Enzymatic Synthesis of a Novel Pterostilbene α-Glucoside by the Combination of Cyclodextrin Glucanotransferase and Amyloglucosidase.

José González-Alfonso,Juan Morales,Jesús Jiménez-Barbero,Julio Polaina,Efres Belmonte-Reche,Antonio Ballesteros,Pablo Peñalver,Ana Poveda,David Rodrigo-Frutos,Francisco Plou,Yoshihiko Hirose,María Fernández-Lobato

doi:10.3390/molecules23061271

Abstract

The synthesis of a novel α-glucosylated derivative of pterostilbene was performed by a transglycosylation reaction using starch as glucosyl donor, catalyzed by cyclodextrin glucanotransferase (CGTase) from Thermoanaerobacter sp. The reaction was carried out in a buffer containing 20% (v/v) DMSO to enhance the solubility of pterostilbene. Due to the formation of several polyglucosylated products with CGTase, the yield of monoglucoside was increased by the treatment with a recombinant amyloglucosidase (STA1) from Saccharomyces cerevisiae (var. diastaticus). This enzyme was not able to hydrolyze the linkage between the glucose and pterostilbene. The monoglucoside was isolated and characterized by combining ESI-MS and 2D-NMR methods. Pterostilbene α-d-glucopyranoside is a novel compound. The α-glucosylation of pterostilbene enhanced its solubility in water to approximately 0.1 g/L. The α-glucosylation caused a slight loss of antioxidant activity towards ABTS˙+ radicals. Pterostilbene α-d-glucopyranoside was less toxic than pterostilbene for human SH-S5Y5 neurons, MRC5 fibroblasts and HT-29 colon cancer cells, and similar for RAW 264.7 macrophages.

Highlights

Dietary phytophenols exhibit a wide range of bioactivities such as antioxidant, antihypertensive, antitumoral, bactericidal, neuroprotective and anti-inflammatory [1]
We describe the enzymatic synthesis of an alpha-glucosyl derivative of pterostilbene by a transglycosylation reaction catalyzed by a transglycosidase, namely cyclodextrin glucanotransferase or glycosyltransferase (CGTase, EC 2.4.1.19) from Thermoanaerobacter sp., which employs starch as glucosyl donor [25]
We studied the antioxidant activity of pterostilbene and its α-glucosylated derivative by the Trolox Equivalent Antioxidant Capacity (TEAC) assay

Summary

Introduction

Dietary phytophenols exhibit a wide range of bioactivities such as antioxidant, antihypertensive, antitumoral, bactericidal, neuroprotective and anti-inflammatory [1]. It is well reported that pterostilbene possesses excellent pharmacological benefits for the prevention and treatment of various types of cancer [4,5], Alzheimer’s disease [6], vascular dementia [7], obesity [8] or diabetes [9]. It exerts beneficial anti-aging effects by lowering several processes such as oxidative damage, inflammation, telomere attrition and cell senescence [10]. Various polyphenols are glycosylated in nature and this glycosylation could play a major role in their absorption [12]

Methods

Results

Conclusion