Jongbin Lim 1, Mario G. Ferruzzi 2 and Bruce R. Hamaker 1 (2017). Different phenolic compounds selectively slow down the hydrolysis rates of sucrose and isomaltose by mammalian mucosal α-glucosidases. The FASEB Journal 31(1).
1Purdue University, West Lafayette, IN
2North Carolina State University, Kannapolis, NC
The mucosal α-glucosidases are major enzymes which convert starch into free glucose in the small intestine. The α-glucosidase complexes, maltase-glucoamylase (MGAM) and sucrose-isomaltase (SI), have two catalytic subunits located on the C- and N- termini (Ct- and Nt-) of their origin proteins. Ct-SI has the higher capacity to digest the α-1, 2 linkage of sucrose, whereas Nt-SI is involved in the hydrolytic activity for the α-1, 6 linkage of isomaltose. In this study, we investigated the inhibition properties of phenolic compounds on Ct- and Nt-SI using four different phenolic compounds [chlorogenic acid, (−)-epicatechin, kaempferol, and naringenin] for the regulation of sucrose and isomaltose digestion in the small intestine. The tested phenolic compounds showed different inhibition properties on the hydrolysis activities for sucrose and isomaltose. Chlorogenic acid had the highest inhibition property on hydrolytic activity for sucrose, while kaempferol was a comparatively potent inhibitor for isomaltase activity of the α-glucosidases. The different inhibition properties may be due to the different affinities of the tested phenolic compounds for Ct- and Nt-SI. The different and selective inhibition properties of phenolics can be applied to modulate the digestion rate of sucrose-rich foods or α-1,6-linked branched starch products for slow and improved glycemic response profiles with potential health benefit.