Herb:- “A plant of which the stem does not become woody or persistent (as in a shrub or tree), but remains more or less soft and succulent, and dies down to the ground (or entirely) after flowering.” This applies to plants of which the leaves or stem and leaves are used for food or medicine, or in some way for their scent or flavour. As per WHO, “Herbs include crude plant material such as leaves, flowers, fruit, seed, stems, wood, bark, roots, rhizomes or other plant parts, which may be entire, fragmented or powdered”. Definitions:-
Herbal drug preparations:- It includes powdered herbal materials, extracts, or tinctures and fatty oils of herbal materials. Preparations, derived from herbal drugs which are prepared by various techniques like extraction, infusion, decoction, maceration, distillation, expression, fractionation, purification, concentration and fermentation are known as herbal drug preparations. It may also consists of preparations made by steeping or heating herbal materials in alcoholic beverages and/or honey, or in other materials.
Herbal medicine:- “Herbs and herbal preparations that are used either to maintain health or to prevent, alleviate or cure a disease.” Example: Tincture made from ginger to relieve an upset stomach. As per WHO, “Herbal medicine include herbs, herbal materials, herbal preparations and finished herbal products. ” Note:- Medicines possessing crude material mixed with chemically distinct substances including isolated phytoconstituents are not termed as herbal medicines.
Herbal medicinal products:- According to WHO “Herbal medicinal products consist of herbal preparations made from one or more herbs. Herbal medicinal products may contain excipients in addition to the active ingredients.” In herbal medicinal products the active ingredient consists exclusively of herbal substances or herbal preparations. Hence, herbal medicinal product may contain, one or more herbal substances or one or more herbal preparations, or one or more such herbal substances in combination with one or more such herbal preparations as active ingredients.
Sources of herbs Herbs or medicinal plants can be obtained from three sources viz: Wild source Cultivated source Modern scientific techniques like tissue culture, polyploidy, mutation, hybridization, genetic engineering, germplasm etc. on cultivated plants.
Wild source: Grow themselves without any type of care, Obtained from unutilized land such as forests, plains, river banks, etc. The wild plants also have reasonable active constituents and sometimes new variety is produced. Advantages: • Economical; No cost of land, caring, fertilizers, irrigation etc. • Less time consuming.
Disadvantages: • The quality of the plants cannot be predicted due to various environmental changes. • They are sparsely distributed, so chances of adulteration and substitution are more. • If the plants are obtained continuously from wild source for prolonged period, may lead to depletion of raw material. • They cannot fulfil the demand when required. • Sometimes genetically different plants are developed.
Cultivated source: Grown in fields under controlled environmental conditions such as soil, climate, rainfall, irrigation, time of sowing and collection, altitude, temperature, fertilizers, manures, pesticides, weeds etc. Advantages: Better yield and therapeutic quality, and give more profit. It ensures regular supply of raw materials due to planned cultivation. Cultivation of medicinal and aromatic plants leads to industrialization and has given rise to several cottage and small scale industries. Rapid growth of phytopharmaceuticals, perfumery and allied industries is possible due to cultivation of medicinal and aromatic plants.
Modern scientific techniques: Plant tissue culture: In vitro cultivation technique of plant cell or tissue under aseptic and controlled environmental conditions, in liquid or on semisolid well-defined nutrient medium for the production of primary and secondary metabolites or to regenerate plant. Advantages: Extinction and decimation problems of medicinal plants can be minimized. Genetic modification is possible.
Disadvantages: • Requires a well-equipped culture laboratory. Involves various steps, viz. preparation, of nutrient medium containing inorganic and organic salts, supplemented with vitamins, plant growth hormone(s) and amino acid as well as sterilization of explant (source of plant tissue), glassware and other accessories inoculation and incubation.
Polyploidy: An increase in number of chromosome in certain tissues or entire plant in multiples of the basic or haploid number is known as polyploidy. Polyploidy is common in nature and provides a major mechanism for adaptation and speciation. Polyploidy in plants is caused by cell generations, physical agents like X- rays, centrifugation, temperature, shock and chemical agent like colchicine. Advantages: Polyploidy plant is usually healthier, stronger and larger. Phytoconstituents of some plants can be increased.
Mutation: Mutation is the change in nucleotide sequence of a gene. This give rise to a new genetic trait or changed genotype. A cell or organism which shows the effect of mutation is called mutant and the agent which causes mutation is known as mutagenic agent. The types involve: natural and artificial (physical, chemical, radiation) mutation. Advantages: Phytoconstituents of some plants can be increased. Chemical mutagens have a successful use in increasing morphine content of Papaver somniferum . Radiation mutagen has increased the yield and diosgenin content of Dioscorea bulbifera .
Hybridization: The process of formation of offspring as a result of interbreeding between two plants of the same or different taxa that differ in one or more heritable traits is called hybridization. The plant produced as a result of interbreeding is called hybrid plant. The types involve: Intervarietal (simple & complex) hybridization and Distant hybridization. Advantages: Phytoconstituents of some plants can be increased. Desirable characters of two different plants can be obtained in a single hybrid plant.
Selection of herbal materials The species or botanical variety selected for cultivation should be the same as specified in the official Pharmacopoeia or official document. In case of newly introduced medicinal plants, the variety selected for cultivation should be identified and documented. Methods of herbal materials selection- A. Randomized approach B. Ecological approach C. Chemosystematics' approach D. Ethno-guided approach
Identification of herbal materials Identification tests should be specific for the herbal material and are usually a combination of three or more of the following: Macroscopic identification Microscopic identification Physical identification Chemical reactions Chromatographic procedures.
Authentication of herbal materials Contd … Herbal materials Taxonomic Authentication Chemical markers Molecular markers Single locus probes Multi locus probes New repetitive DNA markers Arbitrary sequence markers
Molecular markers Single locus probes Multi locus probes New repetitive DNA markers Arbitrary sequence markers RFLP STS ASAPs EST SSCP RLGS Repititive DNA Micro and mini satellites STMS DAMD-PCR ISSR Transposable elements Alu- repeats Repeat complementary pr imers RAPD AP-PCR SCAR AFLP RAMPD CAPs