Synthesis of resveratrol glycosides by cyclodextrin glycosyltransferase from Paenibacillus sp. RB01

Abstract

In this work, resveratrol glycosides were synthesized by transglycosylation reaction from β-cyclodextrin (β-CD) donor to resveratrol catalyzed by cyclodextrin glycosyltransferase (CGTase) from Paenibacillus sp.RB01. The effect of DMSO on CGTase stability was determined. The result showed that the enzyme activities were dramatically decreased when DMSO concentration increased. β-cyclodextrin was chosen as an appropriate glycosyl donor and it was found that 20% (v/v) of DMSO gave the highest production yield. To investigate its synthesis ability, the reaction mixture containing 1.0% (w/v) of resveratrol in 20% (v/v) of DMSO and 1.0% (w/v) of β-cyclodextrin were incubated with 100 U/ml of CGTase at 40°C for 24 hours. Two spots of the expected products were observed at Rf of 0.55 and 0.77. The products were preliminary characterized by glucoamylase and α-glucosidase and it was concluded that the product was glycoside derivative and glucose molecules was attached to resveratrol with α-1,4-linkage. After optimization, the yield was increased by 3.71 times. The main product was collected by HPLC and its molecular mass and its possible structure were analyzed by MS and LC-MS/MS techniques, respectively. The molecular mass of the main product (resveratrol glycoside I, Rt~13.6 minutes ) was found to be 390 Daltons which corresponded to resveratrol monoglucoside having one monoglucosyl group attached to the position of 3-hydroxyl group of resveratrol. The water solubility of resveratrol glycoside I (Rt ~13.6 minutes) and II (Rt ~12.8 minutes) was about 72 and 26 times higher than that of resveratrol, respectively. While the DPPH• scavenging effect (%) of both of resveratrol glycoside I and II were lower than those of resveratrol and vitamin C.