Abstract:  To investigate the regulation of four kinds of food-derived peptides with oral administration on the oxidative and inflammatory system of photoaging skin in SD rats，SD rats with SPF grade were equally distributed as normal group，model group with ultraviolet irradiation and peptides oral administration groups before UV exposure． Before experiment，about 5 cm2 of dorsal hair in all animals were completely removed off and except the animals in normal group， the other animals were exposed to UV irradiation to establish the photoaging model． At the same time， the low，middle and high-dose peptides solution was prepared by dissolving the peptides into water to obtain the concentration of 0. 3，0. 9，and 1. 5g/L， respectively． Consequently，as the sole drinking source， the peptides solution was orally administrated to the SD rats in peptides treating groups． The animals in UV and peptides administration groups were continuously exposed to UV irradiation until the photoaged model was established． After scarification，about 1g of dorsal skin was homogenated in a refiner，with 10% homogenate solution for biochemical detection． The content of methane dicarboxylic aldehyde ( MDA) and the antioxidase activity of SOD，CAT and GSHPX were detected by biochemical assay and the content of inflammatory cytokines of interleukin1β ( IL1β) ， IL2， IL6，IL10 and transforming growth factor β ( TGF-β) were determined by enzymelinked immunosorbent assay ( ELISA) ． The results illustrated that the concentration of MDA， IL1β and IL6 in skin tissue of model group were significant higher while the content of antiinflammatory cytokines of IL2， IL6， IL10 and TGF-β were significantly decreased and the anti-oxidase activity of SOD，CAT and GSH-PX were significantly lower than those in normal control group ( P ＜ 0. 05) ． In comparison with model group，peptides groups exhibited desirable and remarkable regulation on the oxidative and inflammatory status with a dose-dependency manner． On the whole， the remarkable difference among the four kinds of food-derived peptides in protecting skin from photoaging process was observed， in which the sample 2 at high dose enhanced the anti-oxidase activity， reduced the lipid peroxidation level，and improved the immunity suppression and cellular microenvironment． Therefore the peptide of sample 2 can be used as the primary ingredient for developing functional food against photoaging． 

Key words:  SD rat, skin photoaging, peptides, oxidation status, inflammatory regulation