Cationic Manihot esculenta (ME) peel starch was synthesized through etherification method using 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) as cationizing monomer. The optimization of the main factors influencing the degree of substitution (DS) was conducted using central composite design (CCD) and response surface methodology (RSM). The factors assessed include CHPTAC concentration, catalyst sodium hydroxide (NaOH) concentration, and reaction time. The DS values of the cationic starches were obtained between 0.39 and 0.99. The maximum DS value was up to 0.99 at 0.615 mol/L of CHPTAC, 30 % (w/v) NaOH, and a reaction time of 5 h. The finding based on the optimization using RSM reflected that CHPTAC and NaOH concentrations are the key variables determining the DS value, while reaction time has a negligible impact on the etherification process. Furthermore, the chemical composition, morphology, and structure of the cationic ME peel starch were characterized by scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and nuclear magnetic resonance spectroscopy (1H NMR). It was confirmed that the modifying monomers penetrated the surface layer of the starch granules and attached to the starch backbone.

Five types of sulfobutylether-β-cyclodextrin (SBE-β-CD) and carboxymethyl-β-cyclodextrin (CM-β-CD) with different degrees of substitution were synthesized, and six and five racemates were respectively chosen to study the influence of the degree of substitution on the enantioseparation factor. The synthesized SBE-β-CD and CM-β-CD were characterized using 1H NMR spectroscopy and mass spectrometry. The results indicated that the influence of the degree of substitution on enantioseparation for distinct racemates exhibited significant variability. Increasing the degree of substitution of CM-β-CD led to an increasing enantioseparation factor, while SBE-β-CD with a specific degree of substitution provided the optimum enantioseparation factor for some racemates. The optimum enantioseparation factors of N-methyl duloxetine and duloxetine were obtained when a relatively low degree of substitution (DS = 3.5) was selected. And the optimum enantioseparation factor was obtained with a relatively high degree of substitution (DS = 7.5). SBE-β-CD with a low substitution degree of 3.5 was chosen to optimize the countercurrent chromatographic enantioseparation of N-methyl-duloxetine, which resulted in a significant improvement in peak resolution from 0.51 to 0.83. Molecular docking was used to construct three SBE-β-CDs with different degrees and distributions of substitution, and a good agreement was found between the docking results and the experimental results.

The encapsulation of sodium sulfobutylether-β-cyclodextrin (SBE-β-CD) is influenced not only by the degree of substitution (DS) but also by the presence of strong-bonded water (SBW). Guests compete with SBW for positions within the cavity of SBE-β-CD. However, the correlation between DS and SBW was not clear. This study revealed a positive correlation between DS and SBW utilizing Karl Fischer titration. The mechanism may be attributed to molecular polarizability. To explore the impact of SBW inside SBE-β-CD with different DS on encapsulation, density functional theory was employed. Throughout the release process, an increase in enthalpy is unfavorable, while an increase in entropy favors spontaneous reaction occurrence. For SBE-β-CD (DS = 2, 3), enthalpy increase is the primary factor, leading to the retention of SBW within the cavities and consequently hindering guest entry. In contrast, for SBE-β-CD (DS = 4, 7), the situation differs. For SBE10-β-CD, the influence of SBW is minimal. This study aims to elucidate the relationship between DS and SBW, as well as the effect of SBW inside SBE-β-CD with different DS on encapsulation. It is crucial for a comprehensive understanding of the factors affecting the encapsulation of SBE-β-CD, thereby promoting quality control and functional development of SBE-β-CD.

2-Hydroxypropyl-β-cyclodextrin (HPBCD) is one of the most important cyclodextrin derivatives, finding extensive applications in the pharmaceutical sector. Beyond its role as an excipient, HPBCD achieved orphan drug status in 2015 for Niemann-Pick type C disease treatment, prompting research into its therapeutic potential for various disorders. However, the acceptance of HPBCD as an active pharmaceutical ingredient may be impeded by its complex nature. Indeed, HPBCD is not a single entity with a well-defined structure, instead, it is a complex mixture of isomers varying in substituent positions and the degree of hydroxypropylation, posing several challenges for unambiguous characterization. Pharmacopoeias\' methods only address the average hydroxypropylation extent, lacking a rapid approach to characterize the substituent positions on the CD scaffold. Recognizing that the distribution of substituents significantly influences the complexation ability and overall activity of the derivative, primarily by altering cavity dimensions, we present a straightforward and non-destructive method based on liquid state NMR spectroscopy to analyze the positions of the hydroxypropyl sidechains. This method relies on a single set of routine experiments to establish quantitative assignment and it provides a simple yet effective tool to disclose the substitution pattern of this complex material, utilizing easily accessible (400 MHz NMR) instrumentation.

Regioselective modifications of cellulose using activated cellulose derivatives such as 6-halo-6-deoxycelluloses provide a convenient approach for developing sustainable products with properties tailored to specific applications. However, maintaining precise regiochemical control of substituent distribution in 6-halo-6-deoxycelluloses is challenging due to their insolubility in most common solvents and the resulting difficulties in precise structure elucidation by modern instrumental analytical techniques. Herein, an accessible NMR-based approach toward detailed characterization of 6-halo-6-deoxycelluloses, including the determination of the degrees of substitution at carbon 6 (DS6), is presented. It is shown that the direct-dissolution cellulose solvent, tetrabutylphosphonium acetate:DMSO-d6, converts 6-halo-6-deoxycelluloses to 6-monoacetylcellulose, enabling in situ solution-state NMR measurements. A range of 1D and 2D NMR experiments is used to demonstrate the quantitivity of the conversion and provide optimum dissolution conditions. In comparison with other NMR-based derivatization protocols for elucidating the structure of 6-halo-6-deoxycelluloses, the presented approach offers major advantages in terms of accuracy, speed, and simplicity of analysis, and minimal requirements for reagents or NMR instrumentation.

BACKGROUND: Hydroxypropyl-β-cyclodextrin (HPβCD) is one of the derivatized cyclodextrins most widely used as an excipient in the pharmaceutical industry, for its capacity to improve certain drugs properties. Different configurations of HPβCD are possible depending on the number and location of the 2-hydroxypropyl groups substituted on the glucose rings. Rifampicin has become the most commonly clinically used antibiotic against tuberculosis in recent years, despite its low solubility and variable bioavailability. Different techniques and materials have been proposed to enhance the properties of rifampicin: cyclodextrin complexation is one of them. The van der Waals term was the main contribution to the interaction energy, which then decisively conditioned the complex configurations. The size of rifampicin did not allow the whole molecule to fit into the host. Moreover, interaction energy was much greater when the guest was located near each rim of HPβCD, where rifampicin was partially included in the cavity and formed inclusion complexes. The piperazine tail of rifampicin was included inside the host in minimum energy structures and the guest was situated near the primary rim of HPβCD in most cases, although the complex configurations depended on the degree of substitution.
METHODS: A molecular mechanics simulation based on the GROMOS 53A6 force field was applied in this work to study the inclusion complexes formed by twelve configurations of HPβCD, with different degrees of substitution and rifampicin in water solution. We determined the penetration potential, the complex structures with minimum energies, the possibility of forming inclusion complexes other than those of minimum energies and potential energy surfaces.

Lycium barbarum seed dregs (LBSDs) were used for carboxymethyl modification, resulting in three degree of substitution samples (DS). Based on the substitution degree, samples were designated as low degree of substitution insoluble dietary fiber (L-IDF), medium degree of substitution insoluble dietary fiber (M-IDF) and high degree of substitution insoluble dietary fiber (H-IDF). Physicochemical and functional properties of IDFs were examined in relation to carboxymethylation degree. Infrared Fourier transform spectroscopy (FT-IR) confirmed the carboxymethyl group. According to the results, IDF, L-IDF, M-IDF, and H-IDF acquired higher enthalpy changes, and their thermal stability improved significantly. A higher DS resulted in an increase in hydration properties such as water retention capacity and water swelling capacity, as well as functional properties such as glucose adsorption capacity, nitrite ion adsorption capacity, and cholesterol adsorption capacity. As a result, carboxymethylation could effectively enhance the biological properties of L. barbarum seed dreg insoluble dietary fiber (LBSDIDF).

Curdlan is a unique (1,3)-β-D-glucan with bioactivity and exceptional gelling properties. By chemical functionalization such as carboxymethylation, the physicochemical properties of curdlan can be significantly tailored. However, how the carboxymethylation extent of curdlan affects its rheology and gelation characteristics has yet to be fully understood. Herein, we investigated the impact of the degree of substitution (DS, ranging from 0.04 to 0.97) on the rheological and gelation behavior of carboxymethylated curdlan (CMCD). It was found that CMCD with DS below 0.20, resembling native curdlan, still retained its gelling capability. As the DS increased beyond 0.36, there was a significant increase in its water solubility instead of gelation, resulting in transparent solutions with steady/complex viscosities adhering to the Cox-Merz rule. Moreover, CMCD with high DS demonstrated the ability to undergo in-situ gelation in the presence of metal ions, attributed to the nonspecific electrostatic binding. Additionally, in vitro cytocompatibility testing showed positive compatibility across varying DS in CMCD. This research offers a holistic understanding of the viscosifying and gelling behaviors of CMCD with varying DS, thereby fostering their practical application as thickeners and gelling agents in fields ranging from food and biomedicine to cosmetics and beyond.

In this study, phosphorylated derivatives of long-chain inulin with different substitution degrees were prepared. The synthesized samples were named PFXL-1, PFXL-2, PFXL-3, and PFXL-4 according to their degree of substitution (from low to high). The structures of FXL and PFXL were characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy, and the results indicated the successful introduction of phosphate groups. FXL and PFXL were composed of two types of sugar, fructose and glucose, with a molar ratio of 0.977:0.023. The SEM results showed that phosphorylation changed the morphology of FXL from an irregular mass to small spherical aggregates. The XRD pattern showed that the crystallinity was reduced by the introduction of phosphate groups. The Mw of FXL was 2649 g/mol, and the Mw of PFXL-4 increased the most (2965 g/mol). Additionally, PFXL was more stable and uniform, and the absolute value of the PFXL potential reached 7.83 mV. Phosphorylation decreased the weight loss rate of FXL and improved the viscoelastic properties and antioxidant activity of FXL. This study presents a method for the modification of FXL, demonstrating that phosphorylation can enhance its physicochemical properties and physiological activity and suggesting its potential as a functional food and quality modifier.

Keeping the stability of emulsions at low pH is necessary for their successful applications in food and delivery systems. To achieve this goal, hydroxybutyl chitosan (HBC) with three degrees of substitution (DSs) was used as an emulsifier to investigate the effect of HBC structure on the emulsion stability. The DSs of HBC-5, HBC-10, and HBC-20 were 0.66, 1.51, and 2.19, respectively. The stability of oil-in-water emulsions against creaming/coalescence was positively correlated with the DS. As pH decreased to 2, HBC-20-stabilized emulsions were most stable without creaming or coalescence. After 30 days of storage, no changes in the droplet sizes of HBC-20-stabilized emulsions were observed, whereas the droplet sizes of HBC-5/10- stabilized emulsions significantly increased at low pH. The stability of HBC-20- stabilized emulsions at low pH was attributed to the higher surface activity and electrostatic repulsion. Our research revealed that the emulsion stability of HBC under low pH conditions can be controlled by the density of the hydroxybutyl groups in HBC. In vitro digestion further revealed the excellent stability of HBC-20-stabilized emulsions in simulated gastric fluid, which highlighted the enormous potential of HBC-20 to protect liposoluble drugs and nutrients from the extreme pH environment.