Kim Min-Ji, Kim Young-Hoi, Song Geun-Sup, Suzuki Yukio, Kim Myung-Kon
a Department of Food Science and Technology , Chonbuk National University , Jeonju , Republic of Korea.
b Research Institute for Bioresources , Okayama University , Kurashiki , Japan.
Biosci Biotechnol Biochem. 2016;80(2):318-28. doi: 10.1080/09168451.2015.1083398. Epub 2015 Sep 15.
Six α-monoglucosyl derivatives of ginsenoside Rg1 (G-Rg1) were synthesized by transglycosylation reaction of rice seed α-glucosidase in the reaction mixture containing maltose as a glucosyl donor and G-Rg1 as an acceptor. Their chemical structures were identified by spectroscopic analysis, and the effects of reaction time, pH, and glycosyl donors on transglycosylation reaction were investigated. The results showed that rice seed α-glucosidase transfers α-glucosyl group from maltose to G-Rg1 by forming either α-1,3 (α-nigerosyl)-, α-1,4 (α-maltosyl)-, or α-1,6 (α-isomaltosyl)-glucosidic linkages in β-glucose moieties linked at the C6- and C20-position of protopanaxatriol (PPT)-type aglycone. The optimum pH range for the transglycosylation reaction was between 5.0 and 6.0. Rice seed α-glucosidase acted on maltose, soluble starch, and PNP α-D-glucopyranoside as glycosyl donors, but not on glucose, sucrose, or trehalose. These α-monoglucosyl derivatives of G-Rg1 were easily hydrolyzed to G-Rg1 by rat small intestinal and liver α-glucosidase in vitro.
以麦芽糖作为糖基供体、人参皂苷Rg1（G-Rg1）作为受体，通过水稻种子α-葡萄糖苷酶的转糖基化反应合成了6种人参皂苷Rg1的α-单葡萄糖基衍生物。通过光谱分析鉴定了它们的化学结构，并研究了反应时间、pH值和糖基供体对转糖基化反应的影响。结果表明，水稻种子α-葡萄糖苷酶通过在原人参三醇（PPT）型苷元C6-和C20-位连接的β-葡萄糖部分形成α-1,3（α-黑曲霉糖基）-、α-1,4（α-麦芽糖基）-或α-1,6（α-异麦芽糖基）-糖苷键，将麦芽糖的α-葡萄糖基转移至G-Rg1。转糖基化反应的最佳pH范围为5.0至6.0。水稻种子α-葡萄糖苷酶可作用于麦芽糖、可溶性淀粉和对硝基苯基α-D-吡喃葡萄糖苷作为糖基供体，但对葡萄糖、蔗糖或海藻糖无作用。这些G-Rg1的α-单葡萄糖基衍生物在体外易被大鼠小肠和肝脏α-葡萄糖苷酶水解为G-Rg1。
