甜茶的化学成分及其α-葡萄糖苷酶抑制活性研究

Rubus suavissimus is mainly distributed in Guilin, Liuzhou, Wuzhou and other regionsin Guangxi Zhuang Autonomous Region, so it is called as Guangxi tiancha in Chinese. R.suavissimus, together with Siraitia grosvenorii and Stevia rebaudianastevia are praised as threefamous sweet plants in Guangxi Zhuang Autonomous Region. Zhuang and Yao people use theleaves of R. suavissimus as a tea to treat diabetes, and it is known as the divine tea of Yaomedicine. Therefore, R. suavissimus is a combination of sugar, tea and medicine, which has greatpotential for the development of food and medicine. In order to investigate the secondarymetabolites with -glucosidase inhibitory activity from R. suavissimus, herein, the extraction,separation and purification of secondary metabolites were performed on the leaves of R.suavissimus. The structures of purified compounds were determined based on the data of massspectrometry (HR-ESI-MS) and nuclear magnetic resonance (1H NMR and 13C NMR). In addition,the -glucosidase inhibitory activity of the purified compounds were evaluated bypharmacological methods simultaneously. The results were as follows: (1) Ten compounds werepurified and their structures were elucidated as rubusoside (1), kaempferol 3-O-robinobioside (2),gallic acid (3), dehydroconiferyl alcohol (4), 5-methoxydehydroconiferyl alcohol (5),brevifolincarboxylic acid (6), steviolmonoside (7), steviol (8), 16, 17-dihydroxykaurane (9), andquercetin 3-O--D-galactopyranoside (10). (2) Among them, compounds 2, 4, 5 and 9 wereisolated from R. suavissimus for the first time. Compounds 2, 3, 5, 6 and 10 showed stronginhibitory activity on -glucosidase. The IC50 values of compounds 2, 3, 5, 6 and 10 were (0.14 0.03) mg mL-1, (0.36 0.02) mg mL-1, (0.44 0.01) mg mL-1, (0.53 0.04) mg mL-1 and(0.14 0.03) mg mL-1 respectively, which were stronger than the positive control acarbose withthe IC50 values as (0.69 0.02) mg mL-1. Thus, compounds 2, 3, 5, 6 and 10, which were isolatedfrom the leaves of R. suavissimus, could be a potential -glucosidase inhibitors base on theirbioactivity results. Compounds with -glucosidase inhibitory activity from R. suavissimus willprovide the basis for development of hypoglycemic related products.