ABSTRACT
Pantothenic acid and biotin in vitamin supplements are obtained by chemical synthesis rather than by purification from natural sources. Isobutyraldehyde, formaldehyde and cyanide are used as starting materials in the chemical synthesis of pantothenic acid; the intermediate D-pantolactone is condensed with ß-alanine to produce pantothenic acid. The majority of pantothenic acid in foodstuffs is present as CoA or 4'-phosphopantetheine; both these compounds are hydrolyzed by pyrophosphatase and phosphatase in the intestinal lumen to release pantetheine. Biotin in foods is largely protein bound; binding is mediated by an amide linkage between the valeric acid side chain in biotin and e-amino groups in lysines. Studies using jejunal segments from rats provided evidence that intestinal biotin uptake is mediated by both saturable and nonsaturable components. Calcium salts of D-pantothenate are the typical sources of pantothenic acid in oral vitamin supplements. Dexpanthenol is a synthetic analog of pantothenic acid that is commonly used for topical applications.
