PHARMACOGNOSY-I

DEFINATION The term Pharmacognosy has been derived from the 2Greek words: I) pharmakon, which means a drug & ii) gnosis, which means knowledge of or gignosco, which means to acquire knowledge of. Thus the full meaning of the term Pharmacognosy is `knowledge of drugs’ or `to acquire knowledge of drugs’.

Pharmacognosy is the objective study of crud drugs & related substances.Pharmacognosy is an applied science which is concerned with acquiring

knowledge of crud drugs by the application of various scientific disciplines.

SCOPE Pharmacognosy is an important branch of Pharmacy, which is concerned with the study of crud drugs & natural products of pharmaceutical importence.

It deals with the scientific study of structural, physical, chemical & sensory characters of crud drugs obtained from plant, animal & mineral source.

It also includes the study of their history, distribution, cultivation, collection, preparation, identification, evaluation, preservation & commerce.

SUBJECT MATTERS OF PHARMACOGNOSY Pharmacognosy deals with the study of,

Naturally occurring substances having medical propertiesCrud drugs & other natural substances of pharmaceutical importencesChemical constituents of crude drugs & medicinal plants Natural substances used as excipients or pharmaceutic necessities in the

formulation & preparation of pharmaceutical &medicinal products. These include:i) colouring & flavouring agents, ii) suspending agents, iii) diluents & disintegrating agents, iv) sweetening agents, v) binders, adhesives, solifyding agents, etc.

SUBJET MATTERS Substances, which are used as medical & pharmaceutical practices. Example of which include:a) fibers & surgical dressings, b) anesthetic acids, c) filtering agents, such as diatomite & asbestos, d) basses & vehicles, such as agar, gelatin, wax, fixed oils & fats. Beverages with medicinal constituents, e.g. tea, coffee & cocoa which contain caffeine. Spices & condiments, which have medicinal properties, e.g. Cinnamon, Cardamon, Umbelliferous fruits (Coriander, Fennel, Cumin, etc.), Mustard seed, Clove, Ginger, Garlic, etc. Vitamins, enzymes, antibiotics, allergens, pesticides, etc.

Medicinal plants.Traditional medicine.

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HISTORICAL DEVELOPMENT OF PHARMACOGNOSY

Pharmacognosy is regarded as the mother of all science.History of pharmacognosy represents the history of pharmacy & medicine.Pharmacognosy had its origin in the health-related activities of the most

primitive human race of the remote past.The early man sought to alleviate his sufferings of illness & injuries by using

plants.They acquired knowledge of medicinal properties of plants in the following

way:a) By guesswork or trial & error b) While searching for foodc) By superficial resemblance between the plant parts & the affected

organs, that is, by examining the “Signature of Nature”d) By observing other animals instinctive discrimination between toxic

& palatable plantse) By accidental discovery

By a combination of all these means the ancient people acquired a considerable volume of knowledge about drugs.

In course of time a group of people emerged in each community who acquired expertise in collecting, testing & using medicinal plants for treating diseases. These people later became known as `Medicine Men'.

The Medicine Men monopolized the knowledge of drugs and hide that knowledge in some mysterious incantations. They transferred this secret knowledge only to their trusted predecessors of the successive generations, who gradually increased the volume of knowledge about drugs and their uses.

Initially the transfer of the acquired knowledge from generation to generation used to be done verbally by the use of signs & symbols. As civilization progressed, transfer and recording of the knowledge were done in writing.According to recorded history:

Babylonians (about 3000 BC) had knowledge of large number of medicinal plants and their properties.

Some of the plants used are still used almost in the same way and for the same purposes.

The Chinese pharmacopoeia, Pen Tsao, written between 3000 and 2730 BC, includes recipes and therapeutic uses of many Chinese traditional medicines.

Ebers Papurus, written in 1550 BC, recorded that Egyptians possessed a good knowledge of human anatomy & medicinal uses of hundreds of plants which made them capable of embalming dead bodies for making mummies.

Many of the present day drugs, such as Henbane, Mandrake, opium, Pomegranate, Caster oil, Aloe, Onion, many fixed oils & fats, were in common use in Egypt about 4500 years ago.

The earliest plant medicines used in the Ayurvedic system were described around 1200 BC with a list of 127 plants.

The Greek civilization witnessed a highly developed system of medicine which used medicinal plants and minerals. Arab Muslims further enriched this system and developed the Greco-Arabic or Unani system, which formed the basis of modern Allopathic system of medicine.

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The following people contributed significantly to the gradual development of Pharmacognosy:

Hippocrates (460-370 BC). He is regarded as the `Father of medicine' for his contribution to human anatomy and physiology. He collected, identified and used a large number of medicinal plants.

Aristotle (384-322 BC). A student of great philosopher Plato listed more than 500 plants of medicinal importance with their description & uses.

Theophrastus (370-287 BC) collected, identified a large number of medicinal plants and recorded their medicinal properties.

Dioscorides (1st Century AD), a Greek Physician, published five volumes of a book, entitled `De Materia Madica' in 78 AD, which described more than 600 medicinal plants with their collection, storage & uses.

Pliny de Elder (23-70 AD), a Greek botanist, collected and described a large number of medicinal plants with their uses.

Galen (131-200 AD), a Greek pharmacist-physician, described methods of preparing pharmaceutical formulations containing plant and animal drugs. These methods & his other observations on medicinal plants have been recorded in as many as 20 volumes of books. The present day Galenical preparations or Galenicals are prepared according to those methods.

So long the same person, the apothecary (pharmacist-physician), used to do all the works of collection, processing, preparation and dispensing of the medicaments (the works of the pharmacist) and also diagnosing the disease and prescribing the drug (the works of the physician).

With the increase of knowledge of drugs, the volume of work also increased a lot and it become impossible for one person to manage them properly.Thus at this point pharmacy & medicine started developing along two separate paths:

a) One group specialized in diagnosing the disease and prescribing the drug and became known as the physicians or doctors;

b) The other group specialized in collecting, processing, preparing & dispensing the drug and became known as the apothecaries or pharmacist.In this way, Pharmacognosy progressed gradually and formed the basis and beginning of both pharmacy & medicine.

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STRUCTURE OF CELL

DEFINITION OF CELL

The cell is the structural and functional unit of all living organisms. It forms the structure of the body and all organs of a living body

It regulates all life activities of a living organismSTRUCTURE OF A PLANT CELL

It consists of three major parts:a) The cell wallb) The cytoplasmc) The vacuole

THE CELL WALLIt is the outermost covering of the cellIt encloses the cytoplasm and vacuoleIt is composed of long chains of cellulose molecules embedded in a matrix of

hemicellulose & pectinTHE CYTOPLASM

It is a translucent mass of colloidal substances, composed of i) water ii) protein iii) carbohydrate iv) lipoids v) various inorganic substances

It remains surrounded by a semi-permeable membrane, called cytoplasmic membrane or plasma membrane or plasmalema.

It has two parts:a) Outer rigid & dense part, called ectoplasmb) Inner thin fluidly part, called endoplasm There are no organelles in the ectoplasmOrganelles and ergastic substances (starch, aleuorone grains, fat, oil, ca-

oxalate crystals, etc) are present in the endoplasm.Following organelles are present in the endoplasm:i) Nucleus ii) Endoplasmic reticulum iii) Ribosome's iv) Golgi bodiesv) Mitochondria vi) Plastids vii) Lysosomes

i) The Nucleus is a spherical structure, which a) Controls the development & function of the cellb) Remains bounded by a double-membraned covering, called nuclear

envelopec) Is filled with a liquid, called nuclear sap, in which are present one or more

nucleus, nuclear ribosome's and the chromatin material, which are the genetic material made up of DNA (Deoxyribonucleic acid).

FIBRES & SURGICAL DRESSINGSFibres & Surgical dressings are of immense value in medical and

pharmaceutical practices.Dressings are needed for protection and healing of wounds caused by injuries,

burns, microbial infections and surgical operations.Fibres

Fibres are used for dressing purposes both in their normal forms and in woven or fabric forms.

Fibres include natural, regenerated or artificial and synthetic fibres.Natural fibres may be of plant or animal origin.a) Plant fibres include: i) Epidermal trichomes, e.g. Cotton

ii) Phloem fibres, e.g. Juteiii) Pericyclic fibres, e.g. Flax & Hemp

b) Animal fibres include: i) Wool & ii) SilkRegenerated or Artificial fibres are prepared by processing or

regenerating wood cellulose. They

EXTRACTION PROCESSESExtraction is a process of bringing out or removal of the chemical constituents

from the plant or animal tissues with or without the use of a menstruum (solvent). Plant constituents are extracted from both dried & fresh materials.Dried materials must be powdered before extraction.Fresh materials may be directly extracted or homogenized before extraction.

Extraction process may be grouped into the following two groups:i)Extraction without the use of a menstruum, which include processes like Expression: In this process the materials is subjected to hydraulic pressure with or without the application of heat. Expression is again two types:

Cold expression, when no heat is applied during extraction.Hot expression, when heat is applied with pressure during extraction.

Sublimation: Applicable only in extracting sublimable constituents, e.g., caffeine, camphor, etc. In this process the material is directly heated & the sublimed constituent is collected in the solid form.Distillation: Volatile constituents are extracted by this method. The material taken soaked in a distillation flask is heated directly or by steam. The volatile extract co-distils with water, passes through a condenser and is collected in a receiver. i)Extraction with the use of a menstruum. This process can be of two types:

a) Extraction using aqueous solvents, such as water, dilute acid & alkali. These solvents are used to prepare:

Infusion: An extract obtained by treating the plant material with cold or hot water.

Decoction: An extract obtained by boiling the plant material with water.b) Extraction using organic solvents, such as alcohol, chloroform, ether, etc.

Extractions done by using organic solvents include the following methods: Maceration: In this method the powdered plant material is soaked in an organic solvent for a period of time with constant or occasional stirring.

The supernatant liquid (extract) is then decanted and filtered. The process is repeated for complete extraction.Percolation: This method uses a percolator. The powdered material is packed in the percolator. Enough solvent is then poured to soak the powder. Then more solvent is poured & allowed to percolate through the material. The extract is collected in a receiver. The process is continued until extraction is complete.Soxhlet extraction:

This is a continuous process of extraction with a hot solvent.Soxhlet extractors are used for this purpose. This extractor is provided with a

siphoning system.The powdered plant material is packed in a thimble.The solvent is boiled in a flask. The evaporated solvent passes through the

side tube of the extractor and condensed in the condenser, fitted at the top of the extractor.

The condensed hot solvent runs into the thimble and soaks the material & extracts the constituents.

When the chamber holding the thimble becomes full the solvent siphons down to the flask and the process is continuously repeated till extraction is complete. eMu

SAPERATION TECHNIQUESComponents of mixtures of extracted plant constituents are separated,

isolated & characterized by a number of Separation techniques.Out of these techniques Chromatography or Chromatographic methods are

most useful & they are very commonly and popularly used. Original concept of Chromatography

The team Chromatography means Chart of coloures (Chroma means colour; graph means chart).

Chromatography was thus originally conceived as a means of separating chemical substance by making a chart according to their colours (applicable only for coloured substance).

A Russian Botanist, M. Tswett first described the original concept of Chromatography In 1960 in the following way. He used this technique for separating plant pigments from leaf extracts.