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Horopito (Pseudowintera colorata)– a unique New Zealand medicinal herb
Campbell Berry-Kilgour B.Sc (Hons)© 2002 Australian Journal of Medical Herbalism. The main biologically active chemical constituent
of Pseudowintera colorata is the sesquiterpene
dialdehyde polygodiali. It is known that
polygodial is a component of the "hot taste" in
peppery spices common in traditional Japanese
cuisine, Polygodial has been shown to exhibit
fungicidal activity against yeasts and
filamentous fungi.
Pseudowintera colorata has recently been granted
approval for therapeutic use in Australia.
Ethnobotanical Profile
Pseudowintera colorata, (P. colorata), also known
as Horopito, New Zealand Pepper Tree, Winter?s
Bark, and Red Horopito, is member of the
Winteraceae family. It is the least specialized
of all flowering plant families. It has many
ancient features believed to be the same as those
of the earliest evolving plants. In New Zealand,
Horopito appears in the fossil record for more
than sixty five million yearsiv. The main
biologically active chemical constituent of P.
colorata has been identified as the sesquiterpene
dialdehyde polygodial, which has been shown to
possess anti-fungal, and anti-bacterial
properties. Whilst the Winteraceae family occurs
today in most parts of the world, New Zealand has
its own genus, Pseudowintera, with three species.
All have the peppery, aromatic leaves and bark
typical of the family. The leaves are so hot to
taste that sheep, cattle and deer usually avoid
them4. Traditional Human Use P.colorata leaves were traditionally used by
Maori of New Zealand to treat fungal skin
infection, venereal disease, stomach pain and
diarrhoea. A decoction of leaves was used as an
analgesic. Early European settlers to New Zealand
also used P.colorata for medicinal purposes. For
internal use leaves were either chewed or
prepared as a tea. To treat skin complaints
leaves were bruised and steeped in water or
chewed before application 1,5,6. The leaves were
chewed for toothache, and were rubbed on the
breast when weaning infants. There is no
historical evidence of toxicity of P.colorata
leaves by either oral ingestion or topical
application. Structure of Polygodial 9-Deoxymuxigadial (also a
sesquiterpene dialdehyde) may also have
pharmacological activity. Other constituents
include essential oils such as pinenes, limones,
humulene and eugenol, and the flavonoids
quercetin, luteolin and proanthocyanidins7. Many
New Zealand natives exhibit regional variations
in genetic make up and consequently biological
activity. In order to determine the level of any
variation across P. colorata populations, the
private research company Forest Herbs Research
and the New Zealand government owned Industrial
Research Ltd joined forces to conduct the first
comprehensive study of all the major populations
of Horopito. This research demonstrated a five-
fold variation between the most active and the
least active plant populations.
Pharmacology
In 1982 a group from Canterbury University in New
Zealand reported they had isolated a substance
called polygodial in the leaves of New Zealand
native Pseudowintera colorata1. The Canterbury
University team grew cultures of Candida albicans
and measured the zone of inhibition in these
cultures produced by discs of polygodial
extracted from the leaves of P. colorata. They
found it was very effective at inhibiting Candida.
Comparison with the drug amphotericin B (which
is commonly used to treat systemic mycoses) found
that polygodial gave larger zones of inhibition.
Polygodial also suppressed Candida colony growth
from day one, while amphotericin B required 3-4
days incubation.
Antifungal Profile
Polygodial has been shown to possess strong
antifungal activity, comparable to amphotericin B,
against yeast-like fungi Candida albicans,
Candida krusei, Candida utilis, Cryptococcus
neoformans, Saccharomyces cerevisiae and also
filamentous fungi Trichophyton mentagraphytes,
Trichophyton ruburum and Pencillium marneffei8 .
The antifungal activity of polygodial was
generally not reduced by several susceptibility-
testing conditions such as medium type,
incubation temperature, inoculum size, and medium
pH. Polygodial?s antifungal activity was strongly
increased in acidic conditions, however. Fungal
environments in the human host, such as the mouth,
vagina and skin, are often acidic and their
colonisation usually creates a microenvironment
with even lower pH. Under these circumstances,
polygodial can be expected to act as an effective
antifungal agent.
In vitro studies by the Cawthron Institute,
Nelson, New Zealand, show that dried P.colorata
was twice as powerful at killing Candida albicans
(i.e. can kill at half the concentration) as
sodium caprylate (an alternative natural
antifungal), (Table 1) Table 1. Cawthron
Institute Report 1999, Ref. M26050/2.
Mutagenicity
Polygodial is not mutagenic, as determined by
three variants of the Ames salmonella test 9 and
further confirmed by the mammal-based V79/HGPRT
method10. This is unique in that many other
sesquiterpene dialdehydes possessing strong
biological activity are mutagenic. In comparison
with members of this group, polygodial exhibits
the least cytotoxicity for compounds, which have
antifungal activity9, 11. Polygodial and closely
related epipolygodial, controlled fungi (Mucor
miehei, Paecilomyces variotii, Pencillium notatum,
Nematospora corylii and Saccharomyces cerevisiae)
at comparatively low concentrations. At higher
concentrations they inhibited bacteria and algae.
At about the same concentrations required to
control gram-positive organisms (5-20 mcg/ml),
they showed antitumour activity against Ehrlich
ascites tumour cells and lyphocytic leukemia
mouse cells. No mutagenic activity was observed
with polygodial or epipolygodial.
Toxicology
Anke & Sterner found that polygodial exhibited
antifungal, antibacterial and cytotoxic activity9.
No mutagenicity was observed. Huntingdon Life
Sciences Ltd., UK, established that the highest
non-lethal dose to rats of capsules containing
50 powdered Pimpinella
anisum (Anise seed) is greater than 2g/kg body
weight. At 2g/kg
dosing the rats maintained satisfactory body
weight gains and macroscopic examination of the
abdominal and thoracic cavities revealed no
abnormalities12.
Mechanism of Action
Polygodial exhibits fungicidal activity against
yeast-like fungi. This is in comparison to the
actions of some of the fungistatic triazoles,
such as fluconazole. It has been reported in
literature that the antifungal activity of
polygodial is the result of structural disruption
of cell membranes, leading to cell leakage and
ultimately cell death. Radioactive monomer
incorporation studies have shown no selective
inhibition of uptake in polymers of DNA, RNA,
protein or polysaccharide, as all uptake tapered
off after sixty minutes13 . Polygodial produces
amounts of potassium leakage from
yeast cells similar to those produced by
Amphotericin B and miconazole14.
Polygodial?s synergy with Anise seed
The seeds of Pimpinella anisum (aniseed) are used
as a spice throughout the world and also as folk
medicine in South America6. Anethole, identified
as an active principle in aniseed, has previously
been demonstrated to have moderate antifungal
activity. Though not potent enough to be
considered for practical use by itself, Anise
seed has been considered worthy of further
investigation by virtue of being a natural
product isolated from a food spice. Polygodial
has been found to synergise the antifungal
activity of antibiotics such as actinoycin and
rifampicin. Anethole has been shown to exhibit a
significant synergistic effect on the antifungal
activity of polygodial against Candida albicans
and Saccharomyces cerevisiae. Activity increased
sixty four times against S. cerevisiae and thirty
two times against C. albicans. The authors of
this work have concluded ?since the control of
opportunistic yeast pathogens is becoming
increasingly important, the current study to
enhance the total biological activity by
combining two or more substances may provided a
new approach to solve this problem. In particular,
two phytochemicals isolated from common food
spices, anethole and polygodial, may be
considered for practical application.?
Clinical Studies
In 1992 an open study conducted by New Zealand
naturopaths for Forest Herbs Research Limited
examined the therapeutic effect of capsules
containing milled P.colorata and milled Anise
seed, (Kolorex ?), in patients diagnosed with
chronic intestinal candidiasis. This study
demonstrated a symptom improvement rate in 76 (n= 10) of the fluconazole group at seven days and in 90% (n=20) of the P. colorata group at fourteen days15.
Precautions and Contraindications
Although there is no evidence of teratogenicity,
as a precaution P. colorata is not recommended
during pregnancy or lactation. P. colorata works
rapidly against Candida albicans in the digestive
tract. For this reason a Herxheimer reaction (to dead Candida cells) is sometimes experienced in the
first few days of therapy by those with Candida
overgrowth. This is characterised by a headache
and a nauseous feeling, both of which are usually
mild and transient.
?2002 Forest Herbs Research Limited.
? 2002 Australian Journal of Medical Herbalism,
Vol 14, Issue 2, 2002 For More Information and More about Our Products Please Enter Our Website
Related Articles -
yeast infection, antifungal, herbs, medicinal herbs, natural cure, alternative treatment, herb remedies, Pseudowintera colorata, Horopito, Candida albic,
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