Pharmaceutical biotechnology seminar about Secondary Metabolites from Plants Clinical Pharmacy Mansoura University

1. Secondary
Metabolites from
Plants
PHARMACEUTICAL BIOTECHNOLOGY

2. Plant Secondary Metabolites
 Secondary metabolites are those metabolites which are often
produced in a phase of subsequent to growth, have no function in
growth (although they may have survival function), are produced by
certain restricted taxonomic groups of microorganisms, have unusual
chemicals structures, and are often formed as mixtures of closely
related members of a chemical family.
 The simplest definition of secondary products is that they are not
generally included in standard metabolic charts.

3. Plant Secondary Metabolites
 A metabolic intermediate or product, found as a
differentiation product in restricted taxonomic groups, not
essential to growth and the life of the producing organism,
and biosynthesis from one or more general metabolites by a
wider variety of pathways than is available in general
metabolism.
 Secondary metabolites are not essential for growth and tend
to be strain specific. They have a wide range of chemical
structures and biological activities. They are derived by unique
biosynthetic pathways from primary metabolites and
intermediates.

4. Plant Secondary Metabolites
 Biochemical pathways that are not necessary for
growth or reproduction of an organism, but which
can be demonstrated genetically, physiologically or
biochemically.

5. Plant Secondary Metabolites
 Plants produce as amazing diversity of low molecular
weight compounds.
 Of the estimated 400,000 – 500,000 plant species
around the globe, only a small percentage has been
investigated phytochemically and the fraction
subjected to biological or pharmacological screening
is even lower.

6. Plant Secondary Metabolites
 The ability to synthesize secondary metabolites has
been selected through the course of evolution in
different plant lineage when such compounds
address specific needs.
Floral scent volatiles and pigments have evolved to attract insect pollinators
and thus enhance fertilization.
To synthesize toxic chemical has evolved to ward off pathogens and
herbivores or to suppress the growth of neighboring plants.

7. Plant Secondary Metabolites
 Chemicals found in fruits prevent spoilage and act as
signals (in the form of color, aroma, and flavor) of
the presence of potential rewards (sugars, vitamins
and flavor) for animals that eat the fruit and thereby
help to disperse the seeds.
 Other chemicals serve cellular functions that are
unique to the particular plant in which they occur
(e.g. resistance to salt or drought).

8. Natural Products Drug Discovery and
Development

9. Natural Products Drug Discovery and
Development
 Over the ages, human have relied on nature fro their
basic needs for the production of foodstuffs, shelters,
clothing, means of transportations, fertilizers, flavors
and fragrances, and not least medicine.
 Plants have formed the basis of sophisticated
traditional medicine system that have been in
existence thousands of years in countries such as
China and India.

10. Natural Products Drug Discovery and
Development
 About 25% of all prescriptions sold in the US are for natural
products, while another 25% are for structural modifications
of a natural products.
 According to Fransworth (1990) claims that 119 characterized
drugs are still obtained commercially from higher plants and
that 74% were found from ethnobotanical information.
 Fransworth, N.R. (1990) In bioactive compounds from plants.
 John and Wiley Co..

11. Primary and Secondary Metabolism

12. Primary and Secondary Metabolism
Primary metabolism
The biological reactions are essential to maintain life in living organisms
and are known as primary metabolism.
Plant convert sunlight energy to chemical energy, such as ATP, NADPH, by
the mediation of chlorophyll in chloroplasts and synthesize sugars and starch
from CO2 by using ATP and NADPH+.
These carbohydrates are stored and used for differentiation and formation
of plant tissues.

13. Primary and Secondary Metabolism
Secondary metabolism
The metabolisms which are not directly related to maintaining life, are
known as secondary metabolisms.
The products formed by secondary metabolism are called secondary
metabolites.
Secondary metabolite play a role in reinforcement of tissue and tree body
(e.g. cellulose, lignin, suberin), protection against insects, dieses, and plant
regulation (plant hormones).

14. Primary and Secondary Metabolism
 All organisms need to transform and interconvert a vast number of
organic compounds to enable them to live, grow and reproduce.
 All organisms need to provide themselves with energy in the form of
ATP, and a supply of building blocks to construct their own tissues.
 An integrated network of enzyme-mediated and carefully regulated
chemical reactions in used for this purpose, collectively referred to as
intermediary metabolism, and the pathways involved are termed
metabolic pathway.

15. Primary and Secondary Metabolism
 The pathways for generally modifying and synthesizing
carbohydrates, proteins, fats, and nucleic acids are found
to be essentially to same in all organisms, apart from
minor variations.
 – These processes demonstrate the fundamental unity of all living matter, and are
collectively described as primary metabolism, with the compounds involved in
pathways being termed primary metabolites.

16. Primary Metabolisms

17. Primary Metabolisms
 Degradation of carbohydrates and sugars generally
proceeds via the well characterized pathways, known as
glycolysis and the kerbs / citricacid / tricarboxylic acid
cycle, which release energy from the organic compounds
by oxidative reactions.
 Oxidation of fatty acids from fats by the sequence called β-
oxidation also provides energy.

18. Primary Metabolisms
 Aerobic organisms are able to optimize these
processed by adding on a further process, oxidative
phosphorylation. This improves the effeiciency of
oxidation by incorporating a more general process
applicable to oxidation of a wide variety of
substrates rather then having to provide specific
process for each individual substrate.

19. Primary Metabolisms
 Proteins taken in via the diet provide amino acids, but the
proportions of each will almost certainly vary from the organism’s
requirements.
 Most organisms can synthesize only a proportion of the amino acids
they actually require for protein synthesis. Those structures not
synthesized, so-called essential amino acids, must be obtained from
external sources.

20. Secondary Metabolisms

21.  The compounds which synthesized from the secondary metabolisms
are so-called secondary metabolites.
 Secondary metabolites are formed in only specific organisms, or
groups of organisms, ane are expressioin of the individuality of
species.
 Secondary metabolites are not necessarily produced under all
conditions, and in the vast majority of cases the function of these
compounds and their benefit to the organism is not yet known.
 It is this area of secondary metabolism that provides most of the
pharmacologically active natural products.
Secondary Metabolisms

22. Secondary Metabolisms
To make such compounds as sugars, waxes, lignin starch, pigments, or
alkaloids, plants utilize very specific enzymes, each of which catalyzes a
specific metabolic reaction.
The enzymes are proteins called organic catalysts.
These enzymes are coded by specific genes in the plants DNA and are made
via processed we call transcription and traslation.
When there is a series of enzymatically catalyzed reaction in a well- defined
sequence of step, we have what is termed a metabolic pathway.

23. Biosynthetic Pathway

24. Biosynthetic Pathway
 Nucleoside diphosphate sugar pathway: cellulose,
hemicellulose, glycosides.
 Shikimate-cinnamate pathway: lignin, lignans,
hydrolyzed tannins.
 Mixed pathways of 3 and 4: some prenylflavonoids,
quinones and stilbenes.

25. Primary and Secondary Metabolism

26. Primary and Secondary Metabolism
 Primary and secondary metabolites leave a “grey area” at the
boundary, so that some groups of natural products could be assigned
to either divisions.
 Primary metabolites → Biochemistry
 Secondary metabolites → Natural products Chemistry

27. The classes of Secondary Metabolites

28. The classes of Secondary Metabolites
The majority of secondary metabolites belong to one of a number of
families, each of which have particular structural characteristics
arising from the way in which they are built up in nature
(biosynthesis).
The classes of secondary metabolites are:
Polyketides and fatty acids
Terpenoids and steroids
Phenylpropanoids
Alkaloids
Others (specialize amino acids and carbohydrates)

29. Polyketide and Fatty Acids

30. Polyketide and Fatty Acids
 Polyketides are formed by the linear combination of acetate units
derived from the “building block” acetyl co- enzyme A.
 The acetate origin of these compounds leads to a preponderance
of even-numbered carbon chains.
 Many plant oils and animal fats contain long-chain
monocarboxylic acids know as fatty acids.
 In the fatty acids, the carbonyl group of the acetate units is reduced
during the course of the chain assembly process. Dehydrogenation
and oxidative processed may subsequently give the unsaturated fatty
acids.

31. Polyketide and Fatty Acids
The common fatty acids have an even number of carbon atoms,
typically C12 – C20, linked together in a straight chain with up four
double bonds.
In plants the fatty acids and the corresponding alcohol are found in
leave waxes and seed coating:
Myristic acid (C14) is found in nutmeg seeds.
Palmitic acid (C16) is found in almost all plant oils.
Stearic acid (C18) occurs in long amounts in animal fat.

32. Polyketide and Fatty Acids
Unsaturated fatty acids are
important to us in food.
 Oleic acid is the most widely
distributed, and a major
constituent of olive oil.
 Linoleic and linolenic acids are most
highly unsaturated and are found in
linseed oil.
 Linolenic acid is easily oxidized by air,
and is one of the “drying oil” used in
paint and varnishes

33. Polyketide and Fatty Acids
 Linolenic acid is oxidized by plants to
jasmonic acid, which is a signaling
substances that stimulates plant defense
mechanisms.
 Arachidonic acid (C20) is a precursors of
the prostaglandin hormones.

34. Polyketide and Fatty Acids
 Polyacetylenes
 They are a group of naturally occurring
hydrocarbon derivatives characterized by one
or more acetylenic groups in their structures.
 Araliaceae, Campanulaceae, Apiaceae,
 Asteraceae, Pittosporaceae, and some fungi.

35. Done by
Mohammed Amir Abdul Rahman Youssef
Mahmoud Amir Abdul Rahman Youssef