Introduction:

1. EVALUATION OF CRUDE DRUGSSilpa MAssistant professor Dept. Of pharmacology yenepoya pharmacy college & research centre

2. Introduction: • Drug evaluation may be defined as the determination of identity, purity and quality of a drug. • Identity – identification of biological source of the drug. • Quality – the quantity of the active constituents present. • Purity – the extent of foreign organic material present in a crude drug.

3. The evaluation of a crude drug is necessary because of three main reasons • Role in identification of botanical source • Variation in botanicals • Quality control of crude materials • Identification of common adulterants • Safety assessment – documentation for toxicological activity • Standardization of crude drugs

4. Methods of Drug Evaluation: • The evaluation of a drug is drug done by studying its various properties. • The various properties are • Organoleptic property, • Microscopic property, • Biological property, • Chemical property, • Physical property.

5. Organoleptic (Morphological) Evaluation: • This refers to drug evaluation by means of our organs of sense and includes other sensory organs like odour, colour, taste and texture. • It includes the study of morphology and other sensory characters.

6. Study of Gross Morphology: • It includes the visual examination of drug. • These drugs are classified into the following groups. • Barks • Underground structures • Leaves • Flowers • Fruits • Seeds • Herbs

7. Barks: • It includes all the tissues in a woody stem outside the interfascicular cambium which constitutes to the drug. • Barks are collected from the trunk or branches of the trees a narrow strips. • Example: Cinnamon, Cinchona, Ashoka, Kurchi.

8. During drying the drug, it undergoes unequal contractions and assumes different shapes.

9. Underground Structures: • Rhizomes, Roots, Bulbs, Corm and Tubers are the underground structures of the plant. • They are swollen due to the storage of food material like carbohydrates and other chemicals. • Examples: Ginger, Turmeric, Jatamansi.

10. Underground storage roots used as drugs are Ginger Turmeric

11. Leaves: • The shape, margin, base, apex and venation of leaves help in the identification of the drugs. Senna leaves Tulsi leaves

12. Flowers: • These are the reproductive organs of a plant and possess different shapes, size and colour. Saffron extracted from the flowers which is used as an essence in the food.

13. Fruits: • Fruits arise from the ovary and contain seeds. • They be globular, oblong or ellipsoidal in shape. • Examples: Almond, Amla.

14. Seeds: • Seeds are developed from the ovules in the carples of the flowers. They are characterised by the hilium, micropyle etc. • Examples: Linseed, Vomica.

15. (b) Study of Sensory Characters: • Colour, Texture, Odour and Taste are useful in the evaluation of drugs. • Colour • Odour • Taste • Texture

16. Colour: • Some drugs are green in colour when dried in shade. • But they become pale and bleached when dried in sunlight. Terminalia chebula - Fresh and Dried

17. Odour: • The odour of the drug may be either distinct or indistinct. • The terms used for the drugs are aromatic, balsamic, spicy etc. • Mentha, clove are some of the examples for the drugs which have a distinct odour.

18. Taste: • The drugs may be evaluated by tastealso. • The taste may be saline, sour, salty, sweet, bitter, alkaline etc. • The substances without taste are regarded as tasteless. • Examples: Ginger, Capsicum.

19. Texture: • Sometimes drugs can be examinated by their consistency, texture and nature of fracture. • Example: - Colocynth can be compressed easily since its parenchyma is loose.

20. II. Microscopic or Anatomical Evaluation: • This method allows a more detailed examination of a drug and it can be used to identify organized drugs by their known histological characters. • Before examination through a microscope the material must be suitably prepared. • This can be done by powdering, cutting thin sections of the drug or preparing a macerate.

21. Important aspect of microscopical evaluation: A) Histological studies B) Microscopic linear measurements and quantitative microscopy

22. Histological studies • Histological studies are made from very thin sections of drugs. The characteristics of cell walls, cell contents, starch grains, calcium oxalate crystals, trichomes, fibres, vessels, etc. can be studied in details: • lignified trichomes in nux-vomica, • Warty trichomes of senna, • Wavy medullary rays of cascara bark, glandular trichomes of mint etc.

23. Digitalis purpureais adulterated by Verbascumthapsus, Primulavulgaris, Symphytumofficinale. • Digitalis can be distinguished from V. thapsus microscopically by presence of wooly branched trichomes, where P.vulgaris have uniseriate covering trichomes (8-9 celled long) and S. officinale contain multicellulartrichomes forming hook at the top. • But Digitalis have uniseriatemulticellular covering trichomes of 3-5 celled long.

24. Verbascum thapsus, Digitalis purpurea

25. 2)Manchurian liquorice is adulterant of Glycyrrhizaglabra which can be distinghuished by the presence of Exfoliated cork where G. glabra contain Polyhedral tubular cork cells. • Cinchona bark is adulterated with Cuprea bark which can be identified by the presence of numerous Stone cells where cinchona barks rarely contain Stone cells.

26. Study of cell wall constituents Like: Suberin, Cutin, Mucilage etc. • Study of cell inclusions Like: Volatile oil, Fixed oil, Proteins, Starch, Lignin, Calcium oxalate etc. Diameter of starch grains will assist in distinguishing varieties of Ipecacuanha and also cassia bark from cinchona bark and will detect senna stalk in powdered senna leaf.

27. Trichome: • These are another important diagnostic characters helpful in the identification of drugs and detection of adulterants. • Trichomes are the tubular elongated or glandular outgrowth of the epidermal cell. Trichomes are also called as plant hairs. • Trichomesconsist of two parts viz., root (in the epidermis) and body (outside the epidermis).

28. Trichomes are present in most of the parts of the plant such as leaves (senna and digitalis), seeds (nux-vomica and strophanthus), fruits (Helicterisisoraand Ladies finger), etc. • Trichomes are as such functionless, but sometimes, perform secretory function. • The trichomes excrete water and at times, volatile oil as in case of peppermint. • Trichomes are present in most of the aerial parts of the plant, but are absent on roots

30. (I) Covering trichomes (a) Unicellular : 1. Lignified trichomes: Nux-vomica, strophanthus 2. Short, sharply pointed, curved: Cannabis 3. Large, conical, strongly shrunken: Lobelia (b) Multicellular - unbranchedtrichomes (i) Uniseriate 1. Bi-cellular, conical:Datura 2. Four to five celled long: Belladonna (ii) Biseriate : Calendula officinalis (iii) Multiseriate : Male fern (c) Multicellular - branched trichomes 1. Peltate (Plate like arrangement of surrounded cells):Humulus

31. II. glandular trichomes 1.Unicellular glandular trichomes : The stalk is absent e.g. Piper, Betel, Vasaka. 2. Multicellular glandular trichomes 1. Digitalis purpurea. (iii) HYDATHODE SPECIAL TYPES OF TRICHOMES These are organs of absorption or secretion of water developed in certain plants e.g. Piper betal, London pride, etc.

32. Different Type of Trichomes

33. Stomata: • Epidermis of leaf shows different characteristics, e.g. cutical stomata, trichomes, water-pore, cell inclusions, etc. • A stoma is a minute epidermal opening with following characteristics. (i)A central pore (ii) Two kidney shaped similar cells containing chloroplasts known as guard cells and varying number of subsidiary (epidermal) cells covering the guard cells.

34. Primary and most important function of stomata: Gaseous exchange and the secondary function is transpiration.

35. Types of stomata : • Depending upon the type of the guard cells and arrangement of subsidiary cells, stomata are divided into four types. 1. Moss type 2. Gymnospermous type 3. Gramineous type 4. Dicotyledonous type • Out of these, fourth type of the stomata is of diagnostic significance.

36. Dicotyledonous stomata are classified into following types depending upon the form and arrangement of subsidiary cells. • Paracytic or rubiaceous or parallel-celled stomata : • This type of stomata comprises two guard cells covered by two subsidiary cells, the long axes of which are parallel to that of stoma, e.g. coca and senna leaves

37. ii) Diacytic or caryophyllaceous or cross-celled stomata : • The guard cells are covered by two subsidiary cells, as in case of paracytic stoma, but the arrangement of subsidiary cells on the guard cell is at right angle to that of stoma, e.g. peppermint, spearmint, and vasaka

38. iii) Anisocytic or cruciferous or unequal-celled stomata : • The number of guard cells is two, as in all other cases. But, the guard cells are covered by three subsidiary cells, of which one is markedly smaller than the other two, e.g. belladonna, datura and stramonium .

39. iv) Anomocytic or ranunculaceous or irregular-celled stomata : • In this type, stoma is surrounded by varying number of subsidiary cells resembling other epidermal cells, e.g. digitalis and lobelia

40. v) Actinocytic or radiate-celled stomata : The two guard cells are surrounded by a circle of radiating subsidiary cells.

41. Microscope can also be used for a quantitative evaluation of drugs and adulterated powders. • This is done by counting a specific histological feature such as, • Stomatal Number • Stomatal Index • Vein-islet Number • Palisade Ratio • Quantitative Microscopy • Refractive Index

42. Leaf constant • Stomatal Number: • The average number of stomata present per square millimeter of the epidermis is known as stomatal number. • Stomatal number is relatively a constant for a perticular species of same age and hence, it is taken into consideration as a diagnostic character for identification of a leaf drug. • Example: Datura – 141 (upper epidermis)

43. Stomatal Index: • It is the percentafe proportion of the number of stomata to the total number of epidermal cells. • Stomatal number varies considerably with the age of the leaf but stomatal index is relatively constant for a given species. • Example: Atropa – 20.0-23.0 (lower epidermis)

44. Vein-islet Number: • The term “vein-islet” is used for the minute area of photosynthetic tissue encircled by the ultimate divisions of the conducting strands. • Vein-islet number is defined as the number of vein-islets per sq.mm. of leaf surface. • It is constant for a given species of the plant. It is irrespective with the age factor. • Example: Cassia senna (26).

45. Palisade ratio: • It represents the average number of palisade cells beneath one epidermal cell, using four continuous epidermal cells for the count. • It is determined from powdered drugs with the help of camera lucida. • Example: Atropabelladona– 06-10

46. Quantitative Microscopy: • It is an important analytical technique for powdered drug, especially when chemical and other methods of evaluation of crude drug fail as accurate measure of quality. • Example: Lycopodium- spores are very characteristic in shape and appearance.

47. Lycopodium- spores • It is used when especially chemical and other methods of evaluation of drugs fails to determine quality. • Lycopodium spores are very characterized in shape and appearance and uniform in size(25μm) on avg,94000 spores present/mg of lycopodium powder . it consists of 1.well defined particles which may be counted. 2.Single layered cells or tissues the area of which may be traced under suitable magnification and actual area calculated 3.The objects of uniform thickness, the length of which can be measured, and actual area calculated.

48. The percentage purity of an authentic ginger powder calculated as follows • N X W X 94,000 X 100 = % Purity of drug S x M x P • N=NUMBER OF CHARACTERISTIC STRUCTURES(STRACH GRAINS) IN 26 FIELDS • W=WEIGHT IN mg OF LYCOPOSIUM TAKEN • S=NUMBER OF LYCOPODIUM SPORES IN THE SAME 25 FIELDS M=WEIGHT IN mg OF SAMPLE CALCULATED ON BASIS OF DRIED SAMPLE AT 105 C • P=2,86,000 IN CASSE OF GINGER STARCH GRAIN POWDER

49. III. Physical Evaluation: • Physical contents such as elasticity in fibres, viscosity of drugs containing gums, selling factor for mucilage containing materials, froth number of saponin drugs, congealing point of volatile and fixed oils, melting and boiling points and water contents are some important parameters used in the evaluation of drugs. • Ultraviolet light is also used for determing the fluorescence of extracts of some drugs.

50. Physical constants are extensively applied to the active principles of drugs, such as alkaloids, volatile oils, fixed oils etc. • A few of them are:- • Moisture Content • Viscosity • Melting point • Optical Ratation • Refractive Index • Ash Content • Extractive values • Volatile oil Content • Rf Values