Because of the relationship between
Because of the relationship between carbohydrate consumption and chronic diseases such as obesity and type II diabetes (Hu, van Dam, & Liu, 2001), there is mounting interest to evaluate the quality of SGI-1027 through analysis by glycemic index (GI) and Englyst assay, for example (Englyst, Kingman, & Cummings, 1992; Jenkins et al., 1981). GI analysis conducted during clinical trials can provide data on postprandial glycemic response of human subjects (Jenkins et al., 2002). On the other hand, the Englyst assay was developed to determine carbohydrate quality by using microbial or fungal α-glycolytic enzymes at in vitro level instead of testing the human trials (Englyst & Hudson, 1996). However, the Englyst assay utilizes amyloglucosidase from Aspergillus niger, which exhibits different hydrolytic activity toward α-linked carbohydrates than α-glucosidases found in the mammalian intestinal system; thus, it is more applicable to study carbohydrate digestion using mammalian enzymes (Lee, 2012). Although recent studies have been using mammalian mucosal α-glucosidases to evaluate hydrolysis of carbohydrates, little is known about the mechanism of digestion by each individual α-glucosidase (Dyer et al., 2002; Kashimura, Nagai, & Goda, 2008). Therefore, to establish a more accurate carbohydrate digestion model of mammalian mucosal α-glucosidases, we must identify the degradation mechanism of each α-glucosidase and optimize the reaction conditions for in vitro verification.
In this study, we investigated the mechanism of digestion of each mammalian mucosal α-glucosidase on various substrates and established optimal reaction conditions for carbohydrate digestion in vitro. Altogether, our results may support a more precise model of glycemic carbohydrate digestion in the gastrointestinal tract.
Materials and methods
Results and discussion
Conclusion In this study, we investigated the hydrolytic patterns of mammalian α-glucosidases on various glycemic carbohydrates and optimized the reaction conditions of small intestinal α-glucosidases for in vitro analysis. Our results clearly demonstrated that mammalian mucosal α-glucosidases exhibited different hydrolytic activity toward each substrate compared to fungal amyloglucosidase, which is dominantly applied to determine the digestion quality of carbohydrates. Also, it is clearly shown that the additional PPA contributed to digest the large sized carbohydrates such as starches and maltodextrins for assisting the hydrolytic activities of α-glucosidases. Therefore, our carbohydrate digestion model of small intestinal α-glucosidases may be utilized as a novel approach to assessing carbohydrate quality and digestibility.
Acknowledgements This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science & ICT (NRF-2018R1D1A1B07047650). This research was also partially supported by the Nestle Research Project (DUND-101451) for B.-H. Lee, J.-M. Seo, S.-H. Yoo and L. Lamothe.