2. Primary Metabolites
Primary metabolites
chlorophyll
AA’s
Nucleotides
Simple CHO’s
Membrane lipids
*** ARE FOUND
THROUGHOUT THE
PLANT KINGDOM
Fx: Important roles
in growth and
development
photosynthesis
respiration
solute transport
translocation
nutrient assimilation
differentiation
3. 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.
4. 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
plant’s survival.
5. 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
6. 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
7. 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)
8. 3 MAIN GROUPS OF 2º
METABOLITES
TERPENES
PHENOLS
N2-CONTAINING COMPOUNDS
9. Terpenes
Terpenes are lipids
synthesized from acetyl CoA or from the
basic intermediates of glycosides
10. Phenolic compounds
Phenolic compounds are aromatic
substances
Formed via the Shikimic acid Pathway or the
Malonic acid pathway
14. Gums & Mucilages
Very complex CHO’s
Found in excellent
vulnerary, demulcent
& emollient herbs.
E.g. Marshmallow &
Plantain
15. 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)
16. Plant Alcohols
Occurs in plants in
various forms
Constituent of volatile
oils & sterols
Attar of Rose
Menthol in peppermint
Waxes (beeswax)
Cutins
17. 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)
18. 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
19. 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.
20. 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
21. 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
22. 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)
24. 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
25. 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
26. 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
27. 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)
28. 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
29. 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
30. 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.
31. Vitamins
Found in many
medicinal plants
Lemon peel: Vitamin
C
Carrot: Vitamin A
Brewers Yeast: B-
vitamins
Nasturium/watercress:
Vitamin E
32. 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
34. 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.
35. 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
36. Tetragonal Crystal System
Composition:
CaC2O4.3H20
Arises from
supersaturation of the
cell sap with calcium
oxalate
Includes
Prisms
Cluster crystals
(rosette aggregates)
microsphenoids
37. 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
38. NB!!!
When using Calcium
oxalate crystal types
as a diagnostic tool:
Crystal type
Size
Distribution
Should all be noted.
39. Crystal Function
Uncertain
More abundant in plants growing in arid
regions.
Ca: Causes epithelial cells to swell
Deter herbivory?
41. Prisms – Elletaria cardamomum
Found in
Cardamom
• Small single prisms
• Starch masses in
parenchyma
42. 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)
43. Prisms – Cassia senna
Senna
* Single prisms
* Occurs in
parenchyma cells
* Surrounds bundles of
pericyclic fibres
* Forms a crystal
sheath
44. Prisms – Glycyrrhiza glabra
Found in Liquorice
* Single prisms
* Occurs in parechyma
tissue
* Surrounds xylem &
phloem
* Forms an incomplete
crystal sheath
45. Prisms – Rhamnus purshianus
Cascara senega
Crystal sheaths
Similar to liquorice
Occurs with the
phloem fibres
Complete crystal
sheaths
46. Microsphenoids
Atropa belladonna
Aggregates occur in a
crystal layer
Below palisade tissues
When a single cell
contains an aggregate
of microsphenoids
idioblast
48. Diagnostic Value of Calcium
Oxalate Crystals
Absence of crystals
Different form
Different size
all used to identify adulterants or allied
species from medicinal herbs.
49. Diagnostic Value of Calcium
Oxalates
E.g.
Digitalis purpurea:
(used medicinally) no
calcium oxalates
D. thapsi: (not used
medicinally) - small
prisms
50. Diagnostic Value of Calcium
Oxalate Crystals
E.g.
Atropa belladonna:
Leaves have micro-
sphenoids
Phytolacca leaves:
have raphides
51. Diagnostic Value of Calcium
Oxalate Crystals
3 Solanaceous Herbs
Atropa belladonna
• Microspenoids
Datura stramonium
• Cluster crystals
Hyoscyamus nigra
• Prisms
52. 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)