Protective Effects Of Extracts Of Maize Plumule On Oxidative Damage Of Mice Skin Irradiated By Ultraviolet A

In order to investigate the protective effects of the extracts of maize plumule (EMP) on the oxidative damage of mice skin induced by ulraviolte A at the whole organism level and cell level in vitro, the oxidative damage model of mice skin and fibroblast irradiated by ulraviolet A were established.In the mice experiment, the mice were randomly divided into control group, UVA model group, EMP +UVA group and VitC+UVA group; the ultrastructure of skin was observed under electron microscope; the contents of MDA, activities of SOD and CAT in the supernates of mice skins were detected by biochemical method, so as to evaluate the protective effects of EMP on the oxidative damage of mice skin at morphological and biochemical levels. In the fibroblasts experiment, the cells were randomly divided into control group, UVA model group, EMP +UVA group and NAC+UVA group; fibroblasts were cultured by tissue inoculation method and enzymatic digestion method, with DMEM as basic medium; establishment of cell oxidative damage model was based on irradiation dose-cell vitality curve obtained by trypan-blue staining reject test and MTT colorimetry method; the contents of MDA, activities of SOD, CAT, GSH-Px and ratio of GSH/GSSG in fibroblasts were detected by biochemical method; the morphology was observed by hematoxylin-eoxin staining and phase-contrast microscope; the level of BCL-2 and the translocation of NF-κBp65 were detected by immunocytochemical technique; the expression of matrix metalloproteinases-2 and matrix metalloproteinases-9 (mRNA level) were examined by semi-quantitative RT-PCR.Mice experiment results were as follows: cell structural damages and cell apoptosis characters in fibroblasts and epidermic cells of mice skin in UVA model group were observed under electron microscope, and slight cell damages were found in EMP protected groups; EMP could decrease the amounts of MDA (P<0.05) and increase the activities of SOD (P<0.01) and CAT (P<0.05) in mice skins irradiated by UVA. Cell experiment results were as follows: large amounts of cells of high activities could be obtained by enzymatic digestion method in a shorter period; cell crimple, condensation of nuclear chromatin in UVA model group were observed afer a irradiation dose of 7.5 J/cm2, whereas normal cell structure and slighter cell crimple were found in EMP protected groups; EMP could decrease the amounts of MDA (P<0.05), yet increase the activities of SOD, CAT and GSH-Px (P<0.05) and ratio of GSH/GSSG (P<0.05) in fibroblasts irradiated by UVA; EMP could also maintain the level of BCL-2 protein, prohibit the translocation of NF-κBp65, and decrease the expression of metalloproteinases-2 and matrix metalloproteinases-9 at mRNA level in fibroblasts irradiated by UVA.The results indicated that the EMP could protect the oxidative damage of skin biomacromolecules induced by irradiation of ultraviolet A, and maintain the morphology and function of skin histiocyte. The mechanism were probablely due to its abilities to scavenge oxygen free radical or block its producing pathway, maintain activities of anti-oxidant enzymes and redox state, and inhibit expression of oxidative stress-raleted genes which may be promoted by translocation of nuclear transcription factor NF-κBp65; it may have relations with its abilities of maintaining the level of BCL-2 to prohibit cell apoptosis and increase cell anti-oxidative capacity.