Alkaloids Derived from Lysine

Derived from Ornithine
  - Pyrrolidine & Tropane
  - Pyrrolizidine
Derived from Lysine
  - Piperidine
  - Quinolizidine
  - Indolizidine
Derived from Nicotinic Acid
  - Pyridine
Derived from Tyrosine
  - PEA & Simple TIQ
  - Modified BTIQ
  - Phenethylisoquinoline
  - Terpenoid TIQ
  - Amaryllidaceae
Derived from Tryptophan
  - Simple Indole
  - Simple β-Carboline
  - Terpenoid Indole
  - Quinoline
  - Pyrroloindole
  - Ergot
Derived from Anthranilic Acid
  - Quinazoline
  - Quinoline & Acridine
Derived from Histidine
  - Imidazole
Derived by Amination Reactions
  - Acetate-derived
  - Phenylalanine-derived
  - Terpenoid
  - Steroidal
Purine Alkaloids
  - Saxitoxin & Tetrodotoxin

L-Lysine is the homologue of L-ornithine, and it too functions as an alkaloid precursor, using pathways analogous to those noted for ornithine.The extra methylene group in lysine means this amino acid participates in forming six-membered piperidine rings, just as ornithine provided fivemembered pyrrolidine rings. As with ornithine, the carboxyl group is lost, the ε-amino nitrogen rather than the α-amino nitrogen is retained, and lysine thus supplies a C5N building block (Figure 21).

Figure 21