| Summary: | The aquatic ecosystem represents a large number of organisms adapted to living conditions remarkably different from the land-living ones. For instance fish generally possess an eminent bioactive defense to protect them from the high bacterial load in water, and must be expected to harbor a large number of bio-components such as bioactive peptides for this purpose. Tissue and proteins from e.g. fish gills, skin and viscera could be a new source of peptides that could have a nutritional and pharmaceutical value, and be used in health and functional foods and thereby increasing the value adding of secondary marine products. Only few naturally occurring bioactive peptides have been characterized such as the antimicrobial polypeptide piscidines from gills. It is therefore hypothesized, that fish tissue also contains numerous other peptides with other bioactive properties. The approach in this project is therefore to extract and identify naturally occurring bioactive peptides from different tissues from salmon. A number of aqueous extracts were made from gills, skin and belly flap. In order to preserve the bioactivity of the peptides mild extraction procedures as acidic, basic and aqueous solutions were used. Combination of different extraction conditions such as with/without boiling, with/without inhibitor and variation of pH resulted in a total of 36 extracts. The activity of the extracts was analyzed in vitro for ACE (angiotensin-converting enzyme) inhibiting activity, and anti-oxidative activity (Free Radical Scavenging assay). A number of extracts showed high ACE inhibiting and anti-oxidative activity. The extracts were then size fractionated by ultrafiltration using a 10 kDa filter, and relevant fractions below 10 kDa from gills, skin and belly flap were further fractionated by gel-filtration on a Superdex peptide HR 10/30 column. Peptide fractions were collected and freeze-dried and will be further characterized with LCMS and MS/MS.
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