A novel bioactive peptide named τ-AnmTx Ueq 12-1 (short name Ueq 12-1) was isolated and characterized from the sea anemone Urticina eques. Ueq 12-1 is unique among the variety of known sea anemone peptides in terms of its primary and spatial structure. It consists of 45 amino acids including 10 cysteine residues with an unusual distribution and represents a new group of sea anemone peptides. The 3D structure of Ueq 12-1, determined by NMR spectroscopy, represents a new disulfide-stabilized fold partly similar to the defensin-like fold. Ueq 12-1 showed the dual activity of both a moderate antibacterial activity against Gram-positive bacteria and a potentiating activity on the transient receptor potential ankyrin 1 (TRPA1). Ueq 12-1 is a unique peptide potentiator of the TRPA1 receptor that produces analgesic and anti-inflammatory effects in vivo. The antinociceptive properties allow us to consider Ueq 12-1 as a potential analgesic drug lead with antibacterial properties.

Red king crab and snow crab have both become important species for the Norwegian seafood industry. Since the first commercial harvest of red king crab in 2002 and of snow crab in 2012, the Norwegian seafood industry has developed new technology and knowledge for handling these species. This includes new fishing gear, conditions for live storage and processing, handling of byproducts, and entrance into new markets. The total Norwegian quota for red king crab increased from 220 metric tons in 2002 to 2350 metric tons in 2017, with a free-red king crab harvesting zone to the west of the quota-regulated area to prevent further expansion of the crab. At present, there is no established quota for snow crab. In 2016, a volume of about 5300 metric tons of snow crab was landed in Norway. In 2016, the export of red king crab and snow crab in Norway amounted to 529 million and 338 million Norwegian Kroner, respectively. Based on regular surveys of crab populations in the Barents Sea, it is assumed that the volumes red king crab and snow crab will remain steady and increase, respectively. Thus, these industries will continue to be important to the Norwegian seafood industry.

The global problem of microbial resistance to antibiotics has resulted in an urgent need to develop new antimicrobial agents. Natural antimicrobial peptides are considered promising candidates for drug development. Echinoderms, which rely on innate immunity factors in the defence against harmful microorganisms, are sources of novel antimicrobial peptides. This study aimed to isolate and characterise antimicrobial peptides from the Edible sea urchin Echinus esculentus. Using bioassay-guided purification and cDNA cloning, three antimicrobial peptides were characterised from the haemocytes of the sea urchin; two heterodimeric peptides and a cysteine-rich peptide. The peptides were named EeCentrocin 1 and 2 and EeStrongylocin 2, respectively, due to their apparent homology to the published centrocins and strongylocins isolated from the green sea urchin Strongylocentrotus droebachiensis. The two centrocin-like peptides EeCentrocin 1 and 2 are intramolecularly connected via a disulphide bond to form a heterodimeric structure, containing a cationic heavy chain of 30 and 32 amino acids and a light chain of 13 amino acids. Additionally, the light chain of EeCentrocin 2 seems to be N-terminally blocked by a pyroglutamic acid residue. The heavy chains of EeCentrocins 1 and 2 were synthesised and shown to be responsible for the antimicrobial activity of the natural peptides. EeStrongylocin 2 contains 6 cysteines engaged in 3 disulphide bonds. A fourth peptide (Ee4635) was also discovered but not fully characterised. Using mass spectrometric and NMR analyses, EeCentrocins 1 and 2, EeStrongylocin 2 and Ee4635 were all shown to contain post-translationally brominated Trp residues in the 6 position of the indole ring.

EeCentrocin 1 is a potent antimicrobial peptide isolated from the marine sea urchin Echinus esculentus. The peptide has a hetero‐dimeric structure with the antimicrobial activity confined in its largest monomer, the heavy chain (HC), encompassing 30 amino acid residues. The aim of the present study was to develop a shorter drug lead peptide using the heavy chain of EeCentrocin 1 as a starting scaffold and to perform a structure‐activity relationship study with sequence modifications to optimize antimicrobial activity. The experiments consisted of 1) truncation of the heavy chain, 2) replacement of amino acids unfavourable for in vitro antimicrobial activity, and 3) an alanine scan experiment on the truncated and modified heavy chain sequence to identify essential residues for antimicrobial activity. The heavy chain of EeCentrocin 1 was truncated to less than half its initial size, retaining most of its original antimicrobial activity. The truncated and optimized lead peptide (P6) consisted of the 12 N‐terminal amino acid residues from the original EeCentrocin 1 HC sequence and was modified by two amino acid replacements and a C‐terminal amidation. Results from the alanine scan indicated that the generated lead peptide (P6) contained the optimal sequence for antibacterial activity, in which none of the alanine scan peptides could surpass its antimicrobial activity. The lead peptide (P6) was also superior in antifungal activity compared to the other peptides prepared and showed minimal inhibitory concentrations (MICs) in the low micromolar range. In addition, the lead peptide (P6) displayed minor haemolytic and no cytotoxic activity, making it a promising lead for further antimicrobial drug development.

The abundance of fish and zooplankton (1 × 109 tons to 7 × 1010 tons) in the mesopelagic zone of the ocean is a source of novel raw materials that provides opportunities for sustainable new product development. The peculiar conditions of light and pressure in this ecological zone and the position of the specific organisms in the marine food chain results in diversity in their bio-composition. Mesopelagic fish are an underutilized resource, rich in proteins and omega-3 oils, and present opportunities to develop novel feed, food and functional food ingredients and products. However, there is also a need to ensure that this resource is not overfished and is processed to optimize the catch in line with sustainability goals. There is therefore a need to establish sustainable bioprocessing technologies to yield value added products from mesopelagic fish species. In the present study, various protein extracts from the mesopelagic fish Maurolicus muelleri (M) and Meganyctiphanes norvegica (Northern Krill) (K) and combinations of proteins from these species (C) were generated using hydrolysis methods. Protein Hydrolysates were generated using four different enzymes including Alcalase, endocut-01, endogenous M/K enzymes and FoodPro PNL. Hydrolysates were characterized and assessed for their ability to inhibit enzymes important in diseases associated with metabolic syndrome. The ability of generated Hydrolysates to inhibit enzymes including Angiotensin-1-converting enzyme (ACE-1; EC. 3.4.15.1) associated with blood pressure regulation, Acetylcholinesterase (AChE; EC 3.1.1.7) associated with maintenance of the nervous system, and Dipeptidyl peptidase IV (DPP-IV; EC 3.4.14.5) linked with development of type-2-diabetes, was determined. In a separate process, the same mesopelagic fish species were transformed into fishmeal, Hydrolysates, fish-silage, and aqueous extracts (AQ) and screened for bioactivities using the same bioassays. The Hydrolysates contained greater than 60% protein (dry weight basis) when analyzed using the DUMAS method. A hydrolysate from M. muelleri generated using FoodPro PNL (M1) inhibited the ACE-1 enzyme by 89.56% when assayed at a concentration of 1 mg/ml compared to the positive control Captopril©. Aqueous extract two (AQ2) inhibited ACE-1 by 95.28% when assayed at 1 mg/ml compared to the control. Sample M1 inhibited DPP-IV by 100% and aqueous extract one (AQ1) inhibited the same enzyme by 90.08% when assayed at a concentration of 1 mg/ml compared to Sitagliptin used as the positive control. All samples assayed did not significantly inhibit the enzyme AChE–fraction C3 (combined hydrolzate 3: Krill and M. muelleri) inhibited AChE by 27.48% only. Based on these results samples M1, C3, and AQ1 were selected for further characterization and the IC50 values for each were determined in relation to ACE-1 and DPP-IV inhibition as well as their amino acid composition. Glutamate and aspartate were the most abundant amino acids in the selected samples. IC50 values of <0.2 mg/ml and distinct terminal amino acids were identified in each of the three fractions. The study shows that targeting processing of mesopelagic fish have potential to generate Hydrolysates for use in the prevention of type-2-diabetes and hypertension.