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To investigate the effect of sulfated modification on the structure and function of coconut haustorium polysaccharide (CHP), three kinds of sulfated coconut haustorium polysaccharides (SCHP-2, SCHP-3, and SCHP-4) were prepared using sulfation reagents containing different ratios of chlorosulfonic acid and pyridine (v/v, mL/mL: 1/2, 1/3, and 1/4) after extracting CHP from the raw materials of coconut haustorium, and their basic chemical compositions, structural characteristics and antioxidant activity in vitro were compared and analyzed. Results showed that all three sulfation reagents were able to modify CHP (characteristic peaks of S=O and C-O-S were observed near 1100~1250 cm−1 and 820 cm−1 in infrared spectra, respectively), and the degree of substitution (DS) was the highest (0.75) at the ratio of chlorosulfonic acid and pyridine for 1/2. The total sugar, uronic acid content, and molecular weight of the three SCHP decreased, and the molar content of monosaccharides also changed when comparing with that of CHP. The thermal stability had slightly weakened as well (the degradation temperature of polysaccharides decreased from 211.17 ℃ and 282.01 ℃ of CHP to 194.86~207.70 ℃ and 233.35~262.46 ℃ of SCHP, respectively). The results of antioxidant experiments in vitro showed that the scavenging activity of SCHP on DPPH and hydroxyl radicals was lower than that of CHP, and the larger the DS was, the more obvious the decrease in activity was. In terms of the ABTS+ radicals scavenging ability and ferrous ions chelating activity, increasing DS could enhance the activity of SCHP. At 8 mg/mL, the ABTS+ radicals scavenging rate (54.82%) and ferrous ions chelating rate (15.59%) of SCHP-2 were significantly (P

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To investigate the effect of carboxymethylated with different degrees of substitution on the properties of Siraitia grosvenorii polysaccharide (SGP), carboxymethylated Siraitia grosvenorii polysaccharide (CSGP) was prepared by solvent method by using the raw material of SGP. The effects of chloroacetic acid concentration, reaction time, and sodium hydroxide concentration on the degree of substitution were analyzed, and the CSGP with the degree of substitution ranging from 0.28 to 1.09 was prepared. The physicochemical properties of CSGP with different substitution degrees were characterized, and the effects of substitution degrees on hypoglycemic activity and antioxidant activity were investigated by in vitro physiological activity experiments. The high-performance gel permeation chromatography revealed that the molecular mass of CSGP was smaller than that of SGP. The results of FTIR manifested a new absorption peak at 1317 cm−1, indicating that carboxymethyl was successfully introduced into the polysaccharide. The results of scanning electron microscopy showed that with the increase of substitution degree, the surface morphology of CSGP became more fragmented and appeared to curl. Congo red experiment revealed that the triple helix structure of CSGP with high substitution degree disappeared. In vitro physiological activity experiment showed that 6 mg/mL of the CSGP-M had the highest α-amylase inhibition, DPPH, and hydroxyl radical scavenging rates of 44.36%±1.30%, 63.17%±2.07%, and 70.21%±1.89%, respectively. Compared with SGP, CSGP-L and CSGP-H, CSGP-M with medium degree of substitution has the best hypoglycemic activity and antioxidant activity in vitro. When the degree of substitution was increased to 1.09, the inhibition rate of α-amylase, DPPH and hydroxyl radical scavenging rate of CSGP-H decreased to 11.65%±0.26%, 47.45%±0.79%, and 34.85%±0.78%, respectively. The results indicated that CSGP with medium degree of substitution could exert the best physiological activity.

The modification of the biobased polymer chitosan is a broad and widely studied field. Herein, an insight into the hydrophobization of low-molecular-weight chitosan by substitution of amino functionalities with hexanoyl chloride is reported. Thereby, the influence of the pH of the reaction media was investigated. Further, methods for the determination of the degree of substitution based on 1H-NMR, FTIR, and potentiometric titration were compared and discussed regarding their accuracy and precision. 1H-NMR was the most accurate method, while FTIR and the potentiometric titration, though precise and reproducible, underlie the influence of complete protonation and solubility issues. Additionally, the impact of the pH variation during the synthesis on the properties of the samples was investigated by Cd2+ sorption experiments. The adjusted pH values during the synthesis and, therefore, the obtained degrees of substitution possessed a strong impact on the adsorption properties of the final material.

Sucrose polyester (SPE) is a carbohydrate ester compound that has diverse functions, from surfactant to low-calorie food products. Sucrose fatty acid ester with the degree of substitution 1-3 can be used as emulsifier in foods and cosmetics. The enzymatic synthesis of sucrose polyesters can be carried out using lipase in organic solvent and contain small amount of water. In these studies sucrose esters were synthesized by esterification reaction between sucrose with fatty acids from coconut and palm oil using Candida rugosa lipase in n-hexane. Optimization esterification reaction carried out for parameters of incubation time, temperature, and the ratio of the substrate. The optimum incubation time is at 18 hours for coconut oil and 12 hours palm oil, the optimum temperature is 30 oC for coconut and palm oil, and the mole ratio of fatty acid to sucrose is 40:1 for coconut oil and 64:1 for palm oil. Esterification products were characterized by FT-IR. The FT-IR spectrum showed the ester bond was formed as indicated by the wave number 1739.79/cm. Esterification products have 2 substitution degrees.

Micelles self-assembled from drug-conjugated polymers indicate advantages in alleviating the premature release before reaching the intended site. Hyaluronic acid (HA) is known to specifically bind with a transmembrane glycoprotein CD44, overexpressed in many types of cancerous cells, and can also be served as micelle carriers. However, an excess amount of drug conjugation to HA backbone may be detrimental to the receptor-mediated cellular uptake. Up to now, the effect of conjugation densities of drugs has never been determined on the physical properties and biological performance of resulting micelles. In the current study, camptothecin (CPT) was conjugated on HA through 3,3′-dithiodipropionic acid to self-assemble into reduction-sensitive micelles. The substitution degrees of CPT on HA backbone were tuned from around 4–20%, to clarify the effects on the cellular uptake efficiency and cytotoxicities of micelles, as well as the tumor accumulation and antitumor efficacy. The CPT substitution degree of around 15% on HA resulted in micelles with a higher cytotoxicity to 4T1 cells and achieved a better balance between the cellular uptake and reduction-triggered drug release, compared with other micelles. In contrast to a fast kidney clearance and an even distribution in major organs after intravenous injection of free CPT, the optimized micelles were accumulated in tumors, livers and lungs. The micelle content indicated a significant decrease in livers after 24 h, while that in tumors displayed a significant increase to 4.9% of the injection dose. The tumor accumulation of micelles led to strong tumor suppression with minimal systemic toxicity. The in situ tumor inhibition and the accumulation of micelles in liver and lungs inhibited tumor metastasis to these tissues. It demonstrates a feasible strategy to develop drug-HA conjugate micelles with a concise and tunable structure for tumor targeting and reduction-triggered release. Statement of Significance Hyaluronic acid (HA) can be served as micelle carriers and targeting ligands to tumor cells. However, the effects of drug conjugation densities on the physical profile and biological performance of resulting micelles have never been investigated. In the current study, camptothecin is conjugated on HA with reduction-sensitive linkers, and the substitution degrees of camptothecin on HA backbone vary from around 4–20%. The micelles with a substitution degree of around 15% achieve a better balance between the cellular uptake and reduction-triggered drug release and a higher cytotoxicity than others. It demonstrates a feasible strategy to develop drug-HA conjugate micelles with a concise and tunable structure for tumor targeting and reduction-triggered release. [ABSTRACT FROM AUTHOR]

Pea starch ( PS) appears to be very attractive for the peculiar physicochemical characteristics, which is used for the vermicelli, film-forming material due to the high amylose content. The aim of this study was to optimise the hydroxypropylation technology parameters of the microcrystalline pea starch based on pea starch as a raw material, hydrochloric acid as an hydrolysis reagent, epoxy propane as an etherisation reagent by the Box-Behnken method. The thermal properties of hydroxypropylated microcrystalline pea starch were characterised by the thermogravimetric analyser and differential scanning calorimeter, respectively. Through the analysis of Design-Expert software, the regression model and corresponding variances were obtained. In this case, the determination coefficient ( R2) was 0.9631. This implied that 96.31% of the variation could be explained by the regression model. The best reaction conditions for preparing the hydroxypropylated microcrystalline pea starch were as follows: reaction temperature 40 °C, reaction time 16 h, amount of epoxy propane 14%, amount of sodium hydroxide 1.2% and amount of anhydrous sodium sulphate 12%. After the microcrystalline pea starch was hydroxypropylated, its peak temperature, melting enthalpy, temperature range of the endothermic peak increased, but its the thermal stability, onset temperature decreased. [ABSTRACT FROM AUTHOR]

The modification of the biobased polymer chitosan is a broad and widely studied field. Herein, an insight into the hydrophobization of low-molecular-weight chitosan by substitution of amino functionalities with hexanoyl chloride is reported. Thereby, the influence of the pH of the reaction media was investigated. Further, methods for the determination of the degree of substitution based on 1H-NMR, FTIR, and potentiometric titration were compared and discussed regarding their accuracy and precision. 1H-NMR was the most accurate method, while FTIR and the potentiometric titration, though precise and reproducible, underlie the influence of complete protonation and solubility issues. Additionally, the impact of the pH variation during the synthesis on the properties of the samples was investigated by Cd2+ sorption experiments. The adjusted pH values during the synthesis and, therefore, the obtained degrees of substitution possessed a strong impact on the adsorption properties of the final material. [ABSTRACT FROM AUTHOR]