RESUMO
The present work was aimed at the influence of ethanol on the complex formation of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) with oleanolic acid (OA) and ursolic acid (UA), two insoluble isomeric triterpenic acids. Phase solubility studies were carried out to evaluate the solubilizing power of HP-beta-CD, in association with ethanol, toward OA and UA. A mathematical model was applied to explain and predict the solubility of OA and UA influenced by HP-beta-CD and ethanol. The solid complexes were prepared by evaporating the filtrate of samples which was prepared in different complexing media. The solubility of OA is much higher than that of UA in all the tested aqueous solutions. The solubility of OA and UA can be increased over 900 and 200 times, respectively, by forming complex with HP-beta-CD. Ethanol (0.5%, v/v) can help the formation of OA-HP-beta-CD complex, but is harmful to the formation of UA-HP-beta-CD complex. Increasing solubility in water can be achieved by adding ethanol into the complexing media, but the concentration of ethanol should be optimized. The ring E of the chemical compounds has a great influence on the complexing process.
Assuntos
Etanol/química , Ácido Oleanólico/química , Triterpenos/química , beta-Ciclodextrinas/química , 2-Hidroxipropil-beta-Ciclodextrina , Cromatografia Líquida de Alta Pressão , Processamento Eletrônico de Dados , Solubilidade , Ácido UrsólicoRESUMO
Exposure to ultraviolet B (UVB) irradiation is a major risk factor for the development of skin cancer. Therefore, it is important to identify agents that can offer protection against UVB-caused DNA damage. Photocarcinogenesis is caused largely by mutations at the sites of incorrectly repaired DNA photoproducts, of which the most common are the cyclobutane pyrimidine dimers (CPDs). In this study, a DNA damage model of UVB irradiation-induced fibroblasts was established. The immunocytochemical staining, immuno dot blotting and Western blotting were employed in the study. We demonstrated that pre-treatment of fibroblasts with Baicalin dose-dependently reduced the amount of UVB-generated CPDs. Compared with UVB irradiated cells, UVB-induced p53 accumulation was less pronounced in Baicalin-treated cells. Taken together, these results suggest that Baicalin prevent CPDs formation induced by UVB. Baicalin is therefore a promising protective substance against UVB radiation.
Assuntos
Dano ao DNA/efeitos da radiação , Fibroblastos/efeitos da radiação , Flavonoides/farmacologia , Dímeros de Pirimidina/efeitos da radiação , Células Cultivadas , Pré-Escolar , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , Relação Dose-Resposta a Droga , Medicamentos de Ervas Chinesas/farmacologia , Exposição Ambiental/efeitos adversos , Fibroblastos/química , Fibroblastos/metabolismo , Humanos , Lactente , Recém-Nascido , Masculino , Dímeros de Pirimidina/química , Dímeros de Pirimidina/genética , Proteína Supressora de Tumor p53/antagonistas & inibidores , Proteína Supressora de Tumor p53/genética , Raios Ultravioleta/efeitos adversosRESUMO
The fluorescence enhancement of berberine (Berb) as a result of complex with beta-cyclodextrin (beta-CD) is investigated. The association constants of alpha-CD and beta-CD with Berb are 60 and 137 M(-1) at 20 degrees C in pH 7.20 aqueous solution. Effects of temperature on the forming inclusion complexes of beta-CD with Berb have been examined through using fluorescence titration. Enthalpy and entropy values calculated from fluorescence data are -33.7 kJ mol(-1) and 74.3 J x mol(-1) K(-1) respectively. It was found that the dielectric constant of beta-CD cavity is about 24 in a rough analogy with absolute alcohol. These results suggest that the extrusion of 'high energy water' molecules from the cavity of beta-CD and hydrophobic interaction upon the inclusion complex formation are the main forces of the inclusion reaction. Effect of pH on the association of beta-CD with Berb was also studied. Mechanism of the inclusion of beta-CD with Berb is further studied by absorption and NMR measurements. Results show that beta-CD forms a 1:1 inclusion complex with Berb.
