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Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

Seaweeds Polysaccharides

Seaweeds are algae, the arms of which can extend to over 40 m., in length.

They have no roots, stems or leaves, and they are most frequently found in fresh

or salt water, occasionally free floating, e.g. brown sea weeds in Sargasso-Sea in

the middle part of Atlantic Ocean.

Polysaccharides of sea weeds are classified into:

1) Food-reserve polysaccharides: e.g. a) Algal starch

2) Structural polysaccharides: Alginic acid (Sodium alginate), (alkali soluble).

3) Sulfated polysaccharides: e.g. a) Agar-agar (water soluble) b) Carrageenan.

1) Sodium alginate

It is the purified carbohydrate obtained by alkaline extraction of various

species of brown algae (Pheaophyceae) such as Laminaria digitata and L.

saccharina (Family Laminariaceae).

Character:

• Yellowish-white, odorless tasteless powder.

• Readily sol. in water → Viscous colloidal soln.

• The soln. is not coagulated by heating and does not form a jelly on cooling.

• It forms a jelly on adding CaCl 2.

Chemistry:
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