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We wished to investigate the role of a tilapia skin collagen polypeptide (TSCP; molecular weight <3 kDa) in alleviating liver and kidney injuries in aging mice induced by d-galactose (d-gal) and its underlying mechanism of action. First, we characterized TSCP. TSCP was passed through a 3-kDa ultrafiltration membrane, desalted in water by a solid-phase extraction column, purified further by reverse phase-high performance liquid chromatography, and analyzed by electrospray ionization mass spectrometry and tandem mass spectrometry. TSCP contained 17 types of amino acids (AAs) and 41 peptide chains of length 7 AAs to 22 AAs. The content of free AAs and total AAs of TSCP was 13.5% and 93.79%, respectively. Next, we undertook animal experiments. Mice were injected once-daily with D-gal (300 mg/kg body weight, s.c.) for 8 weeks, and TSCP was administered simultaneously once-daily by intragastric gavage. TSCP could visibly improve the decreased body weight, depressed appetite, and mental deterioration of mice triggered by d-gal. TSCP could also alleviate d-gal-induced damage to the liver and kidneys according to histopathology (especially high-dose TSCP). Consistent with these macroscopic and pathologic changes, TSCP could also prevent d-gal-induced increases in serum levels of alanine aminotransferase, aspartate transaminase, alkaline phosphatase, lipid peroxidation, creatinine and uric acid, as well as decreases in serum levels of immunoglobulin (Ig)G and IgM. Moreover, TSCP improved the activities of superoxide dismutase, catalase, and glutathione peroxidase, but also inhibited the increases in the levels of malondialdehyde and inducible nitric oxide synthase expression in the liver and kidneys of d-gal-treated mice. These results suggest that TSCP can alleviate the injuries to the liver and kidneys in aging mice induced by d-gal, and that its mechanism of action might be, at least partially, associated with attenuation of oxidative stress and enhancement of immune function., (Copyright © 2019 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Skin photoaging (SP) is a premature skin-aging damage after repeated exposure to ultraviolet (UV) radiation, mainly characterized by oxidative stress and inflammatory disequilibrium, which makes skin show the typical symptoms of photoaging such as coarse wrinkling, dryness, irregular pigmentation and laxity. Chitosan oligosaccharide (COS), a natural polysaccharide with good humectant property, is the depolymerized product of chitosan with various biological activities, among which the antioxidant and anti-inflammatory effects have been frequently reported in recent years. However, no existing invivo study indicates whether COS has direct protective effect on UV-induced SP. In the current research, we investigated the potential preventive effect of COS against UV-caused damage in hairless mouse dorsal skin. The data showed that COS, by topical application after each UV-radiation for 10 weeks, effectively inhibited the undesirable changes on the skin induced by UV. To be specific, COS obviously alleviated the macroscopic and histopathological damages of mice skin, via mitigating the disrupted collagenous fibers, as well as improving the relative content of type I collagen and the amount of total collagen. Furthermore, COS effectively inhibited the levels of pro-inflammatory cytokines such as TNF-α, IL-1β and IL-6, and markedly improved the activities of antioxidant enzymes (SOD, GSH-Px, CAT), as well as the content of skin hydroxyproline and moisture. These findings demonstrated that this natural polysaccharide attenuated UV-induced SP, at least in part, by virtue of favorable regulation of antioxidant and anti-inflammatory status, which presumably worked in concert to maintain the morphology and level of dermal collagen. [ABSTRACT FROM AUTHOR]