Plants used for the nervous system and pain relief
What is the nervous system? Composed of billions of neurons that
function by conducting impulses Coordinates functioning of all body
systems Major parts of the nervous system
Central nervous system (brain and spinal cord)
Peripheral nervous system (sensory and motor systems)
Neurotransmitters Chemicals that transmit nervous impulses from one
neuron to the next There are over 25 different neurotransmitters known.
Common ones include: Serotonin Epinephrine Dopamine Acetylcholine Norepinephrine
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 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
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 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 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 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 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 Willow bark and others (salicylic
acid – aspirin) Poppy (morphine and codeine) Chili peppers (capsaicin) Marijuana (THC) Ergot (ergotamine) Others
Aspirin: willow bark to Bayer 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 Old world ancient Greece New world - Native American tribes
Path to a synthetic
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
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
Effective and more palatable Soon given the name aspirin
"a" is from the acetylsalicylic acid and the
"spirin" from Spirea the plant from which salicylic acid was first isolated
Physiological action
Three classic properties anti-inflammatory antipyretic (fever reducing) analgesic (pain relieving)
New uses in the prevention of heart attacks, strokes, and colon cancer
Drawbacks: irritates the stomach Reye's syndrome
Mode of action 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 Mechanism is suppression by way of
effects on prostaglandins Prostaglandins are hormone-like
substances that regulate numerous other activities in the body influence the elasticity of blood vessels direct the functioning of blood platelets that
controls blood flow cause redness and fever
Prostaglandins 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 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 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