Aim: In this study, the physicochemical properties of stearyl glycyrrhetinate/β-cyclodextrin (SG/βCD) and SG/γCD complexes were characterized, and the complexes were prepared using the co-milling method. The molecular interactions within the SG/CD complexes were also investigated using nuclear magnetic resonance (NMR) measurements to determine the mode of interaction. Methods: Here, we evaluated the physicochemical properties of SG complexes with CDs prepared by ground mixtures (GM SG/βCD or γCD = 1/1, 1/2). Results: Powder X-ray diffraction (PXRD) showed that the characteristic SG and CD peaks disappeared after co-grinding with GM (SG/CD = molar ratio of 1/2), indicating a halo pattern. Differential scanning calorimetry (DSC) measurements showed that after co-grinding, the endothermic peak due to SG melting, as well as the dehydration peak and the endothermic peak due to SG melting, disappeared. Near-infrared (NIR) spectroscopy results showed that the peaks of SG-derived –CH moieties and CD-derived –OH and –CH moieties broadened in GM, suggesting their involvement in complex formation through SG/CDs intermolecular interactions. In GM (SG/CDs), NMR measurements showed broadened H-A and H-F peaks of the steroid skeleton derived from SG. In GM (SG/βCD = 1/2), the doublet peak, especially OH-3 at the wide edge of CD, shifted to a singlet peak. In GM (SG/γCD = 1/2), the H-3 peak, which is the wide edge of γCD, and the H-6 peak, which is the narrow edge, shifted to broad peaks, suggesting that γCD is deeply encapsulated in the steroidal structure. Conclusions: These findings suggest that complex formation occurred in SG/CDs and that inclusion behavior is different between GM (SG/βCD = 1/2) and GM (SG/γCD = 1/2).

The complex relationship between the molecular structure of ion-exchange resins and carbohydrate elution presents a challenge for the development of polymer materials for high-performance liquid chromatography under a wide range of conditions. We evaluated the effect of the number of methylene groups in the functional chain of the shell on carbohydrate separation. Core-shell ion-exchange resins with a monomer weight ratio of 30:70 (denoted as St-70) were synthesized with a constant cross-linking degree of 40%. The number of methylene groups in the functional chain of the porous polymer shell was varied from two to six (denoted as St-70 (40% Me:2, 4, and 6)) to analyze the carbohydrate separation performance under strongly alkaline conditions. A mixture of inositol, glucose, fructose, and sucrose was separated using a 0.10 or 0.15 mol/L NaOH eluent at flow rates of 0.3-0.7 mL/min. As the number of methylene groups increased, glucose, fructose, and sucrose for St-70 (40% Me:4) at flow rates of 0.3-0.7 mL/min with 0.10 mol/L NaOH eluent showed the largest retention times. The carbohydrates for St-70 (40% Me:4) at flow rates of 0.3, 0.5, and 0.7 mL/min showed the largest theoretical plate numbers when the number of methylene groups was changed from two to six. These results suggest that St-70 core-shell ion-exchange resins are highly efficient for carbohydrate analyses. Their suitability under strongly alkaline conditions facilitates their effective use in electrochemical detection.

This study prepared a paracetamol-β-cyclodextrin inclusion complex via co-precipitation method to address the structural and organoleptic challenges o

Low-molecular-weight lychee polyphenol (Lyp), a standardized oligomeric polyphenol derived from Litchi chinensis fruit, possesses potent antioxidant activity but is susceptible to physicochemical instability, which may limit its practical application. In this study, freeze-dried systems of Lyp with α-, β-, and γ-cyclodextrins (CDs) were prepared to investigate the effects of cyclodextrins on the physicochemical properties and antioxidant activity of Lyp. Powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, near-infrared spectroscopy, and solution-state NMR were employed to characterize the prepared systems. Freeze-drying produced amorphous Lyp/CD systems accompanied by enhanced thermal stability and changes in the hydrogen-bonding environment compared with the corresponding physical mixtures. Solution-state ¹H NMR and NOESY analyses suggested molecular association between Lyp constituents and cyclodextrins, with the βCD system exhibiting the most pronounced spectral changes. Consistent with these physicochemical findings, the freeze-dried βCD system showed the greatest enhancement of DPPH radical scavenging activity among the three cyclodextrins examined. These results suggest that βCD provides the most favorable molecular environment for Lyp, leading to improved physicochemical characteristics and antioxidant performance. The present findings demonstrate that freeze-drying combined with β-cyclodextrin is an effective strategy for improving the physicochemical performance and antioxidant functionality of low-molecular-weight lychee polyphenol.