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- History of medicinal plants
Primitive man used plants for both food and medicine
Knowledge of medicinal use was passed down verbally
First documented use of medicinal plants found in early Egyptian and Asian cultures
Knowledge later spread to Greece and Western World
Hippocrates (460-370 BCE), Theorphrastus (370-287 BCE), Pliny the Elder (CE 23-79), Dioscorides (CE 40-80) described plants that could be used as drugs
94,22,000 species of plants occurring in the world, approximately 35,000-70,000 species were used at one time or the other for medicinal purpose.
In Ayurveda around 8,000 plant species are considered to have medicinal value
Chinese Pharmacopoeia lists over 5,700 traditional medicines, most of which are of plant origin
About 500 herbs are still used in conventional medicine, although whole plants are rarely used
MAP is as old as mankind
Discovery of curative properties may have sprung from human instinct or by change
Discovery may also have resulted from trial and error
Man learnt some of the curative properties of plants from animals as animals intuitively treated themselves
e.g., injured deer rubbing itself against geum
MAP Industry
Plants heal and cure diseases – improve health
Basis of traditional or indigenous health systems
Used by 80% of the populations in most developing countries
Substantial growth in herb and herbal product markets across the world
Herbal products – more than US$ 93 billion
Global market for plant-based drugs is estimated to reach US$ 5 trillion by 2050
Around 70,000 plant species used for medicinal purposes
write down some of the opportunities for particular activities in medicinal and aromatic plants
Cultivation -Rural employment and livelihood improvements
Processing-Establishment of chilling/ distribution units, herbal extraction units, fractionating columns etc. leading to employment generation
By-products-based industries-Manufacturing of vermicompost, perfumed waters, botanical, pesticides, etc
Product development-Marketing of soaps, candles, perfumes, traditional drugs, incenses, etc.
Marketing-Marketing of seeds, plants, oils, drugs, products, etc
connsultancy-Cultivation, processing, financing, marketing, etc
Quality control-Testing laboratories for quality certification
Packaging, storing-G.I. drums, bags, cartoons, godowns, etc.
Transportation-Tractors, trucks, etc
What is a medicinal plant?
Medicinal plants are those that have curative properties due to the presence of various complex chemical substances of different composition, which are found as secondary plant metabolites in one or more parts of these plants.
Secondary metabolites
Produced as a by-product of photosynthesis
Has no direct function in plant growth, but may be needed for survival
Produced to protect themselves or attract pollinators
e.g., scents, pigments, antibiotics, etc.
Can be beneficial or toxic to humans based on their composition secondary metabolites are grouped as:
Alkaloids (N-containing),
Glycosides (N & S containing),
Terpenoids (composed entirely of C & H)
Phenolics (simple sugar with benzene rings and C & H).
Alkaloids
Nitrogen-containing organic compounds found in plant kingdom
Are highly heterogeneous
Produced by bacteria, fungi, plants and animals & also found in natural products
Produced in very small amounts in plants
Synthesized mainly from amino acids
Most alkaloids are bitter in taste
Could be toxic or have pharmaceutical effects – used as medicines & recreational drugs
E.g. local anaesthetic & stimulant cocaine, stimulant caffeine, nicotine, antimalarial drug quinine
All nightshade plants contain alkaloids
Hypothesized to protect plants from insects and other animals
Act as intermediaries in the synthesis of other products
Largest groups, examples include: Morphine and codeine (opium poppy), Nicotine (tobacco), Vincristine (Catharanthus roseus - periwinkle), Ephedrine (Ephedra) etc.
Generally, an alkaloid contains at least one nitrogen atom in an amine-type structure—i.e., one derived from ammonia by replacing hydrogen atoms with hydrogen-carbon groups called hydrocarbons.
Most alkaloids have one or more of their nitrogen atoms as part of a ring of atoms, frequently called a cyclic system.
ii. Glycosides
Are complex organic compounds mainly present in plant world
Consist of two parts
One is sugar molecule
Other is aglycone
Sugar moiety can join aglycone in various ways
Most common bridging atom is oxygen (O-glycosides); it can also be sulfur (S-glycoside), nitrogen (N-glycoside) or carbon (C-glycoside)
Aglycone (or aglycon) = is the compound remaining after the glycosyl group on a glycoside is replaced by a hydrogen atom. For example, the aglycone of a cardiac glycoside would be a steroid molecule
Moiety = a part or functional group of a molecule OR one of two equal parts
Are usually solid, colourless, non-volatile, soluble in water and alcohol
Many plants store chemicals in the form of inactive glycosides
Glycosidic link is resistant to alkaline hydrolysis
Can be activated by enzyme hydrolysis or by dilute mineral acid
Plant glycosides are used asmedications
digoxin (foxglove- Digitalis purpurea) - (used to treat heart conditions),
barbaloin (aloe), etc
iii. Polyphenols
Broadly dived into four classes phenolic acids, flavonoids, stilbenes and lignans.
Phenolic acids are abundant in a stable daily diet that includes sufficient amounts of fruits, vegetables, and whole grains.
The main phenolic acid sources are berries, cherries, apples, citrus fruits, rice bran, passion fruit, mangoes, coffee, kiwis, tea, wheat, corn, and oat flours.
Flavonoids are a diverse group of phytonutrients (plant chemicals) found in almost all fruits and vegetables. Along with carotenoids, they are responsible for the vivid colors in fruits and vegetables.
Stilbenes are natural compounds found in grape skins, red wine, peanuts, blueberries, and cranberries
Lignin is an important organic polymer which is abundant in cell walls of some specific cells. It has many biological functions such as water transport, mechanical support and resistance to various stresses
Polymer = a substance which has a molecular structure built up chiefly or completely from a large number of similar units bonded together, e.g. many synthetic organic materials used as plastics and resins.
Polyphenols of several classes are widespread in plants, having diverse roles in defenses against plant diseases and predators
They include hormone-mimicking phytoestrogens and astringent tannins
Plants containing phytoestrogens have been administered for centuries for gynecological disorders, such as fertility, menstrual, and menopausal problems
E,g., fennel, anise, etc.
In Ayurveda, the astringent rind of the pomegranate, containing polyphenols called punicalagins, is used as a medicine.
Phytoestrogens = compounds that naturally occur in plants
Tannins = a yellowish or brownish bitter-tasting organic substance present in some galls, barks, and other plant tissues, consisting of derivatives of gallic acid
Terpenes
Terpenes and terpenoids of many kinds are found in a variety of medicinal plants, and in resinous plants such as the conifers.
They are strongly aromatic and serve to repel herbivores
Their scent makes them useful in essential oils, whether for perfumes such as rose and lavender, or for aromatherapy.
Essential oil of common thyme (Thymus vulgaris), contains the monoterpene thymol, an antiseptic and antifungal.
Medicinal plant species in the region
India has 8,000 medicinal and 2,500 aromatic plant species having medicinal values
Sri Lanka about 1,400
Nepal about 700
Bhutan about 322
