• Despite the extremely varied characteristics of living organisms, the pathways for generally modifying and synthesizing carbohydrates, proteins, fats, and nucleic
acids are essentially the same in all organisms, apart from minor variations.
– Kingdom Plantae
– Kingdom Animalia
– Kingdom Fungi
– Kingdom Bacteria
• These processes demonstrate the fundamental unity of all living matter, and are collectively described as primary
metabolism, with the compounds involved in the pathways being termed primary metabolites...i.e. CHM411 stuff 

• Necessary for basic survival of an organism
• Used for energy and tissue construction
• Includes most carbohydrates, amino acids and proteins, lipids, nucleic acids, and some vitamins & cofactors

•
•
•
•
•
•
Resource: Dewick, Medicinal Natural Products, Ch. 2
Are assembled from (pieces of) primary metabolites
Are plentiful and diverse in plant-based foods
May be more prevalent or unique to certain genus, species, and similar compounds occur within genuses and families
Often have vital functions in the source
• attractants for propagation of species
• defense against predators
• signaling
May have useful nutritional benefits to humans/other organisms
The genes and enzymes guiding biosynthesis vary from one organism to the next.

Origins of secondary metabolites
Four major pathways to assembly of C skeleton:
• acetate
• shikimate
• mevalonate (all organisms)
• DXP (plants, microbes)
Key precursors:
Phosphoenol pyruvate (PEP)
 shikimate pathway
Acetyl CoA  acetate or
mevalonate pathways
N from amino acids  alkaloids

• C
1
– methyl groups
• C
2
– 2 carbon units from acetate pathway
• C
5
– isoprene
• C
6
C
3
- phenylpropanoid
• C
6
C
2
N – precursor to indole
• C
4
N & C
5
N – heterocyclic amines

C
1
: any molecule
C
2
: Fatty acids
Long chains on most molecules
Polyketides
Some aromatic rings
C
5
: Isoprenoids chains & nonarom. rings
C
6
C
3
:
Phenylpropanoids

C
1 comes from SAM (S-adenosylmethionine)
SAM can attach a methyl group to just about anything
Methyls may be attached to C atoms on chains, rings, attached to oxygen (methoxy), attached to nitrogen (N-methyl)

• C
1
– methyl groups
• C
2
– 2 carbon units from acetate pathway
• C
5
– isoprene
• C
6
C
3
- phenylpropanoid
• C
6
C
2
N – precursor to indole
• C
4
N & C
5
N – heterocyclic amines

Origins of alkaloids
(nitrogen-containing natural products) pyrrolidine piperidine

• Most secondary metabolites are assembled from pieces coming from more than one biosynthetic pathway
• Can you figure out what the building blocks are in each structure?
• Analysis of building blocks helps us understand how the compound was made, what were the precursors?

b
-carotene resveratrol a
-bisabolene linolenic acid