Transcript Plants used to treat infectious disease

Plants used to treat
infectious disease - III
Plant Products as Antimicrobial Agents
Plant Products
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Long history of use as antimicrobials
Very few have made the transition from
herbal remedies to mainstream drugs
Often much weaker than antibiotics
Renewed interest largely due to antibiotic
resistance
Chaulmoogra Oil
Leprosy - Hansen’s Disease
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Chronic skin disease endemic to tropical and
subtropical areas
Caused by bacterium, Mycobacterium leprae
Bacterium discovered by Gerhard Hansen - one of
the first bacteria associated with a disease
Transmitted: contact between susceptible people??
It has the potential to produce mutilation of
extremities and disfigurement of the face
Apparently two forms
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Tuberculoid type may be limited to a few nerves and skin
area
Lepromatous type is disseminated throughout the body
Hansen’s disease in 2004
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407,791 new cases detected worldwide
Around 100 cases occurring in the United
States
WHO listed Brazil, Madagascar,
Mozambique, Tanzania, and Nepal as having
90% of cases
Worldwide: 1-2 million persons are
permanently disabled as a result of Hansen's
disease
Chaulmoogra Oil
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Mentioned in the Hindu Vedas over 2000 years ago
as helping in curing leprosy
Oil reached Europe in the mid-nineteenth century,
but source was unknown
Joseph Rock traveled Asia in 1920's, identified
source of chaulmoogra as Hydnocarpus trees of
India and surrounding countries
Rock sent seeds to Hawaii, where Hydnocarpus
plantations were started
The only effective treatment for leprosy until sulfa
drugs were used in 1946
Chaulmoogra Oil
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Earlier use in Hawaii
Alice Ball (1892-1916) worked on chaulmoogra oil to
treat leprosy
Died in 1916 (24 yrs old) - work was taken over by
Arthur Dean who initially got credit for work with
chaulmoogra oil
Chaulmoogra Oil
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Source: seeds of Hydnocarpus wightiana and
Hydnocarpus anthelmintica is triglyceride of fatty
acids containing cyclopentenyl group
Given by injection to patients with leprosy
Symptoms went away and bacteria disappeared
from nasal secretions but relapse often occurred
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Early cases were completely cured
More established cases had relapse
Today standard treatment is combined drug therapy
– 3 antibiotics: dapsone, rifampin, and clofazimine
Herbal Remedies
Herbal Remedies
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Many herbal remedies on the mass market
are known to have antimicrobial activity
One example: berberine
Several herbal remedies containing the
alkaloid berberine show antimicrobial activity
against a variety of bacteria, fungi,
protozoans, worms, chlamydia, and viruses
Extracts of these plants used in Ayurvedic
and Chinese medicine for about 3000 years
Berberine containing herbals and plant
part used
Scientific Name
Berberis aquifolium
Berberis aristata
Berberis vulgaris
Coptis chinensis
Common Name
Oregon grape
Tree turmeric
Barberry
Coptis,
goldenthread
Hydrastis canadensis Goldenseal
Plant Part Used
Rhizome, roots
Root
Outer bark, root
Rhizome
Rhizome, root
Berberine research on-going
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Much of the research focused on its use in
cases of diarrhea, including that caused by
Vibrio cholerae and Escherichia coli
In one study, berberine had antimicrobial
activity against gram-positive and gramnegative bacteria, fungi, and protozoa
Berberine has been also shown to inhibit HIV1 reverse transcriptase
Berberine as an antimicrobial
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Activity still weak compared to antibiotics
Possibly do to MDR pumps in bacterial cell
membranes
Research focus on MDR inhibitors in Berberis
fremontii and other species of berberine
containing plants
Herbs and Spices
Herbs and spices
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Herbs are aromatic leaves or seeds from
plants of temperate origin
Spices are aromatic fruits, flowers, bark or
other plant parts of tropical origin
While herbs and spices are mainly
associated with cooking, they are also used,
as natural dyes, in perfume, cosmetics, and
traditionally used in medicine
Essential Oils
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Value of herbs and spices due to essential
oils
Most commonly found in leaves, flowers, and
fruits where they occur in glandular trichomes
Chemically, essential oils are most commonly
terpenes, but may be phenolics
History of spices
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Early history
Ebers Papyrus
Ancient Greece and Rome
Dark Ages
Venice and Genoa – Marco Polo
Prince Henry of Portugal
Age of Exploration
16th to 19th centuries
Herbs and spices
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Over the past 30 years dozens of studies
have focused on the antimicrobial properties
of herbs and spices
Most spices have antimicrobial properties
Growing feeling that the enduring value of
spices is actually due to these antimicrobial
properties
Paul Sherman from Cornell one of the
leading proponents of this hypothesis
Why use spices?
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Obvious answer is that they impart pleasing
tastes to foods:
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Why do people find taste appealing?
Why are there preferences for certain spices in
cuisine of different regions?
Predictions based on spice use
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Sherman and his students developed an
antimicrobial hypothesis
If spices kill microorganisms or inhibit their
growth or production of toxins, then spice use
would protect us from food borne illness and
food poisoning
To test the hypothesis, they developed critical
predictions
Antimicrobial activity
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Prediction 1 - Spices used in cooking exhibit
antimicrobial activity
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Overwhelming evidence that most spices have
antimicrobial properties
Inhibition of bacterial especially important
because they are more common in food poisoning
than fungi
Spice use in hotter countries
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Prediction 2: Use of spices should be greater in hot
climates where unrefrigerated foods spoil quickly
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Looked at spice use in traditional recipes and correlated it
with temperature
Use of spices greater in hotter area
 Percent of recipes calling for at least one spice and the
number of different spices were all greater in warmer
countries - especially true for highly inhibitory spices
(inhibited 75% of bacteria tested)
Spices kill food-borne bacteria
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Prediction 3: Spices used in each country
should be particularly effective against the
local bacteria
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Unfortunately no lists of native food-borne
bacteria
Sherman et al looked at effectiveness of native
recipes in killing 30 common food-borne bacteria
As annual temp increased, the estimated percent
of bacteria that would be inhibited also increased
More spices used with meats
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Prediction 4: Within a country meat recipes
should be spicier than vegetable recipes
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Unrefrigerated meats associated with more foodborne disease outbreaks and food poisoning
Meat-based recipes from all 36 countries called
for an average of 3.9 spices, significantly more
than 2.4 spices in average vegetable recipes
More spices in hotter areas
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Prediction 5: Within a country, recipes from
lower latitudes and altitudes should be spicier
than higher latitudes and altitudes
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Difficult to find recipes tied to altitude
In US and China, recipes from southern latitudes
used a greater variety of spices and spices used
more often
Southern recipes contained spices more likely to
kill or inhibit bacteria
Alternate Hypotheses
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Spices disguise the smell and taste of spoiled foods
- ignores dangers of spoiled meats which could be
deadly
Spices used as medicines - dosage is different and
all people use the food
Spices used in hotter climates because it helped
increase perspiration (only works for chilis and
horseradish)
Spices used because they taste good - some spices
initially distasteful - yet people continue to use