PLANT AND SOCIETY
ESTELLE LEVETIN & KAREN
MCMAHON
Chapter 19
MEDICINAL PLANTS
• Medicinal properties of plants due to their
secondary metabolites like
• Alkaloids
• Terpenoids
• Glycosides
• Saponins
• Phenolic compounds
• Concentration is important
ALKALOIDS
•
•
•
•
•
•
•
•
Diverse group of compounds
3,000 identified in 4,000 species
Most of them occur in herbaceous dicots
Fabaceae
Solanaceae
Rubiaceae
Vary in their chemical structure
Contain nitrogen, alkaline and bitter taste
•
•
•
•
•
•
•
•
•
•
Alkaloids affect the psychology of animals
Neurotransmitters
Some are hallucinogenic or poisonous
Quantity of dose
Caffeine
Nicotine
Cocaine
Morphine
Quinine and
Ephedrine
ASPIRIN
Salix spp.
ASPIRIN
• Most widely used synthetic drug
• America alone consume 80 million pills a day
• Bark of willow trees (Salix spp.) an effective
treatment for fever and relieving pain
• Salicin, glycosides of salicylic acid occurs in
many sp. of Salix
• Aspirin valued for three classical properties
• Anti-inflammatory
• Anti-pyretic (fever reducing)
• Analgesic (pain relieving)
• Used in prevention of heart attacks, strokes,
ovarian cancer
• Enhance the immune system in protecting body
against bacteria and viruses
• Salicylic acid found in many plants
• Capable of being translocated through
phloem
• Believed to be naturally occurring growth
hormones
• Provides protection to plants
• Plants respond to pathogens by activating
network of defenses
Systemic acquired resistance
• Salicylic acid, signal turns on this system
response
• Results in synthesis of specific proteins that
increase resistance
• External application of salicylic acid or even
aspirin (acetylsalicylic acid) to plants stimulate
this immune response
• Stimulation of salicylic acid in an infected
plant turn on responses in neighboring plants
• Healthy plants nearby absorbed the airborne
methyl salicylate molecules
• Converting back to salicylic acid
• Stimulated defense make healthy plants
more resistant to pathogen
Atropa belladonna (Solanaceae))
Atropa belladona
• Used as drug due to alkaloid Atropine
• Called deadly nightshade because it is very
poisonous
• women use drops from the leaves to make
their pupils expand and produce wide-eyed,
innocent look
• used to treat glaucoma
GLYCOSIDES
• Widespread in plant kingdom
• A sugar molecule (glyco-) attached to active
component
• Cyanogenic glycosides
• Cyanogenic glycosides release cyanide (HCN)
upon breakdown e.g., Cassava
• Cardioactive glycosides and saponins
Cardioactive glycosides
• Cardioactive glycosides and saponin contain a
steroid molecule as the active component
• Cardioactive glycosides effect on contraction of
heat muscles
• Digitalis
• Milkweeds and Oleander contain cardioactive
glycosides
Cardioactive glycosides
Foxglove and Control of heart disease
• Several million heart patients rely on digitalis
in U.S
• Digitalis purpurea, purple foxglove, attractive
biennial
• Ornamental plant
• Leaves contain over 30 glycosides (digoxin,
digitoxin)
Digitalis purpurea
Cyanogenic glycosides
• Seeds, pits, bark of many members of rose
family (apples, pears, almonds, apricots,
peaches) contain amygdalin
• (Pits of apricots rich source of amygdalin
(used in preparation of laetrile for cancer
treatment)
• Laetrile releases HCN only in presence of
tumor cells and selectively destroys them
MALARIA AND FEVER BARK TREE
• Disease initiated through bite of female
Anopheles mosquito
• Quina-quina belongs to family Rubiaceae
(coffee family)
• Quinine attacks merozoite stage, killing the
parasite in bloodstream
Sources of Quinine – Cinchona
succirubra
Efficacy of Quinine
• Quinine is traditional and effective for
malaria
• Synthetic preventatives such as chloroquine,
maloprim, and fansidar have largely replaced
the use of quinine
• Many strains of Plasmodium have developed
resistances to the synthetics and the
synthetics are more toxic
Lippia as a sweetener
• In Pre-Columbian America, several plants of
the genus Lippia were used as sweeteners. (F.
Verbenaceae – the verbenas)
• In the 20th century, L. dulcis was chemically
analyzed and a new sweetener was found,
hernandulcin, that is 800 to 1000 times
sweeter than sucrose
Lippia dulcis – sweetener from
Scientific Common
Name
Name
Aloe
vera
Cannabis
Sativa
Burn
Family
Liliaceae
Active
Medicinal Use
Principle
Aloin
Marijauna Cannabaceae THC
Cinchona Fever
Rubiaceae Quinine
sp.
Bark Tree
Skin injuries
Chemotherapy
Malaria
Scientific
Name
Common Family Active Medicinal Use
Name
Principle
Ephedra sp. Ephedra Ephedraceae Ephedrine Asthma
Papaver
Chaul- Papaveraceae Morphine Pain,
Somniferum moogra
cough
Eucalyptus Eucalyptus Myrtaceae Eucalyptol Anesglobulus
thetic
RECOMMENDED LINKS
• http://books.google.com.pk/books?id=AUOrV71X3AoC&pg=PA203&dq=as
pirin+pathway+in+plants&hl=en&ei=WfshTvLLJsSzrAe1zsjlAg&sa=X&oi=bo
ok_result&ct=result&resnum=2&ved=0CDIQ6AEwAQ#v=onepage&q=aspir
in%20pathway%20in%20plants&f=false
• http://books.google.com.pk/books?id=AxUhFMcwSrMC&printsec=frontco
ver&dq=salicylic+acid&hl=en&ei=d_8hTojxDYjmrAelyvyCAg&sa=X&oi=boo
k_result&ct=result&resnum=1&ved=0CC0Q6AEwAA#v=onepage&q&f=fals
e