19 Mar 2019

Article on the effect of α-glucosylation of epigallocatechin gallate published in Frontiers in Nutrition

(–)-Epigallocatechin gallate (EGCG), the predominant catechin (≥50%) in green tea (Camellia sinensis), displays several bioactive properties but its stability and bioavailability are low. In this work, the properties of two a-glucosyl derivatives of EGCG (3′- and 7-O-α-D-glucopyranoside), obtained by enzymatic synthesis, were assessed. The α-glucosylation enhanced the pH and thermal stability of EGCG. The analysis of scavenging activity toward ABTS·+ radicals showed that the alpha-glucosylation at C-7 of A-ring caused a higher loss of antioxidant activity compared with the sugar conjugation at C-3′ of B-ring. The 3′-glucoside also showed higher potential to alleviate intracelular reactive oxygen species (ROS) levels and to boost REDOX activity. The toxicity of EGCG and its monoglucosides was tested in human SH-S5Y5 neurons, RAW 264.7 macrophages, MRC5 fibroblasts, and HT-29 colon cancer cells. Interestingly, the 3′-O-α-D-glucoside increased the viability of neural cells in vitro (2.75-fold at 100μM) in the presence of H2O2, whilst EGCG gave rise only to a 1.7-fold enhancement. In conclusion, the α-glucoside of EGCG at C-3′ has a great potential for nutraceutical, cosmetic and biomedical applications.
Cell viability assays in presence of EGCG and its a-glucosides 1 and 2 on: (A) SH-SY5Y neuronal cells; (B) RAW 264.7 macrophages; (C) MRC5 fibroblasts; (D) HT-29 colon cancer cells. The values are referred to the control (cells containing 1% DMSO). The data is expressed as mean ± SD (n = 8, *p < 0.05 vs. control group; #p < 0.05 vs. EGCG (100μM) group).

''Effect of a-glucosylation on the stability, antioxidant properties, toxicity and neuroprotective activity of (-)-epigallocatechin gallate''. Jose L. Gonzalez-Alfonso, P. Peñalver, A.O. Ballesteros, J.C. Morales and F.J. Plou. Frontiers in Nutrition, (2019) doi: 10.3389/fnut.2019.00030