Page 4 - phytochemistry II -pharmD general
P. 4
5. Have potent pharmacological effect on animals .
6. They are ppted by alkaloidal ppting reagents.
b) Proto alkaloids:
➢ Biogenetically they are derived from amino acids, BUT
➢ They lack a heterocyclic ring e.g. Ephedrine (nitrogen atom is not involved in
heterocyclic ring).
c) Pseudo alkaloids:
❑ They are biogenetically unrelated to amino acids (They are not derived
from amino acids).
e.g. purine bases [caffeine, theobromine and theophylline]
The Role of Alkaloids in Plants
1. Protective against insects and herbivores (bitterness and toxicity).
2. Products of detoxification in metabolic reactions (waste products of
metabolism).
3. Source of nitrogen in case of nitrogen deficiency.
4. Growth regulators in certain metabolic systems.
5. Source of energy in case of deficiency in carbon dioxide assimilation,
especially those alkaloids containing a sugar moiety.
Occurrence and distribution of alkaloids:
1- Plant kingdom:
• Families: Compositae, Rununculaceae, Solanaceae, Rubiaceae and
Papaveraceae.
Alkaloids may present in definite organ of the plant:
• In bark … cinchona
• In rhizomes … Ipeca
• In leaves … Tea, Coca
• In fruits … Hemlock & papaver
• In seeds … Nux vomica
3
