4ODglucopyranosylDglucopyranose

4-O-D-glucopyranosyl is a descriptor used in organic chemistry and natural products to denote a glucosyl substituent formed when a glucose unit is attached to another molecule via the oxygen at the 4-position of the aglycone. The glucopyranose moiety is usually in the D-configuration and can be in the alpha or beta anomer, depending on the enzymatic or chemical glycosylation conditions. In systematic nomenclature, the prefix 4-O-β-D-glucopyranosyl (or 4-O-α-D-glucopyranosyl) is placed before the name of the aglycone to indicate the site and configuration of attachment.

Biosynthesis and chemistry: In nature, UDP-glucose-dependent glycosyltransferases mediate the transfer of glucose from UDP-glucose to hydroxyl groups on aglycones, creating O-glycosidic bonds at various positions that include the 4-position. Chemically, 4-O-glucosylation can be achieved by selective protection/deprotection strategies and glycosyl donors.

Properties and significance: The 4-O-glucoside linkage increases aqueous solubility, alters stability, and can modulate biological activity and bioavailability. Many plant secondary metabolites exist as 4-O-glucosides or other glycosides, and hydrolysis by glycosidases releases the aglycone and glucose.

See also: glycoside, glucoside, glycosyltransferase, UDP-glucose.