Cellulose as laxative
Posted by biochemistryquestions on May 3, 2008
Answer to C-05
Answer (a)
Cellulose is a polymer of hundreds to thousands of Beta-D-glucose molecules linked by beta-1,4 O-glycosidic linkages (the OH of the Beta anomeric carbon of the glucose residues is linked to the OH in carbon 4 of the adjacent residue of glucose). The repeated dimer (Beta-D-glucose linked to another D-glucose through a Beta 1,4-O-glycosidic linkage) is called cellobiose.
Cellulose is the most abundant organic compound in nature, since it forms around 30 % of plants, but unfortunately, what could be an abundant source of glucose, can not be used by human beings, since we lack, as other animals, the enzyme necessary for hydrolyzing the beta 1,4 O-glycosidic linkages between molecules of glucose. In fact, ruminants and termites do not produce the necessary enzymes for digestion of cellulose, but they have in the gastrointestinal tract some bacteria that produce the required enzymes, that is why they can take advantage of the glucose in cellulose.
Since cellulose can not be digested by human beings and it is a very hydrophilic compound, it can absorb water in the intestines producing a softer and bulkier stool that stimulates peristalsis.
Cellulose derivatives as methylcellulose, ethylcellulose and others are used in Medicine as components of laxatives, artificial tears, tablet coating, etc.
