Evaluation of Stability of Amylose Inclusion Complexes Depending on Guest Polymers and Their Application to Supramolecular Polymeric Materials
This paper describes the evaluation of the stability of amylose–polymer inclusion complexes under solution state in dimethyl sulfoxide (DMSO) depending on guest polymers. The three complexes were prepared by the vine-twining polymerization method using polytetrahydrofuran (PTHF), poly(ε-caprolactone) (PCL), and poly(l-lactide) (PLLA) as guest polymers. The stability investigation was conducted at desired temperatures (25, 30, 40, 60 °C) in DMSO solutions of the complexes. Consequently, the amylose–PTHF inclusion complex was dissociated at 25 °C, while the other complexes were stable under the same conditions. When the temperatures were elevated, the amylose–PCL and amylose–PLLA complexes were dissociated at 40 and 60 °C, respectively. We also found that amylose inclusion supramolecular polymers which were prepared by the vine-twining polymerization using primer-guest conjugates formed films by the acetylation of amylose segments. The film from acetylated amylose–PLLA supramolecular polymer had higher storage modulus than that from acetylated amylose–PTHF supramolecular polymer, as a function of temperature.
Improvement of phenolic compounds extraction from high-starch lotus (Nelumbo nucifera G.) seed kernels using glycerol: New insights to amylose/amylopectin - Phenolic relationships.
Lotus seed kernel (LSK) has high starch content and possesses many bioactivities, which are mainly attributed to its phenolics. In the present study, LSK phenolics were extracted using aqueous glycerol, and the obtained phenolics and its starch properties were observed for their correlations. Response surface methodology indicated significant quadratic effect of temperature and significant linear effect of glycerol on LSK phenolics (p < 0.05). Temperature also had a significant effect on LSK starch solubility and swelling power and % leaching amylose (p < 0.05). Leaching amylose in the presence of glycerol and swelling power showed positive correlations with LSK phenolics in a linear relationship (r = 0.825, p < 0.01) below 50 °C and a monotonic relationship (rs = 0.933, p < 0.01) above 60 °C, respectively. A building block backbone model was adopted to illustrate the interaction between amylose/amylopectin-glycerol, and most importantly, their relationship to LSK phenolics.
Phosphorylase-catalyzed N-formyl-alpha-glucosaminylation of maltooligosaccharides.
This paper describes the phosphorylase-catalyzed enzymatic N-formyl-alpha-glucosaminylation of maltooligosaccharides for direct incorporation of 2-deoxy-2-formamido-alpha-D-glucopyranose units into maltooligosaccharides. When the reaction of 2-deoxy-2-formamido-alpha-D-glucopyranose-1-phosphate (GlcNF-1-P) as the glycosyl donor and maltotetraose as a glycosyl acceptor was performed in the presence of phosphorylase, the N-formyl-alpha-D-glucosaminylated pentasaccharide was produced, as confirmed by MALDI-TOF MS. Furthermore, the glucoamylase-catalyzed reaction of the crude products supported that the 2-deoxy-2-formamido-alpha-D-glucopyranoside unit was positioned at the non-reducing end of the pentasaccharide. The pentasaccharide was isolated from the crude products and its structure was further determined by the (1)H NMR analysis. On the other hand, when the phosphorylase-catalyzed reactions of maltotriose and maltopentaose using GlcNF-1-P were conducted, no N-formyl-alpha-glucosaminylation took place in the former system, whereas the latter system gave N-formyl-alpha-D-glucosaminylated oligosaccharides with various degrees of polymerization. These results could be explained by the recognition behavior of phosphorylase toward maltooligosaccharides.