Herbal Medicine, Steps Involved In The Selection, Identification, And Processing Ofherbal Raw Materials

HERB
It consists of entire plant or any part of the plant like leaves, flowers, fruits, roots and rhizomes, bark,
tubers, stems and branches
HERBAL DRUG
These consist of plants or any part of plants, usually in unprocessed or crude forms (crude drug)
which have medicinal value.
They include different parts of plant like entire aerial part, flowers, fruits, seeds, bark, leaves, roots
rhizomes etc The constituents and their therapeutic activity may be known or unknown.
HERBAL DRUG PREPARATION
They are processed form of herbs. They are derived from herbal drugs by various techniques like
extraction, fractionalization, purification, concentration, fermentation and may be in the form of
powders, extracts, tinctures, fixed oils, volatile oils, resins, gums, etc.
They contain a mixture of various constituents. However pure isolated compounds do not come under
this category.
HERBAL MEDICINAL PRODUCTS (FINISHED HERBAL PRODUCTS)
These are the medicinal products which contain exclusive herbal drugs or herbal drug preparations
which are made from one or more herbs.
It includes various herbal formulations like tablets, syrups, capsules, semisolid dosage forms, etc.
They may contain excipients in addition to active ingredients.
FIXED COMBINATION
It includes herbal medicinal products which contain more than one herbal drug preparations
SOURCE OF HERBS
Herbs or medicinal plants can be obtained from two sources viz:-
a) Wild source b) Cultivated source
a) Wild source
The plants are obtained from the wild source such as forests, plains, river banks, etc, where they are
found in their wild form.
Collection from wild sources is suitable for plants which are abundant in nature and are easily
available.
Obtaining herbs from a wild source is easy, economical, less time consuming, and has a decreased
cost of labour, however it also offers various disadvantages such as the quality of the plants cannot be
predicted due to various environmental changes.
The plants will not be uniform in their growth and yielding characteristics.
Modern scientific techniques cannot be applied to increase the yield as well as quality.
If the plants are obtained continuously from wild sources for prolonged periods it may lead to
depletion of raw materials from the wild.
b) Cultivated source
In recent times, medicinal plants have been systematically cultivated by applying modern scientific
techniques.
Obtaining herbs from cultivated sources offer various advantages which are as follows.
 Quality and purity is ensured.
 Better yield and more profit
 Ensures regular supply of raw material
 Application of modern scientific techniques is possible.
STEPS INVOLVED IN THE SELECTION, IDENTIFICATION, AND PROCESSING OF
HERBAL RAW MATERIALS
Herbs are subjected to various stages starting from their selection, identification, cultivation,
collection, storage and processing until the final product is formed. The detailed steps involved in the
processing of herbal drugs are discussed below.
Steps involved in processing of Herbal Drugs
Selection of Herbs

1.Identification & Authentication

2.Cultivation of Herbs

3.Collection of Herbs

4.Processing of Herbal Raw Material
a) Selection of herbs
The species or botanical variety selected for cultivation should be the same as specified in the official
Pharmacopoeia or national documents. In case of newly introduced medicinal plants, the variety
selected for cultivation should be identified and documented.
b) Identification and authentication of herbal materials
 Botanical identity
The species, subspecies, genus, variety etc of the plant for cultivation should be verified from a
qualified botanist/ institute and recorded.
 Specimens
In case of a new plant with medicinal properties whose identity is not known, a specimen el the plant
should be submitted to a regional national herbarium for identification and documentation.
 Seeds and other propagation materials
The suppliers of seeds and other propagation materials should specify all the necessary information
relating to the identity, quality as well as their breeding history. The seeds and propagation material
should be free from contamination and diseases in order to promote healthy plant growth
Cultivation of medicinal plants
Cultivation of medicinal plants requires intensive care and management as various factors such as
environment, soil, irrigation pests, etc, play a vital role. These factors vary from one plant to another.
Scientific documented methods should be followed, if no data available traditional methods should be
adopted and a systematic method should be developed through research Good agricultural practices in
cultivation (GACP) and conservation agriculture (CA) which aims to improve, conserve and make
more efficient use of natural resources.
d) Collection of herbs
For the collection of medicinal plants, a proper time should be selected. Herbs are selected for
collection at a stage when they yield the maximum amount of chemical constituents. Skilled labour
should be employed as they are trained to identify and select the herbs at a proper stage. The age of
the plant also plays a vital factor for their selection. Diseased plants should be rejected. Season of
collection should also be given due consideration while selecting the plants for collection.
e) Processing of herbal raw materials
Processing of herbal raw materials involves various stages from which the crude drugs undergo after
harvesting.It can be classified into primary and secondary processing which are further sub
categorized as follows.
PROCESSING OF HERBAL RAW MATERIAL
Primary processing

Primary Processing
It includes simple procedures by which the herbs are prepared like sorting of different parts, garbling,
cleaning, drying, etc. The details of these processes are as follows:

1. Garbling: This process helps in ensuring the purity and cleanliness of the harvested material.
   Dirt like soil, dust, impurities like insects, dead tissues and residual non medicinal plants are separated
   from the raw material.
   The process depends on the part of the plant to be prepared.
   The process may involve procedures such as removing dirt and foreign substances, discarding
   damaged parts, peeling of barks, sieving, trimming, removal of hairs from roots, removal of seeds
   from fruits, stripping of leaves from stems.
   This may be done by mechanical means but in some cases it is usually performed manually by hands.
2. Washing : After garbling the herbal raw material should be cleaned well to remove the traces remaining soil, dirt and other impurities from the surface.The roots, rhizomes and tubers are washed with clean water.During the washing process, scraping and brushing may be necessary.
3. Parboiling (Blanching) : After washing, certain herbal raw materials need to undergo a parboiling process in which they are put
   in boiling water for a short period.
   This may help in improving the storage of the raw material and prevent insect/mould contamination.
   It may also facilitate in further processing such as removal of stubborn impurities as well as outer
   coats/ covering of raw materials.
4. Leaching: Some impurities can be removed by subjecting the plant material under running water known as
   leaching.
   However the duration of leaching should be controlled to prevent loss of chemical constituents
   present in the drug.
5. Drying : In some cases, the plant material should be thoroughly dried after washing in order to prevent the
   deterioration and degradation of active constituents.
   They must be dried as soon as possible to remove moisture and reduce the damage due to microbial or
   mould infestation.
   Drying also prevents the activation of certain enzymes which may otherwise degrade the active
   ingredients and also facilitate grinding and milling of the raw material Depending on the drug and
   nature of ingredients, different drying methods can be used which are as follows:
   a. Natural drying
   b. Sun drying
   Most herbal raw material can be dried in open air under direct sunshine provided the climate is
   suitable. The duration of the drying process depends on the physical structure of the plant material and weather conditions. The plant material should be spread out in thin layers, care should be taken to prevent contamination by dust impurities. While drying the plant material should also be protected from insects, birds rodents, pests and other domestic animals.
   Shade drying:
   Some medicinal plants cannot be directly exposed to sunlight, hence one to be dried under shade.
   This drying process is slow but helps in minimizing loss colour, volatile oils and aromatic
   components from being evaporated.
   Artificial drying:
   Drying by artificial heat is more rapid than open air drying and is necessary in rainy season and
   regions where there is high humidity. The temperature and equipment used for drying depends on the physical and chemical nature of the
   drug and its constituents. Various equipment such as tray dryers, spray dryers, vacuum dryers are used. Overheating may lead to excessive loss of volatile components as well as decomposition of chemical constituents. The temperature should be kept below 60°C wherever possible.

Secondary Processing

It refers to the steps applied to herbs in addition to primary processing. The secondary processing differs from one herb to another depending on the nature of active ingredients as well as therapeutic properties. Secondary processing includes techniques such as removal of foreign substances, prevention of
microbial/ infestation, enhancing the efficacy of drugs, reducing the toxicity, extraction using suitable
solvents, concentration and drying of extracts. These are further standardized by different methods
The following processes are carried out in the secondary processing of herbal raw materials. Cutting Sectioning and Communition.

1. Cutting/sectioning : After thoroughly drying, the herbal materials are processed by cutting and sectioning into smaller sizes which are convenient for storage as well as extraction. Various sizes can be obtained depending on the part of herb and extraction methods used. It may be small particles, coarse powder or fine powder.
2. Aging/sweating : Aging refers to storing the raw material for a specified time after harvesting It is generally done under sun or in shade for up to a year. During the process of aging excessive water is evaporated and enzymatic reactions may occur to alter the chemical composition of herbal material.
   Example: Cascara bark should be aged for at least one year prior to use in medicinal preparations to
   reduce its irritant effects.Sweating is done by subjecting the herbal materials at a temperature between 45 to 656 with high humidity for a period ranging from one week to few months. The herbal materials are stacked between woollen blankets or other kind of cloth. The sweating
   process is considered a hydrolytic and oxidative process in which some of the chemical ingredients of the herbs are hydrolysed or oxidised.
   Example: Vanilla beans are subjected to sweating between woollen blankets for about 2 months
   during which they lose up to 80% of weight and develop a characteristic desirable colour and odour.
3. Baking/roasting : It is a process of drug heating where the herbal material is heated in ovens.
   The temperature of heating and duration of baking/ roasting vary from one herbal material to another until the drug develops a specific colour.
   Example: Nutmeg is roasted till they turn to a yellowish brown colour.
4. Boiling/steaming : In the boiling process the drug is cooked in water or any other liquid solvent such vinegar, wine, milk or animal urine.
   Example: Acorus calamus rhizome is boiled in cows urine to enhance its anticonvulsant effects.
   In the steaming process the herbal material is kept in contact with steam using a steamer resulting in
   development of moist texture.
   Example: Roots of Polygonum multiforum are steamed in the presence of black bean decoction to
   enhance its tonic effects.
5. Stir frying : It is a process in which the herbal materials are put in a pot of frying pan and continuously stirred or tossed for a specific period under heat until the external colour changes, charred or even carbonized. To facilitate uniform heating the drug material can be admixed with sand, talc or clay.
   Example: Liquorice roots and rhizomes are stir fried with honey.
6. Fumigation : Sometimes the harvested raw materials are subjected to fumes.
   Fumigation with sulphur dioxide is commonly employed for some medicinal herbs for the purpose of preserving colour, improved appearance, bleaching and preventing the growth of insects and moulds.

Extraction of herbal materials
Extraction is a process of separation in which the chemical constituents present in plants and tissues
are removed by using selective solvents which are called as menstruum.
Herbal extracts include infusions, decoctions, fluid extracts, tinctures and powdered extracts. The
herbal preparation so obtained may be ready for use as a medicinal agent or it may be further
processed to finished products as tablets, capsules and pills.
i. Infusion
It is a liquid preparation obtained by extracting herbal materials with either cold or hot water without
boiling. Other solvents may also be used.
ii. Decoction
It is a liquid preparation obtained by boiling the herbal materials with water.
iii. Fluid extract
It is a liquid preparation obtained by maceration or percolation of herbal materials in alcohol. The
ratio will be one part of liquid containing one part of herbs (1:1).
iv. Tinctures
It is a dilute alcoholic extract of herbal materials typically made up of 1 part of herbal material with 5
to 10 parts of the solvent
v. Powdered extract
It is a form of herbal preparation which is processed into dried, granulated or powdered materials