The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

Anti-inflammatory potential of baicalein combined with silk fibroin protein in a zebrafish model (Danio rerio)

Baicalein (BA) is a flavonoid with wide-ranging pharmacological activity. However, its biological evaluation is hampered by its low solubility in aqueous medium, making forms of incorporation that improve its solubility necessary. In the present study, BA was combined with a solution of silk fibroin protein (SF), a biomaterial used too as a drug carrier, to evaluate the anti-inflammatory potential of this combination, in vivo, in an experimental model, zebrafish (Danio rerio). Baicalein-silk fibroin (BASF) improved the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical scavenging rate (95%) in comparison with BA in solution. The acute toxicity study and histopathological analysis in zebrafish showed that BASF has low cytotoxic potential, except for the maxim dose of 2000 mg/kg. The use of BA in combination with SF enhanced the anti-inflammatory effect of flavonoids by inducing inflammatory peritoneal edema through carrageenan and achieved 77.6% inhibition of abdominal edema at a dose of 75 mg/kg. The results showed that the BASF, significantly increases the bioavailability and therapeutic effect of flavonoids and several results observed in this study may help in the development of new drugs.

Host-guest interaction and properties of cucurbit[8]uril with chloramphenicol

The interaction between cucurbit[8]uril (Q[8]) and chloramphenicol (CPE) was investigated using single-crystal X-ray diffraction spectroscopy, isothermal titration calorimetry (ITC) and UV–vis, NMR and IR spectroscopy. The effects of Q[8] on the stability, in vitro release performance and antibacterial activity of CPE were also studied. The results showed that CPE and Q[8] formed a 1:1 inclusion complex (CPE@Q[8]) with an inclusion constant of 5.474 × 10⁵ L/mol. The intervention of Q[8] did not affect the stability of CPE, but obviously reduced the release rate of CPE in artificial gastric and intestinal juice; Q[8] has a slow-release effect on CPE. The antibacterial results showed that the minimum inhibitory concentration (MIC) of CPE and CPE@Q[8] toward Escherichia coli (E. coli) was 1.5 × 10^–3 and 1.0 × 10^–3 mol/L, respectively, and toward Staphylococcus aureus (S. aureus), the MIC was 2.0 × 10^–3 mol/L for both CPE and CPE@Q[8]. Therefore, Q[8] enhanced the inhibitory activity of CPE against E. coli.

The Cyclobutanocucurbit[5-8]uril Family: Electronegative Cavities in Contrast to Classical Cucurbituril while the Electropositive Outer Surface Acts as a Crystal Packing Driver

The structural parameters for the cyclobutanoQ[5-8] family were determined through single crystal X-ray diffraction. It was found that the electropositive cyclobutano methylene protons (CH2) are important in forming interlinking crystal packing arrangements driven by the dipole-dipole interactions between these protons and the portal carbonyl O of a near neighbor. This type of interaction was observed across the whole family. Electrostatic potential maps also confirmed the electropositive nature of the cyclobutano CH2 but, more importantly, it was established that the cavities are electronegative in contrast to classical Q[5-8], which are near neutral.

Host-guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

In this study, we investigated the host-guest interactions between oroxin A (OA) and cucurbit[8]uril (Q[8]) using 1H NMR, MS, UV-vis and IR spectroscopy. The results showed that OA and Q[8] formed an inclusion compound (OA@Q[8]) with a molar ratio of 1:1 and a binding constant of 1.299 × 107 L·mol-1. In addition, the effect of Q[8] on the properties of OA was investigated through comparative experiments. The solubility of OA in water increased 22.47-fold when the concentration of Q[8] was 1 × 10-4 mol·L-1. Q[8] hardly affected the antioxidant capacity of OA, while the cumulative release of OA in gastric juice increased 2.3-fold after forming the inclusion compound with Q[8].