كليدواژه :
Curcumin , Curcumin degradation products , Horseradish peroxidase , Stability , DMSO , Thermal
چكيده فارسي :
Curcumin is a polyphenol compound that can be degraded to diverse chemical species. It has a variety of biological activities like antioxidant, antinflammatory, antitumour, antimicrobial and anticancer activities. Curcumin is stable in acidic conditions, but degrades to the other products in basic pH values. Degradation products of curcumin include ferulic acid, ferulic aldehyde, feruloyl methane, vanillin, and trans-6-(4 -hydroxy-3 -methoxyphenyl)-2,4-dioxo-5-hexenal. Our previous investigation indicated that curcumin increases activity of the peroxidase enzyme and enhances its tolerance against oxidative conditions. Here, we are trying to find out if curcumin and its degradation products increase stability of the peroxidase enzyme on the other desaturating conditions. To do this, the effect of mentioned compounds on stability of Horseradish peroxidase (HRP) against high temperatures and organic solvent was evaluated. The enzyme activity was measured with colorimetric method and its structure was evaluated by fluorescence spectroscopy. The results of fluorescence spectroscopy indicated that the emission intensity of HRP increases and red-shift occurs in the spectra upon addition of DMSO. This result implied that DMSO causes to denaturing of HRP. Curcumin and its degradation products have no remarkable effect on the stability of the enzyme in dimethyl sulfoxide (DMSO). In addition, they decrease thermal stability of HRP slightly. In agreement with the previous observations, our results indicated that curcumin and its degradation products increase stability of HRP at high concentration of hydrogen peroxide. Curcumin is more effective than the degradation products for increasing oxidative stability of the enzyme. It can be concluded that curcumin stabilizes the peroxidase enzyme on the oxidative condition without any remarkable effect on stability of the enzyme on the other denaturing condition
