Transcript B3.1 L11 Medicinal Plants

Learning Objectives:
•To describe the importance and
medicinal value of drugs produced by
plants.
Yams are a source of
steroids. The most
important yam steroid is
diosgenin which can be
converted into
progesterone for use in the
birth-control pills.
Colchicine is found in the autumn crocus, also
known as meadow saffron.
It is an anti-inflammatory used primarily for
treating gout.
Digitalin is found in foxglove plant.
It is used to treat heart failure.
Foxglove extract was first shown to be
effective in 1785 by an English doctor
named William Withering. However,
foxglove plants were used for
centuries prior to this for treating
many different illnesses.
The use of willow bark dates back
to the time of Hippocrates (400
BC) when patients were advised
to chew it to reduce fever and
inflammation. It continues to be
used today for the treatment of
pain, headache, and
inflammatory conditions.
Ergotamine constricts blood vessels and is
used to treat migraines. It is found in ergot, a
fungus that grows on rye plants. This drug is
chemically similar to LSD, and a disorder
called St. Anthony's Fire, with symptoms
similar to the experience of an LSD trip, can
result from eating rye infected with ergot.
Morphine is a highly potent drug and is the principal
active agent in opium. Like other opioids, e.g.heroin,
morphine acts directly on the central nervous system
to relieve pain. Morphine is highly addictive.
Patients on morphine often report insomnia, visual
hallucinations and nightmares.
Pseudoephedrine is a decongestant found in common
cold remedies such as Sudafed.
It is found in the ephedra plant, which is also the source
of the dangerous diet drug ephedrine.
•Chamomile (Matricaria recutita) - soothes indigestion and
colic, eases tension, and is good for skin irritations.
• Echinacea - boosts the immune system, and lessens the
severity of colds and flu
• Lavender - calms and relaxes, eases pain and is antiseptic
for cuts and bruises.
• Lemon balm - soothes nervous tension and anxiety,
promotes sleep, and is good for cold sores.
• Peppermint - good for digestion, wind and headaches.
• Rosemary - helps memory and concentration, improves
mood, sweetens breath.
• St John's Wort - anti-depressant and promotes skin healing
Drugs from plants
• Why do they extract the chemical from the
plant – why not get patients to eat the
plant?
• List the advantages and disadvantages of
using medicines derived directly from
plants, as opposed to synthesised drugs
Advantages:
• Less additives
• Active ingredient difficult to synthesise – need to work in
conjunction with others,
Disadvantages:
• Difficult to control dosage
• More expensive (due to extraction and purifying process)
Limited supplies
• What are the options available if supplies
of a medicinal plant are limited?
Limited supplies
• Cultivating the plant in its native area
• cultivating the plant in other areas
• finding alternative plant sources
(particularly if these can be grown faster or
more of the necessary ingredient can be
harvested from them)
• synthesising the active compounds
• synthesising similar compounds and
testing them for medicinal effects