Abstract
The stilbene compound resveratrol was glycosylated to give its 4′-O-β-D-glucoside as the major product in addition to its 3-O-β-D-glucoside by a plant glucosyltransferase from Phytolacca americana expressed in recombinant Escherichia coli. This enzyme transformed pterostilbene to its 4′-O-β-D-glucoside, and converted pinostilbene to its 4′-O-β-D-glucoside as a major product and its 3-O-β-D-glucoside as a minor product. An analysis of antioxidant capacity showed that the above stilbene glycosides had lower oxygen radical absorbance capacity (ORAC) values than those of the corresponding stilbene aglycones. The 3-O-β-D-glucoside of resveratrol showed the highest ORAC value among the stilbene glycosides tested, and pinostilbene had the highest value among the stilbene compounds. The tyrosinase inhibitory activities of the stilbene aglycones were improved by glycosylation; the stilbene glycosides had higher activities than the stilbene aglycones. Resveratrol 3-O-β-D-glucoside had the highest tyrosinase inhibitory activity among the stilbene compounds tested.
将白藜芦醇化合物白藜芦醇糖苷化,通过植物糖苷转移酶从美国梅花树中表达的重组大肠杆菌中,主要产物是其4'-O-β-D-葡萄糖苷,同时也生成其3-O-β-D-葡萄糖苷。该酶将白藜芦醇转化为其4'-O-β-D-葡萄糖苷,将松栲白藜芦醇转变为其4'-O-β-D-葡萄糖苷作为主要产物,3-O-β-D-葡萄糖苷为次要产物。抗氧化能力分析显示,上述白藜芦醇糖苷的氧自由基吸收能力(ORAC)值低于相应的白藜芦醇原芸豆素。白藜芦醇的3-O-β-D-葡萄糖苷在测试的白藜芦醇糖苷中显示出最高的ORAC值,而松栲白藜芦醇在白藜芦醇化合物中具有最高的值。白藜芦醇原芸豆素的酪氨酸酶抑制活性通过糖苷化得到改善;白藜芦醇糖苷的活性高于白藜芦醇原芸豆素。白藜芦醇3-O-β-D-葡萄糖苷在测试的白藜芦醇化合物中显示出最高的酪氨酸酶抑制活性。