1. Medicinal Plants

2. Prehistoric times
No one knows where or when plants first began to be used to treat disease
Accidental discovery of some new plant food that eased pain might have been the beginning of folk knowledge
Early evidence: the grave of a Neanderthal man buried 60,000 years ago. Pollen analysis indicated that plants buried with the corpse were all of medicinal value

3. Recorded history
Earliest record 4,000 year old Sumerian clay tablet recorded numerous plant remedies
Ancient Egyptian civilization had a wealth of information on medicinal plants - Ebers Papyrus 3500 yrs ago

4. Ancient China
The Pun-tsao, a pharmacopoeia published around 1600, contained thousands of herbal cures that are attributed to the works of Shen-nung, China's legendary Emperor who lived over 4500 years ago

5. Ancient India
Herbal medicine dates back several thousand years to the Rig-Veda, the collection of Hindu sacred verses
This is the basis of a health care system known as Ayurvedic medicine
One useful plant that has come from Ayurvedic tradition is snakeroot, Rauwolfia serpentina

6. Foundations of western medicine
These ancient records indicate that in all parts of the world native peoples discovered and developed medicinal uses of local plants
Herbal medicine of ancient Greece laid the foundations of our Western medicine

7. Ancient Greek and Roman medicine
Greek physician Hippocrates ( B.C.), known as the Father of Medicine used various herbal remedies in his treatments
Roman physician Dioscorides (1st century A.D.) wrote De Materia Medica which contained an account of over 600 species of plants with medicinal value.

8. De Materia Medica
Descriptions of plants, directions on the preparation, uses, and side effects
Many still in use
willow bark tea - precursor to aspirin
Some have been lost
Greek and Roman women used silphium as an effective contraceptive for 1,000 yrs - now extinct
Standard medical reference for 1500 years
Little new knowledge was added in Europe during the Dark Ages

9. Age of herbals
Beginning of Renaissance in the early 15th century saw a renewal of learning
Botanically - revival of herbalism for medicinal plants
Coupled with the invention of the printing press in 1440 ushered in the Age of Herbals

10. Herbals Beautifully illustrated books that described plants
When to collect, useful parts
Medicinal and culinary uses
Also included a lot of misinformation and superstition
Often advocated the Doctrine of Signatures

11. Doctrine of Signatures
Medicinal use recognized by distinct "signatures" visible on the plant which corresponded to human anatomy
Red juice of bloodwort to treat blood disorders
Lobed appearance of liverworts to aid the liver
Belief in this concept developed independently among different cultures

12. 18th Century
As science progressed, a dichotomy in medicine developed between practitioners of herbal medicine and regular physicians
About this same time a similar split occurred between herbalism and scientific botany

13. Path to modern medicine
Many herbal remedies had a sound scientific basis
Some became useful prescriptions drugs
William Withering was the first to scientifically investigate a folk remedy
His studies ( ) of foxglove to treat dropsy (congestive heart failure) set standard for pharmaceutical chemistry

14. 19th Century
Scientists began purifying the active extracts from medicinal plants
Breakthrough in pharmaceutical chemistry came when Serturner isolated morphine from opium poppy in 1806
First synthetic drugs were developed in the middle of the 19th century based on natural products

15. 20th Century
Direct use of plant extracts continued to decrease in the late 19th and 20th centuries
Today medicinal plants still contribute significantly to prescription drugs
25% of prescriptions written in the U.S. contain plant-derived active ingredients
50% if fungal products are included
An even larger percent based on semi-synthetic or wholly synthetic ingredients originally isolated from plants

16. Late 20th century
Renewed interest in investigating plants for medically useful compounds
Recent success of taxol from the Pacific yew tree has shown this interest is worth pursuing

17. Herbal medicine today
75%-90% of the rural population in developing nations rely on herbal medicine as their only health care
Medicinal herbs are sold alongside vegetables in village markets
Practitioners of herbal medicine undergo extensive training to learn the plants, their uses, and preparation of remedies

18. People's Republic of China
Traditional herbal medicine incorporated into a modern health care system
Blend of herbal medicine, acupuncture, and Western medicine
Thousands of species of medicinal herbs are available for the Chinese herbalist
Chinese apothecaries contain an incredible assortment of dried plant specimens
Prescriptions filled with blends of specific herbs

19. India Traditional systems separate from Western medicine
At universities medical students are trained in Western medicine
Most people use traditional systems:
Ayurvedic medicine - Hindu origin
Unani medicine - Muslim and Greek origin
Economics also a factor - manufactured pharmaceuticals too expensive for most

20. Other areas
Interest in medicinal plants has focused on indigenous peoples in many parts of the world
Ethnobotanists are spending time with local tribes and learning their medical lore before they are lost forever
Especially important among native peoples in the tropical rain forests

21. Tropical rain forests
Widespread destruction threatens to eliminate thousands of species that have never been scientifically investigated for medical potential
Erosion of tribal cultures is also a threat to the knowledge of herbal practices
As younger members of native groups are drawn away from tribal lifestyles, oral traditions are not passed on

22. Active principles in plants
Secondary plant products
Two major categories of these compounds
alkaloids
glycosides
Other types of compounds are also important - essential oils

23. Alkaloids Diverse group of compounds Over 3000 have been identified
Most occur in herbaceous dicots and fungi
Three families that are particularly known for their alkaloids: Fabaceae (legume family), the Solanaceae (nightshade family) and the Rubiaceae (coffee family)

24. Chemistry of alkaloids
Vary greatly in chemical structure
Alkaloids share several characteristics:
they contain nitrogen
they are usually alkaline
they have a bitter taste

25. Physiological effects of alkaloids
Diverse effects with the most pronounced on the nervous system
Can also have psychological effects
Some medicinally important, some psychoactive, some poisonous
Often a fine line between a medicinal and toxic dose
Common alkaloids: caffeine, nicotine, cocaine, morphine, quinine, ephedrine

26. Psychoactive Compounds
Affect the central nervous system - often by influencing neurotransmitters
Categories of psychoactive cmpds
Stimulants
Hallucinogens
Depressants
May also be narcotic

27. Narcotic Compounds
By definition a narcotic drug induces central nervous system depression resulting in numbness, lethargy, sleep
In current use, a narcotic is a psychoactive drug that is dangerously addictive
Addictive cmpds elicit: psychological dependence, physiological dependence, and/or tolerance

28. Glycosides
Also widespread in the plant kingdom and second in importance as medicines or toxins
Have sugar molecule (glyco-) is attached to the active component
Active portion variable, sugar is glucose
Generally categorized by the active component: cyanogenic glycosides, cardiac glycosides, and saponins.

29. Cyanogenic glycosides
Release cyanide (HCN) upon breakdown
Cassava contains cyanogenic glycosides
Seeds, pits, and bark of many members of the rose family (apples, pears, almonds, apricots, cherries, peaches, and plums) contain amygdalin, a cyanogenic glycoside

30. Amygdalin Apricot pits are rich in amygdalin
Ground up for preparation of laetrile, a controversial cancer treatment
Theoretically, laetrile releases HCN only in the presence of tumor cells and selectively destroys them
Not proven and laetrile not approved for cancer therapy in the United States

31. Cardiac glycosides Steroid molecule is active component
Cardiac glycosides effect the contraction of heart muscle
In proper doses, some are used to treat various forms of heart failure
Best known is digitalis
Some of the deadliest plants, such as milkweed and oleander, contain toxic levels of cardiac glycosides

32. Saponins Steroid molecule is active component
Can be highly toxic causing severe gastric irritation and hemolytic anemia
One useful saponin is disogenin from yams (Dioscorea spp.) which can be used to synthesis various hormones such as progesterone (ingredient in birth control pills) and cortisone

33. Some important medicinal plants
Foxglove - heart disease - digitalis
Willow bark tea - pain, fever - aspirin
Fever Bark Tree - malaria - quinine
Snakeroot - hypertension - reserpine
Aloe - burns - various glycosides
Vinca - leukemia - vincristine
Taxus - ovarian & breast cancer - taxol

34. Foxglove and heart disease
Foxglove - Digitalis purpurea
Extract called digitalis
Long history as a folk remedy for congestive heart failure (dropsy)
William Withering investigated this remedy from first scientific study of a medicinal plant

35. Digitalis purpurea
Purple foxglove - an attractive biennial with large purple bell-shaped flowers
Often used as a garden ornamental
Leaves contain over 30 cardiac glycosides with digoxin and digitoxin the most medically significant
Concentration of glycosides highest before flowering
Leaves dried, powdered, then extracted

36. Foxglove
Digitalis purpurea

37. Physiological action
Digitalis slows heart rate and increases strength of each heartbeat
Results: more blood is pumped with each contraction
Improved circulation, decreases edema, and increases kidney output
Effective treatment - not a cure
Fine line between a therapeutic and toxic dose of digitalis

38. 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

39. 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)

40. 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

41. 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

42. 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

43. Malaria and fever bark tree
Malaria known since antiquity, is still the world's most prevalent disease
2 to 3 million people die each year from malaria, and at least one million of these deaths are young children
Today malaria largely confined to tropical and subtropical countries in Asia, Africa, South America, and Central America

44. Malaria Caused by unicellular parasites in genus Plasmodium
Spread by bite of Anopheles mosquito
Parasite multiplies in liver and released in blood stream
Invade red blood cells - multiply and rupture RBC
Cycle repeats every few days -symptoms fever, chills, anemia....death

45. Fever bark tree Native to the eastern slopes of the Andes Mountains
Called quina-quina by the Incas
Several species of Cinchona
Small evergreen trees belong to the Rubiaceae, the coffee family
Fever reducing powers of the tree were well known to the Incas who shared knowledge with Jesuit missionaries

46. Jesuit’s bark Jesuits used bark to treat people with malaria
In Countess of Cinchon, wife of the Viceroy of Peru - miraculous recovery spread reputation of the bark
Years later Linnaeus named the genus Cinchona in honor of the countess
By the end of the 17th century the powdered bark of the quina-quina tree was the standard treatment for malaria

47. Quinine In 1820 two French scientists isolated the alkaloid quinine
Within a few years purified quinine was available commercially
Demand for the bark increased even more
36 alkaloids in Cinchona bark - 4 have anti-malarial properties
Quinine is the most effective

48. Synthetics During World War II synthetics were developed
Today the most widely used drug for malaria is chloroquine which is less toxic and more effective than quinine
Widespread use of chloroquine has resulted in chloroquine-resistant strains of the parasite
Quinine used for these infections in combination with other drugs

49. Physiological action Quinine kills parasite in blood stream
Also effective as a prophylactic to prevent initial infection of red blood cells in travelers
"gin and tonic"
Recently scientists have been investigating anti-malarial properties of weed Artemesia annua, wormwood

50. Snakeroot, schizophrenia, and hypertension
Snakeroot, Rauwolfia serpentina
"doctrine of signatures"- because long coiled roots resembled a snake, healers believed that the root could be used for treating snake bites
For over 4000 years, Hindu healers used the root for the treatment of snakebites, insect stings, and even mental illness

51. Rauwolfia serpentina and reserpine
In 1952 the alkaloid reserpine was isolated from the roots
Later dozens of alkaloids found
The sedative effects of reserpine made it valuable as a tranquilizers - side effect was a reduction in blood pressure
Today, this is actually the principal application of reserpine, as a treatment for hypertension

52. Burn plant - Aloe vera
Well known folk remedy is use of Aloe vera sap for minor burns
Used for thousands of years as treatments for various skin ailments
Aloe vera (A. barbadensis) the best known member of the genus but other Aloe species also used

53. Aloe leaves Thick mucilaginous sap Soothing effect on injured skin
Numerous compounds including several anthraquinone glycosides collectively referred to as aloin
Chrysophanic acid also present - possibly the compound with the greatest healing effect on skin

54. Action
Sap promotes faster healing with less scaring by stimulating cell growth
Inhibits bacterial and fungal infection
Compounds in the sap inhibit pain, itching, and inflammation
In recent years the cosmetic industry has capitalized on the moisturizing effects of the sap and it can be found in a variety of skin creams, shampoos, sun screen lotions, and bath oils

55. Cancer therapy
Cancer is a diverse group of diseases characterized by uncontrolled growth of abnormal cells.
Today in the United States cancer is the leading cause of death
Search for cancer cures is relentless
Plants have figured prominently in folk remedies for cancer
Over 3000 plant species had been used

56. Search for drugs
In the late 1950's National Cancer Institute and USDA began search for plants with anti-cancer properties
Thousands of plants have been scientifically screened, and several have become standard chemotherapy for different forms of cancers
Search is not over since only a small percentage have been screened

57. Vinblastine and vincristine
Treatments for leukemia and lymphoma
Alkaloids from Madagascar periwinkle, Catharanthus roseus (Vinca rosea)
Used by traditional healers as treatment for diabetes

59. Screening
Investigating this claim in the 1950's, scientists at the University of Western Ontario in Canada and Eli Lilly Pharmaceuticals in Indianapolis found no evidence of usefulness in treating diabetes
Extracts from the leaves were found to be effective against leukemia cells and
Alkaloids responsible were identified

60. Use today Vincristine and vinblastine major chemotherapeutic agents
Vincristine has been especially effective for treating acute childhood leukemia, often with 99% remission rates
Vinblastine has been especially effective for treating Hodgkin's disease
Both alkaloids also used for other types of cancer

61. Pacific yew trees and taxol
Taxol obtained from the bark of the Pacific yew, Taxus brevifolia
Anti-tumor properties were first discovered in the 1960's during the screening program of the National Cancer Institute
Taxol - only recently approved
Clinical trials showed taxol especially promising in treating ovarian and breast cancer

62. Taxus - yew

63. Supply of taxol
Original from bark of mature Pacific yew trees, a slow-growing conifer of old-growth forests in the Pacific NW
Concern about destruction of ancient forests
New sources
Other species of Taxus contain taxol
Tissue cultures of bark cells promising
Recently synthesized in the laboratory

64. What’s in the future Search for medicinal plants continues
Especially in tropical rain forests
Time is critical before plants are lost and cultural knowledge of the plants are lost
Same is true among native peoples everywhere includes Native Americans