Study On The Preparation Of Collagen Peptide From Eel Skin And Its Improvement On Skin Photoaging

Eels(Anguilla)are widely distributed in coastal areas of China,which has the high edible and medicinal value,but also produce lots of leftover wastes.Fish skin is a good extraction material of collagen.This study takes eel skin as research object and discussed the characteristics of the structure of collagen extracting by acid extraction and enzymatic extraction method.The collagen of eel skin was digested using an in vitro gastrointestinal digestion model.The hydrolysis was selected to produce collagen polypeptides.The antioxidant mechanism of polypeptides was investigated by different tests in vitro.Protective effects of eel skin collagen and collagen polypeptides on UV-irradiated skin photoaging of mice were discussed.The determination of the basic nutritional components of the eel skin found that the protein in the dry matter of the eel skin was 77%,and the proportion of the other components was very small.The loss of collagen in the extraction process of acid extraction and enzymatic extraction was discussed and study the structural characteristics of the collagen extracting ASC and PSC by two extraction methods.Collagen loss analysis results are as follows:the yield of ASC was 18.68%(dry weight),the yield of PSC was 29.92%(dry weight);the purity of ASC was 85.7%,PSC was 80.8%;in the process of extraction of collagen to non-collagen,degreasing,salting out respectively caused by the loss of the collagen was 50.74 mg/and 100 g,10.40 mg/100 g,2.29 mg/100 g.Protein electrophoresis found that ASC and PSC may have(α1)3 structure,similar to I type collagen.The FTIR spectra showed that they had the same functional groups,the low structure and high structure similarity were high,while collagen retained a large number of three helix structure.The collagen of eel skin was digested by human gastrointestinal digestive fluid.Three collagen peptides of different molecular weight(Mr>5 kDa>、kDa<Mr<5 kDa、Mr<3 kDa)are obtained by separation and purification,freeze drying.By several in vitro chemical test,the antioxidant abilities of different ultrafiltration fractions were compared.The results showed that:the eel skin collagen peptide of DPPH-,HO-and O2·-showed strong radical scavenging activity,peptides with lower molecular weight,free radical scavenging activity increases,and there is a dose-response relationship;Caco-2 cells eel skin collagen peptide of H2O2 under oxidative stress has protective effect.The ultraviolet induced mice skin photoaging model was used to study the protective effect of the eel skin collagen and collagen peptide on UV damage.The results showed that the physiological activity of collagen peptide was higher than collagen,and it could effectively alleviate the photoaging of skin caused by ultraviolet radiation.Eel skin collagen peptide increased the visceral index of photoaging mice,prevented the atrophy and degeneration of immune organs,and alleviated skin aging.Eel skin collagen peptide can improve the activities of SOD,GSH-Px,CAT and other antioxidant enzymes in skin and serum of photoaging model mice,reduce the MDA content(P<0.05,P<0.01),thereby alleviating the oxidative stress caused by ultraviolet radiation,and balancing the oxidation environment in vivo.The collagen peptide of eel skin can effectively maintain the moisture of the skin.The results show that the morphology of skin tissue,eel skin collagen peptide can effectively improve the degree of disorder of photoaging skin in a mouse model of accessory organs,improve the arrangement and distribution of elastic fibers,increase the content of collagen fiber,and promote the skin of photoaging mice.