In Vivo Hepatoprotective Effects of a Peptide Fraction from Krill Protein Hydrolysates against Alcohol-Induced Oxidative Damage.

BACKGROUND: Krill (Euphausia superba) represent the largest animal biomass on earth, and are a rich source of high-quality protein with essential amino acids. Krill-derived peptides are renowned for their antioxidant activities. Hence, these peptides may have protective effects against oxidative stress. Alcoholic liver disease is a prevalent cause of death worldwide. The present study explores the hepatoprotective effects of krill peptide hydrolysate fractions against ethanol-induced liver damage in BALB/c mice. METHODS: Hydrolysis was carried out by mimicking the gastrointestinal digestion environment and the filtrate was fractionated based on molecular weight (<1 kDa, 1-3 kDa, and >3 kDa). The 1-3 kDa fraction (KPF), which indicated the highest antioxidant effect, was further investigated for its effect on weight and survival rate increase in mice and its influence on serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and liver cholesterol levels. Moreover, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels were measured, followed by Nrf2 and HO-1 expression. Histopathology studies were conducted to assess hepatic tissue damage. RESULTS: KPF enhanced the weight and survival rate of mice while reducing serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and liver cholesterol levels. Moreover, KPF upregulated SOD, CAT, and GPx in liver tissues, while downregulating tumor necrosis factor α and interleukin-6 mRNA expression. KPF further increased Nrf2 and HO-1 expression and suppressed ethanol-induced apoptotic proteins in the liver. Histopathology of KPF-treated mice showed less hepatic tissue damage compared to ethanol-treated mice. CONCLUSIONS: Hydrolysates and bioactive peptides prepared from krill can be employed as functional foods to enhance liver function and health. Further investigations of KPF could lead to the development of functional foods.

Cytoprotective Effects of an Aqueous Extracts from Atrina Pectinate Meat in H2O2-Induced Oxidative Stress in a Human Hepatocyte.

In the present study, we investigated the antioxidant activity of an aqueous extract from Atrina pectinate meat (APW) against H2O2-induced oxidative stress in a human hepatocyte. The extraction yield of APW was 30.01 ± 0.83% and which contained the highest taurine content among free amino acid contents. APW led to the high antioxidant activity showing 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, good reducing power and oxygen radical absorbance capacity (ORAC) value. Also, the results showed that APW improved the cell viability decreased by H2O2 stimulation as well as the reduction of intracellular reactive oxygen species (ROS) generation in hepatocytes. Additionally, APW up-regulated the production of antioxidant mechanisms related enzymes such as catalase and superoxide dismutase (SOD), compared to the only H2O2-treated hepatocytes. Moreover, APW increased the expressions of nuclear Nrf2 and cytosolic HO-1 in H2O2-treated hepatocytes. Interestingly, the treatment of ZnPP, a HO-1 inhibitor abolished the cell viability and intracellular ROS generation induced by APW treatment. In conclusion, this study suggests that APW protects H2O2 induced oxidative stress via up-regulating of Nrf2/HO-1 signal pathway in hepatocytes.

Radio-Protective Effects of Loliolus beka Gray Meat Consisted of a Plentiful Taurine Against Damages Caused by Gamma Ray Irradiation.

Gamma ray irradiation causes immune suppression, in which oxidative stress reduces cell viability and damages immune cells. In the present study, we investigated whether Loliolus beka gray meat (LBM), which contains large amounts of taurine, protects against damage of murine splenocytes by oxidative stress. An aqueous extract of LBM (LBMW) was prepared, which contained plentiful levels of taurine. LBMW improved cell viability of gamma ray-irradiated murine splenocytes, an effect that was associated with significant reduction in the production of reactive oxygen species (ROS). We also showed that the production of nitric oxide (NO) and ROS in gamma ray-irradiated zebrafish embryos, as well as the death of the embryos, were diminished by LBMW. These data suggest that the consumption of taurine-rich foods, such as LBM, may be used in the protection of cells against oxidative stress.