Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

The objective of this study is to prepare a novel delivery vector, glycyrrhetinic acid -conjugated-β-cyclodextrin (GA-CD) for liver targeting, and investigate the effects of the emodin-GA-CD inclusion complex (E-GA-CD complex) on liver cancer therapy. GA-CD was synthesized from GA and CD, and was used to encapsulate emodin to form an E-GA-CD complex. Proton nuclear magnetic resonance spectroscopy, two-dimensional rotating-frame Overhauser effect spectroscopy, and differential scanning calorimetry were used to characterize GA-CD and the E-GA-CD complex. Liver cell targeting bioactivity of the E-GA-CD complex was investigated by cellular uptake, cell viability, and biodistribution. In vitro results revealed that the E-GA-CD complex exhibited increased cellular uptake and cytotoxicity against Hep3B cells compared to free emodin. In vivo biodistribution results indicated that mice treated with the E-GA-CD complex exhibited greater emodin uptake in liver tissue than emodin-treated mice, suggesting that the E-GA-CD complex was effective in targeting liver cells.

A simple and cost-effective method for the synthesis of sulfated β-cyclodextrin, one of the most widely used chiral mobile phase additives, using sulfamic acid as a sulfonating agent has been described. The method was optimized, and the synthesized product was characterized by spectroscopic, size-exclusion chromatographic, thermal, and microscopic methods and was compared to the marketed Sigma Aldrich sulfated β-cyclodextrin. β-Cyclodextrin, hydroxypropyl β-cyclodextrin, sulfated β-cyclodextrin (marketed and synthesized) were evaluated as chiral mobile phase additives for the enantiomeric separation of cloperastine, an antitussive agent, using reversed-phase HPLC. Under optimized conditions, a resolution of 3.14 was achieved within 15 min on an achiral Kromasil C₈ (150 × 4.6 mm, 5 µm) column, with 5 mM monopotassium phosphate containing 10 mM synthesized sulfated β-cyclodextrin pH 3.0 and 45% methanol as mobile phase. The method utilizing synthesized sulfated β-cyclodextrin as chiral mobile phase additive was validated as per ICH guidelines and applied for the quantitative determination of cloperastine enantiomers in active pharmaceutical ingredients and pharmaceutical formulations. The selectivity changes imparted by sulfated β-cyclodextrin were proven to be beneficial for chiral separation. For the enantiomeric separation of cloperastine, synthesized sulfated β-cyclodextrin afforded better resolution than marketed sulfated β-cyclodextrin.

Doxycycline hyclate is Biopharmaceutical Classification System, class I drug (high solubility and high permeability), but it is associated with poor photostability. It is in the class of tetracycline antibiotic, which is used to treat various infections, but its bioavailability is compromised due to its sensitivity to light and aqueous instability. In this paper, the influence of inclusion complexation with different cyclodextrins, i.e., αCD, γCD, HPβCD and RMβCD, on the photostability of doxycycline hyclate in aqueous media was investigated. Host–guest inclusion complexes were prepared by freeze- drying method. The prepared complexes were characterized for drug content, SEM, XRPD, in vitro permeation studies and photostability studies. XRPD showed diffused peaks for most of the complexes, while SEM showed irregularly shaped particles. The formulation D20 (Drug: γCD in 1:20 molar ratio) showed the highest % drug content (83.72 ± 1.2%), and the formulations D1 (Drug: αCD in 1: 2 molar ratio) showed the lowest % drug content among all the CD complexes. It was found that the photodegradation of the drug was reduced significantly upon complexation. For Drug: CD complexes, the photostability of the aqueous solution of drug/CD complexes was found to be in the order of γCD > RMβCD > HPβCD > αCD with maximum photostability shown by Drug: γCD (1:20 molar ratio) complex. The obtained results suggested that cyclodextrin complexation can be used as an alternative approach for increasing the photostability of doxycycline hyclate.

Molecular dynamics simulations were performed in aqueous solution to elucidate an atomistic level picture of complex formation between cucurbit[7]uril (CB7) and three standard aromatic amino acids: tyrosine, tryptophan, and phenylalanine. It was found that all three amino acids formed stable host–guest complexes with CB7, in which the side chain was included inside the hydrophobic cavity and the ammonium and carboxylate groups were excluded. The major forces driving complexation, as calculated from the MM-PBSA method, were the electrostatic and van der Waal interactions. To better understand the effect of pH and the roles of the ammonium and carboxylate groups in the complexation process, simulations were performed for phenylalanine considering different protonation state (at low and high pH) as well as for the deaminated and decarboxylated forms of phenylalanine. The results showed that, compared to phenylalanine at neutral pH (exists as zwitterion), low pH resulted in an increased complex stability for the cationic form, deamination and high pH reduced the stability, while decarboxylation did not result in a significant change. Results from quantum-chemical calculations correlated well with the simulation data.

Graphical abstract

A series of azobenzene-bridged dipillar[5]arenes were conveniently synthesized by coupling reaction of aminoalkyl-functionalized pillar[5]arenes with azobenzene-4,4’-dioxyacetic acid or azobenzene-4,4’-dioxybutanoic acid in dry chloroform under the combinatorial catalysis of HOBt/EDCl. ¹H NMR, 2D NOESY spectra and single crystal structure clearly indicated that the unique bis-[1]rotaxanes could be formed by threading two diaminoalkylene units into the two cavities of pillar[5]arenes depending on the length of the diaminoalkylene chains. Under light irradiation at 365 nm, the trans-azobenzene unit transferred to cis-configuration, while the basic bis-[1]rotaxane structure was kept unchanged.

Graphic abstract

The aim of this study was for the first time to determine the effect of 11 buffers on a γ-cyclodextrin complex, and use these and previous reported data to systematically explore the effect of buffers on different cyclodextrin complexes, considering differences in cavity size and exterior between the cyclodextrins. The effect of 11 buffers on the binding between γ-cyclodextrin and the bile salt taurochenodeoxycholate was determined using isothermal titration calorimetry, and the stability constant of the complex ranged from 6.1 × 10⁴ to 9.0 × 10⁴ M⁻¹, depending on the buffer species. Three buffers (citric, maleic and 2-morpholinoethane-sulfonic acid) decreased the stability constant of the complex compared to the stability in water, though to a degree that has limited practical relevance. As for other cyclodextrin complexes, the stability constant depended on the buffer species present in solution. The analysis showed that the size of the cyclodextrin cavity, rather than the exterior, was paramount for the effect of carboxylic acid buffers, suggesting formation of regular inclusion complexes between carboxylic acid buffers and cyclodextrins.

Among gynaecological cancers, ovarian cancer is known to be highly sensitive to chemotherapy. However, it is often detected at an advanced stage since it exhibits few early symptoms, and therefore, patients tend to show poor prognosis. Therefore, the development of new anticancer agents for the treatment advanced stage cancers is required. We previously reported that folic acid-modified methyl-β-cyclodextrin (FA-M-β-CyD) is a promising anticancer agent that exhibits selective antitumor activity in cancers cells. However, the antitumor effect of FA-M-β-CyD in ovarian cancer is not known. Therefore, in this study, we investigated the antitumor effect of FA-M-β-CyD in ovarian cancer. FA-M-β-CyD showed excellent cytotoxic activity in the reduced folate carrier (RFC) positive human ovarian cancer ES-2 cells line. We found that the cytotoxic activity of FA-M-β-CyD in ES-2 (RFC+) cells is unlikely to be a result of apoptosis triggered by a decrease in mitochondrial membrane potential. Moreover, FA-M-β-CyD prolonged the survival of BALB/c nude mice bearing ES-2 (RFC+) cells. These results suggest the potential of FA-M-β-CyD as an antitumor agent for treatment of metastatic ovarian cancer.