Medically Important Plants

PRESENTED BY:Ms Liziwe Mugivhisa

Main objective

Plant derived substances of

medical & veterinary

significanceRelationship between botany & medicine

Strategies for

collecting medicinal

plants

Remedial drugs of plant

origin

Drugs with origin in

indigenous ethno-

pharmacology

Secondary plant

metabolites

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

IntroductionImportance 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)

Agathosma betulina (buchu)

–Evergreen flowering plant–In Western parts of S.A–Uses:• Flavouring agent

in teas, candy, liquor

• Herbal remedy

AFRICAN TRADITIONAL MEDICINEmedicinal plants

Aloe ferox (Cape aloe)

–Indigenous to S.A

–Uses:• Bitter aloes– Purgative

medication• Non-bitter aloes– Gel in cosmetics

AFRICAN TRADITIONAL MEDICINEmedicinal 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 MEDICINEmedicinal 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 MEDICINEmedicinal plants

Harpagophytum procumbens (devil’s claw)

–Found in Namibia–Uses:• To reduce pain &

fever• Anti-inflammatory• Stimulates

digestion• Treatment of

arthritis

AFRICAN TRADITIONAL MEDICINEmedicinal plants

Hypoxis

hemerocallidea

(African potato)

•Miracle muti / wonder

potato

•Most traded

•Believed to cure HIV

AFRICAN TRADITIONAL MEDICINEmedicinal plants

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 Plant Families

Selective Harvesting

Ethnobotanical approach

• Complete

collection of

plants in an

area

• Plants

collected &

screened

without

regard of

other intrinsic

qualities

• Targets plant

families

known to be

rich in

biologically

active

compounds

• Close

relatives of

plants known

to produce

useful

compounds

collected &

analysed

• Careful

selection of a

particular

plant for a

particular

patient

• Involves

having a prior

knowledge,

training &

experience

• Employs local

people’s

knowledge

•Drugs with

origins in

indigenous

ethnopharmacol

ogy

• 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 usedPart used Characteristics Example of plant

Roots Fleshy / woodyDestructive (whole plant uprooted)

Thesium hystrix - kleinswartsorm

Bulbs Fleshy underground structure made ofnumerous layers of fleshy scales which are leaf basesDestructive (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 groundOf stem origin partly stem & partly root

Hypoxis hemerocallidea – African potato

Bark Outer protective layer of tree trunkFormed 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

Roots

•Fleshy / woody

•Harvesting destructive

– whole plant often

destroyed

– Eg. Thesium hystrix -

kleinswartsorm

Plant parts used

Roots

Bulbs•Fleshy underground structure

– numerous layers of fleshy

scales which are leaf bases

•Harvesting destructive

– whole plant removed

– Eg. Crinum macowanii – umduze

– Onions & garlic bulbs

•Bulbs contain alkaloids

•Uses:

– Treat Kidney & bladder

infections

– Protective charm

Plant parts used

bulb

Crinum macowanii - umduze

Rhizomes•Woody / fleshy elongated stem

•usually grows horizontally

below ground

•Roots into the ground

– Eg. Siphonochilus

aethiopicus – isiphephetho

– Wild ginger

•Uses:

– Protection against

lightening & snakes

– Chewed to treat asthma

Plant parts used

Rhizomes

Siphonochilus aethiopicus -

isiphephetho

Plant parts used

Tubers •Swollen, fleshy structure below

ground

•Of stem origin

– partly stem & partly root

– Eg. Hypoxis hemerocallidea –

African potato

•Uses:

– May boost immune system

– For diabetes, haemorrhaging

– (nutrient status – 50 thousand

times more than in veggies) Tubers

Hypoxis hemerocallidea – African

potato

Plant parts used

Rhizomes

Bark

•Outer protective layer of tree trunk

•Formed by layers of living cells above

wood

•high conc. of active ingredients

– Eg. Warburgia salutaris –

shibaha –(pepper bark)

– Oak bark, willow bark

•Uses:

– Dried & ground

• Smoked or as expectorant

– Powder – snuff (clear sinuses)

– Powder in water (cure sores on

mouth)Bark

Warburgia salutaris – shibaha

Plant parts used

Leaves, stems & flowers

Leaves,stems & flowers•Leaves & twigs rarely separated

– Eg. Cannabis sativa – dagga

•Uses:

– Through smoking, vapourising,

oral ingestion, in teas

– With psychoactive chemical

compounds

– Recreation, religious & spiritual

moods

– food

Cannabis sativa

Plant parts used

Gum & nectar•Gum from a damaged stem

– defense mechanism

against wood-boring

insects &

– 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

Acacia senegal

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 administrationMethod 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 MetabolitesPlant Metabolites

properties structure Examples

Alkaloids • Basic substances

• Nitrogen bound in a ring system

• Most have an effect on the body

• Caffein from tea & bean plants

• Camellia sinensis

• Coffea arabica• Nicotine from

Nicotiana tabacum

Glycosides

• Yield 1 / more sugar & other compounds when hydrolysed

Secondary Plant MetabolitesPlant

Metabolite

s

properties structure

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