Gallotannin

A gallotannin is any of a class of molecules belonging to the hydrolysable tannins. Gallotannins are polymers formed when gallic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.

Metabolism

Gallate 1-beta-glucosyltransferase uses UDP-glucose and gallate to produce UDP and 1-galloyl-β-D-glucose. Beta-glucogallin O-galloyltransferase uses 1-O-galloyl-β-D-glucose to produce D-glucose and 1-O,6-O-digalloyl-β-D-glucose. Beta-glucogallin-tetrakisgalloylglucose O-galloyltransferase uses 1-O-galloyl-β-D-glucose and 1,2,3,6-tetrakis-O-galloyl-β-D-glucose to produce D-glucose and 1,2,3,4,6-pentakis-O-galloyl-β-D-glucose (1,2,3,4,6-penta-O-galloyl-β-D-glucose, the common precursor of gallotannins and the related ellagitannins).^[1]

Tannase is a key enzyme in the degradation of gallotannins that uses digallic acid and H₂O to produce gallic acid.

See also

• List of antioxidants in food

References

1. Cammann, Jessica; Denzel, Klaus; Schilling, Gerhard; Gross, Georg G. (August 1989). "Biosynthesis of gallotannins: β-Glucogallin-dependent formation of 1,2,3,4,6-pentagalloylglucose by enzymatic galloylation of 1,2,3,6-tetragalloylglucose". Archives of Biochemistry and Biophysics. 273 (1): 58–63. doi:10.1016/0003-9861(89)90161-6. PMID 2757399.