Preparation, characterization and evaluation of an inclusion complex of steviolbioside with γ-cyclodextrin

Characterization and In Vitro Prebiotic Activity of Pterostilbene/β-Cyclodextrin Inclusion Complexes

Pterostilbene (PTS) has multiple benefits, but poor water solubility and bioavailability limit its application. PTS/β-CD inclusion complexes were synthesized through the phase solubility method to enhance their water solubility. The inclusion complexes were characterized through Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, nuclear magnetic resonance, and molecular docking techniques. The results demonstrated that PTS and β-CD successfully created inclusion complexes with a host-guest ratio of 1:1 and a stability constant of 166.7 M-1. To further investigate its prebiotic function, simulated digestion experiments revealed that β-CD exhibited resistance to digestion, allowing it to reach the colon intact. During gastrointestinal digestion, PTS in the PTS/β-CD inclusion complexes was gradually released. Following digestion, the in vitro fermentation of healthy human feces further confirmed the probiotic properties. Compared to the β-CD and fructooligosaccharide (FOS) groups, the PTS/β-CD group significantly increased the production of acetic acid, butyric acid, and lactic acid, respectively. Additionally, beneficial bacteria, such as Bifidobacterium and Lactobacillus, proliferated in the PTS/β-CD group, while the relative abundance of potential pathogenic bacteria, such as Lactococcus, Streptococcus, and Klebsiella, was significantly reduced. Compared to the blank group, propionic acid and butyric acid concentrations in the β-CD group were significantly higher. The abundance of Lactobacillus and other key bacterial species in the β-CD group increased, while the relative abundance of Klebsiella and other pathogens decreased significantly. In conclusion, PTS/β-CD inclusion complexes altered the composition of intestinal flora, promoting the proliferation of beneficial bacteria and inhibiting the growth of harmful bacteria, thereby demonstrating dual probiotic functionality.

Release Characteristics of an Essential Oil Component Encapsulated with Cyclodextrin Shell Matrices

BACKGROUND

Essential oils are poor aqueous solubility and high volatility compounds. The encapsulation of essential oils with Cyclodextrins (CDs) can protect them from adverse environmental conditions and improve their stability. Therefore, increasing the functional capabilities of essential oils when they were used as additives in pharmaceutical and food systems. Additionally, the release of active compounds is an important issue. However, there were few studies about the effect of different CDs on the release of drugs after encapsulation. Therefore, the information on the study of release models is considerably limited.

OBJECTIVE

This study aimed to (i) characterize the physico-chemical properties and release behavior of myrcene encapsulated in the four different shell matrices of α-CD, β-CD, γ-CD and 2-hydroxypropyl-β- cyclodextrin (HP-β-CD), which were selected from the perspective of stability, and (ii) determine the release mechanism of myrcene in Inclusion Complexes (ICs).

METHODS

ICs of myrcene and four CDs were prepared by freeze-drying. The physico-chemical properties of ICs were fully characterized by laser diffraction particle size analyzer, Scanning Electron Microscope (SEM), Fourier-Transform Infrared spectroscopy (FT-IR) and Differential Scanning Calorimeter (DSC). The release behaviors of ICs at 50, 60, 70 and 80 °C were determined and described by zeroorder or first-order kinetics with the Henderson-Pabis, Peppas, Avrami and Page mathematical models. Moreover, the possible binding modes of ICs were identified with molecular modelling technique.

RESULTS

Firstly, the structure of Particle Size Distribution (PSD), FT-IR, DSC and SEM showed that (i) CDs could effectively encapsulate the myrcene molecules, and (ii) the release kinetics were well simulated by Avrami and Page models. Secondly, the release rates of the ICs experienced an unsteady state in the early stage, and gradually became almost constants period after 20 hours. Except that the release of myrcene in γ-CD/myrcene belonged to the first-order kinetic, the release models of the remaining three ICs belonged to diffusion mode. Thirdly, the calculated binding energies of the optimized structures for α-CD/myrcene, β-CD/myrcene, γ-CD/myrcene, and HP-β-CD/myrcene ICs were -4.28, -3.82, -4.04, and -3.72 kcal/mol, respectively. Finally, the encapsulation of myrcene with α-CD and β-CD was preferable according to the stability and release characteristics.

CONCLUSION

The encapsulation of myrcene was profoundly affected by the type of CDs, and the stability could be improved by complexation with suitable CDs. The binding behavior between guest and CD molecules, and the release profile of the guest molecules could be effectively explained by the kinetics parameters and molecular modelling. This study can provide an effective basis and guide for screening suitable shell matrices.

A Cyclodextrin-Based Controlled Release System in the Simulation of In Vitro Small Intestine

A novel cyclodextrin (CD)-based controlled release system was developed in the small intestine to control the rate of drug release, on the premise of enteric-coated tablets. The system was designed based on the enzymes exogenous β-cyclodextrin glycosyltransferase (β-CGTase) and endogenous maltase-glucoamylase (MG), wherein MG is secreted in the small intestine and substituted by a congenerous amyloglucosidase (AG). The vanillin-/curcumin-β-CD complexes were prepared and detected by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), and host CD degradation was measured based on the glucose yield. The combination of β-CGTase and AG was also functional in the CD complex system. The variations in the concentrations of added β-CGTase, with AG constantly in excess, could effectively alter the rate of host CD degradation and guest release by monitoring glucose production and color disappearance, thus, demonstrating that guest release in the CD complex system could be precisely controlled by changing the amount of β-CGTase used. Thus, the in vitro simulation of the system indicated that a novel controlled release system, based on endogenous MG, could be established in the small intestine. The CD-based controlled release system can be potentially applied in drug delivery and absorption in the small intestine.

Preparation and characterization of phloretin by complexation with cyclodextrins

RP and DPPH scavenging activity tests revealed that the antioxidant activity of phloretin improved after the formation of inclusion complexes.