Enzymatic synthesis and characterization of novel epigallocatechin gallate glucosides

Three epigallocatechin gallate (EGCG) glucosides were synthesized by the acceptor reaction of a glucansucrase from Leuconostoc mesenteroides B-1299CB with EGCG and sucrose. After 1H, 13C, heteronuclear single quantum coherence, 1H–1H correlation spectroscopy, and heteronuclear multiple bond correlation nuclear magnetic resonance analyses, the glucosides were identified as (−)-epigallocatechin gallate 4′′-O-α-d-glucopyranoside (EGCG-G1), (−)-epigallocatechin gallate 7,4′′-di-O-α-d-glucopyranoside (EGCG-G2A), and (−)-epigallocatechin gallate 4′,4′′-di-O-α-d-glucopyranoside (EGCG-G2B). Two of the compounds (EGCG-G1 and EGCG-G2A) are reported for the first time. The EGCG glucosides exhibited antioxidant effects, depending on their structures (EGCG > EGCG-G1 > EGCG-G2A > EGCG-G2B). They also uniformly exhibited greater browning resistance than was observed in EGCG. Also, the water solubility of EGCG-G1, EGCG-G2A, and EGCG-G2B were 69, 126, and 122 times higher, respectively, than that of EGCG.