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Plants used for the nervous
system and pain relief
What is the nervous system?
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Composed of billions of neurons that
function by conducting impulses
Coordinates functioning of all body
systems
Major parts of the nervous system
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Central nervous system (brain and spinal
cord)
Peripheral nervous system (sensory and
motor systems)
Neurotransmitters
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Chemicals that transmit nervous impulses from one
neuron to the next
There are over 25 different neurotransmitters known.
Common ones include:
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Serotonin
Epinephrine
Dopamine
Acetylcholine
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Norepinephrine
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Some plant compounds mimic neurotransmitters or
interfere with their normal function
Levels of neurotransmitters in brain can alter mood
and perception and impact thinking and learning
Pain
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Pain is detected by a class of neurons called
nociceptors
Different nociceptors respond to heat,
pressure, or chemicals released from
damaged or inflamed tissue
Prostaglandins increase pain by sensitizing
the receptors (lowers threshold)
Chronic pain affects 97 million people in US
and costs about $100 billion/year
Endorphins
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Endorphins are polypeptides that act as
chemical painkillers
Produced naturally in the body
Able to bind to the receptors in the
brain to give relief from pain
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responsible for the so called runner's high,
loss of pain when severe injury occurs
analgesic effects of acupuncture
released into the brain during laughter
Endorphins
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Sometimes called the body’s natural
opiates
Morphine, codeine, heroin and other
opiates mimic endorphins and bind to
the same receptors in brain
Plants and Pain
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Plants have been popular sources of
pain remedies in just about every
culture on earth
Plants boiled and/or beaten and ground
into teas, pastes, poultices, and
ointments to ease the pain
A short list of plants
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Willow bark, comfrey leaves, coriander, sage,
and sarsaparilla root were common old world
remedies
Sweet birch bark, cinchona bark, and hot
peppers were common plant remedies used
by people in the new world
Banana and aloe plants also fought pain, as
compounds found in their leaves and stems
were used to soothe burns and blisters
An even shorter list
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Willow bark and others (salicylic acid –
aspirin)
Poppy (morphine and codeine)
Chili peppers (capsaicin)
Marijuana (THC)
Ergot (ergotamine)
Others
Aspirin: willow bark to Bayer
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Most widely used synthetic drug but
origins are botanical
Bark of willow trees (Salix spp.) used by
many cultures for reducing fever and
relieving pain - in form of a tea
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Old world ancient Greece
New world - Native American tribes
Path to a synthetic
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In 1828 salicin was first isolated and
over the next decade the extraction
method was refined
Salicin is a glycoside of salicylic acid
Salicylates occur widely in species of
Salix as well as many other plants
including meadowsweet (Spirea
ulmaria)
Salicylic acid
Next step
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Laboratory synthesis of salicylic acid in
the mid-19th century
Salicylic acid was an inexpensive
treatment for many ailments rheumatic fever, gout, arthritis
Had side effects - especially gastric
In 1898 Felix Hoffman, a chemist at
Bayer Company came across
acetylsalicylic acid
Acetylsalicylic acid
Acetylsalicylic acid
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Effective and more palatable
Soon given the name aspirin
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"a" is from the acetylsalicylic acid and the
"spirin" from Spirea the plant from which
salicylic acid was first isolated
Physiological action
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Three classic properties
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anti-inflammatory
antipyretic (fever reducing)
analgesic (pain relieving)
New uses in the prevention of heart
attacks, strokes, and colon cancer
Drawbacks:
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irritates the stomach
Reye's syndrome
Mode of action
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Key to understanding some of the action of
aspirin was discovery by British researcher
John Vane
Looking at role of aspirin and heart attacks
Vane showed that low doses of aspirin
suppressed the aggregation of blood platelets
which is necessary for blood clots
Blood clots can block blood vessels and lead to
heart attacks
Prostaglandins
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Mechanism is suppression by way of effects
on prostaglandins
Prostaglandins are hormone-like substances
that regulate numerous other activities in the
body
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influence the elasticity of blood vessels
direct the functioning of blood platelets that
controls blood flow
cause redness and fever
Prostaglandins
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Prostaglandins are released from
injured cells
Also released from cells stimulated by
other hormones
Over production of prostaglandins can
lead to headaches, fever, menstrual
cramps, inflammation, blood clots, etc
Salicylic Acid in Plants
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Since initial discover identified in many plants
Now believed that salicylic acid is a naturally
occurring plant hormone involved in many
reactions including plant protection
Plants respond to attack by a host of
defenses - many already discussed
Plants also respond with a broad based
defense mechanism known as Systemic
Acquired Resistance
Systemic Acquired Resistance
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Helps plant protect against secondary
infections
Salicylic acid is signal that turns on SAR
SAR turns on synthesis of specific proteins
that increase resistance
External application of salycylic acid will turn
on response
Will also turn on responses in nearby plants
by conversion to volatile methyl salicylic acid