Pantothenic acid (B5)
The structure of pantothenic acid consists of an alanine chain in peptide linkage with dihydroxy, dimethyl butyric acid (Fig. 8.10).
Pantothenic acid is highly soluble in water.
Pantothenic acid exists in the free form and in combination with b- mercapto ethylamine, adenine ribose and phosphoric acid. The later form is called as co-enzyme A (CoA).
The metabolic functions of pantothenic acid are due to its coenzyme derivative CoA, which participates in several metabolic reactions. CoA gains further importance after its conversion to form acetyl CoA.
· Acetyl - Co A plays a key role in carbohydrate, protein and lipid metabolism.
· Acetyl - Co A is the precursor of cholesterol. It is the main source for the synthesis of cholesterol as well as steroid hormones.
· Acetyl - Co A combines with choline to form acetyl choline.
· Some of the amino acids require Co A for their activation.
Dried yeast, liver, royal gelly are the rich sources of pantothenic acid. Egg yolk, meat, fish, milk are good sources.
The recommended daily allowance of pantothenic acid as follows:
Infants - 1.5 - 2.5 mg/day
Children - 5 - 8 mg/day
Adults - 5-12 mg/day
Pregnant and lactating women - 10-15 mg/day.
Pantothenic acid and its salts are readily absorbed from the small intestine through the portal vein into the general circulation. If ingested in excess of the requirements, it is not stored in the body; but is excreted in urine or metabolised by the tissues.
Deficiency of this vitamin results in nausea, vomitting, certain gastro intestinal tract disorders, inadequate growth, anemia, fatty liver and failure in gaining weights.