RESUMO
The present study was aimed to investigate the role and mechanisms of kallistatin in protection against oxidative stress-induced hepatic stellate cell damage. The effects of kallistatin on the viability, the intracellular superoxide level and Akt, eNOS molecules were investigated in human hepatic stellate cell line LX-2 and the incompletely activated primary rat hepatic stellate cells. Two different oxidative-stress related models, the hydrogen peroxide model and the iron-overload model were used in the experiments. The results show that kallistatin protected the hepatic stellate cells from oxidative damage and repaired the cell damage by oxidative stress. The main mechanism is antioxidant activity of kallistatin, which can remove the oxidized substances inside the cells. On the other way, kallistatin activates Akt and eNOS molecules to generate the antioxidant effect. Our results help to explore new anti-fibrotic targets.
RESUMO
In order to prepare antioxidant peptide through hydrolyzing low-value protein resources with bacterial extracellular proteases and to discover novel proteases, crude extracellular protease from Pseudoalteromonas sp. SHK1-2 was obtained through fermentation which was used to hydrolyze collagen extracted from Cirrhinus molitorella skin. Small peptide fraction was isolated from hydrolysate by ultrafiltration and Sephadex LH-20 size exclusion chromatography and showed 1, 1-diphenyl-2-picrylhydrazyl radical scavenging activity (35.6%±7%), oxygen radical absorbance capacity and inhibition of DNA oxidation damage. The molecule weight was 776.2 Da, and amino acid sequence was Thr-Ala-Gly-His-Pro- Gly-Thr-His through liquid chromatography mass spectrum. Our findings suggest that peptide obtained from low-value protein of fish waste by hydrolysis with bacterial protease has antioxidant activity.