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					Plant Metabolites & Ergastic Cell
           Contents
             Primary Metabolites
   Primary metabolites
                             Fx: Important roles
   chlorophyll               in growth and
   AA’s                      development
   Nucleotides              photosynthesis
   Simple CHO’s             respiration
   Membrane lipids          solute transport
                             translocation
                             nutrient assimilation
   *** ARE FOUND            differentiation
    THROUGHOUT THE
    PLANT KINGDOM
       Secondary Metabolites
 Definition:                Differ from 1º metabolites
 All organic compounds       in that they have a
 Have no direct function
                              restricted distribution in
                              the plant kingdom
  in growth and
  development                Therefore: Only

 Also called secondary
                              particular secondary
                              metabolites are found
  products or natural
  products                    in only one specific
                              plant species or a
                              taxonomically related
                              group of species.
       Secondary Metabolite Fx
                   be functionless end
 Initially thought to
  products of metabolism or metabolic waste
  products

 Responsible for   characteristics, odours,
  pungencies & colours of plants. Others
  give plants their medicinal, culinary or
  poisonous values.

 They are  synthesized to aid the producing
  plant’s survival.
Secondary Metabolite Function
 Ecological functions      in plants: protect
 against herbivory

 Protect against infection   by microbial
 pathogens

 Attract pollinators   & seed distributing
 animals

 Act as   agents for plant-plant competition
        Evolution of 2º Metabolites
 2º Metabolites evolved through mutations in the basic
  metabolic pathways
  appearance of new compounds
       happened to be toxic or a deterrent to herbivores and pathogens
         • As long as they were not toxic to the plant itself and were produced
           at a low metabolic cost
 They gave the plants containing them greater
  reproduction fitness than undefended plants (plant-
  plant competition)
 Undefended plants therefore left more descendants
  while the protected plants left less
       And passed their defensive traits on to the next generation
 The defence compounds (secondary
  metabolites) that increase reproductive
  fitness of plants by warding off fungi,
  bacteria and herbivores, also make them
  undesirable as food by humans.
 Many NB crop plants have been artificially
  selected for producing relatively low levels
  of these compounds, which make them
  more susceptible to insects and disease
 (e.g. of Wheat)
    3 MAIN GROUPS OF 2º
       METABOLITES

 TERPENES


 PHENOLS


 N2-CONTAINING COMPOUNDS
                  Terpenes
 Terpenes are    lipids

     synthesized from acetyl CoA or from the
      basic intermediates of glycosides
         Phenolic compounds

 Phenolic compounds are      aromatic
 substances

     Formed via the Shikimic acid Pathway or the
      Malonic acid pathway
Nitrogen-containing compounds

    e.g. alkaloids

    synthesized from AA’s
Active Plant Constituents
              Carbohydrates
 Sugars (glucose,
  xylose)
 Starches (energy
  stores)
 Cellulose (structural
  support)
 Gums & mucilage
          Gums & Mucilages
 Very complex CHO’s
 Found in excellent
  vulnerary, demulcent
  & emollient herbs.
 E.g. Marshmallow &
  Plantain
               Gums & Mucilage Fx
   Relax Gut lining
   Relax Respiratory
    System
   Reduce irritation and
    inflammation (GIT,
    Respiratory, US)
   MO: soak up large
    amounts of water
    sticky jelly: dry
    irritated skin,
    inflamed/painful tissues
   Some stimulate
    immune system: e.g.
    Acemannan (Aloe
    vera)
                  Plant Alcohols
 Occurs in plants in
  various forms
 Constituent of volatile
  oils & sterols

       Attar of Rose
       Menthol in peppermint
       Waxes (beeswax)
       Cutins
                            Phenols
 Phenol = basic building
  block for many plant
  constituents
 Simple/complex in nature


   Fx:
       anti-inflammatory
       Anti-septic

 E.g. Salicylic acid
  (Willow)
 Eugenol (Clove)
 Thymol (Thyme)
         Volatile Oil Function
   Anti-spetic
    (Garlic/Thyme oil)
   Stimulate tissue
     irritation e.g.
    Mustard
     numbing e.g.
    Camphor oil).
   Aid digestion
   CNS action
   Insect repellent
   Anti-inflammatory
   Anti-allergenic
              Proanthrocyanins
   Closely related to
    tannins & flavonoids
   Phenols
   Fx: powerful anti-
    oxidants
   Protect circulation
    from damage:
    especially circulation
    of the heart, hands,
    feet & eyes.
   E.g. Crataegus spp.
                           Tannins
 Fx – give herbs their
  astringent & heamostypic
  action
 Act on proteins and form
  a protective layer on the
  skin & mucous
  membranes
       Bind the tissues of the gut
       Reduce diarrhoea &
        internal bleeding
       Externally: Rxing burns,
        sealing wounds & reducing
        inflammation.
       Heal infections of the eye,
        mouth, vagina, cervix &
        rectum (mucous membrane
        tissues)                         Tannins - phenols
                        Coumarins
 (smell of cut grass)
 Limited effects on the
  body
 Di-coumarol, (metabolite)
   powerful anti-clotting
  agent.
 Functions:
       Allopathic: Basis for
        warfarin (thrombosis in
        small doses): Horse
        Chestnut
       (Rat poison in large doses)
       Visnaga – powerful smooth
        muscle relaxant
                Anthraquinones
   Plants containing
    anthraquinones 
    effective purgatives
   (& good natural dyes)
   Senna & Aloe
   Also make stool more
    liquid (Constipation)
   Fx: gently stimulate
    colon 8-12 hrs after
    ingestion (stimulate
    peristalsis)
   Can only Fx when natural
    bile is present.
   Tend to cause colonic
    pain (over-stimulate colon
    wall)
               Glycosides
 Flavonoids
 Saponins
 Phenolic glycosides
 Cardiac Glycosides
 Cyanogenic Glycosides
                   Flavonoids
   One of the most common
    group of plant
    constituents
   Polyphenols
   Wide range of actions
   Anti-spasmoidic
   Anti-inflammatory
   Anti-oxidant
   Diuretic
   Circulatory Stimulants
   Cardiac stimulants
   Anti-viral
   hepatic
                          Saponins
 Pharmaceutical Chemists
   synthesis of cortisone
  (anti-inflammatory) & sex
  hormones
 Saponins in herbs do not
  act in the same way 
  body can use them as
  building blocks to form
  appropriate chemicals.

    Fx:
       anti-inflammatory
       Expectorant
       Aid nutrient absorption
             Cardiac Glycosides

   Discovered from
    Foxglove (1785) 
    recognised to support a
    failing heart
   Many flowering plants
    contain cardiac
    glycosides
   Fx: increase heart
    efficiency
   Steady tachycardia
   NO CARDIAC STRAIN
   Strong diuretic
          Cyanogenic Glycosides
 Based on cyanide
  (toxic)
 Small doses
       Sedative
       Relaxant effect on
        heart & muscle
 Wild cherry bark:
  suppress & soothe
  dry, irritating coughs.
 Fruit kernels (apricot)
                   Bitter Principles
 Group of chemicals with
  an exceedingly bitter
  taste
 Wide diversity of structure
 Most belong to the
  iridoids, some to terpenes
 Fx: stimulate digestive
  juices & appetite
       Aid the liver
       Anti-biotic
       Anti-fungal
       Anti-tumour
       Play specific roles
        depending on herb &
        chemical combination e.g.
        Valerian & Devil’s claw
                      Alkaloids
   The most potent group of
    plant constituents
   Effect: body & mind
   Some: effect on lungs,
    liver, nerves, GIT
   Fx in plant: ± source of
    excessive N2. (makes
    them pharmacologically
    active).
   Divided into 13 groups
    based on their chemical
    structure (no general
    effects)
   E.g. Atropine (Atropa
    belladonna)  reduce
    spasms, relieve pain &
    dry up bodily secretions
                  Glucosilinates
   Found exclusively in the
    Brassica Family (Mustard
    & Cabbage)
   Instant blistering &
    inflammatory effect on the
    skin
   Applied to painful areas
    to increase blood flow
   Helps remove excessive
    waste products
   Eating: produce a strong
    pungent taste.
                       Vitamins
   Found in many
    medicinal plants
       Lemon peel: Vitamin
        C
       Carrot: Vitamin A
       Brewers Yeast: B-
        vitamins
       Nasturium/watercress:
        Vitamin E
                       Minerals
   Plants draw minerals
    from the soil and convert
    them into a form which is
    easily absorbed & used
    by the body.
   Kelp: I2
   Dandelion: K
   Horsetail: Silica
   Nettle: Fe & Ca
   Brewers Yeast:
    Chromium
CALCIUM OXALATE
   CRYSTALS
           Calcium Oxalate
 Numerous crystals  occur in plants
 Ca-oxalate is one of the most common
 Like trichomes & stomata, it also has
  diagnostic value
 X polymorphs are characteristic in x plant
  spp.
              Crystal Systems
 In plants  2 crystal systems exist
 All crystal polymorphs belong to one of
  these systems
 Systems
     Tetragonal System
     Monoclinic System
 Systems differ
     in the amount of water they attain
     OD
        Tetragonal Crystal System
 Composition:
  CaC2O4.3H20
 Arises from
  supersaturation of the
  cell sap with calcium
  oxalate
 Includes
       Prisms
       Cluster crystals
        (rosette aggregates)
       microsphenoids
      Monoclinic Crystal System
 Chemical composition:  CaC2O4.H20
 Form in the presence of excess oxalic acid
 Crystal forms include
     Some prisms
     Needle-like crystals (raphides)
     Sphaero-crystals
                           NB!!!
   When using Calcium
    oxalate crystal types
    as a diagnostic tool:

       Crystal type
       Size
       Distribution

    Should all be noted.
           Crystal Function
 Uncertain
 More  abundant in plants growing in arid
  regions.
 Ca: Causes epithelial cells to swell
 Deter herbivory?
Crystal Forms
          Prisms

    Cluster Crystals

    Microsphenoids

         Raphides

    Sheaero-crystals
Prisms – Elletaria cardamomum
   Found in
     Cardamom
       • Small single prisms
       • Starch masses in
         parenchyma
    Prisms – Hyosciamus niger
   Black henbane
     • Single prisms
           Some have a
            crystalline outgrowth
            (plug)
     • Twin prisms
           In crystal layer of
            spongy mesophyll
            cells (directly below
            palisade tissues)
    Prisms – Cassia senna
Senna
 * Single prisms
 * Occurs in
  parenchyma cells
 * Surrounds bundles of
  pericyclic fibres
 * Forms a crystal
  sheath
   Prisms – Glycyrrhiza glabra
Found in Liquorice
* Single prisms
* Occurs in parechyma
  tissue
* Surrounds xylem &
  phloem
* Forms an incomplete
  crystal sheath
Prisms – Rhamnus purshianus
   Cascara senega
       Crystal sheaths
       Similar to liquorice
       Occurs with the
        phloem fibres
       Complete crystal
        sheaths
                 Microsphenoids
   Atropa belladonna
       Aggregates occur in a
        crystal layer
       Below palisade tissues

       When a single cell
        contains an aggregate
        of microsphenoids
          idioblast
                        Raphides
   Occur
       Singly
         • E.g. Ipecavanha


       In bundles
         • E.g Squill
     Diagnostic Value of Calcium
          Oxalate Crystals
 Absence of   crystals
 Different form
 Different size
     all used to identify adulterants or allied
    species from medicinal herbs.
       Diagnostic Value of Calcium
                Oxalates
   E.g.

    Digitalis purpurea:
    (used medicinally) no
    calcium oxalates

    D. thapsi: (not used
    medicinally) - small
    prisms
      Diagnostic Value of Calcium
           Oxalate Crystals
   E.g.
    Atropa belladonna:
    Leaves have micro-
    sphenoids

Phytolacca leaves:
  have raphides
        Diagnostic Value of Calcium
             Oxalate Crystals
   3 Solanaceous Herbs
       Atropa belladonna
         • Microspenoids


       Datura stramonium
         • Cluster crystals


       Hyoscyamus nigra
         • Prisms
       LESSON TAKE-AWAY




 Definition & types/effects of adulteration
 Difference between 1º & 2º metabolites.
 E.g’s & Functions of metabolites
 Types of Ca-O crystals (E.g’s & Dx value)
End of Lesson
   Thank You!

				
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posted:12/25/2011
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