RESUMEN
A series of experiments were performed to systematically analyze the effect of nanoparticle (NP) size on the catalytic behavior of enzyme-NP conjugates, and a shielding model based on diffusion-collision theory was developed to explain the correlation between the size effects and the kinetic responses.
Asunto(s)
Biocatálisis , Lipasa/química , Lipasa/metabolismo , Modelos Químicos , Nanopartículas/química , Tamaño de la Partícula , Candida/enzimología , CinéticaRESUMEN
Kinetic and thermodynamic studies reveal that the property of significantly enhanced catalytic activity with colloidal stability is attributed to an efficacious means of tuning enzyme-substrate association by varying with the rate constants in the presence of functionalized gold nanoparticles.
Asunto(s)
Enzimas Inmovilizadas/metabolismo , Oro/química , Lipasa/metabolismo , Nanopartículas del Metal/química , Biocatálisis , Coloides/química , Cinética , Tamaño de la Partícula , Cloruro de Sodio/química , Propiedades de Superficie , TermodinámicaRESUMEN
Cirsium arisanense Kitamura (Compositae) has been used for hundreds of years in Taiwan as a folk medicine for hepatoprotection. However, no scientific research has demonstrated this effect. In the present study, we extracted the phenol-containing aqueous components of C. arisanense roots (CaR) and leaves/stem (CaL), and then assessed their hepatoprotective activities in both human hepatocellular carcinoma Hep 3B cells and C57BL/6 mice strain. High performance liquid chromatography (HPLC) analysis revealed that the components of CaR and CaL differed from those of the positive control silymarin. CaR exhibited a higher phenolic content and antioxidant capacity than CaL. Hep 3B cells treated with silymarin (0-200 microg/ml) demonstrated a concentration-dependent decrease in viability; however, both CaR and CaL did not exhibit any apparent cytotoxicity. Silymarin at 100 microg/ml, as well as CaR and CaL, not only protect Hep 3B cells from tacrine-induced hepatotoxicity but also decrease the expression of hepatitis B surface antigen (HBsAg). Moreover, an animal experiment demonstrated that CaR, CaL, and silymarin have hepatoprotective effects in C57BL/6 mice injected with tacrine, and they significantly decrease the levels of plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST). These effects of CaR and silymarin, but not of CaL, may occur via an increase in the hepatic glutathione level and the elimination of the nitric oxide production. In conclusion, the phenol-containing aqueous components from C. arisanense have potential in hepatoprotection.