Abstract: Glycosylation of quercetin was carried out using microbial-derived glycosyltransferases GT-1, GT-2 and BTGT-1. It was found that the three enzymes can catalyze the production of quercetin-3-O-glucose (isoquercitrin) with quercetin and UDP-glucose as substrate. The product formation rates of GT-1,GT-2 and BTGT-1 catalytic reactions were 5.33%, 15.18% and 63.82%, respectively. The water-soluble and anti-inflammatory activity of quercetin, quercetin-3-O-glucose and quercetin-N-acetyl-D-glucosamine in vitro were tested. It was found that the water solubility of isoquercitrin and quercetin-N-acetyl-D-glucosamine was 13.8 times and 15.4 times higher than that of quercetin, respectively, clearly suggesting that glycosylation can greatly improve water solubility of quercetin. The toxic effect of quercetin glycoside on RAW264.7 cells was lower than that of quercetin at the same concentration, but the three compounds showed significant effects on the release of NO, IL-1β and IL-6 in LPS-induced RAW264.7 cells in a dose-dependent manner, which futher displayed that they have a certain anti-inflammation potential.

Key words: quercetin, glycosyltransferase, quercetin glycoside, water solubility, RAW264.7, anti-inflammatory

摘要： 利用微生物来源的糖基转移酶GT-1、GT-2和BTGT-1对槲皮素进行糖基化修饰。研究发现这3种酶均能够催化以槲皮素和UDP-葡萄糖为底物生成槲皮素-3-O-β-D-葡萄糖（异槲皮苷），GT-1、 GT-2和BTGT-1催化反应的产物生成率分别为5.33%、15.18%和63.82%。通过对槲皮素、异槲皮苷和槲皮素-N-乙酰-D-氨基葡萄糖进行水溶性以及体外细胞抗炎活性检测，发现槲皮素经糖基化后其水溶性得到较大提高，异槲皮苷和槲皮素-N-乙酰-D-氨基葡萄糖水溶性分别是槲皮素的13.8倍和15.4倍。同等浓度下槲皮素糖苷对RAW264.7 细胞的毒性作用低于槲皮素，且3种化合物在一定浓度范围内对LPS诱导RAW264.7细胞释放NO、 IL-1β、IL-6 都有显著的抑制作用，且呈剂量依赖性，研究表明3种化合物都具有一定的抗炎作用。

关键词: 槲皮素, 糖基转移酶, 槲皮素糖苷, 水溶性, RAW264.7, 抗炎