Enhancement of the water solubility and antioxidant capacities of mangiferin by transglucosylation using a cyclodextrin glycosyltransferase

This study aimed to enhance the water solubility and antioxidant properties of mangiferin by transglucosylation using cyclodextrin glycosyltransferase (CGTase) from Thermoanaerobacter sp. The highest mangiferin to mangiferin glucoside conversion yield achieved was 88.9% using 60 mU/mL CGTase, 25 mM mangiferin, and 10% starch (w/v), with incubation at 60 °C for 10 h. The product of transglucosylation was purified and its chemical structure was determined to be glucosyl-α-(1→4)-mangiferin (MGF-g1) using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and nuclear magnetic resonance spectroscopy. The water solubility of MGF-g1 was 5,093 times higher than that of mangiferin. MGF-g1 exhibited 1.6-fold higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, 1.24-fold higher oxygen radical antioxidant capacity, and 1.19-fold higher ferric reducing ability power, compared to mangiferin. Moreover, the cyclooxygenase-2 inhibitory activity (IC50) of mangiferin and MGF-g1 were 76.44 ± 11.7 μM and 59.74 ± 2.8 μM, respectively. Our results suggest that the novel MGF-g1 has potential applications as a functional material in the food and pharmaceutical industries. •The novel glucosyl-α-(1→4)-mangiferin was synthesized by using thermostable CGTase.•The 88.9% conversion yield was obtained at 60 mU/mL CGTase, 25 mM mangiferin and 10% starch at 60 °C for 10 h.•Water solubility of glucosyl-α-(1→4)-mangiferin was 5093 times higher than that of mangiferin.•The glucosyl-α-(1→4)-mangiferin showed higher antioxidant activity compared to mangiferin.