Laboratory of Chemical Biology, College of Life Sciences and Technology, China Pharmaceutical University, 639 Longmian Road, Nanjing, Jiangsu Province 211198, PR China.
Department of Pharmaceutical Analysis and Metabolomics, Jiangsu Province Academy of Traditional Chinese Medicine, 100 Shizi St. Hongshan Rd. Nanjing, Jiangsu Province 210028, PR China.
J Agric Food Chem. 2020 Aug 12;68(32):8702-8709. doi: 10.1021/acs.jafc.0c03236. Epub 2020 Jul 30.
Monoglucosylation of rubusoside not only could increase its structural diversity but may also improve its taste. To biosynthesize the monoglucosyl rubusosides, a series of glycosyltransferases and glycosynthases were screened to identify the enzymes capable of specifically glycosylating the hydroxyl groups of the 13-O-β-d-glucosyl and 19-COO-β-d-glucosyl moieties. After structural characterization, the effect of structure on sweetness and taste was established based on these rubusoside-derived analogues, including two first characterized compounds. β-Monoglucosylation of two 2-hydroxyl groups, as well as α-monoglucosylations of the 4- and 6-hydroxyl groups of the 13-glucosyl moiety, could significantly increase the relative sweetness of rubusoside to 140 while maintaining or improving the taste quality. In contrast, monoglucosylations of other hydroxyl groups in our study usually decreased the taste quality of the rubusoside. Additionally, the possibility of a negative influence of these monoglucosylated derivatives on the function of islets was preliminarily excluded, which should facilitate the development of rubusoside-derived sweeteners.
新葡糖苷基毛蕊花糖苷的单葡糖苷化不仅可以增加其结构多样性，还可能改善其口感。为了生物合成单葡糖苷基毛蕊花糖苷，我们筛选了一系列糖基转移酶和糖基合成酶，以鉴定能够特异性地对 13-O-β-D-葡萄糖基和 19-COO-β-D-葡萄糖基部分的羟基进行糖基化的酶。在结构表征之后，我们基于这些毛蕊花糖苷衍生的类似物，包括两种首次表征的化合物，确定了结构对甜度和口感的影响。2-位羟基的β-单葡糖苷化，以及 13-葡萄糖基部分的 4-位和 6-位羟基的α-单葡糖苷化，可使毛蕊花糖苷的相对甜度显著提高到 140，同时保持或改善口感质量。相比之下，我们研究中的其他羟基的单葡糖苷化通常会降低毛蕊花糖苷的口感质量。此外，这些单葡糖苷化衍生物对胰岛功能产生负面影响的可能性初步被排除，这应该有助于毛蕊花糖苷衍生甜味剂的开发。
