Module 2 - pcog

• Brief history of Pharmacognosy:

  • Babylonians made clay models
  • Egyptians used plants for embalming and mummification
  • Hindus practiced ayurveda, the "science of life" and "mother of all healing arts"
  • Greeks had Pedanios Dioscorides' "De Materia Medica" with 600 plants like aloe, belladonna, colchicum, digitalis, ergot, and opium
  • Claudius Galen introduced "Galenical Pharmacy"
  • Germans like C.A. Seydler coined the term pharmacognosy and J.A. Schmidt first used "pharmacognosy" in Lehrbuch der Materia Medica
  • Others like Fluckiger provided a comprehensive definition of pharmacognosy
• Terms to remember in Pharmacognosy:

  • Natural Substances: directly obtained from plants and animals in nature
  • Synthetic: made totally or partially in the lab using starting materials from nature
  • Crude Drugs: vegetable or animal drugs collected and dried
  • Extractives/Derivatives: chief principles of crude drugs separated and used in a specific manner
  • Indigenous Plant: plants growing in their native country
  • Naturalized Plant: plants growing in a foreign land or locality other than their native source
• Methods of Extraction:

  • Maceration: solid ingredients soaked in solvent for at least 3 days with agitation
  • Digestion: maceration with gentle heat
  • Percolation: slow passage of solvent through a column of the drug
  • Decoction: boiling in water for 15 minutes
  • Infusion: maceration in cold or hot water
• Preparation of Crude Drugs:

  • Collection: best time to collect based on the plant part
  • Harvesting: use of mechanical devices for large-scale collection
  • Drying: process to prevent microbial growth and enzymatic degradation
  • Curing: special drying process to enhance the property of active components
  • Garbling: final step of removing extraneous materials
  • Packaging, Storage, Preservation: methods for protecting and maintaining marketability of crude drugs
• Classification of Drugs:

  • Morphologic: based on the plant part used
  • Taxonomic: based on natural relationship or phylogeny
  • Pharmacologic/Therapeutic: based on therapeutic effect
  • Chemical: preferred method for classification
• Carbohydrates in Pharmacognosy:

  • Monosaccharides: building blocks that can be hydrolyzed to simple sugars
  • Disaccharides: two monosaccharide units linked by a glycosidic bond
  • Oligosaccharides: 3-10 monosaccharide units
  • Polysaccharides: more than 10 monosaccharides
• Monosaccharides:

  • Pentose (5C): Ribose found in RNA, Xylose from xylan hydrolysis
  • Hexose (6C): Glucose (α and β forms), Fructose, Galactose
• Hexose (6C) Sugars:

  • Glucose: abundant in nature, used as nutrient
  • Fructose: sweetest monosaccharide, used in infant feeding formula
  • Galactose: brain sugar, found in milk and neuronal fibers
• Glucose is present in the human blood in the amount of 60 to 90 mg in 100 mL blood
• Sucrose is a disaccharide composed of glucose and fructose linked by β, 1-2 glucosidic bonds
• Maltose is a disaccharide composed of glucose and glucose linked by β, 1-4 glucosidic bonds
• Lactose is a disaccharide composed of galactose and glucose linked by β, 1-4 glucosidic bonds
• Lactulose is a disaccharide composed of galactose and fructose linked by 1-4 glucosidic bonds
• Sucrose is the only disaccharide that occurs free in nature and is a non-reducing sugar
• Lactose is also a non-reducing sugar
• Lactulose is a semi-synthetic sugar prepared by alkaline rearrangement of lactose
• Lactulose is metabolized by the colonic flora to lactic and acetic acid, causing irritation of the GI tract and a laxative effect
• All monosaccharides are reducing sugars, while all disaccharides are non-reducing sugars except for maltose and lactose
• Starch hydrolysis products include liquid glucose, dextrin, maltotriose, and maltose
• Polysaccharides can be homoglycan/homopolysaccharide or heteroglycan/heteropolysaccharide
• Starch is a homoglycan composed of glucose units and is a storage polysaccharide in plants
• Amylose is a linear homoglycan of glucose units linked by α 1,4 bonds
• Amylopectin is a branched homoglycan of glucose units with α 1,4 and α 1,6 bonds
• Glycogen is a homoglycan storage polysaccharide in animals, more branched than starch
• Glycogen is stored in the liver and skeletal muscles
• Inulin is obtained from the cell sap of underground plant organs and is used to improve digestion and estimate glomerular filtration rate
• Chitin is a homoglycan of N-acetylglucosamine found in exoskeletons of mollusks, arthropods, and fungi
• Glycosaminoglycans (GAGs) are components of the extracellular matrix of connective tissues, composed of amino sugar and uronic acid
• Hyaluronic acid is a non-sulfated glycosaminoglycan widely distributed in connective tissues
• Chondroitin sulfate is a sulfated glycosaminoglycan that provides resistance to compression in cartilage
• Proteoglycans are heavily glycosylated proteins consisting of a core protein bonded with glycosaminoglycan chains
• Glycolipids are carbohydrate-attached lipids associated with cell membranes
• Glycoproteins are small proteins with polysaccharide chains that stabilize cell membrane structure
• Various types of mucopolysaccharidoses are associated with deficiencies in specific enzymes and lead to different clinical features
• Compounds metabolically related to carbohydrates
• Oxidation of aldoses:

  • Glucose aldehyde group becomes aldonic
  • Glucose terminal alcohol group becomes uronic acid
  • Glucose aldehyde and terminal group become aldaric
• Products of oxidative metabolism of carbohydrates
• Cherry juice:

  • From fresh ripe cherry fruits (Prunus cerasi)
  • Contains 1% malic acid
  • Used to prepare cherry syrup
• Malic acid:

  • Iupac name: 2-hydroxybutanedioic acid
  • Indirect permanganate oxidation method
• Citric acid:

  • Efflorescent
  • Antidote for sodium hydroxide poisoning
  • Component of effervescent granules
  • Discovered from lemon juice by Scheele