Correction to: Creation of Straight-Chain Cationic Polysaccharide-Based Bile Salt Sequestrants Made from Euglenoid ß-1,3-Glucan as Potential Antidiabetic Agents.

The corresponding author (Motonari Shibakami) inadvertently failed to include his ORCID ID: http://orcid.org/0000-0003-4484-2982 In the published article.

Creation of Straight-Chain Cationic Polysaccharide-Based Bile Salt Sequestrants Made from Euglenoid ß-1,3-Glucan as Potential Antidiabetic Agents.

PURPOSE: Straight-chain polysaccharides have a greater potential of selectively adsorbing hydrophobic bile salts than resin-based bile salt sequesters because of ionic and hydrophobic interactions; hence, they may possess antidiabetic activity. The feasibility of using cationic polysaccharides made from euglenoid ß-1,3-glucan (referred to as paramylon) as potential antidiabetic agents was examined by using in vitro and animal experiments. METHODS: Cationic straight-chain polysaccharides were synthesized from euglenoid polysaccharide and glycidyltrimethylammonium chloride. The effects of administration of the synthetic polysaccharide on metabolic syndrome-related indicators were examined in high-fat diet-induced obesity mice. The degree of adsorption of bile salts by the polysaccharides was evaluated using spectroscopic analysis. RESULTS: Administration of the cationic paramylon derivatives significantly reduced body and mesenteric fat weight in high-fat diet-induced obesity mice. A noteworthy effect was that glucagon-like peptide-1 (GLP-1) secretion was approximately three times higher in diet-induced obesity mice receiving cationic paramylon derivatives than in those receiving cellulose as a control. CONCLUSIONS: Our results indicate that these cationic paramylon derivatives are potential GLP-1 secretagogues suitable for further study.

Synthesis of nanofiber-formable carboxymethylated Euglena-derived ß-1,3-glucan.

Carboxymethylation of paramylon, a storage polysaccharide of Euglena, was explored using homogeneous and heterogeneous reaction systems. Homogeneous reactions yielded carboxymethyl paramylons with a low degree of substitution of carboxymethyl group (DScm) of ∼0.13. Heterogeneous reactions of paramylon with chloroacetic acid in a mixture of 2-propanol and a NaOH aqueous solution yielded carboxymethyl paramylons with a high DScm of up to ∼0.80. An essential step for successful carboxymethylation using the heterogeneous reaction systems devised in this study was the pretreatment of a paramylon particle to break its inherent highly crystalline state into an amorphous one. A high degree of substitution provided carboxymethyl paramylons with a nanofiber-forming ability in the aqueous phase while a low degree provided them with a fiber-forming ability in both the aqueous and solid phases.

Preparation of transparent self-standing thin films made from acetylated euglenoid ß-1,3-glucans.

The feasibility of using acetylparamylon to prepare self-standing optical films was investigated. Its thermal stability, represented by the glass transition temperature, and 5% weight loss temperature are equivalent to those of acetylcellulose. The mechanical properties (maximum stress, elongation at break, and elastic modulus) of acetylparamylon films prepared by solution casting were comparable to those of acetylcellulose films. The degrees of their transparency and birefringence were the same as those of the acetylcellulose film. These results, together with the finding that acetylparamylon with a higher degree of acetylation formed a thin film with fewer micrometer-sized defects and that acetylparamylon with a lower degree of acetylation formed a thin film with a nanometer-level flat surface, suggest that acetylparamylon is a feasible material for self-standing optical film.

One-pot synthesis of thermoplastic mixed paramylon esters using trifluoroacetic anhydride.

Mixed paramylon esters prepared from paramylon (a storage polysaccharide of Euglena), acetic acid, and a long-chain fatty acid by one-pot synthesis using trifluoroacetic anhydride as a promoter and solvent were shown to have thermoplasticity. Size exclusion chromatography indicated that the mixed paramylon esters had a weight average molecular weight of approximately 4.9-6.7×10(5). Thermal analysis showed that these esters were stable in terms of the glass transition temperature (>90°C) and 5% weight loss temperature (>320°C). The degree of substitution of the long alkyl chain group, a dominant factor determining thermoplasticity, was controlled by tuning the feed molar ratio of acetic acid and long-chain fatty acid to paramylon. These results implied that the one-pot synthesis is useful for preparing structurally-well defined thermoplastic mixed paramylon esters with high molecular weight.

Thermoplasticization of euglenoid ß-1,3-glucans by mixed esterification.

We experimentally demonstrated that paramylon, a storage polysaccharide of Euglena gracilis, is efficiently thermoplasticized by adding acyl groups that differ in alkyl chain length. Glass transition temperature of mixed paramylon esters was higher than those of plant-based polylactic acid (PLA), poly 11-aminoundecanoic acid (PA11), and petroleum-based acrylonitrile-butadiene-styrene (ABS) resin and was comparable to that of cellulose acetate stearate (CAS). Their thermoplasticity was equivalent to or higher than those of these reference plastics. The bending strength and bending elastic modulus of injection molded test specimens made from mixed paramylon esters were comparable to those of the reference plastics. While their impact strength was lower than that of specimens made from ABS resin and CAS, it was comparable to those of PLA and PA11. Euglenoid ß-1,3-glucans are thus a potential component of thermoplastic materials.

Preparation of carboxylic acid-bearing polysaccharide nanofiber made from euglenoid ß-1,3-glucans.

This paper introduces a new strategy for creating surface modified polysaccharide nanofibers. To demonstrate proof of principle, the synthesis, structure, and self-assembly behavior of a carboxylic acid-bearing polysaccharide made from paramylon (ß-1,3-glucan) and succinic anhydride were investigated. Examination by a combination of NMR, FT-IR, and SEC-MALLS confirmed that successful preparation of the desired succinylated paramylon without significant depolymerization. NMR, SEC-MALLS, visible absorption and CD spectroscopic analyses indicated that the paramylon derivative forms the triplex structure in solutions. SEM observation revealed that succinylated paramylon forms a nanofiber that has carboxylic acid on the surface.

Polysaccharide nanofiber made from euglenoid alga.

We have fabricated a polysaccharide nanofiber made from paramylon (ß-1,3-glucan), a storage polysaccharide stored as a micrometer-sized particle in the cell of euglenoid alga. Preparation of this nanofiber primarily hinges on the bottom-up approach. First, paramylon, which is originally present in the form of a bundle of nanofibers in a particle, was fibrillated to a randomly coiled polymer by dissolving the particle in a 1.0-mol/L NaOH aqueous solution. Second, the randomly coiled polymer was allowed to self-assemble into a triplex as the NaOH concentration was reduced to 0.25-0.20mol/L. Third, a 20-nm-width nanofiber made from the triplex emerged in the solution when the NaOH concentration was reduced to approximately 0.20mol/L.