Introduction to Pharmacognosy Lecture Notes PDF

Medicinal Plants PG 101 Introduction to Pharmacognosy Lecture No. 2 Dr. Nermeen Bahaa Lecturer of Pharmacognosy [email protected]  Learning Outcomes (LOs) ‫المخرجات التعليمية‬ By The End of Introduction L...

Medicinal Plants PG 101 Introduction to Pharmacognosy Lecture No. 2 Dr. Nermeen Bahaa Lecturer of Pharmacognosy [email protected]  Learning Outcomes (LOs) ‫المخرجات التعليمية‬ By The End of Introduction Lectures, Students Should Possess Knowledge and Understanding Concerning: 1-1-1-2-1: Identify The Steps of Preparation of Crude Drugs From The Farm to The Firm, According to WHO Guidelines. 2-2-1-1-1: Recognize The Different Methods of Natural Drug Adulteration Ensuring Maximum Purity. Cultivation ‫زراعة‬ Collection ‫حصاد‬ Drying ‫تجفيف‬ Packing ‫تغليف‬ Storage ‫تخزين‬ 3-Drying of Medicinal Plants Drying is defined as decreasing moisture content to preserve the product for extended shelf life.  Objectives of drying crude drugs 1. To help in their preservation. 2. To fix their constituents, by preventing reactions (enzymatic hydrolysis of A.C.) that may occur in presence of water. 3. To prevent the growth of micro-organisms such as bacteria and fungi so avoid deterioration on storage. 4. To facilitate their grinding. 5. To reduce their size (bulk) and weight.  Methods of drying A. Natural drying using natural air B. Artificial drying A. Natural drying 1- Shade drying 2- Sun drying exposure spreading in the shade to direct sun Retain the natural For drugs which are colour of the drug e.g. not affected by direct Senna leaf action of sunlight. Preserve its sensitive The drug is covered at active constituents. night or in periods of rain. e.g. Peppermint…..why? 1. Shade drying 2. Sun drying B-Artificial drying Rapid method At well-controlled temperature Immediately stops enzymatic action Prevents the decomposition of active principles 1-Tray drying: 2-Vacuum drying It is used mainly for drugs sensitive to high temperature e.g Digitalis leaves.  3-Freeze-drying (lyophilization) A very mild method. Works by freezing the material then reducing the surrounding pressure allowing the frozen water to sublimate directly from solid to the gas phase. Requires a relatively complicated apparatus that is much more expensive than hot-air drying, so it is not used as a routine method. Very important for drying heat-sensitive substances, e.g., antibiotics and proteins. Freeze Dryer (Lyophilizer) Other techniques include drying ovens direct fire, infrared radiation bmstabiltherm02_6.jpg Infrared radiation Drying oven “An Absolutely dried drug” is that drug which is completely freed from water. A Drug stored in wooden cases, paper bags, reabsorbs 8-10% of moisture and is called “Air-dry drug” N. B. In the dried drug, the enzymes are not destroyed but only rendered inactive due to the low water content. As soon as water is added, they become active again. Hence, dried drugs must be protected from moisture during storage. Inactive enzyme  Grinding Important for making the drug particles of uniform size. Produces a certain amount of heat which must be controlled with heat-sensitive crude drugs. Mills cooled with liquid nitrogen are available for such purposes. Cold grinding is also preferable for crude drugs containing volatile oils. Following grinding, the material must be sifted to ensure the proper particle size by sieving.  4-Bulk packaging and labelling of medicinal plants Dried medicinal plant materials should be packaged as quickly as possible to Prevent deterioration of the product. Protect against unnecessary exposure to potential pest attacks and other sources of contamination. Processed medicinal plant materials should be packaged in clean, dry boxes, bags or other containers. Fragile medicinal plant materials should be packaged in rigid containers. A label affixed to the packaging should clearly indicate: 1- The scientific name of the medicinal plant. 2-The plant part. 3-The place of origin (cultivation or collection site). 4-The cultivation or collection date. 5- The names of the grower/collector and the processor. 6-Quantitative information. 7-A number that clearly identifies the production batch. 5-Preservation and Storage  WHO’s Guidelines for Storage of crude drugs 1-Storage facilities for medicinal material should be: i-Well aerated ii- Dry iii-Protected from light iv-When necessary be supplied with air- conditioning and humidity control equipment v-With facilities to protect against rodents and insects  WHO’s Guidelines for Storage of crude drugs 2-Herbal drugs containing essential oils should be stored in dry conditions and with daily temperature control to avoid loss of their aroma.  WHO’s Guidelines for Storage of crude drugs 3-Fresh medicinal plant material should be stored at appropriate low temperature. 4-Small quantities of crude drugs should be stored in: Airtight, Moisture proof and Light proof containers such as tins ,cans, amber colored glass containers.  Aromatic drugs lose their odour. Absorbent cotton loses its General absorbance power. undesirable changes Drugs containing fixed oil may be that may rancid. occur Drugs containing volatile oils may be during bad resinified. storage: Sensitive drugs may lose their activity. e.g. Digitalis leaves.  1. Physiochemical factors: Principal factors responsible Moisture ‫الرطوبة‬ for deterioration Light ‫الضوء‬ of crude drugs during Temperature ‫الحرارة‬ storage: Oxygen (Air) ‫األوكسجين‬ 2-Biological factors Bacteria ‫البكتريا‬ Moulds ‫عفن‬ Worms ‫الديدان‬ Insects and rodents ‫الحشرات والقوارض‬  Control of infestation: 1. Heat treatment: By exposing the drug to temperature of 60-65°C to kill insects. It is effective especially for insect eggs that are not penetrated by insecticide. 2. Fumigation: Fumigation by Volatile insecticide in closed area. Examples of gases used: T-gas (90% Carbon Carbon Ethylene oxide tetrachloride bisulfide and + 10% CO2 ) is (advantage: cyanide (highly used for non- poisonous) medicinal inflammable) plants. Fumigation should be repeated at intervals, to permit eggs to hatch and young larvae to be killed. 3. Liming: ‫التجيير‬ Drugs are dipped in freshly slaked lime (Ca hydroxide) or sprinkled with quick lime (Ca oxide) to coat the drug Ginger with a fine powder that clogs breathing tubes of larvae and adult insects (partial protection). e.g.: ginger ‫الزنجبيل‬ nutmeg ‫جوزالطيب‬ Nutmeg 4. Low temperature storage: insect killed by extremely low temperatures Exposure to sub-freezing temp (-10 to -150 C) for 12-18 hours.  Rodents Drugs present in paper, cloths, cardboard or wooden containers are affected by rodents that Can Drugs are better cause spoilage to stored in glass, drugs during storage plastic or metal containers  ANTU = alpha naphthyl thio urea is an example of rodenticides used to eliminate rats and mice. Exception Drugs required to be stored for at least one year before use: Cascara and Frangula barks: Used as laxatives They contain a glycoside which causes emesis (vomiting) as a side effect, but during storage, the glycoside is hydrolysed, thus the bark loses this side effect, and does not cause vomiting anymore. Stabilization (or inactivation of enzymes) helps to keep drugs without change in shape and active constituents.  Stabilization It is a process of stabilizing the active constituents of the crude drugs. On long storage, enzymatic reactions will slowly destroy the constituents, because the last traces of water, in the crude drug, can never be removed. In many cases, this is not desired.  Stabilization may be Temporary Permanent a-Temporary (partial stabilization) Keeping drug in absolute dry conditions, in a container containing a dehydrating agent, such as quick lime. b- Complete stabilization Destruction of enzyme = permanent stabilization:, this is done by exposing the fresh drug to alcohol vapours or immersing the fresh drug in alcohol.  Fermentation Fermentation or enzymatic transformation of the original plant constituents is sometimes desirable. The fresh material is exposed to raised temperatures (30-40 °C) and humidity, to accelerate the enzymatic processes. This treatment is usually called fermentation as followed in tea factory.  What is the difference between green and black tea?  Fermentation is mostly used to remove bitter or unpleasant-tasting substances or to promote the formation of aromatic compounds with a pleasant smell or taste. It is mainly applied to drugs used as spices or stimulants, e.g., vanilla, tea, and cocoa. Adulteration of Drugs and Detection of Adulterants. Adulteration ‫الغش‬ Adulteration = The action of making something poorer in quality by several ways. It occurs when a drug is scarce, or its price is high. The adulterant must be cheap and available in large amounts. Adulteration involves: 1. Sophistication 2. Substitution 3. Admixture 4. Spoilage 5. Inferiority 1-Sophistication or True Adulteration: It is the addition of an inferior material to any article with intend to defraud (cheat) e.g., Addition of Wheat flour to powdered Ginger with enough Capsicum to restore pungency and Curcuma to maintain the colour.  2-Substitution An entirely different article is used or sold in place of the one required or asked for. N.B. substitution is not sophistication as none of the original article is present, yet. legally it is adulteration i. Substitution with inferior commercial variety e.g. Arabian senna, Dog Senna instead of Alexandrian Senna  ii. Substitution of superficially similar but cheaper natural substances having no relation to genuine drugs e.g. Xanthium leaves for Stramonium leaves. 3-Admixture ‫اختالط‬ The addition of one article to another through accident, ignorance or carelessness. Admixture may occur through faulty collection: e.g. collecting other parts of the same plant, or another plant by mistake. 4-Spoilage ‫التلف‬ A form of deterioration in which quality of usefulness of an article is destroyed by the action of bacteria or fungi, rendering the article unfit for human consumption. 5-Inferiority It is any substandard condition for any reason e.g. Dried ripe seeds of Nux vomica containing less than 1.15% strychnine is considered of inferior quality.  Macro and micro-morphology investigation Linear measurements Solubility testing Detection of Qualitative tests Adulteration Quantitative assays Pharmacopeial constants Comparison with authentic sample of the drug Test yourself questions MCQ: 1- All the following are true about freeze drying EXCEPT: a. A mild drying method. b. Much more expensive than hot air drying. c. The frozen water in the material sublimates directly from the solid phase to the gas phase. d. Used for drying large amounts of woody drugs. 2- Why should we store Cascara and Frangula barks for at least one year before use? a. To lose their emetic effect. b. To prevent hydrolysis of the glycosides. c. To lose their laxative effect. d. To increase their emetic effect. MCQ: 3- Physiochemical factors responsible for deterioration of crude drugs during storage: a. Moisture. b. Temperature. c. Bacteria. d. a & b. 4- All the following are Artificial drying techniques, except: a. Tray drying b. Lyophilization c. Vacuum drying d. Shade drying State whether the following statement is true or false: 1. During fermentation, the fresh material is exposed to raised temperature and humidity. 2. Cold grinding is preferable for crude drugs containing volatile oils. 3. Artificial drying activates enzymatic action. 4. Alpha naphthyl thio urea is a chemical substance used to eliminate worms. 5. Permanent stabilization is done by exposing the fresh drug to alcohol vapors or immersion in alcohol Complete: 1. Addition of wheat flour to powdered Ginger is an example of ………….when enough Capsicum is added to restore ……… and Curcuma to maintain ……… 2. Fragile medicinal plant materials should be packaged in ………. Scientific term: 1. A form of deterioration in which quality of usefulness of an article is destroyed by the action of bacteria or fungi. (……………..) 2. The action of making something poorer in quality by several ways. (……..…) Give reason: Fumigation should be repeated at intervals?