Transcript File

Medically Important Plants
PRESENTED BY:
Ms Liziwe Mugivhisa
Main objective
Plant derived
substances of medical
& veterinary
significance
Relationship
between
botany &
medicine
Drugs with
origin in
indigenous
ethnopharmacology
Secondary
plant
metabolites
Strategies
for
collecting
medicinal
plants
Remedial drugs
of plant origin
Psychoactive
drugs of
plant origin
Poisonous
plants
Objectives
• Methods for collecting plants with medicinal value
• Plant parts used for medicinal purposes
• Methods of preparation & administration
• Secondary plant metabolites
Introduction
Importance of Medicinal plants
•
Medicinal plants & plant-derived medicines widely used in traditional
cultures
•
120 drugs extracted from plants
•
Examples of plant-derived medicines
– Quinine (tree called Cinchona), morphine & codeine (poppy),
colchicines (Colchicum autumnale), atropine (Belladonna or Deadly
Nightshade), reserpine (Rauwolfia Vomitoria), & digoxin (Digitalis
spp)
– new anticancer drugs
• taxol [Pacific yew tree (Taxus brevifolia)]
• vincristine (periwinkle)
AFRICAN TRADITIONAL MEDICINE
• oldest & most diverse of all medicine systems
• wide range of plants therapeutically used by indigenous peoples
to maintain health
• The Khoi-Sans have a:
– material medica (with about 86 plant species) typically for
medicinal use including:
• general tonics, fever remedies, Sedatives, Stomachics,
Diuretics, laxatives, numerous wound healing plants
AFRICAN TRADITIONAL MEDICINE
Well known S.A medicinal plants
– Agathosma betulina (buchu)
– Aloe ferox (Cape aloe)
– Artemisia afra (African wormwood)
– Aspalathus linearis (rooibos tea)
– Harpagophytum procumbens (devil’s claw)
– Hypoxis hemerocallidea (African potato)
AFRICAN TRADITIONAL MEDICINE
medicinal plants
Agathosma
betulina (buchu)
– Evergreen
flowering plant
– In Western parts
of S.A
– Uses:
• Flavouring agent
in teas, candy,
liquor
• Herbal remedy
AFRICAN TRADITIONAL MEDICINE
medicinal plants
Aloe ferox
(Cape aloe)
– Indigenous to S.A
– Uses:
• Bitter aloes
– Purgative medication
• Non-bitter aloes
– Gel in cosmetics
AFRICAN TRADITIONAL MEDICINE
medicinal plants
Artemisia afra
(African wormwood)
– Found as far as in Ethopia
– Uses:
• Roots, stems & leaves
– Used as enemas, lotions,
inhalations (smoked /
snuffed) or as essential
oils
– Used as moth repellent &
organic insecticidal spray
AFRICAN TRADITIONAL MEDICINE
medicinal plants
Aspalathus linearis
(rooibos tea)
– Endemic to western coast of
Western Cape
– Uses:
• Herbal tea
• levels of antioxidants
• caffein & tannin
• Assists with nervous
tension, allergies, digestive
problems
• Alleviates colic, asthmas,
dermatological problems
• Cancer fighting qualities
AFRICAN TRADITIONAL MEDICINE
medicinal plants
Harpagophytum
procumbens
(devil’s claw)
– Found in Namibia
– Uses:
• To reduce pain &
fever
• Anti-inflammatory
• Stimulates
digestion
• Treatment of
arthritis
AFRICAN TRADITIONAL MEDICINE
medicinal plants
Hypoxis hemerocallidea
(African potato)
• Miracle muti / wonder
potato
• Most traded
• Believed to cure HIV
BOTANY & MEDICINE
• Relationship between botany & medicine
– Carl Linnaeus
• Father of modern botany
• Had a medical degree
• Used knowledge in study of plants in practice
of medicine
– Asa Gray
• Founder of the Harvard’s Gray Herbarium
• Studied medicine
ETHNOBOTANY IN DRUG DEVELOPMENT
Ethnobotany
•
Inter-relationship between plants & medicine
– Study of how plants are utilized by human cultures
– Relates & interacts with Botany, Medicine, Nutrition, Agriculture
& anthropology
•
Employs local peoples knowledge about medical uses of plants & their
environment
•
Ethnobotanists:
– work as mediators & facillitators
•
Preserve indigenous discoveries & make them accessible & useful
Methods for collecting plants with medicinal value
• Collection & analysis of information on plants’ uses
essential
– For drug development
– Plants used as starting materials
• Ethnobotany
– Use of plants by indigenous cultures
– Provides information to pre-screen for selection
of specific plants for pharmacological studies
Methods for collecting plants with medicinal value
Random
Method
Targeted
Selective
Plant Families Harvesting
Ethnobotanical
approach
• Complete
• Targets plant
•
• Careful
collection of
families known
selection of a
plants in an
to be rich in
particular plant
area
biologically
for a particular
active
patient
• Plants collected
compounds
& screened
without regard
• Involves having
a prior
• Close relatives
knowledge,
of other
of plants known
training &
intrinsic
to produce
experience
qualities
useful
Employs local
people’s knowledge
•Drugs with origins
in indigenous
ethnopharmacology
• reserpine,
quinine, aspirin,
vincristine
Methods for collecting plants with medicinal value
Random Method
• Complete collection of plants in an area
• Large number of plants collected for screening
depending on:
– season
– no. of fertile plants present
• Plants collected & screened without regard of:
– taxonomic affinities / ethnobotanical context / other
essential qualities
Methods for collecting plants with medicinal value
Targeted Plant Families
•
Targets plant families known to be rich in biologically active compounds
•
Phylogenetic survey
– Close relatives of plants known to produce useful compounds
collected & analysed
– Families which are of focus of collection because they are known to
produce biologically active compounds
• Apocynaceae
• Euphorbiaceae
• Minispermaceae
• Solanaceae
Methods for collecting plants with medicinal value
Selective Harvesting
• Careful selection of a particular plant needed for a particular
patient
• Involves having a prior:
– knowledge, training & experience
• Factors considered before collection:
– Particular favoured locality
– Correct season of collection
– Best area on a mountain slope
– Soil type & soil moisture
– Time of the day
Methods for collecting plants with medicinal value
Ethnobotanical approach
• Uses knowledge of local people about plants & their environment
• Requires:
– collaboration between
• Ethnobotanist, chemists, pharmacologists
– Protection & recognition of local & indigenous knowledge,
practises
– Agreement among parties on
• Responsibilities
• Benefit sharing
• compensation
Plant parts used
Part used
Characteristics
Example of plant
Roots
Fleshy / woody
Destructive (whole plant uprooted)
Thesium hystrix kleinswartsorm
Bulbs
Fleshy underground structure made of
numerous layers of fleshy scales which are leaf
bases
Destructive (whole plant removed)
Crinum macowanii – umduze
Rhizomes
Woody / fleshy elongated stem
grows horizontally below ground & roots into the
ground
Siphonochilus aethiopicus isiphephetho
Tubers
Swollen, fleshy structure below ground
Of stem origin
partly stem & partly root
Hypoxis hemerocallidea –
African potato
Bark
Outer protective layer of tree trunk
Formed by layers of living cells above wood
Warburgia salutaris - shibaha
Leaves, stems
& flowers
Leaves & twigs rarely separated when used in
medicine
Cannabis sativa - dagga
Gum & nectar
defense mechanism to seal off wound
Acacia senegal
Fruit & seeds
Rarely used for medicinal purposes
Papaver somniferum & Atropa
Belladonna –Deadly night
shade
Plant parts used
Roots
• Fleshy / woody
• Harvesting destructive
– whole plant often
destroyed
– Eg. Thesium hystrix kleinswartsorm
Roots
Plant parts used
Bulbs
•
Fleshy underground structure
– numerous layers of fleshy scales
which are leaf bases
•
Harvesting destructive
Crinum macowanii - umduze
– whole plant removed
– Eg. Crinum macowanii – umduze
– Onions & garlic bulbs
•
Bulbs contain alkaloids
•
Uses:
– Treat Kidney & bladder infections
– Protective charm
bulb
Plant parts used
Rhizomes
•
Woody / fleshy elongated stem
•
usually grows horizontally below
ground
•
Siphonochilus aethiopicus - isiphephetho
Roots into the ground
– Eg. Siphonochilus aethiopicus
– isiphephetho
– Wild ginger
•
Uses:
– Protection against lightening
& snakes
– Chewed to treat asthma
Rhizomes
Plant parts used
Tubers
•
Swollen, fleshy structure below ground
•
Of stem origin
– partly stem & partly root
Hypoxis hemerocallidea – African potato
– Eg. Hypoxis hemerocallidea –
African potato
•
Uses:
– May boost immune system
– For diabetes, haemorrhaging
– (nutrient status – 50 thousand
times more than in veggies)
Tubers
Plant parts used
Bark
•
Outer protective layer of tree trunk
•
Formed by layers of living cells above
wood
•
high conc. of active ingredients
– Eg. Warburgia salutaris – shibaha –
Warburgia salutaris – shibaha
(pepper bark)
– Oak bark, willow bark
•
Uses:
– Dried & ground
• Smoked or as expectorant
Rhizomes
– Powder – snuff (clear sinuses)
– Powder in water (cure sores on
mouth)
Bark
Plant parts used
Leaves,stems & flowers
•
Leaves & twigs rarely separated
– Eg. Cannabis sativa – dagga
•
Uses:
– Through smoking, vapourising,
Cannabis sativa
oral ingestion, in teas
– With psychoactive chemical
compounds
– Recreation, religious & spiritual
moods
– food
Leaves, stems & flowers
Plant parts used
Gum & nectar
•
Gum from a damaged stem
– defense mechanism against
wood-boring insects &
Acacia senegal
– to seal off wound to keep
wood-rotting fungi &
bacteria out
– Eg. Acacia senegal
•
Uses:
– Treatment of bleeding,
diarrhea, gonorrhea
– Dried seeds - food
Gum & nectar
Plant parts used
Fruit & seeds
• Seeds within fruit or on their own
– Eg. Moringa seeds
– Roasted & pounded
– Antibiotic & anti-inflammatory
• Fruit used dried
– Eg. Prunes – laxatives
– Apricots – treat anemia
– Lemon – epilepsy & colds
– Almonds - headaches
Fruit & seeds
Methods of administration & Preparation
Method of preparation
•
Critical
– includes knowing amount of dry plant material to be used
– addition of appropriate volumes of solvents (water/alcohol) & boiling
time
Methods used
Extracts
•
prepared by extracting active ingredients with suitable solvents such as
water / alcohol
Methods of administration & Preparation cont.
Infusion
•
Macerating (soaking) crude drug in cold or boiling water
•
Problem
– there may be fungus / bacterial growth
•
Advisable to use within 12 hrs (bottled / refrigerated)
•
Eg. tea
Methods of administration & Preparation cont.
Inhalations
•
Liquid preparations
– containing part / all volatile ingredients
• to be brought in contact with lining of respiratory tract by
inhaling
• (Eg. Steaming)
Linctuses
•
Viscous liquid containing sugar & medicinal substances / syrups
•
Possess demulcent (soothing agent)
•
expectorant/ sedative properties
•
Local action on mucous membrane
•
Sipped / swallowed without addition of water
Methods of administration & Preparation cont.
Liniments
• Liquid / semi-liquid preparations intended for external application
• May contain substances possessing analgesic, soothing /
stimulating properties
• Eg. Balms (rubbed to create friction for sore muscles)
Lotions
•
Intended for application to skin
•
May be aqueous / alcoholic solutions
•
For eczema
•
Eg. Calamine
Methods of administration & Preparation cont.
Mixtures
• Can be used orally
• Can consist of combinations of medicaments
dissolved, suspended / diffused in water / aqueous
solution
Nasal Drops
• for instillation into nostrils by means of pipette
• consist of liquid preparations
Methods of administration & Preparation cont.
Ointments
•
Semi-solid preparations
•
dissolved / dispersed in suitable basis of
animal, vegetable, mineral / synthetic origin
•
Used as emollients (balms), as protective preparations on skin or as vehicles for
topical applications of medicaments
Tinctures
•
Alcoholic liquids containing active ingredients of
vegetable drugs
•
prepared by maceration (soaking) / percolation
•
obtained by dilution of corresponding liquid extracts
Snuffs
•
Preparations of finely powdered, dried medicinal plants
•
drawn up into nostrils through inhalation
Common methods of administration
Method
Characteristics
Orally
• For infusions, decoctions, syrups & tinctures, powdered herbs
• Followed by mouthful of water
Sublingually
(Under the
tongue)
• For rapid absorption
• No acidic action of stomach, no metabolism by liver
Rectally
• By use of syringes / tubes
• For drugs made in form of enema
• Rapid absorption
Topically
• Directly to skin into underlying tissues / to sprains, bruises,
burns
• Eg. Specific infusions, decoctions, tinctures, lotions, ointments
Nasally
• For dried & powdered snuffs
• To induce sneezing
• soluble phytochemicals directly into the cerebral circulation
Steaming
• Inhalations by steaming in hot water
• Herbal steaming to introduce volatile phytochemicals into lungs
or nose
Bathing
• Herbal mixtures added to bath to relieve rash / measels
Secondary Plant Metabolites
•
Phytochemicals (Chemical & biochemical) adaptations for protection of plants
•
Perform non-vital functions not related to growth & development in plants
•
Play a role in defense & survival of plants
•
Perform non-vital functions (not related to growth & development)
•
Render plants useful:
– in traditional medicine
– As flavouring agents
– For recreational purposes
– Extracted & purified for use in modern medicine
– Eg. Family Brassicaceae
• Plants have mustard oil glycosides
• Only insects tolerant to these can feed on leaves
•
Beneficial to the plant & restrict palatability of the plant
Secondary Plant Metabolites
Plant
Metabolites
properties
Alkaloids
•
•
•
Glycosides
•
Basic substances
Nitrogen bound in
a ring system
Most have an
effect on the body
Yield 1 / more
sugar & other
compounds when
hydrolysed
structure
Examples
•
•
•
•
Caffein from tea &
bean plants
Camellia sinensis
Coffea arabica
Nicotine from
Nicotiana tabacum
Secondary Plant Metabolites
Plant
properties
Metabolites
Flavonoids
•
Polyphenolic
•
Contain 15 carbon atoms in 2 benzene rings
joined by linear carbon atoms
•
Contribute to yellow colours in plants
•
Eg. In rooibos tea
Essential oils •
Highly concentrated
•
Highly volatile & Evaporate in open air
•
Complex chemistry
•
Consist of hundreds of components
•
For treatment of a wide variety of disorders
•
Due to tiny molecular structure absorbed
into the bloodstream
structure