Phacog 1.4.


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Phacog 1.4.

  1. 1. 4/15/2012 CULTIVATION, COLLECTION & PREPARATION OF CRUDE DRUGS Phcog-1.4. Crude drugs cultivated or uncultured plants Processing of crude drugs Some cases: pharmacopoeias specify cultivated spp. Such as Fennel, ginger, cinnamon & opium Opium: only official growers may legally produce herbs. Other herbs: senna, tragacanth etc, may be collected from By Abdul Ghani Karimi wild or cultivated species. Department of Pharmacognosy, Faculty of Pharmacy Date: 13.01.1390DISADVANTAGES OF WILD PLANT COLLECTION ADVANTAGES OF CULTIVATED HERBS Only desired spp are collected uniform quality.Sparse distribution e.g. Sceletium tortuosumPotentially difficult to transport herb to area of processing. Collection, transport & access to processing facilitiesDifficult access (e.g. Forests, Mountains etc) is improved.Collector ignorance admixture of other plants, collection of Better control of soil quality, pests & plant disease.undesired plant parts or stage of development or during an Supply: Constant & Regular (Controlled).incorrect season loss of medicinal activity. Herb collectors – trained. 1. Collecting of medicinal plants B. Rules for collection The following general rules are based onA. Suitable time for collection assuming that the material is best collected when the organ in question has reached its The amount of a constituent is usually not constant optimal state of development: throughout the life of a plant. 1. Roots and rhizomes are collected at the end of the vegetation period, The stage at which a plant is collected or harvested is, i.e. usually in the autumn. In most cases they must be washed free of therefore, very important for maximizing the yield of the adhering soil and sand. 2. Bark is collected in the spring. desired constituent. 3. Leaves and herbs are collected at the flowering stage. The differences are sometimes not only quantitative but 4. Flowers are usually gathered when fully developed. also qualitative. 5. Fruits and seeds are collected when fully ripe. 1
  2. 2. 4/15/2012 C. Methods of collection 2. Preservation of plant material Medicinal plants must be largely collected by • The plant material must first be preserved so that the active compounds will remain unchanged hand. This is especially true in the case of wild during transport and storage. plants. • The cells of living plants contain not only low molecular-weight compounds and enzymes, but With cultivation on a large scale, it may be they also have many kinds of barriers that keep these constituents apart. possible to use modern agricultural harvesters, • When the plant dies, the barriers are quickly broken but in many cases, e.g. barks, manual collection is down and the enzymes then get the opportunity to promote various chemical changes in the other cell unavoidable. Thus, the cost of drug production is constituents, e.g. by oxidation or hydrolysis. • Preservation aims at limiting these processes as largely the cost of the labor involved. far as possible. • To stop the enzymic processes, the water content must be broughtA. Drying down to about 10 %. The most common method for preserving plant material is drying. • Drying must be done quickly, in other words at raised temperatures Enzymic processes take place in aqueous solution. and with rapid and efficient removal of the water vapor. Rapid removal of the water from the cell will, therefore, largely prevent degradation of the cell • The most efficient drying is achieved in large driers of the tunnel type. constituents. • The plant material is spread out on shallow trays, which are placed on Drying also decreases the risk of external attack, e.g. by mobile racks and passed into a tunnel where they meet a stream of moulds. warm air. Living plant material has a high water content: leaves may contain 60-90% water, roots and rhizomes 70-85%, and wood 40-50%. 60-90% 70-85% 40-50% • The air temperature is kept at 20-40 °C for thin materials such as The lowest percentage, often no more than 5-10%, is found in 10% leaves, but is often raised to 60-70 °C for plant parts that are harder to seeds. seeds dry, e.g. roots and barks. B. Freeze-drying Freeze-• When the crude drug has been collected under primitive Freeze-drying (lyophilization) is a very mild method. conditions, without access to a drier, it must be dried in the open. Frozen material is placed in an evacuated• The material should be spread out in shallow layers with good apparatus which has a cold surface maintained at - ventilation to facilitate the drying. 60 to -80 °C. Water vapor from the frozen material then passes rapidly to the cold surface.• The choice of sunshine or shade is determined by the sensitivity The method requires a relatively complicated to light of the constituents. apparatus and is much more expensive than hot-airhot- drying.• In a dried drug the enzymes are not destroyed but only rendered For this reason, it is not used as a routine method, inactive due to the low water content. As soon as water is added, but it is very important for drying heat-sensitive heat- substances, e.g. antibiotics and proteins proteins. they become active again. Hence, dried drugs must be protected from moisture during storage. 2
  3. 3. 4/15/2012C. Stabilization D. Fermentation On long storage, enzymic reactions will slowly destroy the Enzymic transformation of the original plant constituents is constituents, because the last traces of water can never be sometimes desirable. removed. The fresh material is then placed in thick layers, sometimes In order to avoid this degradation, the enzymes should be covered and often exposed to raised temperatures (30-40 °C) destroyed before drying, a process usually called stabilization stabilization. and humidity, so as to accelerate the enzymic processes. The most common method being brief exposure (a few This treatment is usually called fermentation. minutes only) of the plant material to ethanol vapor under pressure (0.5 atm). The fermented product must, of course, be dried afterwards Stabilization may be of value for the isolation of compounds to prevent attack by microorganisms, e.g. moulds. that are very susceptible to enzymic degradation. Fermentation is mostly used to remove bitter or 3. Standardization of Crude Drugs unpleasant-tasting substances or to promote the • Standardization of drug means adjustment of the quality and formation of aromatic compounds with a pleasant smell quantity of drugs according to standards. or taste. • Completion of drying of crude drugs It is mainly applied to drugs used as spices or stimulants, • Wet of crud drugs e.g. vanilla, tea and cacao. cacao. • Removing foreign matters • Removing of other parts of plant which does not important • Removing of deteriorate parts • Departing of unlimited particles WHO Monograph for Herbal Drugs 4. Storage of crude drugs • There are great differences in the stability of crude drugs because of slow enzymic changes in the constituents. • Drugs containing glycosides and esters are usually less stable than those containing alkaloids. • Drugs with essential oils deteriorate rather quickly through evaporation, oxidation and polymerization of the substances constituting the essential oil. • Tannins on the other hand, have an almost unlimited durability. 3
  4. 4. 4/15/2012 • In order to keep crude drugs as long as possible: 5. Evaluation of Crude Drugs • Evaluation of drug means confirmation of its identity and 1. It is essential to store them in a dry condition in determination of its quality and purity and detection of carefully closed containers. nature of adulterant by various parameters like morphological, microscopical, physical, chemical and 2. It is also advisable to exclude light, because - even biological observations. if it does not affect the active constituents - it • The evaluation of crude drug is necessary because of 3 almost always causes changes in the appearance of main reasons. the drug, especially loss of color. 1. Biochemical variation in the drug. 3. It is also necessary to protect the drug against insect attack. 2. Deterioration due to treatment and storage. 3. Substitution and adulteration, as a result of carelessness, ignorance or fraud. Morphological or Organoleptic Evaluation Microscopical Evaluation• It refers to evaluation of drugs by colour, odour, • Diagnostic character of leaf taste, size, shape and special features like touch, texture, etc. • Stomata• It is a technique of qualitative evaluation based on • Trichomes the study of morphological and sensory profiles of whole drugs. Diagnostic Character of Leaves Types of Trichomes Palisade Ratios of various leaf-drugs 4
  5. 5. 4/15/2012 Stomata and stomatal index Type of Glandular trichomes Preliminary phytochemical screening Chemical Evaluation Preliminary Qualitative chemicalphytochemical screening examinations Qualitative chemical examinations Physical Evaluation 1. Detection of Alkaloids • Physical standards are to be determined for 2. Detection of carbohydrates and glycosides drugs, wherever possible. 3. Detection of saponins 4. Detection of phenolic compounds and tannins • These are rarely constant for crude drugs, but 5. Detection of gum and mucilage may help in evaluation, specifically with 6. Detection of volatile oils reference to moisture content, specific gravity, 7. Detection of phytosterols density, optical rotation, refractive index and 8. Detection of fixed oil and fats solubility in different solvents. 9. Detection of protein and free amino acids 5
  6. 6. 4/15/2012 Moisture Content Volatile oil Content Physical Optical rotation evaluation Crude Drugs with Limit For Moisture Content Moisture Refractive content index Foreign organic Ash content Solubility matter Ash soluble in Water-soluble Alcohol-solubleGeneral Ash HCl extractives extractives Sulphated Ash Ether-soluble extractives OPTICAL ROTATION Refractive index • Optically active compounds have the property of rotating • When a ray of light passes from one medium to another of the plane of polarized light.This property is known as different density, then the ratio of velocity of light in vacuum optical rotation. to its velocity in substance is termed as refractive index of second medium. • Normally, the optical rotation is determined at 25˚c using sodium lamp as the source of light. • It is constant for a pure drug and varied with wavelength of incident light, temperature and pressure. • E.g. : • E.g. : Extractives Alcohol soluble extractive 6
  7. 7. 4/15/2012 Ash contents Ether-soluble Extractives Volatile Oil Content Foreign organic matter • The parts of the organ or organs other than those named in the definition and description of the drug are defined as foreign organic matter. • The maximum limit for the foreign matter is defined in the monograph of crude drugs. • If it exceeds the limits, deterioration in quality of the drug takes place. Diagrams of HPLC & GC Chromatographic Techniques• Thin Layer Chromatography (TLC)• Column Chromatography• High Performance Chromatography (HPLC)• Gas Liquid Chromatography (GLC)• Spectroscopic Methods 7
  8. 8. 4/15/2012 W.H.O. Guidelines for General limits Biological Evaluation (Contaminants in herbal drugs) • Hepatoprotective activity • Hypoglycemic activity • Anti fertility testing • Anti inflammatory activity • Neuropharmacological activity • Testing for anti ulcer activity • Anti-insect activity • Microbiological Assays 6. Classification of Plant Drugs Alphabetical Classification • Alphabetical • Latin/vernacular names • Taxonomic • Advantage: quick reference • Morphological • Disadvantage: no indication of the • Pharmacological/Therapeutic interrelationships between plants (drugs) • Chemical/Biogenic • Used in – Dictionaries – Pharmacopoeias Taxonomic Classification Morphological Classifications• Plants classified based on their botanical classification. • (Plant) Drugs are divided into organized and• (Plant) Drugs are arranged according to the plants they unorganized drugs. – Based on plant morphology are derived from (class, order, family, genera & species).• Advantage: Precise & ordered arrangement (no • Advantage – Practical application to the study of plant drugs. ambiguity)• Disadvantage: Botanical knowledge decreases over the • Disadvantage – Microscopical studies are needed to identify powdered years in students. herbs.• < popular with teaching 8
  9. 9. 4/15/2012 Morphological Classification Pharmacological/Therapeutic Classification• Organized drugs • Unorganized drugs • Plant drugs are grouped according to their pharmacological action of the most important active – Leaves – Dried latices constituent in the plant. – Flowers – Extracts – Fruits – Gums – OR – Seeds – Resins – Herbs – Oils • According to the drug’s therapeutic use. – Whole organisms – Fats • Disadvantage: The constituents of one drug may – Woods – waxes have more than one therapeutic action (fall into – Barks numerous groups. E.g. Flavonoids). – Rhizomes – Roots Biogenic/Chemical Classification• Drugs are classified according to the main active chemical constituent available in the plant. – OR• The biosynthetic pathways of the main active constituent.• Advantage: Popular for teaching when Pharmacognosy is phytochemically based.• Disadvantage: Ambiguities: Plants contain more than one group of active constituents each with different actions. 9