Information about the medicinal properties of plants

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 (460-377
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 (1775-1785) 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 1775-1785 - 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 1638 - 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