Screening for metabolic syndrome application of a herring by-product hydrolysate after separation by electrodialysis with ultrafiltration
The seafood industry is an important producer of by-products which can represents 50% of fish and contain valuable molecules for the human health. The research of bioactive peptides has increased since the last decades and marine organisms revealed a high richness. A herring milt hydrolysate has been separated by electrodialysis with ultrafiltration membrane (EDUF). Four fractions were collected: two anionic and two cationic, with respectively higher presence of acidic amino acids for the first ones and basic amino acids for the seconds. The higher migration rate was reported for the cationic, revealing the higher presence of cationic peptides and free basic amino acids in the initial milt herring hydrolysate. Both cationic fractions have decreased the inducible nitric oxide synthase (iNOS) activation in the macrophage cells at 1ng/ml (-11.65% and -13.22%) and 100pg/ml (-17.58% and 15.51%), demonstrating their in vitro anti-inflammatory effect. The oxygen radical absorbance capacity (ORAC) test, revealed an antioxidant activity of 460.67µmolTE/g for the initial hydrolysate, 386.20µmolTE/g after EDUF separation and 343.49 µmolTE/g for the anionic fraction. No effects on the glucose uptake activity was reported for any fraction. In addition two new cationic peptide sequences (IVPAS and FDKPVSPLL) from herring milt hydrolysate were identified and demonstrated an in vitro anti-inflammatory activity. This study highlighted the potential use of milt herring hydrolysate for metabolic syndrome.