Synthesis and characterization of a novel potato starch derivative with cationic acetylcholine groups

A novel substance, cationic acetylcholine potato starch (CAPS), was developed for the first time. The synthesis process had three steps: first, carboxymethyl potato starch (CMPS) was synthesized under sodium hydroxide alkaline condition and in isopropyl alcohol organic media; second, bromocholine chloride (BCC) was synthesized with sulphuric acid as a catalytic agent; finally, CAPS was synthesized by the reaction of CMPS with BCC in N,N'-dimethylformamide (DMF). The degree of substitution (DS) of CAPS was determined by ammonia gas-sensing electrode and elemental analysis. CAPS was characterized by Fourier transformed infrared (FTIR) and near infrared (FTNIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC).     

Simple organocatalytic route for the synthesis of starch esters

Starch acetates and starch butyrates with degree of substitution (DS) in the range of 0.06–1.54 were prepared by a simple direct solvent-free organocatalytic methodology of starch acylation. The starch esters synthesized have important applications in the food and pharmaceutical industries, among others. The acylation methodology used involves a non-toxic biobased α-hydroxycarboxylic acid as catalyst, and proceeds with high efficiency in absence of solvents. The effect of reaction time on the advance of starch modification was studied as a simple way to control the level of substitution achieved, when all other reaction parameters were kept constant. Starch esters were characterized by means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). FTIR spectroscopy qualitatively confirmed the esterification of starch by the appearance of bands which are associated with esters groups. Scanning electron microscopy showed that the granular structure of the polysaccharide was preserved upon acylation, although acylated granules had rougher surfaces; and wrinkles, grooves and deformed zones appeared in some granules at high DS. Thermogravimetric analysis showed a gradual reduction in the water content of acylated starches, as well as noticeable changes in their thermal properties at increasing DS. X-ray diffraction analysis showed that the acetylation treatment led to lower crystallinity at increasing DS, although characteristic corn starch A-type patterns could be identified even at the highest DS achieved (DS = 1.23). Specific bands and weight losses derived from FTIR and TGA data could be very well correlated with the substitution degree achieved in acetylated starches at DS lower/equal than 0.6. The organocatalytic methodology described for the synthesis of starch acetates and butyrates has the potential to be easily extended to the synthesis of other starch esters using a variety of anhydrides or carboxylic acids as acylating agents     

Synthesis of starch derivatives with labile cationic groups

A new route to starch derivatives bearing hydrolyzable cationic groups was developed. This was based on reacting starch compounds with betaine derivatives in the presence of diisopropylcarbodiimide and 4-dimethylaminopyridine as coupling reagents in an aprotic polar solvent. Water-soluble starches with a perfectly controlled degree of substitution were thus obtained which were fully characterized by infrared, ¹H and ¹³C spectroscopy and viscosity measurements. The cationic groups grafted on the polysaccharides are shown to hydrolyze slowly upon storage at room temperature.     

Succinoylation of sago starch in the N,N-dimethylacetamide/lithium chloride system

The modification reaction of sago starch with succinic anhydride (SA) using pyridine (PY) and/or 4-dimethyaminopyridine (DMAP) as catalyst and N,N-dimethylacetamide (DMA)/lithium chloride (LiCl) system as solvent was studied. A series of succinylated starch derivatives were prepared with a degree of substitution (DS) ranging from 0.14 to 1.54. The structure of the resulting polymers determined by means of ¹³C NMR spectroscopy indicated that substitution preferably occurs at the C₂ and C₆ hydroxyl groups. The thermal stability of the material was decreased by chemical modification. Effects of reactant molar ratio, reaction time, and the concentrations of DMAP and LiCl on the reaction efficiency are discussed.     

Preparation and characterization of hemicellulosic derivatives containing carbamoylethyl and carboxyethyl groups

A series of novel water-soluble hemicellulosic derivatives, containing carbamoylethyl and carboxyethyl groups, were heterogeneously synthesized from wheat-straw hemicelluloses with acrylamide (AA) under alkaline conditions. The factors such as reaction temperature, reaction time, molar ratio of catalysis to xylose unit in hemicelluloses and molar ratio of acrylamide to xylose unit in hemicelluloses, were investigated. The average degree of substitution (DS) was calculated by ¹H NMR spectroscopy. DS values up to 0.23 in a one-step synthesis of hemicelluloses derivatives were obtained. Under optimum conditions (60 °C, NaOH to xylose unit in hemicelluloses molar ratio of 0.8, AA to xylose unit in hemicelluloses molar ratio of 8.0, reaction time of 1 h) an expected ratio of carbamoylethyl group to carboxyethyl group of 4.8 in the hemicellulosic derivatives was obtained. The structural features of the hemicellulosic derivatives were characterized by FTIR, NMR spectroscopy, and by elemental analysis. The current work provides a facile method for the synthesis of hemicellulose derivatives with bifunctional groups, which could be used as wet-end additives in the papermaking industry.     

Microwave-assisted methylation of cassava starch with dimethyl carbonate

A novel and environmentally friendly process for the methylation of cassava starch with dimethyl carbonate (DMC) could be accelerated by employing a combined strategy: using disodium hydrogen phosphate (Na₂HPO₄) as the catalyst (chemical means) and microwave irradiation as the energy source (physical means). By varying the volume of 5% sodium chloride aqueous solution between 50 and 150 mL, the amount of Na₂HPO₄ between 0 and 1.25 g, the volume of DMC between 75 and 200 mL, and the microwave time from 5 to 20 min, methyl cassava starch with degree of substitution (DS) values in the range of 0.033 and 1.087 was prepared. The chemical structure of methyl cassava starch was analyzed by ¹H NMR spectroscopy.     

Carboxymethyl Chinese yam starch: synthesis, characterization, and influence of reaction parameters

Carboxymethyl starch (CMS) was obtained as a product of the reaction of starch and monochloroacetic acid (MCA) in the presence of sodium hydroxide. The influence of the molar ratio of NaOH/AGU, the molar ratio of MCA/AGU, the reaction time, reaction temperature, and the water content on the degree of substitution (DS) was studied. The optimal molar ratio of NaOH/AGU and MCA/AGU is 2.4 and 1.0, respectively. Increase of the ratio of NaOH/AGU or MCA/AGU leads to an increase in DS, but only to certain extent. The highest values of the DS were obtained when the carboxymethylation was performed at 60 °C for 2.5 h. The water content in the reaction media ethanol was optimal at 20% (v/v). The scanning electron micrographs (SEMs) revealed that the carboxymethylation affected the structural arrangement of the starch and caused granular disintegration. The particle size distribution (PSD) also displayed that the average particle diameter increased greatly after modification from 37.37 μm to 72.88 μm. Wide angle X-ray diffractometry (XRD) revealed that starch crystallinity was obviously reduced after carboxymethylation. The new bands at 1600 cm⁻¹ and 1426 cm⁻¹ in FT-IR indicated that the starch granules were substituted.     

Synthesize and characterization of organic-soluble acylated chitosan

Acylated chitosan was synthesized by reaction of chitosan and stearoyl chloride. The chemical structures and physical properties of the prepared compounds were confirmed by Fourier transform infrared (FT-IR), ¹H Nuclear Magnetic Resonance (¹H NMR) spectroscopy, X-ray diffraction (XRD) and Thermogravimetric (TG) techniques. The degree of substitution (DS) was calculated by ¹H NMR and ranged from 1.8 to 3.8. The synthesized compounds exhibited an excellent solubility in organic solvents. XRD analysis showed that they had high crystalline structure. TG results demonstrated that thermal stability of the prepared compounds was lower than that of chitosan, the weight loss decreased with increase of DS. This procedure could be a facile method to prepare organic-soluble chitosan derivatives.     

Synthesis,characterization and antifungal activity of quaternary derivatives of chitosan on Aspergillus flavus

Two series of new chitosan derivatives were synthesized by reaction of deacetylated chitosan (CH) with propyl (CH-Propyl) and pentyl (CH-Pentyl) trimethylammonium bromides to obtain derivatives with increasing degrees of substitution (DS). The derivatives were characterized by ¹H NMR and potentiometric titration techniques and their antifungal activities on the mycelial growth of Aspergillus flavus were investigated in vitro. The antifungal activities increase with DS and the more substituted derivatives of both series, CH-Propyl and CH-Pentyl, exhibited antifungal activities respectively three and six times higher than those obtained with commercial and deacetylated chitosan. The minimum inhibitory concentrations (MIC) were evaluated at 24, 48 and 72 h by varying the polymer concentration from 0.5 to 16 g/L and the results showed that the quaternary derivatives inhibited the fungus growth at polymer concentrations four times lower than that obtained with deacetylated chitosan (CH). The chitosans modified with pentyltrimethylammonium bromide exhibited higher activity and results are discussed taking into account the degree of substitution (DS).     

Effects of reaction conditions on the physicochemical properties of cationic starch studied by RSM

Granular cationic starches were prepared in aqueous phase without the addition of swelling inhibiting salts. Response surface methodology (RSM) was performed to analyze the effects of reaction conditions on physicochemical properties of the products. As the reaction time was prolonged from 2 to 5 and to 24 h, the relative contribution of the temperature to degree of substitution (DS) turned from minor to prominent. Good correlations were observed between the DS and the pasting temperature of the 2, 5, and 24 h cationized starches. By contrast, variation in the correlations between DS and the other physicochemical properties, with respect to reaction durations, revealed the processing pattern of cationization in starch granules along extending reaction times. This deduced pattern was confirmed by the granular and molecular characterizations using confocal laser scanning microscopy and high performance anion exchange chromatography, respectively.     

Preparation and Application of Carboxymethyl Yam (Dioscorea esculenta) Starch

Yam (Dioscorea esculenta) starch was modified by carboxymethylation. The effect of reaction parameters, amount of sodium hydroxide (NaOH), amount of sodium monochloroacetate (SMCA), and reaction time on the degree of substitution (DS) of carboxymethyl yam starch (CMS), was studied using the Box–Behnken experimental design. Physicochemical and potency to be a tablet disintegrant of CMS were evaluated. CMS with DS in the range of 0.08–0.19 were obtained. The results from regression analysis indicated that the most important factor in controlling DS was the amount of NaOH followed by SMCA content and reaction time. However, high concentration of NaOH and SMCA lowered the DS. The optimal conditions to achieve the highest DS (0.19) were found to be at molar ratios of NaOH and SMCA to anhydroglucose unit of 1.80 and 2.35, respectively, and with the reaction time of 4.8 h. The swelling power and viscosity of CMS increased with an increase in the degree of modification. CMS showed satisfying tablet disintegrant properties. The tablets containing 1.0–4.0 % CMS disintegrated faster than 5 min. Hence carboxymethyl yam starch can be used as an excellent tablet disintegrant in low concentration.     

Synthesis and cytotoxicity evaluation of novel acylated starch nanoparticles

Starch nanoparticles (StNPs) were acylated under ambient conditions to obtain various nanosized derivatives formed stable suspension in water and soluble in organic solvents. The degree of substitution (DS) was determined using ¹H NMR technique. The cytotoxicity potential of the derivatised StNPs was evaluated in mouse embryonic fibroblast (3T3L1) cells and A549 tumor cell line using MTT cell viability assay. Other parameters that determine the oxidative stress viz., reactive oxygen species (ROS) generation, intracellular reduced glutathione (GSH), superoxide generation and acridine orange/ethidium bromide staining were also investigated. The present study led to the conclusion that cytotoxic activity of acylated starch nanoparticles was dependent on their dosage, DS and type of substitution. The non-toxic nature in non-cancerous cells reveals that the nanoparticles (NPs) can be used for cancer therapy and drug delivery. The nanoparticles also offered reasonable binding propensity with CT-DNA.     

Homogeneous modification of cellulose with succinic anhydride in ionic liquid using 4-dimethylaminopyridine as a catalyst

Cellulose, extracted from sugarcane bagasse, was successfully succinylated in ionic liquid 1-buty-3-methylimidazolium (BMIMCl) using 4-dimethylaminopyridine (DMAP) as a catalyst. Parameters investigated included the mass ratio of DMAP/succinic anhydride in a range from 0% to 15%, reaction time (from 30 to 120 min), reaction temperature (from 60 to 110 °C). The succinylated cellulosic derivatives had a degree of substitution (DS) ranging from 0.24 to 2.34. It was found that the DS of succinylated cellulosic derivatives using DMAP as a catalyst was higher than that without any catalyst under the same reaction conditions. The products were characterized by FT-IR, solid-state CP/MAS ¹³C NMR, and thermal analysis. FT-IR and solid-state CP/MAS ¹³C NMR spectra showed that succinoylation occurred at C-6, C-2 and C-3 positions. The thermal stability of the succinylated cellulose decreased upon chemical modification.     

Preparation and Characterization of Octenyl Succinic Anhydride Modified Taro Starch Nanoparticles

The polar surface and hydrophilicity of starch nanoparticles (SNPs) result in their poor dispersibility in nonpolar solvent and poor compatibility with hydrophobic polymers, which limited the application in hydrophobic system. To improve their hydrophobicity, SNPs prepared through self-assembly of short chain amylose debranched from cooked taro starch, were modified by octenyl succinic anhydride (OSA). Size via dynamic light scattering of OSA-SNPs increased compared with SNPs. Fourier transform infrared spectroscopy data indicated the OSA-SNPs had a new absorption peak at 1727 cm^-1, which was the characteristic peak of carbonyl, indicating the formation of the ester bond. The dispersibility of the modified SNPs in the mixture of water with nonpolar solvent increased with increasing of degree of substitution (DS). OSA-SNPs appear to be a potential agent to stabilize the oil-water systems.     

Synthesis of potato starch sulfate and optimization of the reaction conditions

Potato starch sulfate was obtained by the reaction between potato starch and chlorosulfonic acid in pyridine. It was characterized by FT-IR and SEM. The reaction conditions were studied systematically, which included the volume ratio of pyridine to chlorosulfonic acid, reaction temperature and time in preparing sulfating agent process, and the ratio of starch mass to chlorosulfonic acid volume, reaction temperature and time in sulfation process. Meantime, the degree of substitution (DS) of each sample was determined via barium sulfate–glutin nephelometery method. By investigating the relationship between these conditions and DS, the optimal conditions were obtained with the maximum DS.     

Synthesis and characterization of quaternized β-chitin

Water-soluble 2′-O-hydroxypropyltrimethylammoniumchitin chloride (2′-O-HTACCt) was prepared directly from β-chitin and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA) in basic medium. The effect of alkali concentration, reaction temperature, reaction time, and dosage of CTA on yield and degree of substitution (DS) of 2′-O-HTACCt were studied. These quaternized chitin derivatives were characterized by FTIR and ¹H NMR spectroscopy, conductometric titration, and elemental analysis methods. Research results indicate that β-chitin can react directly with CTA to produce a water-soluble 2′-O-HTACCt derivative with a high DS. The optimal preparation conditions were determined to be 35-40 wt % (aq NaOH), 40 °C (reaction temperature), 6 h (reaction time), and 4 (molar ratio of CTA to β-chitin unit).     

Structure and chain conformation of five water-soluble derivatives of a β-d-glucan isolated from Ganoderma lucidum

A linear water-insoluble (1→3)-β-d-glucan, coded as GL-IV-I, was isolated from the fruit body of Ganoderma lucidum by extracting with NaOH solution. Its derivatives were prepared by using sulfation, carboxymethylation, hydroxyethylation, hydroxypropylation, and methylation, respectively, and these were labeled as S-GL, CM-GL, HE-GL, HP-GL and M-GL. Five derivatives exhibited good water solubility. Their structures and chain conformations were investigated with infrared spectroscopy, elemental analysis (EA), one- and two-dimensional NMR spectroscopy, laser light scattering (LLS), and size-exclusion chromatography combined with LLS (SEC-LLS). The reactivity of the hydroxyl group of GL-IV-I was ordered as C-6 > C-4 > C-2 for the five derivatives. The degree of substitution (DS) of the derivatives was calculated from EA and NMR spectroscopy to be from 0.32 to 1.18. The weight-average molecular mass (M_w) of GL-IV-I, S-GL, CM-GL, HE-GL, HP-GL, and M-GL was 13.3 × 10⁴, 10.1 × 10⁴, 6.3 × 10⁴, 7.2 × 10⁴, 5.1 × 10⁴, and 14.1 × 10⁴, respectively. The conformation analysis studies revealed that GL-IV-I exists as a compact coil in dimethyl sulfoxide, whereas the five derivatives are slightly expanded flexible chains in 0.9% aqueous NaCl solution.     

Cellulose acetates from linters and sisal: correlation between synthesis conditions in DMAc/LiCl and product properties

We report the acetylation of celluloses from sisal (untreated and alkali treated) and cotton linters (alkali treated), under homogeneous solution conditions, using DMAc/LiCl as solvent system. Our target was to evaluate the effects of cellulose dissolution and reactions conditions on the product properties. The products were characterized in terms of degree of substitution (DS) by 1H NMR, and molar weight distribution (MWD) by size exclusion chromatography. Changes in the DS of the products were correlated with reaction conditions and solution properties. It was found that the dissolution of celluloses and degree of substitution of cellulose derivatives depends on a fine adjustment of the dissolution/derivatization conditions, as well as on the origin (sisal or linters) of celluloses.     

Ultra high pressure (UHP)-assisted acetylation of corn starch

Potential roles of ultra high pressure (UHP) in starch granule reactivity and properties of acetylated starch were investigated. Corn starch was substituted with acetic anhydride at pressure range of 0.1–400 MPa for 15 min; also, conventional reaction (30 °C, 60 min) was conducted as reaction control. Native and acetylated corn starches were assessed with respect to degree of substitution (DS), X-ray diffraction pattern/relative crystallinity, starch solubility/swelling power, gelatinization, and pasting behavior. For the UHP-assisted acetylated starches, DS values increased along with increasing pressure levels from 200 to 400 MPa, and reaction at 400 MPa exhibited maximum reactivity (though lower than the DS value of the reaction control). Both UHP-assisted and conventional acetylation of starch likely occurred predominantly at amorphous regions within granules. Gelatinization and pasting properties of the UHP-assisted acetylated starches may be less influenced by UHP treatment in acetylation reaction, though restricted starch solubility/swelling were observed.     

Preparation of chitin butyrate by using phosphoryl mixed anhydride system

Acylation of chitin with butyric acid was performed in the presence of trifluoroacetic anhydride/phosphoric acid mediated system. The products were characterized by ¹H NMR and FT-IR spectroscopy and their solubility was tested in different organic solvents. Inclusion of butyric acid moieties into the parent molecule was confirmed from the ¹H NMR and FT-IR spectra. FT-IR analysis revealed that the degree of acid substitution (DS) of the products was in a range of 1.9–2.38, which increased with increasing the amounts of butyric acid added to the reaction system. Degree of N-deacetylation (DD) of the products, as determined by ¹H NMR was between 54.2% and 65.6%. The products with DS >2.0 were soluble in dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, methanol, acetone, chloroform, and acetic acid.