Inclusion complexes between chrysin and amino-appended ß-cyclodextrins (ACDs): Binding behavior, water solubility, in vitro antioxidant activity and cytotoxicity.

Solid inclusion complexes between chrysin and four amino-appended ß-cyclodextrins (ACDs) were prepared by suspension method and characterized in solid and solution states by kinds of analytical methods. The scanning electron microscopy (SEM) showed distinct micro-morphologies of them. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis revealed their unique thermal properties, such as decomposition temperatures and endothermic points. Powder X-ray diffractometry (XRD) analysis disclosed their unique crystal patterns. Their nuclear magnetic resonance (NMR) analyses provided the variations of chemical shifts before and after the formation of inclusion complexes. Their binding stability constants (Ks) were 574, 842, 704, and 474 L·mol-1, respectively, as determined by spectral titration. A 1:1 inclusion mode with self-assembly of their amino side chains inside the ACD cavity was proposed based on Job plot and 2D-ROESY experiments. Water solubility of chrysin was promoted up to 4411.98 µg·mL-1 after formation of inclusion complexes with ACDs, better than that of ß-CD and its derivatives, i.e., HP- and SBE-ß-CD. In vitro antioxidant activity of chrysin was also improved after inclusion complexation by the DPPH scavenging assay. Furthermore, in vitro cytotoxicity of solid inclusion complexes towards three human cancer cell lines, A549, HT-29 and HCT116 were enhanced significantly.

Solid inclusion complexes of oleanolic acid with amino-appended ß-cyclodextrins (ACDs): Preparation, characterization, water solubility and anticancer activity.

Oleanolic acid (OA) is a pentacyclic triterpenoid acid of natural abundance in plants which possesses important biological activities. However, its medicinal applications were severely impeded by the poor water solubility and resultant low bioavailability and potency. In this work, studies on solid inclusion complexes of OA with a series of amino-appended ß-cyclodextrins (ACDs) were conducted in order to address this issue. These complexes were prepared by suspension method and were well characterized by NMR, SEM, XRD, TG, DSC and Zeta potential measurement. The 2:1 inclusion mode of ACDs/OA complexes was elucidated by elaborate 2D NMR (ROESY). Besides, water solubility of OA was dramatically promoted by inclusion complexation with ACDs. Moreover, in vitro anticancer activities of OA against human cancer cell lines HepG2, HT29 and HCT116 were significantly enhanced after formation of inclusion complexes, while the apoptotic response results indicated their induction of apoptosis of cancer cells. This could provide a novel approach to development of novel pharmaceutical formulations of OA.