Synthesis of Hesperidin Glycosides by Cyclodextrin Glucanotransferase and Stabilization of the Natural Pigments.

Abstract

An improved method for the synthesis of hesperidin glycosides was developed using both β-cyclodextrin (β-CD) and α-rhamnosidase treatments. The reaction, which contained 0.5% (8.2mM) hesperidin as an acceptor, 5% soluble starch as a donor and 2 units/ml of cyclodextrin glucanotransferase (CGTase) from an alkalophilic Bacillus species was incubated at 40°C and pH 10 for 16h, was used as the standard reaction. During the transglycosylation reaction, both β-CD and an alkaline pH were very effective for solubilizing hesperidin, and the amount of hesperidin glycosides formed by CGTase with 5% β-CD as a donor at pH 10 was about 50 times greater than the amount formed with soluble starch at pH 5. During the purification steps, α-rhamnosidase hydrolyzed the unreacted hesperidin into lower molecular weight and more hydrophobic compounds (hesperetin-7-glucoside), but it did not hydrolyze the hesperidin glycosides. Therefore, hesperidin glycosides were easily separated from the unreacted hesperidin using Sephadex LH-20. Various kinds of natural pigments were stabilized against ultraviolet radiation using the prepared hesperidin glycosides.