Isomaltomegalosaccharide (IMS) is a long chimeric glucosaccharide composed of α-(1 → 6)- and α-(1 → 4)-linked segments at nonreducing and reducing ends, respectively; the hydrophilicity and hydrophobicity of these segments are expected to lead to bifunctionality. We enzymatically synthesized IMS with average degrees of polymerization (DPs) of 15.8, 19.3, and 23.5, where α-(1 → 4)-segments had DPs of 3, 6, and 9, respectively. IMS exhibited considerably higher water solubility than maltodextrin because of the α-(1 → 6)-segment and an identical resistance to thermal degradation as short dextran. Interaction of IMS with a fluorescent probe of 2-p-toluidinylnaphthalene-6-sulfonate demonstrated that IMS was more hydrophobic than maltodextrin, where the degree of hydrophobicity increased as DP of α-(1 → 4)-segment increased (9 > 6 > 3). Fluorescent pyrene-estimating polarity of IMS was found to be similar to that of methanol or 1-butanol. The bifunctional IMS enhanced the water solubility of quercetin-3-O-glucoside and quercetin: the solubilization of less-soluble bioactive substances is beneficial in carbohydrate industry.
Keywords: Bifunctionality; Chimeric structure; Dextran dextrinase; Isomaltomegalosaccharide; Quercetin flavonoid; Water solubility enhancement.
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