zero (many farmed birds) to
almost 20% (some feral birds), also reflecting significant differences
in basal diet. So far, we have been unable to find any clear correlations
between pigment or 18:3 content of a CO and its anti-inflammatory
potency.
Evidence
for the variability in anti-inflammatory potency (AIP) of different
emu oils was obtained using the rat adjuvant arthritis model (Snowden
& Whitehouse 1997). To
eliminate variations in PE content between clarified oils, 15% v/v
cineole (eucalyptol) was added to all samples before testing.
Olive oil was used as dilutent in dose-response studies with
the maximum daily topical dose being 2 ml/kg of emu oil applied
for four days to shaved dorsum of rats from the time of onset of
arthritic symptoms.
Some
oils were equipotent with oral aspirin in the rat assay (ED50+300mg/kg)
and showed analgestis activity in preliminary clinical studies.
These active oils were fractionated to yield low-triglyceride concentrates
with significant reproducible AIP (ED50+10mg/kg) when applied transdermally
in bland oils (olive, lard, inactive emu oils).
Remarkably these active concentrates (10mg/kg) effectively
ablated arthritis development when co-administered with arthritigesic
adjuvants (Ghosh et al 1995), a property shared with very few NSAIDs,
e.g. nimesulide, oxindole, zinc monoglycerolate and Lyprinol (Whitehouse
et al 1990, 1997).
The
best sources of active oils to date have been from Aboriginal owned
farms in Western Australia and Queensland, with brood stock recently
derived from feral birds and fed a mixture of grains with natural
additives from the local bush.
Ghosh
P, Whitehouse M, Turner A, Dawson M, US patent No. 5,432,924.
Snowden
J, Whitehous M (1997) Inflammopharmacol (in press)
Whitehoue
MW, Rainsford, KD, et al (1990) Agents Actions 31, 47
Whitehouse
MW, Macrides TA, et al (1997) accompanying Abstract
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