BIO 201: Botany
MEDICINAL PLANTS

CATEGORIES OF PLANTS AND MEDICINE

In reality a narrow distinction between the three categories:
    MEDICINAL - of positive value to the body by slowing or stopping a disease
    PSYCHOACTIVE - mind altering, no long term effect
    POISONOUS OR TOXIC - distinct negative effect on body, either short or long term

HISTORY OF MEDICINAL PLANTS

Original healing by herbal medicines used 4000 years ago
      first evidence from Mesopotamia with Ebers Papyrus
      listed plants, animals and minerals of medicinal value

Father of medicine is Hippocrates (400 BC) - Greece & Italy
      used a variety of plants to aid healing
      his ideal was that health of patient most important
      developed oath (Hippocratic Oath) that placed health of patient first

Age of herbals starting with the discovery of the printing press (ca. 1440)
      numerous books written with information on value of plants
      many book simply took previous material and added on to it

Doctrine of Signatures developed by 1500 AD
      a statement developed by herbalists
      signal from God that a plant’s usefulness was related to its shape or features
      (eg. heart shaped leaves, hairy stem)

By 1700s studies lead to relationship between plants & healing
      foxglove and change in heart rate (Withering)
      isolated specific plants to treat specific diseases

By 1800s first chemical extracts being produced
      able to isolate a specific chemical from a specific plant for a specific disease
      salicylic acid (aspirin) from willow
      morphine from opium poppy

Still number of persons who prefer the direct plants or extracts
      persons = HERBALISTS

CURRENT METHODS TO STUDY HERBAL MEDICINES

Phytotherapy = use of plant extracts as medicines
      natural origin, not chemically altered (aka alternative medicine)
      modern science is used in the process to verify
      publications in this area have dramatically increased in last 20 years

Plant extracts are used rather than isolated chemicals
For example: St. John’s wort is used as an antidepressant
      the “active ingredient” is hypericin
      a second chemical in the plant is hyperforin which has antibiotic uses
Common to have multiple chemicals in one plant with different values
      Hence many plants have multiple uses

A drug is used to treat a diagnosable disease (as defined by the FDA)
      commonly treated with a specific chemical
      malaria treated with quinine (originally extracted from the Fever bark tree)

An herb is used to treat symptoms

• Aid digestion
• Soften skin
• Improve memory

Many times treatments with plants are to avoid disease rather than to treat disease

The quality of herbal extracts is influenced by many factors, including:

• Genetic variation of the plant species
• Growth conditions (sun, water, fertilizer)

• Portion of plant collected
• Post harvest processing
• How stored (temperature, light)

CURRENT PROCESS FOR DEVELOPING NEW DRUGS

Process of discovering, developing, and testing a drug takes about 10 years and $50 - $100 million

1) collections of plants material - make use of:
      a) ask native what they use
      b) test other portions of known plants
      c) test species related to those of known value
      d) randomly sample plants

2) laboratory screening of targeted collections
      a) initial mass testing in vitro to determine any usefulness
      b) selective testing of positives
      c) isolating a chemical of value

3) developing drugs for use and gaining approval
      a) non human tests
      b) human screening (trials)
      c) FDA approval as a drug

EXAMPLES OF MEDICINAL PLANTS

Consider:

• Plant name
• What it is used for
• Herbal or drug
• Where it is native & now grown

Fever bark tree – treatment of malaria (a specific disease)
      contains the chemical quinine; concentrated in bark
      now a variety of synthetic drugs, including Chloroquine
      native to northwestern South America (Andes mountains), still only there

Foxglove – treatment of heart diseases
      stimulate the heart by strengthening the muscles
      high concentrations cause irregular heartbeat (toxic)
      contain digitoxin & digoxin throughout plant, but mostly in leaves
      a native of western Europe, now grown worldwide in temperate climates

Madagascar periwinkle – treatment of forms of leukemia
      contains several anticancer chemicals found throughout plant
      isolated drugs include: vinblastine, vindesine
      plant a native of Madagascar where it is endangered due to clearing of forests
      but is a common garden (bedding) flower
      ironically, cannot be grown in Louisiana for medicinal purposes!

Cabbage, turnips greens, kale, collard – group of plants from mustard family
      great examples of use for herbal treatments
      suppress cancer causing substances, clearly antioxidants
      eat raw or lightly cooked leaves
      long in cultivation, origins in the Mediterranean region

Echinacea – native American plant to treat infections
      Thought to be stimulator of the immune system, acting as an antimicrobial
      hence herbal use (from roots) for treating colds
      recent studies have been contradictory & controversial
       * some found 50% reduction in cold occurrence
       * others found no significant effects
      a native of eastern North America