INTRODUCTION Pharmacognosy
- applied science that deals with the biological, biochemical and economic features of drugs of biological origin and their constituents
Focuses of Pharmacognosy
Identification of plants and animals Chemistry
Evaluation, preservation and use of crude drugs Toxicology
History, distribution, collection and selection Preparation for commerce
Brief History
Papyrus Ebers
- Egyptian document - George Ebers
- uses of plants and animals Dioscorides
- De Materia Medica - 600 medical plants Claudius Galen
- drugs from animals and plants - “galenicals”
- documented methods of preparation of drugs
C.A. Seydler
- introduced the term “pharmacognosy” - pharmakon – drug
- gnosis – knowledge Schmidt
- first to use the term “pharmacognosy” Drug Constituents
Natural – directly obtained from nature (e.g. camphor tree camphor)
Synthetic – manufactured
o Semi-synthetic – natural raw material, chemically modified (e.g. pinene camphor)
o Totally synthetic – from chemicals (e.g. cyclopentadiene camphor)
Crude Drugs – vegetable or animal drugs that consist of natural substances that have undergone only the process of collection and drying
Derivatives or Extractives – chief principles or constituents of crude drugs that are separated and used in a specific manner
Naturalized Plants – grow in localities other than their native country
Indigenous Plants – growing in their native country
Preparation of Crude Drugs
1) Collection – select the species to cultivate 2) Harvesting
- gather the samples on a specific and proper period or season
- can use manual labor or mechanical device
3) Drying
- remove moisture to prevent fungal and microbial growth
- fixes the constituent
- converts the drug into a form more convenient for shipping and handling
o temperature control o regulation of airflow 4) Curing
- special drying process that enhances the property of the active ingredient o Cascara sagrada (fresh)
reduced glycoside which is irritating
o Cascara sagrada (cured x 1 year with MgO) oxidized
glycoside which is less irritating 5) Garbling
- final step
- physical process of separating
extraneous materials (dirt, soil, insects, other plants/ plant parts)
6) Preservation, Storage and Packaging - protect and market the drug
Classification of Drugs
Morphologic Classification – based on the plant or animal part used
Taxonomic Classification – based on natural relationship or phylogeny
Pharmacologic or Therapeutic Classification – based on the drug’s therapeutic effect
Chemical Classification
- preferred in the method of study - based on the chemical class of the
active ingredient
CARBOHYDRATES AND RELATED COMPOUNDS Carbohydrates
- most abundant group of organic molecules - first products of photosynthesis
6CO2 + 6H2O C6H12O6 + 6O2
- general/ empirical formula (CH2O)n
- polyhydric aldehydes and ketones
Functions of Carbohydrates
provide significant amount of energy (e.g. glucose)
storage of energy (e.g. starch, glycogen) cell components (e.g. glycoproteins) structural components (e.g. chitin)
Classes of Carbohydrates
1) Sugars (monosaccharides, disaccharides, oligosaccharides)
2) Polysaccharides Monosaccharides
- simplest CHO unit
- cannot be [H2O] into simpler sugars - building blocks of CHO
1) Diose (2C) – e.g. hydroxyacetaldehyde (doesn’t occur in nature)
2) Triose (3C) – e.g. glyceraldehydes, dihydroxyacetone
3) Tetrose (4C) – e.g. erythrose
4) Pentose (5C) Ribose
- aldopentose
- product of gum [H2O] Ribulose – ketopentose Xylose
- aldopentose, diagnostic aid for intestinal absorption
- wood sugar, absorbed but not metabolized
- simplest sugar in plants - not found free, occur as xylan
polymer Xylulose – ketopentose 5) Hexose (6C)
Glucose (accepted chemical name) - Dextrose
- aldohexose
- most abundant form: -D glucose
- grape sugar - physiologic sugar - obtained by controlled
enzymatic [H2O] of starch - as nutrient by mouth, by
injection (caloric agent) Fructose
- ketohexose - fruit sugar
- sweetest sugar, bitter aftertaste - obtained by inversion of
aqueous solution of sucrose or hydrolysis of inulin
- as nutrient for DM patient beneficial in acidosis
- as nutrient in infant formulas - high fructose sweeteners
obtained from isomerization of glucose by glucose isomerise Galactose
- aldohexose
- C4 epimer of glucose - found in milk (as lactose) - found in neuronal fibers (as
o Gaucher’s Disease inability to breakdown galactose
- Mucic Acid Test (+) white ppt with oxidizing acid
galactose galactaric acid (mucic acid)
6) Heptose (7C)
Sedoheptulose – ketoheptose 7) Nonose (9C)
Neuraminic acid/ sialic acid
Disaccharides
- composed of 2 monosaccharides linked by glycosidic bond
1) Sucrose
- table sugar - glucose + fructose
- -1,2 bond (reducing groups are linked together)
- non-reducing sugar - sources:
o beet (Beta vulgaris) cut into limp slivers (cossettes)
o sugarcane (Saccharum officinalum)
o sugar maple (Acer saccharum) o sugarcane juice boiled with lime
(neutralize plant acids, coagulate albumins)
sucrose – decolorized with SO2
molasses – residual dark-colored syrup after the complete crystallization - only disaccharide that occurs free in
nature
- undergo inversion
sucrose glucose + fructose
- pharmaceutic necessity in preparation of Syrup, NF 85% (sufficiently bacteriostatic, self-preserving) masks disagreeable taste of drugs
- demulcent, nutrient
2) Maltose
- malt sugar
- major degradation product of starch - glucose + glucose - -1,4 bond - reducing sugar 3) Lactose - milk sugar - glucose + galactose - -1,4 bond - reducing sugar
- from cow’s milk (cow - Bos taurus) - uses:
o tablet diluents (because it is inactive)
o infant feed (important to establish normal flora in the gut Lactobacillus sp.)
4) Milk products
Butter – formed when fat globules unite Buttermilk – liquid left when fat
globules unite
Skimmed milk – milk left after the separation of cream
Coagulum – formed when skimmed milk is treated with rennin
Cheese – treated coagulum
Whey – liquid left after separation of coagulum
Condensed milk – partial evaporation of milk in a vacuum with subsequent sterilization usually by autoclaving Malted milk – milk evaporated with
malt extract
Kumyss – fermented milk 5) Lactulose
- Duphalac®, Lilac® - fructose + galactose - -1,4 bond
- semi-synthetic sugar
lactose lactulose (alkaline rearrangement)
- MOA
o not absorbed in small intestine o fermented in large intestine
into lactic acid and acetic acid (laxative effect)
Oligosaccharides
- 3 or more monosaccharides 1) Maltotriose
- 3 glucose units
- intermediate product of starch hydrolysis
2) Dextrin
- several glucose units
- responsible for browning of bread - product of partial [H2O] of starch (acid/
heat)
starch dextrin maltotriose maltose glucose
Polysaccharides - glycans
- complex, high molecular weight polymers of monosaccharides linked by glycosidic bonds Heteroglycan – different monosaccharides Homoglycan – same monosaccharides Homoglycans
1) Cellulose
- structural polysaccharide in plants - homopolyglycan
- -1,4 bond
Purified cotton (Gossypium hirsutum) Powdered cellulose – mechanically
disintegrated -cellulose (disintegrant) Microcrystalline cellulose – partially
depolymerised -cellulose (diluents) Pyroxylin
- cellulose nitrate (nitric and sulphuric acid)
- soluble gun cotton - preparation of collodions 2) Chitin
- structural polysaccharide in animals
- in arthropods (exoskeleton) and molluscs (shells)
- homoglycan of N-acetylglucosamine 3) Starch
- storage polysaccharide in plants - components:
Amylose Amylopectin
Linearity linear more branched
(q 25-30 units)
Bonds -1,4 -1,4 -1,6
Solubility in H2O less soluble more soluble Size 250-300 units > 1000 units Iodine dark blue color blue-violet color
glutens – tacky proteins that retard the free flow of starch
- official sources:
o corn (Zea mays)
o potato (Solanum tuberosum) o rice (Oryza sativa)
o wheat (Triticum aestivum) - other sources: arrowroot (Maranta
arundinacea) - uses: o dusting powder o diluents o binder o disintegrant
o antidote for iodine poisoning starch paste – dispersing starch in cold water,
boiling until the granules swell and burst forming a translucent solution
heta starch
- contains ≥ 90% amylopectin - more soluble
- plasma expander in shock patient 4) Glycogen
- storage polysaccharide for animals - more branched than starch (q 10 units) - supplies energy (glucose) 8-12 hrs - Glycogen Storage Diseases:
o GSD Type I
- Von Gierke’s Disease - deficiency of
glucose-6-phosphatase
glycogen glucose-6-PO4 glucose
5) Inulin
- polyfructan - -2,1 bond
- abundant in family Asteraceae (compositae) e.g. sunflower - improve digestion
- diagnostic aid to estimate GFR (inulin clearance), not secreted not reabsorbed 6) Dextran
- homopolyglycan - -1,6 bond
- from sucrose by action of a
transglycolase enzyme system (dextran sucrose) found in Leuconostoc
mesenteroides
- used as a plasma expander
- preparation: Iron dextran hematinic (IV/IM)
Heteroglycans (more than 1 type of sugar) 1) D-gluco-D-mannan – glucose + mannose Metabolically Related 1) Acids a. Citric acid - tricarboxylic acid - discovered by Scheele in lemons - acidulant in effervescent preparations - salts: o systemic alkalizers o anticoagulants b. Tartaric acid - dicarboxylic acid
- byproduct of wine industry - buffer and acidulant in
effervescent preparation Denige’s Test – differentiate citric and tartaric
acid
c. Lactic acid
- lactic fermentation of sugars - acidulant in feeding formulas
2) Alcohols
a. Ethanol
- ≥ 92.3% or ≥ 94.9% EtOH at 15.56˚C
- 70% local anti-infective Diluted alcohol – 48.4-49.5% ~ 50% alcohol Brandy – wine
Whisky – fermented malted grain Rum – fermented molasses
b. Mannitol
- manna (dried saccharine exudates of Fraxinus ornus) - laxative (osmotic), not
absorbed
- also used to estimate GFR - sugar alcohol (from mannose)
c. Sorbitol or Glucitol
- moutain ash (Sorbus aucuparia) - reduction product of glucose - humectants
- non-caloric sweetener d. Dulcitol or Galactitol – reduction
product of galactose Gums and Mucilages
Gums
- natural hydrocolloids that maybe anionic or non-ionic as their salts
- translucent and amorphous - typically heteropolysaccharides - occur as salts of Ca++
and Mg++ - protective for plant injury
Linear Branched
less soluble more soluble
less stable more stable
less gelling (viscosity
enhancers) gelating agent
- general uses:
o ingredient in dental and other adhesive o bulk laxatives
o pharmaceutic necessity: binder,
emulsifying/ suspending agent, viscosity enhancer, gelling agent
- precipitated from solution by lead acetate or alcohol (e.g. acacia gum)
1) Shrub and Tree Exudates a. Tragacanth - gum tragacanth - Astragalus gummifer - composed of: o bassorin - ⅔ H2O swells in water o tragacanth - ⅓ H2O dissolves in water - most acid-resistant hydrocolloid - suspending agent (5-6%) - emulsifying agent - 3 forms: o Vermiform - worm-like, coiled - natural injuries - yellowish-brown o Tragacanth sorts - irregular tear-shaped - natural injuries - yellowish-brown
o Ribbon and Flake Gum - ribbon/ flaked - from man-made transverse incision of the bark - preferred form/ grade b. Acacia - Egyptian gum - Gum Arabic - Acacia senegal
- Arabin Ca, Mg, K salt or Arabic acid
- stable below 60% alcohol - 12-15% H2O - stable at pH 2-10 - suspending agent (35-38%) c. Ghatti Gum - Indian gum - Anogiessus latifolia - branched hydrocolloid - discontinuous mucilage
substitute for acacia d. Karaya Gum
- Sterculia gum
- Sterculia urens, S. villosa, S. tragacantha
- has a fetid odor
- one of the least soluble plant gums
- discontinuous mucilage 2) Marine Gums
a. Algin
- Na alginate (Na salt of alginic acid), suspending agent - Macrocystis pyrifera Laminaria spp. Ascophyllum spp. Ecklonia spp. Nereocystis spp. b. Agar - Japanese isinglass - Gellidum cartilagineum Gracilaria confervoides Rhodophycaceae - composed of: o agarose (SO4) o agaropectin (SO4) - uses: o laxative
o suspending and gelling agent
o culture medium c. Carrageenan
- highly sulphated
- Chondrus (Chrondrus crispus) - Irish moss ( Gigartina
memillosa)
- stabilizer, gelling agent, demulcent, bulk laxative - ingredient in toothpaste
Kappa () Iota () Lambda () stable helix stable helix no stable helix gelling property gelling property
non-gelling property (viscosity enhancer) d. Danish Agar - Furcellaran - Furcellara fastiglata - similar to K-carrageenan - gelling, suspending agent 3) Seed Gums
a. Plantago Seeds
- Metamucil®, C-lium® - Psyllium seed, Plantain seed - Spanish or French (Plantago
psyllium, Psyllium indica) - Indian or Blonde (Plantago
ovata)
- gum is present in the seed coat - bulk-forming laxative b. Guar Gum - endosperm of Guaran - Cyamopsis tetragonolobus - Galactomannan - bulk laxative c. Locust Bean Gum
- endosperm of Carob (Ceratonia siliqua) - St. John’s Bread - Galactomannan - thickener, stabilizer - chocolate substitute 4) Plant Extractives a. Pectin
- intracellular cementing material - dilute acid extraction from rind
of fruits
- Pomelo (Citrus grandis) Orange (C. aurantium) Dalanghita (C. nobilis)
Ponkan/ Tangerine (C. sinensis) Kalamansi (C. microcarpa) Grapefruit (C. paradisi) Lemon (C. limon)
Apple pomace (Pyrus malus)
- forms:
o protopectin (unripe fruits)
o pectin (ripe fruits) o pectinic acid (overripe
fruits) - uses: o protectant o suspending agent o anti-diarrheal (Kaolin-pectin) 5) Starch and Cellulose Derivatives 6) Microbial Gums
a. Xanthan Gum
- high molecular weight gum from the action of bacterium Xanthomonas campestris on a suitable carbohydrate
- pseudoplastic flow responsible for ability of toothpaste and ointments to retain form and be able to spread readily
