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Pharmacognosy general introduction

Pharmacognosy general introduction. General introduction. Pharmacognosy: means the knowledge of drugs. ● This word is derived from the Greek words: Pharmakon : which means drug. gnosis: which means knowledge of.

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Pharmacognosy general introduction

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  1. Pharmacognosy general introduction

  2. General introduction Pharmacognosy: means the knowledge of drugs. ●This word is derived from the Greek words: Pharmakon: which means drug. gnosis: which means knowledge of. This science is related to the study of the structural, chemical and sensory characters of crude drugs of vegetable, mineral and animal origin. It includes also their cultivation, collection, preservation, preparation for the market as well as their evaluation.

  3. Crude drug means the collected and usually dried or fresh plant or animal product of medicinal use without any further processing (such as extraction or any modification). Source of Crude (Natural) Drugs Mineral: Sulfur – Kaolin – Prepared chalk Plant: Senna – Henbane – Opium Animal: Cod liver oil – Beeswax – Musk - Venom Official and unofficial drug: An official drug is that which is described in the pharmacopoeia (a book recognized by the government as a legal authority for standards).

  4. History of pharmacognosy and folk medicine: ■In the earliest times, man studied the plants and animals as a source of food. ■ In the meantime by observation, trial and error , man was able to distinguish between poisonous and non poisonous plants and also to discover the healing properties of some of them. ■ The collective data about the therapeutically used plants forms the well-known “Folk Medicine”

  5. ■ The ancient people described hundreds of herbs besides drugs of animal and mineral origin, which are used as remedies for many diseases as shown by ancient documents. e.g. ancient Egyptians, Babylonians, old Indian medicine, Chinese medicine and Greek.

  6. ■ We must not forget the role of Arab scientists such as Ibn Sina, Ibn Al-Bitar, Gaber Ibn Hayan and Abu Baker El-Razi. ■ Nowadays there is a strong tendency to return back to nature to replace the Synthetic drugs by the natural Products for both safety and Efficiency.

  7. Nomenclature of Natural Drugs (Origin) There are three origins of each drug: 1- The biological (natural or botanical) origin. 2- The geographical origin 3- The commercial origin.

  8. 1- The biological (natural or botanical) origin. ■ The natural origin of a drug is the plant or animal yielding it. ■ The Binomial system of naming the plants is introduced by swedish biologist (Linnaeus). ■ Example Atropa belladonna Barosma betulina Piper nigrum

  9. Atropa belladonna Second name started with a small letter The species First name always written In capital letter (The genus) Barosma betulina Piper nigrum N.B. The second name may start with a capital letter when it is named after a person e.g. CinchonaLedgeriana, named after Charles Ledger who brought its seeds from Barazil.

  10. Cassia acutifoliaDehle ■The botanical names are followed by the names of persons. These refer to the botanist who first described the species or variety. Generic name Specific name the botanist who first described the species

  11. The specific name is usually chosen to indicate one of the following: 1- Some morphological characteristics of the plant. Piper nigrum (black). Atropa belladonna (beautiful lady) Barosma betulina (serrate margin) 2- The geographical source e.g. Cannabis indica L. 3- The pharmaceutical activity or active constituents Ipomea purga (purgative) Quillaia saponaria (contain saponins)

  12. 4- A general meaning or a special indication: e.g. Triticum sativa (cultivated). 5- After the person who discovered it. e.g. CinchonaLedgeriana (after Ledger) The generic name may also indicate a certain character of the drug e.g. Xanthoxylum meaning yellow wood.

  13. 2- The geographical origin ■The geographical source or habitat is the region in which the plant or animal yielding the drug. ■ It is important to note that plants cultivated in a certain geographic area will develop the desired type of active constituents. e.g.Cannabis grown in its habitat India is rich in the narcotic resin and contain less fibers While that grown in Italy is rich in the fibers and contain less resin.

  14. 3- The commercial origin. This refers to the place of the drug production or transport e.g. Alexandrian senna is indigenous to tropical Africa and cultivated in Sudan but was first exported from Alexandria and hence its name.

  15. Production of Crude drugs I) Cultivation of medicinal plants. II) Collection. III) Drying.

  16. I) Cultivation of medicinal plants. ■ Medicinal plants are either grown wildly or cultivated. Plants growing in their native land are said to be indigenous to this land, e.g., Aconitum napellus in the mountainous regions of Europe. ■ When plants grow in a foreign land or in a locality other than their nature home, they are said to be naturalized, e.g., Datura stramonium was introduced into and naturalized in U.S.A. from Europe.

  17. ■ Many crude drugs are collected from wild plants (Gentian), ■ others are collected entirely from cultivated plants (Cinnamon), ■ but sometimes, a crude drug is obtained from both wild and cultivated sources (Senna leaves).

  18. The collection of wild plants for medicinal use is frequently accompanied by several disadvantages: 1- Wild plants are found in sparse distributions over unlimited areas. 2- Difficulty in collection and transport because they are mostly growing in deserts, or forests far from any means of transport. 3- Continuous extensive collection may lead to extinction or a serious plant deficiency.

  19. 4- Adulteration: Collection of crude drugs from wild sources may lead to adulteration due to ignorance of collectors who may collect: a) The desired plant with others. b) Undesirable organ of the desired plant. c) The desired plant at improper time. 5- The collected amount of wild plants may be insufficient for the market needs and may lead to monopoly. For the preceding reasons, cultivation of medicinal plants is necessary for a regular supply of drugs.

  20. Advantages of cultivation of medicinal plants:- 1- Concentration of the plants in a small area and therefore simplifying collection. 2- Control of the purity of the product. 3- Improvement of the drug by controlling certain factors in cultivation as: a) Treatment of seeds before sowing to ensure germination, e.g., soaking hyoscyamus seeds in sulfuric acid fastens germination and their treatment with colchicine increases the alkaloid content of crop. b) The use of fertilizers which increase the active constituents of the plants, by providing the essential elements for plants nutrition such as N, K and P. c) Controlling insect infestation.

  21. 4- Cultivation assures a regular and constant supply and helps to break down monopolies such as in cases of Cinchona, Cloves and Nutmeg. 5- Cultivation of drugs in proximity to the factory is an advantage for making fresh green extracts. 6- Cultivation helps study of the constituents of plants grown under controlled conditions.

  22. Disadvantages of cultivation: 1- The high cost of production except when carried on large scale. 2- Some medicinal plants require imitation to particular habitat, e.g., - Cannabis requires tropical climate for production of narcotic resin. - Cinchona requires damp hot weather. - Aloes requires a heavy rain fall. 3- Cultivation may modify the morphological as well as the anatomical characters of the wild plant so that the identification of the plant becomes difficult.

  23. II) Collection In order to ensure maximum quality and quantity of their active constituents, medicinal plants must be collected 1- at the proper time 2- at the proper stage of development 1- Time of collection: a- Time of the year: The nature and the amount of active constituents varies through out the year. Rhubarb and Rumex contain no anthraquinones in winter, but instead they contain anthranols which are converted to anthraquinone compounds in summer.

  24. b- Time of the day: The time of the day would affect the active constituents of drugs, e.g.: 1- Digitalis leaves collected in the afternoon contain more cardiac glycosides than those collected in the morning. It has been suggested that these glycosides undergo decomposition during night and recombine again with the sugars resulting from photosynthesis during daytime. 2- Solanaceous leaves have higher alkaloid content in the morning than those collected in the afternoon.

  25. 2- Stage of the development of the plant: The percentage of active principles depends on the stage of maturity and age of the plants collected. Examples: 1- Solanaceous leaves contain the maximum amount of alkaloids at the flowering stage. 2- Santonica flowers are rich in the bitter principle santonin when they are nonexpanded and show sharp depression in it upon expansion.

  26. Collection of leaves: ■Generally, they are collected at the beginning of the flowering stage when they contain the optimum percentage of their active principles. ■ Collection should be done in dry weather, as wet weather may cause deterioration and discoloration during drying process. ■The method of collection varies, e.g.; Senna: The whole plant is cut and the leaves are picked off after drying in the sun. Digitalis and coca leaves: are gathered directly from the plants.

  27. Collection of Flowers: It must be carried out in fine dry weather in order to fix the color of the product. Cloves and Santonica are collected in bud stage (before expansion). Chamomile flower are collected just after full expansion.

  28. Collection of barks: It is usually done in the spring or in early summer when the cambium is active and the bark can be easily stripped off from the trunk and branches

  29. Preparation of drugs before drying After collection of crude drugs, they need some sort of preparation before drying. 1- Cleaning:- Underground organs must be freed from soil particle. This is done by shaking, brushing or washing under water stream.

  30. 2- Garbling:- Is the process of the removal of foreign matters such as sand, dirt and un-required parts of the same plant, ….. etc. ■Garbling can be achieved either by hands or by a special machine. ■ Metallic particles can be removed by passing the drug over a big magnet.

  31. 3-Decortication:- The removal of outer unrequired tissues by (decortication) Example:- decortication process is made for the following reasons:- 1- Lack or low percentage of active principles in the outer parts. 2- Presence of unrequired constituents in the outer tissues. 3- Acquire a good appearance.

  32. III) Drying of crude drugs: Fresh plants usually contain high percentage of moisture (up to 80 or 90%). Drying is the removal of water or most of it from fresh living tissues. The duration of drying process varies from a few hours to many weeks. Moisture must be removed in order to:- 1- Stop the enzymatic action that might change the active constituent, i.e., to fix the active constituents. 2- Avoid deterioration upon storage by preventing the growth of microorganisms (bacteria and fungi). 3- Facilitate packing and storage. 4- Lower the transportation cost as the weight of the drug is greatly reduced. 5- Facilitate grinding of drug.

  33. The most important factors in drying process are temperature and time:- To use as low temperature as possible. To carry out the operation as rapid as possible. There is an optimum combination of temperature and time factor for each drug. If an enzymatic reaction is required, the drying process is carried out slowly as in case of Vanilla pods to release vanillin to be less bitter If the enzymatic hydrolysis is not desired, drying must be carried as quickly as possible as in case of digitalis and drugs containing volatile oils.

  34. Methods of drying I) Natural drying:- (Use of climatic heat) (1) Sun drying. (2) Shade drying. II) Artifical drying:- (1) Direct fire. (2) Stoves. (3)Drying chambers. (4) Vacuum drying. (5) Freeze drying or lyophilization.

  35. I) Natural drying (Use of climatic heat) ●Generally, the drug is spread and turned over from time to time and protected from rain and moisture by covering at night. 1- sun drying: It can be used for drugs which are not affected by direct exposure to sun heat and light e.g. Senna leaves. 2- Shade drying: It is a frequently used method at air temp. in shade, e.g. flowers whose colors are destroyed by direct exposure to sunlight.

  36. II) Artifical drying ▲It is suitable method in countries (as west Africa) where weather does not fit the natural drying due to very high humidity. ▲The temp. must be adjusted not to destroy the active constituents (usually not exceeding 60oC) Advantages: 1- Immediately stops the enzymatic action. 2- More rapid drying.

  37. (1) Direct fire. It imparts smoky odor to the drugs and produces gelatinization of starch. (2) Stoves (ovens) It must be done carefully to prevent damage or burning of the drug. (3)Drying chambers. It is a controlled and most Preferable method where drugs Are put on shelves in chambers having openings to allow Entrance of a warm steam of air through an inlet near the floor and the exit of the moist warm air through an outlet near the roof. Exit of moist warm air Entrance of warm steam of air

  38. (4) Vacuum drying. ☻It is used for the drugs sensitive to high temp. ☻The chambers are air tight and connected to an efficient vacuum pump. ☻As the pressure is lowered, the water content of the drug is removed at higher rate and at lower temp. e.g. Digitalis leaves.

  39. 5) Freeze drying or lyophilization ☻ This method is generally used for drying the extremely delicate product such as serum and for food stuffs such as orange juice and coffee extracts. ☻ The principle of this process is the removal of water content of the drug when present in the frozen state under vacuum at which it is sublimes into vapours directly without passingthrough the liquid state.

  40. Effect of drying on crude drugs: 1-Odor:- Change of the natural odor of drugs may occur on drying, e.g. Digitalis and Hyoscyamus lose their bad odor when dried. Fresh vanilla pods are odorless and on drying they get a fragrant aromatic odordue to liberation of vanillin. 2- Taste:- The taste of the drug may be altered on drying e.g. gentian is very bitter when fresh, becoming pleasant on drying.

  41. 3- Constituents: During drying, enzymatic action changes the constituents of some drugs. These changes may be desirable or undesirable. Desirable changes: e.g., Vanilla pods The drying process is carried out slowly to allow optimum hydrolysis of glucoside, glucovanillin, to vanillin. Undesirable changes: e.g., Digitalis leaves The changes of active constituents are not required, thus drying must be carried out quickly to prevent the enzymatic hydrolysis. Rapid drying prevent the decomposition of active principles. Therefore, the best method is vacuum drying.

  42. Quizz I-Choose the correct answer: 1- Leaf drugs are best collected in ----------------------. a- dry weather b- wet weather c- damp weather d- hot weather 2- Slow drying of fresh drugs is recommended when ---------------------. a- The active constituents is thermolabile b- the hydrolysis of the active constituents is desirable d- the active constituents is volatile oils c- the hydrolysis of the active constituents is undesirable

  43. 3- In term Piper nigrum , the word nigrum refers to -------------------. a- species b- black c- genus d- both a &b 4- Cultivation of medicinal plants give a chance for --------------------. a- extinction b- drug improvement c- monopoly d-drug adultration

  44. 5- A drug listed and described in pharmacopoeia is termed ---------------------. a- crude drug b- official drug c- wild drug d- cultivated drug 6- Seasonal variation of constituents is well observed in ---------------. a- ginkgo leaves b- solanaceous leaves c- digitalis leaves d- rhubarb rhizome & root

  45. II- Give reason (s) for the following: 1- Decortication of some drugs is essential 2- Drying of crude drugs

  46. The answer: 1- a- dry weather 2- b- the hydrolysis of the active constituents is desirable 3- d- both a &b 4- b- drug improvement 5-b- official drug 6- d- rhubarb rhizome & root

  47. II- 1- Decortication of some drugs is essential 1- Lack or low percentage of active principles in the outer parts. 2- Presence of unrequired constituents in the outer tissues. 3- Acquire a good appearance. 2- Drying of crude drugs 1- Stop the enzymatic action that might change the active constituent, i.e., to fix the active constituents. 2- Avoid deterioration upon storage by preventing the growth of microorganisms (bacteria and fungi). 3- Facilitate packing and storage. 4- Lower the transportation cost as the weight of the drug is greatly reduced. 5- Facilitate grinding of drug.

  48. Adulteration of Natural Products

  49. Adulteration of Natural Products In general adulteration occurs when the drug is either: 1- Scarce Or 2- Expensive The adulterant must be 1- Cheap and 2- Available in fairly large amount Types of Adulteration: 1- Sophistication 2- Substitution 3- Admixture 4- Inferiority 5- Deterioration 6- Addition of worthless or spoilage heavy materials

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