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Pharmacognosy

Pharmacognosy

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Pharmacognosy

  1. 1. pharmacognosy Dr. Ashutosh Tiwari M.D. 1st Year SAIMS Indore 09/01/2014
  2. 2. Pharmacognosy • Pharmacognosy is the study of medicines derived from natural sources. • The American Society of Pharmacognosy defines pharmacognosy as "the study of the physical, chemical, biochemical and biological properties of drugs, drug substances or potential drugs or drug substances of natural origin as well as the search for new drugs from natural sources”
  3. 3. Pharmacognosy • Although pharmacognosy is principally concerned with plant materials, there are a small number of animal products which are traditionally encompassed within the subject; • Examples: – Produced from wild (whale, musk, deer) – Fish (cod and halibut) – domesticated animals (hog, sheep, cattle) –lanolin and milk products, hormones, endocrine prods, and some enzymes – Wild insects (cantharides) – Cultivated (beeswax) • Marine organisms, both plant and animal, with potent pharmacological actions are receiving increasing attention in the search for new drugs.
  4. 4. Pharmacognosy • Materials having no pharmacological action which are of interest to pharmacognosists are natural fibres, flavouring and suspending agents, colourants, disintegrants, stabilizers and filtering and support media. • Other areas that have natural associations with the subject are poisonous and hallucinogenic plants, allergens, herbicides, insecticides and molluscicides.”
  5. 5. Pharmacognosy • Recently it includes: – Modern isolation techniques – Pharmacological testing procedures to prepare purified substances – Cultivation and propagation by tissue culture
  6. 6. The history of natural products in medicine • A great proportion of the natural products are used as drugs • The study of drugs used by traditional healers is an important object of pharmacognostical research
  7. 7. Ayurveda (Charak) 2500-600 BC - India
  8. 8. Egyptians (Ebers papyrus, 1550 BC)
  9. 9. Sumerians and Akkadians (300 BC)
  10. 10. Authors of antiquity Hippocrates (460-377 BC) “The Father of Medicine”
  11. 11. Dioscorides (40-80 AD) “De Materia Medica” (600 medicinal plants)
  12. 12. The Islamic era Ibn Al tabari (770850) ” ‫فردوس‬‫الحكمه‬ “
  13. 13. Ibn Sina (980-1037) ” ‫القانون‬‫في‬‫الطب‬ “
  14. 14. Ibn Al bitar (1148-1197) ” ‫الجامع‬‫لمفردات‬‫األدوية‬‫واألغذية‬ “
  15. 15. The era of European exploration overseas (16th and 17th century)
  16. 16. History • The word ‘Pharmacognosy’ is derived from: – pharmakon ‘a drug’ (Greek) – gignosco ‘ to acquire knowledge of’ (Greek) – or cognosco ‘to know about’ (Latin) • The term "pharmacognosy" was used for the first time by the Austrian physician Schmidt in his Lehrbuch der materia medica in 1811 and in 1815 by Crr. Anotheus Seydler in a work titled Analecta Pharmacognostica.
  17. 17. History • It is a recognised fact that in the historical development of any subject the role of certain individuals is of considerable importance. • The first British pharmacognosist was Jonathan Pereira (1804–1853), who as the first teacher of the subject gave it its pharmaceutical basis. He may be considered as the founder of British pharmacognosy. • Daniel Hanbury (1825–1875) was the most outstanding applied pharmacognosist while the contribution made by E. M. Holmes (1843–1930) as an applied pharmacognosist stands out both in quality and quantity. • Dr. Chandrakant Kotate, Father of Indian Pharmacognosy
  18. 18. The era of pure compounds • Isolation of morphine from opium (1806) • Strychnine (1817) • Quinine and caffeine (1820) • Nicotine (1828) • Atropine (1833) • Cocaine (1855)
  19. 19. • 19th century: the chemical structures of many of the isolated compounds were determined • 20th century: the discovery of important drugs from the animal kingdom, particularly hormones and vitamins • microorganisms have become a very important source of drugs
  20. 20. Pharmacognosy: Fields • Medical ethnobotany: the study of the traditional use of plants for medicinal purposes; • Ethnopharmacology: the study of the pharmacological qualities of traditional medicinal substances; • Study of phytotherapy (the medicinal use of plant extracts); • Phytochemistry, the study of chemicals derived from plants (including the identification of new drug candidates derived from plant sources).
  21. 21. Pharmacognosy: Fields • Zoopharmacognosy, the process by which animals self-medicate, by selecting and using plants, soils, and insects to treat and prevent disease • Marine pharmacognosy, the study of chemicals derived from marine organisms.
  22. 22. Phytochemicals • All plants produce chemical compounds as part of their normal metabolic activities. These phytochemicals are divided into • (1) Primary metabolites such as sugars and fats, which are found in all plants; • (2) Secondary metabolites—compounds which are found in a smaller range of plants, serving a more specific function
  23. 23. Phytochemicals • some secondary metabolites are toxins used to deter predators and others are pheromones used to attract insects for pollination. • It is these secondary metabolites and pigments that can have therapeutic actions in humans and which can be refined to produce drugs— examples are inulin from the roots of dahlias, quinine from the cinchona, morphine and codeine from the poppy, and digoxin from the foxglove.
  24. 24. Phytochemicals • Plants synthesize variety of phytochemicals but most are derivatives of a few biochemical motifs: • Alkaloids • Phenolics • Glycosides • Terpenes
  25. 25. Phytochemicals • Alkaloids are a class of chemical compounds containing a nitrogen ring. • Glycosides is a molecule in which a sugar is bound to a non-carbohydrate moiety, usually a small organic molecule. • Polyphenols (also known as phenolics) are compounds contain phenol rings. • Terpenes and terpenoids are the primary constituents of resin, essential oils of many types of plants and flowers.
  26. 26. Alkaloids • Examples are – the local anesthetic and stimulant cocaine; – the psychedelic psilocin; – the stimulant caffeine, nicotine; – the analgesic morphine; – the antibacterial berberine; – the anticancer compound vincristine; – the antihypertension agent reserpine; – the cholinomimetic galantamine; – the spasmolysis agent atropine; – the vasodilator vincamine; – the anti-arhythmia compound quinidine; – the anti-asthma ephedrine; – the antimalarial drug quinine.
  27. 27. Classification • Vegetable drugs can be arranged for study under the following headings: – Alphabetical – Morphological – Taxonomical – Pharmacological / Therapeutic – Chemical
  28. 28. Alphabetical • Either Latin or vernacular names may be used. • This arrangement is employed for dictionaries, pharmacopoeias, etc. • Although suitable for quick reference it gives no indication of inter-relationships between drugs.
  29. 29. Morphological • Drugs are arranged according to their morphological or external characters of the plant parts or animal parts, i.e. which part of the plant is used as a drug – Organized drugs : obtained from the direct parts of the plants and containing cellular tissues – e.g. leaves (digitalis, senna, belladona), flowers (clove, saffron), fruits (amla, cardamom, cumin), seeds (ispaghula, linseed, physostigma), herbs (ergot, vinca), barks (cinchona), rhizomes and roots (aconite, ginseng, ipecac, rauwolfia), hair & fibres (flax)
  30. 30. Morphological – Unorganized drugs: prepared from plants by some intermediate physical processes such as incision, drying or extraction with a solvent and not containing any cellular plant tissues – e.g. latex (opium), dried juice (aloe), extracts (agar, catechu, pectin), waxes (beeswax), gums (acacia, guargum), resins (benzoin, colophony, tolu balsam), volatile oil (turpentine, cinnamon, peppermint, clove), fixed oils & fat (arachis, castor, olive, cod liver), • Advantage: More convenient for practical study especially when the chemical nature of the drug is not clearly understood • Disadvantage: there is no correlation of chemical constituents with the therapeutic actions
  31. 31. Taxonomic • Drugs are arranged according to the plants from which they are obtained, in kingdom, subkingdom, division, class, order, family, genus and species – Advantage: It allows for a precise and ordered arrangement and accommodates any drug without ambiguity; helpful for studying evolutionary developments – Disadvantage: does not correlate in between the chemical constituents and biological activity of the drugs
  32. 32. Taxonomic • Class – Angiospermae (Angiosperms): plants that produce flowers – Gymnospermae (Gymnosperms): Plants which do not produce flowers • Subclass – Dicotyledonae (Dicotyledons, Dicots): plants with two seed leaves – Monotyledonae (Monotyledons, Monocots): plants with one seed leaf
  33. 33. Taxonomic • Superorder: A group of related plant families, classified in the order in which they are thought to have developed their differences from a common ancestor • Each superorder is further divided into several orders; the names of the orders end in -ales
  34. 34. Taxonomic • Family – Each order is divided into families – These are plants with many botanical features in common, and are the highest classification normally used. – The names of the families end in –aceae • Subfamily – The family may be further divided into a number of subfamilies, which group together plants within the family that have some significant botanical differences. – Subfamilies end in -oideae
  35. 35. Taxonomic • Genus – Part of the plant name that is most familiar; the normal name that you give a plant • Papaver (poppy) • Arachis (peanut) • Species – Level that defines an individual plant – The name describes some aspect of the plant – the color of the flowers, size or shape of the leaves, or it may be named after the place where it was found. – Should be written after the genus name, in small letters
  36. 36. Pharmacological/Therapeutic • This classification involves the grouping of drugs according to the pharmacological action of their most important constituent or their therapeutic use. • Advantage: More relevant and mostly followed method • Disadvantage: Drugs having different action on the body get classified separately in more than one group that causes ambiguity and confusion
  37. 37. Pharmacological/Therapeutic Drugs acting on G.I.T. • Carminative - Fennel, Cardamom, Mentha • Emetic - Ipecac • Antiamoebic - Kurchi, Ipecac • Laxative - Agar, Isabgol, Banana • Purgative - Senna, Castor oil • Cathartic - Senna
  38. 38. Pharmacological/Therapeutic Drugs acting on Respiratory System • Antitussive - Opium (codeine) • Bronchodilators - Ephedra, Tea • Expectorant - Vasaka, Liquorice, Ipecac
  39. 39. Pharmacological/Therapeutic Drugs acting on Autonomic Nervous System • Adrenergic - Ephedra • Cholinergic - Physostigma, Pilocarpus • Anticholinergic - Datura, Belladonna
  40. 40. Pharmacological/Therapeutic Drugs acting on Cardiovascular System • Cardiotonic - Digitalis, Strophantus, Squill • Cardiac depressant - Cinchona, Veratrum • Vasoconstrictor - Ergot • Antihypertensive - Rauwolfia
  41. 41. Pharmacological/Therapeutic Drugs acting on Central Nervous System • Central analgesic - Opium (morphine) • CNS depressant - Belladonna, Opium, Hyoscyamus • CNS stimulant - Tea, Coffee • Analeptic - Nux vomica, Camphor, Lobelia
  42. 42. Pharmacological/Therapeutic • Antispasmodic - Datura, Hyoscyamus, Opium, Curare • Anticancer - Vinca, Podophyllum, Taxus • Antirrheumatic - Aconite, Colchicum, Guggal • Anthelminthic - Quassia, Vidang • Astringent - Catechu, Myrobalans • Antimalarial - Cinchona, Artemesia • Immunomodulatory - Ginseng, Ashwagandha, Tulsi • Immunizing agent - Vaccines, Sera, Antitoxin • Drugs acting Skin Membrane - Beeswax, Wool fat, Balsam of Tolu, Balsam of Peru • Chemotherapeutic - Antibiotics • Local anesthetic - Coca
  43. 43. Chemical • Crude drugs are classified depending upon the active constituents • Irrespective of the morphological or taxonomical characters, the drugs with similar chemical constituents are grouped together • Advantage: it is a popular approach for phytochemical studies • Disadvantage: ambiguities arise when particular drugs possess a number of compounds belonging to different groups of compounds.
  44. 44. Chemical Chemical Constituent Group • Alkaloids - Cinchona, Datura, Vinca, Ipecac, Nux vomica • Glycosides - Senna, Aloe, ginseng, Digitalis • Carbohydrates & its derivatives - Acacia, Starch, Isabgol • Volatile oil - Clove, Coriander, Fennel, Cinnamon, Cumin • Resin and Resin Combination - Benzoin, Tolu Balsam, Balsam of Peru • Tannins - Catechu, Tea • Enzymes - Papain, Casein, Trypsin • Lipids - Beeswax, Kokum butter, Lanolin
  45. 45. Production of natural drug products 1. Collection (wild) 2. Cultivation (commercial), collection, harvesting, drying, garbling, packaging, storage and preservation e.g. ginseng, ginkgo, peppermint 3. Fermentation (Recombinant DNA technology or Genetically engineered drugs) 4. Cell-culture techniques 5. Microbial transformation 6. Biologics (prepared from the blood of animals)
  46. 46. The role of natural products in drug discovery 1. Combinatorial chemistry 2. High-throughput screening of natural products 3. Combinatorial biosynthesis 4. Ethnopharmacology
  47. 47. Scope of Pharmacognosy • 1. ISOLATION OR ANALYSIS OF PHYTOCHEMICAL : • Eg ; Strong acting substances such as glycosides from digitalis leaves, • Alkaloids from the plants of Belladonna, Hyocyamus, Rauwlofia • Morphine and other alkaloids from the plant opium were isolated and clinical uses studied
  48. 48. 2. STRUCTURE ACTIVITY RELATIONSHIP : Eg : Tubocurarine and Toxiferine from curare plant have muscle relaxant properties because of quaternary ammonium groups. The hypotensive and tranquillizing actions of reserpine are due to the trimethoxy benzoic acid
  49. 49. 3. DRUGS OBTAINED BY PARTIAL SYNTHESIS OF NATURAL PRODUCTS: Eg : Preparation of Steroid hormones from diosgenin by acetolysis and oxidation and further preparation of cortisone by microbial reactions. 4. NATURAL PRODUCTS AS MODELS FOR SYNTHESIS OF NEW DRUGS : Eg: Morphine is the model of a large group of potent drugs . Cocaine for local anaesthetics Atropine for certain spasmolytics
  50. 50. 5. DRUGS OF DIRECT THERAPEUTIC USES : • Among the natural constituents which even now cannot be replaced are important group of antibiotics, steroids, ergot alkaloids, vincristine etc 6.CULTIVATION AND COLLECTION OF MEDICINAL PLANTS : • clove, cinchona , cinnamon, senna, opium, etc 7. PREPARATION OF HERBAL FORMULATIONS : • churnas, asvas, aristas, leha, etc 8. DEVELOPMENT OF TISSUE CULTURED PLANTS
  51. 51. Biological method of evaluation SIGNIFICANCE: 1.The method is generally used when standardization is not done satisfactorily by chemical or physical methods 2.When the quantity of the drug /sample are very less, then the drugs are evaluated by biological methods These methods are performed on living animals, isolating living organ and tissue, animal preparation, and microorganism ( Bioassay)
  52. 52. Following method is used as 1.Anti inflammatory activity 2.Analgesic activity 3.Antipyretic activity 4.Anti ulcer activity 5.Antidiabetic activity 6.Anthelmintic activity on earth worms 7.Cardiac activity- on frog and pigeon 8.Microbiological methods- living bacteria, yeast, molds are used for the assaying vitamins and to determine the activity of antibiotic drugs
  53. 53. Why do we need plants? 1. Source of drug molecules – They provide a number of extremely useful drugs that are difficult, if not impossible, to produce commercially by synthetic means • Most drugs can be synthesised • Still more economical to use the plant Papaver opium -> morphine, codeine (strong analgesic) Ergot fungus –> ergotamine (migraine), ergometrine (direct action on uterine muscle)
  54. 54. Why do we need plants? 2. Source of complex molecules that can be modified to medicinal compounds • Example: Soya: saponins -> steroids – Some natural products contain compounds that demonstrate little or no activity themselves but which can be modified by chemical or biological methods to produce potent drugs not easily obtained by other methods • Baccatin III -> Taxol – Supply basic compounds that may be modified slightly to render them more effective or less toxic
  55. 55. 3. Their utility as prototypes or models for synthetic drugs possessing physiologic activities similar to the originals COOH HO COOH OH3C O H3C COOH CH3 CH3 Salicylic Acid Aspirin Ibuprofen
  56. 56. Morphine: No better painkiller. Once structure worked out wanted to improve it. What is required? Diacetylmorphine (heroin): OH group -> O-O-diacetyl. Still addictive? Codeine: Methylate hydroxyl phenolic; O-Me. 1/5 analgesic capacity of morphine, useful to suppress cough reflex Dihydromorphinone: Reduced =, oxidised 2y alc. Potential analgesic. Source of compounds to use as templates for designing new drugs
  57. 57. Dihydrocodeine: Me-ether of previous. More powerful than codeine, less than morphine. Dextromethorphan: Good against cough reflex Is lower ring necessary? Pentazocin Phenazocine Is middle ring needed? Pethidine Methadone
  58. 58. Why do we need plants? 4. Source of toxic molecules • To study the way the body responds to their pharmacological use • Investigating pharmacological mechanisms picrotoxin – nerve conduction
  59. 59. Why do we need plants? • 5. Source of novel structures • these might never be thought of Catharanthus periwinkle -> vincristine (alkaloid dimer)
  60. 60. Why do we need plants? • 6. Source of plant drugs • As a powder or extract • The pure compound is often not isolated because: » Active ingredient is unknown » Active ingredient is unstable » Isolation process is too costly
  61. 61. Future • About 500,000 species of higher plants on earth • <10% investigated and only for one activity • Huge potential in plant kingdom

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