Glucogallin is chemical compound formed from gallic acid and β-D-glucose. It can be found in oaks species like the North American white oak (Quercus alba), European red oak (Quercus robur) and Amla fruit (Phyllanthus emblica).

It is formed as the first step in the biosynthesis of gallotannins in a pathway using the enzymes beta-glucogallin O-galloyltransferase and beta-glucogallin-tetrakisgalloylglucose O-galloyltransferase.

β-Glucogallin is aldose reductase inhibitor.

Glucogalllin is formed by the enzyme gallate 1-beta-glucosyltransferase which forms the glucosyl derivative of gallic acid using UDP-glucose as the source of the transferred sugar unit giving uridine diphosphate (UDP) as byproduct. This enzyme can be found in oak leaf preparations.

The enzyme beta-glucogallin O-galloyltransferase takes two molecules of glucogallin and gives one of the gallotannin, 1,6-digalloylglucose, and one of D-glucose. The product 1,6-digalloylglucose can react with another unit of glucogallin to give 1,2,6-trigalloylglucose.

By a similar mechanism, additional glucogallin units are added until β-penta-O-galloyl-glucose is formed.