A BRIEF HISTORY OF PHARMACOGNOSY
In 780 AD , a Greek pharmaco-botanist Pedanios Dioscorides wrote and described about 600 plants with medicinal properties in his book “De materia medica libre cinque(concerning medical matter in five volumes).
Galen was a Greek pharmacist-physician who lived in Rome and who describe the method of preparing formulas containing plant and animal drugs and the term ”galenical pharmacy” was originated.
In 19th century material medica (medical matter) undergo divisions: 1.pharmacology – the actions of drugs
2.pharmacognosy – all aspects of drugs with lesser emphasis on action
The word “pharmacognosy” formed from 2 Greek words pharmakon (drugs) and gnosis (knowledge) was introduced by C.A Seydler ( Chr. Aenotheus), a medical student in Halle/Saale, Germany who used the title Anaclectica pharmacognosthica for his dissertation in 1815
Fluckiger – presented the most comprehensive idea of the scope of Pharmacognosy which he define as the simultaneous application of various scientific disciplines with the object of acquiring knowledge of drugs.
Pharmacognosy may be defined as “an applied science that deals with the biologic, biochemical and economic features of natural drugs and their constituents that originate in the plant and animal kingdom.
Recent historical research has found an earlier usage of “Pharmacognosis” in book Lerbuch der Materia medica published in Vienna in 1811which was published By J.A. Schmidt to describe the study of medicinal plants and properties.
In 19th century, chemist began to synthesize large number of organic compounds with structures of ever-increasing complexity, some of which were useful therapeutic agents. Thus there came 3 basic discipline devoted to drugs: 1.pharmacology which deals with drug actions and effects
2.pharmacognosy- covering all information on medicines from natural sources (plants, animals and microorganism 3.medicinal chemistry- the science of synthetic drugs
In the last decades of 29th century, 3 significant events occurred which have already produced fundamental changes in both public and scientists towards pharmacognosy. 1.use of classical plant drugs for the treatment of many ailments usually of the self-limiting variety 2.major pharmaceutical manufacturers recognized the plants with reputation as remedies provide the best source of constituents that can serve as either as new drug or as prototype for them 3.greatest revolution which is still in its infancy as far as drug discovery is concerned is described as recombinant DNA technology, genetic engineering or more specifically pharmacobiotechnology. which involves the transfer of genetic material from one organism to another permitting the later to produce in quantity a component of the former that is useful as a drug.
VALUE OF NATURAL PRODUCTS:
Four significant roles of natural sources in modern medicine 1.they provide a number of extremely useful; drugs that are difficult to produce commercially by synthetic means
Examples: alkaloids of the opium poppy, ergot, solanaceous plants, cardiotonic glycosides, antibiotics, serum. vaccines 1.natural sources also supply basic compounds that may be modified slightly to render them more effective or less toxic
Examples : numerous variation of the morphine molecule
1.their utility as prototypes or models for synthetic drugs possessing physiological activities similar to the original
Examples: procaine and similar local anesthetics (cocaine)
1.natural products contain compound that demonstrate little or no activity
which can be modified by chemical or biological methods to produce potent drugs.
vegetable or animal drugs that consist of natural substances that have undergone only the processes of collection and drying
Classification: Composition Botanical * Pharmaceutically Pharmacological * Pharmacologically Chemical
refers to those substances found in nature that comprises whole plants and anatomic parts thereof that have not had changes made in their molecular structure as found in nature. Derivatives or Extractives
refers to single substance or mixture of substances which are considered as the chief constituents obtained by the process of extraction.
Solvent or menstruum
liquid or liquid mixture which removes only those substances which dissolved by extraction
the undissolved portion of the drug that remains after extraction process is completed.
Geographic source and Habitat
region in which the plant or animal yielding the drug grows
plants growing in their native countries
plants growing in s foreign land or in a locality other than their native homes.
PREPARATION OD RUGS FOR THE COMMERCIAL MARKET:
1.Collection – collection of drugs from cultivated plants always ensures a true natural source and a reliable product. The most advantageous collection time is when the part of the plant that constitutes the drug is highest in its content of active principle and when the material will dry to give the maximum quality and appearance, flower tops/leaves – when photosynthesis is active
flower – prior or just about the time of pollination seed – collection when fully matured gums and oleoresin – gathered during dry weather
fruits – collecting near the ripening period 2. Harvesting – the mode of harvesting varies with each drug produced and with the pharmaceutic requirements of each drug. Mechanical devices : pickers, mowers, binders, swath, steel 3. Drying
prevent action of bacteria
fixes the constituents
facilitate grinding and milling
prevent environmental hydrolysis
types of drying:
Artificial Air Drying
*leaves and underground plant parts – screen trays, 40-60degreesC *drug cont’g volatile oil – air drying, temp 35degreesC * large & fleshly roots – slit or slice
* bark, root, rhizome, seed and some fruit – not be raised over 35oC 4. Garbling – is the final stage in the preparation of crude
drugs. * consists of the removal of extraneous matter such as other parts of the plant, dirt and added adulterants and is carried out after the drug is dried and before it is baled of packaged.
5. Packaging, Storage and Preservation:
* compressed bales *bags * paper boxes *sacks * barrels * cans * casks * matting foam
EVALUATION OF DRUGS:
To evaluate means to identify and to determine the quality and purity of drugs
1.Organoleptic – refers to the evaluation of drugs by means of the organs of sense and includes the macroscopic appearance of the drug. 2.Microscopic- essential in the study of adulterant in powdered plants. 3.Biologic – pharmacological activity of certain drugs has been applied to their evaluation and standardization Organisms used for Biological evaluation of drugs:
microbiological method ( yeast/molds) – assaying of vitamins living microscopic animals (Daphnia) – Digitalis
Gold fish – standardization
Frogs – standardization
Vitamins (rats/mice) – suffering aviyaminosis
Guinea pigs – test in toxicity and antigenesity diphtheria Young adult domestic chicken- standardizing ergot
Pigeon – assaying digitalis
Cat – assaying digitalis
Rabbits – used in curare alkaloid
Dogs – test for Veratrum viride( antihypertension)
Human – noting the drugs for complete evaluation
1.Chemical- the active constituents of many natural drugs have been determine Chemical tests – conduct color reaction
Chemical assay – cellular and non-drug of plants origin that represent active principle and purification of the chief principle *saponification number
*acid value of fixed oil
2.Physical – extensively applied to the active principle of drugs * solubility * specific gravity * optical rotation * congealing point * refractive index * melting point * water content
CLASSIFICATION OF DRUGS:
1.Morphology – refers to the classification of plants and animals 2.Taxonomy – refers to the natural relationship or phylogeny among plants and animals. 3.pharmacologic or therapeutic – refers to medicinal and their therapeutic effects 4.chemical constituent – activity and therapeutic use of drugs base on chemical constituent.
CHEMISTRY OF NATURAL DRUG PRODUCTS
Constituents – chemical compounds found in plants and animals Active Constituents – compounds that are responsible for the therapeutic effect 1.pharmaceutically active- cause chemical changes in the medicinal preparation. Ex. Preparation containing tannic acid with iron cause pre- capitation.
1.pharmacologically active – responsible for the therapeutic activity which may either single chemical substances (sugars, starches,plantacids, enzymes, glycosides, steroids, alkaloids, proteins, hormones and vitamins and mixtures chemical substances ( fixed oils, fats, waxes, volatile oils, resins, oleoresins, oleo-gum-resins and balsams.
Inert constituents – no definite pharmacologic activity
(starch, coloring matter) Secondary plant substance –extracted , crystallized and purified where the presence of inert matter in active constituents which may modify or prevent absorbability or potency of the active constituents.
3 Principal factors that influenced the secondary constituents of drug plants 1. heredity (genetic composition)
2. ontogeny (stage of development)
3. environment (soil, climate, associated flora and method of cultivation)
Drug biosynthesis or biogenesis – study of the biochemical pathways leading to the formation of secondary constituents used as drugs (example: that amino acids and their simple derivatives served as precursors of structurally ,complex alkaloids. )
These active constituents and the drugs containing them are:1.CARBOHYDRATES AND RELATED COMPOUNDS
Compounds composed of carbon, hydrogen and oxygen as polyhydroxy aldehyde or ketone alcohols.
1.GLYCOSIDES : Substances that on hydrolysis yield one or more sugars among the products of the reaction.
1.TANNINS : a group of complex phenolic compounds capable of combining with proteins.
1.LIPIDS : compounds comprising fixed, fats and waxes
5. VOLATILE OILS : essential oils that represent odoriferous principles of plants.
1.RESINS AND RESIN COMBINATIONS : compounds comprising
resins, oleoresins, oleo-gum-resin and balsams.
1.ALKALOIDS : nitrogenous crystalline or oily compounds, usually basic in character.
7. VITAMINS AND VITAMINS CONTAINING DRUGS : chemical
compounds necessary for normal growth and functions of animals.
1.7. BIOLOGICS : products composed of antigenic matter or antibody Preparations capable of developing state of immunity in the patient.
1.HERBS AND HEALTH FOODS : products of natural origin used by the laity in the self-treatment of disease states or less-then optimal health conditions. Many are without therapeutic effect and some are toxic.