Synthesis of guaiacol-alpha-D: -glucoside and curcumin-bis-alpha-D: -glucoside by an amyloglucosidase from Rhizopus.

Guaiacol (2-methoxyphenol) and curcumin [1E,6E-1,7-di(4-hydroxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione] were converted into their corresponding glucosides using glucose and an amyloglucosidase from Rhizopus. Guaiacol-alpha-D: -glucoside yields ranged from 3 to 52% with the highest at pH 7.0. Curcumin-bis-alpha-D: -glucoside yields ranged from 3 to 48% with the highest at pH 4.0 with 50% (w/w D: -glucose) of enzyme. The phenolic hydroxyl group of guaiacol and both phenolic hydroxyl groups of curcumin were glucosylated at the C1 carbon of alpha-D: -glucose indicating that the enzymatic reaction is stereospecific. Both guaiacol-alpha-D: -glucoside and curcumin-bis-alpha-D: -glucosides had antioxidant activities.