Page 122 - Pharmd general phytochemistry I-Final2024_LEUCTERS

Guar gum

Occurrence:
 Guar gum is obtained from the ground endosperm of the Indian leguminous plant

Cyamopsis tetragonolobus and has recently received some attention as a possible

oral hypoglycaemic drug.
Chemical composition:
 The principal constituent of the gum is galactomannan, which readily forms a

viscous gel with water.
Uses:

1- It can produce changes in gastric emptying and in the gastrointestinal transition

time, which can delay absorption of sugars and oligosaccharides from the gut.

2- It lowers cholesterol levels, possibly by binding bile salts in the gut.

Agar

Occurrence:
 Agar is the dried colloidal concentrate from a decoction of various red algae

particularly species of Gelidium, Pterocladi (Gelidaceae) and Graciaria

(Gracilariaceae).

Chemical composition:
 Agar is a heterogenous polysaccharide consisting of two principal constituents of

which are agarose and agaropectin.

Agarose
 is a neutral galactose polymer (free from sulfate) which is principally responsible for

the gel strength of agar.

Agaropectin
 It appears to be a sulphonated polysaccharide in which galactose and uronic acid

units are partly esterified with sulfuric acid.

Uses:
1 - Preparation of culture media.
2- As an emulsifying agent and a suspending agent.
3- Treatment of chronic constipation.
4- As a tablet excipient and disintegrant.
5- Agarose is used for electrophoretic separation of globulin and other proteins for

techniques involving gel filtration and gel chromatography.

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