Plant Metabolites & Ergastic Cell Contents

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Plant Metabolites Ergastic Cell Contents
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Primary Metabolites

• Primary metabolites
• chlorophyll
• AAs
• Nucleotides
• Simple CHOs
• Membrane lipids
• ARE FOUND THROUGHOUT THE PLANT KINGDOM

• Fx Important roles in growth and development
• photosynthesis
• respiration
• solute transport
• translocation
• nutrient assimilation
• differentiation

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Secondary Metabolites

• Definition
• All organic compounds
• Have no direct function in growth and development
• Also called secondary products or natural products

• Differ from 1º metabolites in that they have a
  restricted distribution in the plant kingdom
• Therefore Only particular secondary metabolites
  are found in only one specific plant species or a
  taxonomically related group of species.

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Secondary Metabolite Fx

• Initially thought to be functionless end 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 plants
  survival.

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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

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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

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• 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)

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3 MAIN GROUPS OF 2º METABOLITES

• TERPENES
• PHENOLS
• N2-CONTAINING COMPOUNDS

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Terpenes

• Terpenes are lipids
• synthesized from acetyl CoA or from the basic
  intermediates of glycosides

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Phenolic compounds

• Phenolic compounds are aromatic substances
• Formed via the Shikimic acid Pathway or the
  Malonic acid pathway

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Nitrogen-containing compounds

• e.g. alkaloids
• synthesized from AAs

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Active Plant Constituents
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Carbohydrates

• Sugars (glucose, xylose)
• Starches (energy stores)
• Cellulose (structural support)
• Gums mucilage

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Gums Mucilages

• Very complex CHOs
• Found in excellent vulnerary, demulcent
  emollient herbs.
• E.g. Marshmallow Plantain

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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)

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Plant Alcohols

• Occurs in plants in various forms
• Constituent of volatile oils sterols
• Attar of Rose
• Menthol in peppermint
• Waxes (beeswax)
• Cutins

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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)

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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

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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.

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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

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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

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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)

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Glycosides

• Flavonoids
• Saponins
• Phenolic glycosides
• Cardiac Glycosides
• Cyanogenic Glycosides

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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

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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

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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

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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)

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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 Devils claw

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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

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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.

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Vitamins

• Found in many medicinal plants
• Lemon peel Vitamin C
• Carrot Vitamin A
• Brewers Yeast B-vitamins
• Nasturium/watercress Vitamin E

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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

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CALCIUM OXALATE CRYSTALS
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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.

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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

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Tetragonal Crystal System

• Composition CaC2O4.3H20
• Arises from supersaturation of the cell sap with
  calcium oxalate
• Includes
• Prisms
• Cluster crystals (rosette aggregates)
• microsphenoids

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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

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NB!!!

• When using Calcium oxalate crystal types as a
  diagnostic tool
• Crystal type
• Size
• Distribution
• Should all be noted.

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Crystal Function

• Uncertain
• More abundant in plants growing in arid regions.
• Ca Causes epithelial cells to swell
• Deter herbivory?

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Crystal Forms

• Prisms
• Cluster Crystals
• Microsphenoids
• Raphides
• Sheaero-crystals

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Prisms Elletaria cardamomum

• Found in
• Cardamom
• Small single prisms
• Starch masses in parenchyma

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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)

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Prisms Cassia senna

• Senna
• Single prisms
• Occurs in parenchyma cells
• Surrounds bundles of pericyclic fibres
• Forms a crystal sheath

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Prisms Glycyrrhiza glabra

• Found in Liquorice
• Single prisms
• Occurs in parechyma tissue
• Surrounds xylem phloem
• Forms an incomplete crystal sheath

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Prisms Rhamnus purshianus

• Cascara senega
• Crystal sheaths
• Similar to liquorice
• Occurs with the phloem fibres
• Complete crystal sheaths

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Microsphenoids

• Atropa belladonna
• Aggregates occur in a crystal layer
• Below palisade tissues
• When a single cell contains an aggregate of
  microsphenoids ? idioblast

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Raphides

• Occur
• Singly
• E.g. Ipecavanha
• In bundles
• E.g Squill

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Diagnostic Value of Calcium Oxalate Crystals

• Absence of crystals
• Different form
• Different size
• ? all used to identify adulterants or allied
  species from medicinal herbs.

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Diagnostic Value of Calcium Oxalates

• E.g.
• Digitalis purpurea (used medicinally) no
  calcium oxalates
• D. thapsi (not used medicinally) - small
  prisms

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Diagnostic Value of Calcium Oxalate Crystals

• E.g.
• Atropa belladonna
• Leaves have micro-sphenoids
• Phytolacca leaves have raphides

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Diagnostic Value of Calcium Oxalate Crystals

• 3 Solanaceous Herbs
• Atropa belladonna
• Microspenoids
• Datura stramonium
• Cluster crystals
• Hyoscyamus nigra
• Prisms

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LESSON TAKE-AWAY

• Definition types/effects of adulteration
• Difference between 1º 2º metabolites.
• E.gs Functions of metabolites
• Types of Ca-O crystals (E.gs Dx value)

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End of Lesson

• Thank You!