This document discusses several types of secondary plant metabolites including phenolics, terpenoids, alkaloids, and others. Phenolics are derived from the shikimate pathway and include classes like phenols, hydroxybenzoates, flavonoids, and lignins. Terpenoids are made from the acetate-mevalonate pathway and include mono-, sesqui-, and diterpenes. Alkaloids contain nitrogen and can be toxic or used medicinally as in morphine, quinine, and caffeine. Secondary metabolites provide benefits to plants such as protection from predators and pathogens, attracting pollinators, and some have pharmaceutical applications.

1. FUNDAMENTALS OF BIO
CHEMISTRY
(BIC – 102)
Submitted by,
Jayasankar.p
(2015037019)
SECONDARY METABOLITES

2. Metabolites
• Primary metabolites: Molecules that are essential
for growth and development of an organism.
• Secondary metabolites: molecules that are not
essential for growth and development of an
organism.

3. Secondary metabolites are derived
from primary metabolites

4. Why secondary metabolites?
• Chemical warfare to protect plants from the attacks by
predators, pathogens, or competitors
• Attract pollinators or seed dispersal agents
• Important for abiotic stresses
• Medicine
• Industrial additives

5. SECONDARY METABOLITES
Organic compounds produced by the plants which
have no direct role in the growth and development are
called as secondary metabolites.
Estimates suggest that there are about 100,000
secondary compounds that are produced by the plants
and the structures of more than 15000 alkaloids, 300
terpenes, several thousand phenyl propanoids, 1000
flavonids, 500 quinones, 700 polyacetylenes and 800
non-protien amino acids have already been
characterized.

6. These secondary compounds produced by plants are
grouped into five major groups.
Phenolics
Terpenoids
Alkaloids
Special nitrogen metabolites
Cuticular compounds

7. PHENOLICS:
Phenolics are a group of compounds characterized by at
least one aromatic ring bearing one or more hydroxyl
group.
Most of the thousands of phenolics known to date are of
plant origin.
Phenolics are synthesized by the shikimate pathway.
Phosphoenolpyruvate and erythrose-4-phosphate are the
precursors for phenolics for phenolics biosynthesis.

8. The major classes of phenolics found in plants
S.NO.
class Carbon
skeleton
Example
1. Simple phenols C6 catechol
2. Hydroxybenzoates C6- C1 Gallic,
catechuic acid,
salicyclic acid
3. Hydroxycinnamates C6-C3 Caffeic acid,
coumaric acid
4. Naphthoquinones C6-C4 Juglone

9. 5. Xanthones C6-C1-C6 Hydroxyxanthone
6. Stilbenes C6-C2-C6 Resveratrol
7. Flavonoids C6-C3C6 Quercetin
8. Polyphenols (C6-C3)n
(C6-C3-C6)n
Lignins, condensed
tannins

10. Functions of phenolics:
Phenolics are of great important as cell wall
compounds.they form part of cell wall structures such
as lignins, cutin and suberins, which provide
mechanical support and function as barriers against
microbial attack.
The flavonoids and anthocyanins contribute to flower
and fruit colours. This is important for attracting
insescts and animals to the plant for pollination and
seed dispersal.
Plants rich in polyphenols were used as tanning agents
in leather industries.

11. Phenolics also play a defensive role in plants by protecing
against predators. Simple phenolic acids, polyphenolics like
tannis and phenolic resins at the plant surface are effective
feeding deterrents.
Phenolic also function as single molecules in the interaction
between nitrogen fixing bacteria and leguminous plants. These
plants exude flavonoids which act selectively in Rhizobia as
inducers of nodulation gene transcription.
Phenolic pigments of fruits are most widespread food colours
occurring in fruit juices, wines and jams. Anthocyanins have
considerable potential in the food industry as safe and
effective food additives.

12. More Phenolics
 Some phenolics form polymers.
 Tannins are astringent to the taste. They give
dryness (astringency) to dry wines. They can also
be used to tan leather. They often give water a
tea-colored look. Tannins are common in pines
and oaks.
 Lignin is a major structural component of wood.
The exact structure of lignin is complex and not
known.

14. Myristicin from Nutmeg

15. Anthocyanins

16. Tannins

17. Terpenoids
 Terpenoids are dimers and polymers of 5 carbon
precursors called isoprene units (C5 H8).
 Terpenoids often evaporate from plants and
contribute to the haze we see on hot sunny days.
They are expensive to make; they often take 2%
of the carbon fixed in photosynthesis; carbon
that could otherwise be used for sugars.

18. Terpenoids:
Terpenes are lipids which have the basic five carbon unit called
isoprene. They are also called isoprenes.
Plants produce a great variety of isoprenoids. Some of these are
primary metabolites such as plant hormones, carotenoids and
steroids. However, majority of these compounds are secondary
metabolites.
Terpenoids are biosynthesized by acetate-mevalonate pathyway.
The precursor used is acetyl CoA.
Terpenes are classified according to the number of five carbon
units present in the molecule.

19. Classification of terpenoids
class Number of carbons
Hemiterpene 5
Monoterpene 10
Sesquiterpene 15
Diterpene 20
Sesterterpene 25
Triterpene 30
Tetraterpene 40
polyterpene 5n

20. Functions of terpenoids:
Monoterpeniods interfere with basic metabolic,
physiological, and behavioural functions of insects.
Some exhibit acute toxicity, whereas otheres function as
repellents, attractants, antifeedants or affect growth,
development and reproduction.
A number of monoterpenes possess antimicrobial
activity.
Steols are triterpenoids and play structural role in
plants.
Saponis and glycosidic triterpenoids protect plants
against fungal attack.

21. Sesquiterpenoids function as feeding deterrents, insect
juvenile hormones, pheromones and plant growth
regulators abscisic acid.
An alkaloid diterpene, ryanodine is one of the most
potent naturally occurring insecticides against
lepidopteran larvae.
Some diterpenses such as agugarns and clerodin function
as insect antifeedant.
Gibberellic acids, are diterpenses that function as growth
regulator.
Hemigossypolone, gossypol and heliocides are toxic and
antifeedants to several insects.

22. Beta-carotene

23. Pine Resin

24. Rubber Tapping

25. Alkaloids
 Alkaloids generally include alkaline substances
that have nitrogen as part of a ring structure.
More than 6500 alkaloids are known and are the
largest class of secondary compounds. They are
very common in certain plant families, especially:
 Fabaceae – peas and beans
 Asteraceae - sunflowers
 Papaveraceae - poppies
 Solanaceae – nightshade, tomato
 Apocynaceae - dogbanes
 Asclepiadaceae - milkweeds
 Rutaceae - citrus

26. ALKALOIDS:
Alkaloids are nitrogen containing compounds having at leave
some basicity.
They usually heterocyclic and occur primarily in higher plants
and some micro organisms.
They usually exhibit significant physicological activity in
humans and animals and represent one of the largest and most
diverse groups of secondary products.
Poisons – conine
Narcotics – morphine
Stimulants – caffeine
Medicine – Taxol

27. Classification of alkaloids
1) True alkaloids – possess heterocyclic ring and are
derived from amino acids. Eg. Nicotine, Quinine.
2) Protoalkaloids – Do not possess heterocyclic ring
but are derived from amino acids. Eg, colchicine
3) Pseudoalkaloids – Not derived from amino acids.
Eg. Caffeine, theophylline.

28. Functions :
Alkaloids play a defense role in plants against insets other
arthropods and vertebrates.
Some alkaloids have allelopathic effects.
Some alkaloids possess physicological actions in humans.
For example vinblastine and vincristine are potent
anticancer drugs.
Alkaloids act as reserve substances able to supply nitrogen.
They are end products of detoxification meachanisms.
Some alkaloids function as antimicrobial compounds.

29. Pharmaceutial uses of alkaloids
Many alkaloids exhibit marked pharmacological
activity, and some fine important uses in medicine.
 Atropine, present in datura species is used widely in medicine as
anticholinergic drug. It is also used to dilate the pupil eye
surgery.
 Morphine and codeine are narcotic analgesics, and codeine is
also an antitussive agent, less toxic and less habit-forming than
morphine.
 Colchicines, from the corms and seeds of the autumn crocus, is
used as a gout suppressant.
 Caffenine, which occurs in coffee, tea, and cocoa is a central
nervous system stimulant; it is used as a cardiac and respiratory
stimulant and as an antidote to barbiturate and morphine
pensioning.

30. Codeine from opium poppy

31. Atropine – from Belladonna
aka Deadly Nightshade

32. Quinine from Chinchona

34. THANK YOU !!!