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Plants used to treat infectious disease - III
Plant Products as Antimicrobial Agents
Plant Products
• 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
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
Tuberculoid type may be limited to a few nerves and skin area
Lepromatous type is disseminated throughout the body
Hansen’s disease in 2004
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
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
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
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 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
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 Common Name Plant Part Used
Berberis aquifolium Oregon grape Rhizome, roots
Berberis aristata Tree turmeric Root
Berberis vulgaris Barberry Outer bark, root
Coptis chinensis Coptis,goldenthread
Rhizome
Hydrastis canadensis Goldenseal Rhizome, root
Berberine research on-going
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 gram-negative bacteria, fungi, and protozoa
Berberine has been also shown to inhibit HIV-1 reverse transcriptase
Berberine as an antimicrobial 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
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
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
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
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?
Obvious answer is that they impart pleasing tastes to foods: Why do people find taste appealing? Why are there preferences for certain spices in
cuisine of different regions?
Predictions based on spice use 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
Prediction 1 - Spices used in cooking exhibit antimicrobial activity 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
Prediction 2: Use of spices should be greater in hot climates where unrefrigerated foods spoil quickly 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 Prediction 3: Spices used in each country
should be particularly effective against the local bacteria 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
Prediction 4: Within a country meat recipes should be spicier than vegetable recipes Unrefrigerated meats associated with more food-
borne 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
Prediction 5: Within a country, recipes from lower latitudes and altitudes should be spicier than higher latitudes and altitudes 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
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