Enzymatic synthesis of piceid glycosides by cyclodextrin glucanotransferase

Abstract

Novel glycosides of piceid (3,4′-5-trihydroxy stilbene 3-O-β-d-glucoside) were produced by the transglycosylation reactions of cyclodextrin glucanotransferase (CGTase) from Bacillus macerans, with piceid (PicG1) and maltodextrin as the acceptor and donor substrates, respectively. The reactions were performed at 40°C with 2.56mM piceid (0.1% w/v) and maltodextrin (5% w/v) in 0.02M citrate phosphate buffer, pH 6.0 containing 5% (v/v) methanol for 6h. Glucose, maltose, sucrose, maltotriose and α-cyclodextrin (α-CD) were also used to analyze their ability to function as donor substrates, for the glycosylation of piceid. Among the different donor substrates used, the maximum transfer efficiency (TE) of glycosylation of piceid was observed for α-cyclodextrin (78.9%) followed by maltodextrin (72.1%). The partially purified piceid glycoside products (PicG2 and PicG3) were identified by mass spectrometry.