According to the PCI Syllabus ,B Pharm V Sem Sub : Pharmacognosy and Phytochemistry II
It contains the general introduction of metabolic Pathways ,Metabolites and How primary metabolites are linked with secondary metabolites
3. Metabolic pathways
Metabolic pathway is a linked series of chemical
reactions occurring within a cell.
Pathways are required for the maintenance of
homeostasis within an organism and the flux of
metabolites through a pathway is regulated depending
on the needs of the cell and the availability of the
substrate.
The end product of a pathway may be used
immediately, initiate another metabolic pathway or be
stored for later use.
4. Classification of Metabolic Pathway
Metabolic pathways can be classified as
Catabolic (Energy generating )
Anabolic (Energy utilizing)
Catabolic pathway
A catabolic pathway is an exergonic system that
produces chemical energy in the form of ATP, GTP,
NADH, NADPH, FADH2, etc. from energy containing
sources such as carbohydrates, fats, and proteins.
The end products are often carbon dioxide, water, and
ammonia.
5. Anabolic pathways
In contrast to catabolic pathways, anabolic
pathways require an energy input to construct
macromolecules such as polypeptides, nucleic
acids, proteins, polysaccharides, and lipids.
An anabolic pathway is a biosynthetic pathway-
combines smaller molecules to form larger and
more complex ones.
6. What is Biosynthesis?
Biosynthesis is a process of forming larger organic
compounds from small subunits within a living
organism
Biosynthesis is also known as anabolism since simple
compounds are joined together to form
macromolecules by enzymes.
As an example, photosynthesis occurs inside the
chloroplast. The light energy is converted into
chemical energy during photosynthesis. The larger
molecule glucose is biosynthesized from water and
carbon dioxide by photosynthetic organisms.(ATP,
Enzyme, Cofactors)
7. Types of Metabolites
Primary metabolites:
Basic constituents.
Simple and generally don’t have any biological or
pharmacological action.
Are primarily utilized by plants for building their body and
are responsible for primary physiological functioning of the
body
Eg- starch, chlorophyll, aleurone grains, calcium oxalate
crystals, cellulose
Secondary metabolites:
From the primary metabolites, secondary metabolites are
synthesized. Generally they have potent biological and/or
pharmacological action. Also known as Active constituents
Eg-Alkaloids ,Glycosides ,Flavanoids
8. CO2 +H2O
Photosynthesis
Glucose
Glycolysi
s PPP
Phosphoen
ol Pyruvate
Acetyl CoA
TCA
Carbohydrate
s
Glycosides
Polysacchari
des
Erythrose 4
Phosphate
Shikimic
Acid
Pathway
Shikimic acid
S A Metabolites:
Phenyl
Propanoid
,Lignin
,Coumarin
,Tannin
Aromatic
Amino Acids
Alkaloids
Acetate
Melonate
Pathway
Mevalonic
Acid
Pathway
Malonyl
Co A
Mevalonic
Acid
Isoprenoid
s
Terpenoid
s
Lipids
Fatty
Acids
Protein
Alkaloids
Squalene Steroids
Aliphatic
Amino
Acids
BASIC
METABOLI
C
PATHWAY
S
Pyruvate
9. Explanation
The first metabolic pathway is photosynthesis in which
carbon dioxide from the atmosphere and water from the
soil through roots are react together in the presence of
Sunlight to synthesize Glucose(Pri. Metabolite) as the end
product
Glucose enters into other metabolic Pathways as the
starting material .Like in Glycolysis , Pentose Phosphate
Pathway and also in the Synthesis of Glycosides (Sec.
Metabolite) and Polysacchrides
In Glycolysis ,Glucose breakdowns into Pyruvate , Where
Phospho Phenol Pyruvate is one of the intermediate.
One of the intermediate of pentose phosphate pathway is
erythrose 4 phosphate.
10. Phospho Phenol Pyruvate and erythrose 4 phosphate
are the starting compounds of Shikimic acid Pathway.
One of the intermediate of Shikimic acid Pathway is
Shikimic acid.
Through Shikimic acid various metabolites are
synthesized: Phenyl Propanoid ,Lignin ,Coumarin
,Tannin
Aromatic amino acids are produced through Shikimic
acid Pathway : Phenyalanine ,Tyrosine ,Tryptophan.
Aromatic amines are the precursor of various
alkaloids.
11. From Phosphoenol Pyruvate ,Pyruvate is formed which get
converted into acetyl CoA through enzyme CoA.
Acetyl CoA goes into two different Acetate Pathways
Acetate Melonate Pathway : In this Malonyl CoA is
synthesized .Various acetyl group attached to Malonyl
CoA and forms fatty acids and then Lipids (Sec.
Metabolites) are synthesized
Mevalonic Acid Pathway :In this Mevalonic Acid is
synthesized which then forms Isoprenoids through
series of chemical reactions and then terpenoids (Sec.
Metabolites) are synthesized.Isoprenoids are the
starting material of steroid synthesis .
12. Acetyl CoA also enters into TCA cycle
TCA provides precursors of certain amino acids which
then form proteins (Pri. Metabolites)and then
alkaloids (Sec. Alkaloids).
Primary Metabolic Pathways : Photosynthesis
,Glycolysis ,Pentose Phosphate Pathway ,TCA etc.
Secondary Metabolic Pathway : Shikimic Acid
Pathway ,Acetate Pathway .
