Page 3 - Phytochemistry 2 (06-PG 605)

b) Proto alkaloids:
 Biogenetically They are derived from amino acids . but
 They lack a heterocyclic ring e.g. Ephedrine (nitrogen atom is not
incorporated 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

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