Page 105 - PG 504-theoretical notes-phyto-1-2024-2025..

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

3) Decrease the level of serum cholesterol and triglycerides, hence benefits

lipidemia and the cardiovascular system

B) Heteropolysaccharides

▪ They can be divided into two distinct groups:

1) Heteropolysaccharides without acid group, e.g. Neutral hemicellulose ( -

Cellulose).

2) Heteropolysaccharides containing acid group, e.g. Acidic hemicellulose (-

Cellulose), Gums, mucilages and pectin. The acidic heteropolysaccharides

contain one or more uronic acid units in their molecular structure. They are

sometimes called derived carbohydrates.

I- Hemicelluloses

They associate cellulose in the cell wall of the plant. They are insoluble in

water but soluble in dilute alkalis. Hemicellulose is a polysaccharide related to

cellulose that comprises about 20% of the biomass of most plants. Hemicellulose

consists of shorter chains – between 500 and 3000 sugar units. Furthermore,

hemicellulose is branched, whereas cellulose is unbranched. In contrast to

cellulose, hemicellulose is derived from several sugars in addition to glucose,

especially xylose but also including mannose, galatose, and arabinose. On

hydrolysis by dilute acids they afford sugars and uronic acids. They include two

types of polysaccharides:

1) Neutral hemicellulose ( - Cellulose):

They are short chain polysaccharides. They are simple pentosans or

hexosans, collectively named cellulosans. They give only simple

86