Abstract
The biggest obstacles in the application of marine peptides are two-fold, as in the case of non-marine plant and animal-derived bioactive peptides: elucidating correlation between the peptide structure and its effect and demonstrating its stability in vivo. The structures of marine bioactive peptides are highly variable and complex and dependent on the sources from which they are isolated. They can be cyclical, in the form of depsipeptides, and often contain secondary structures. Because of steric factors, marine-derived peptides can be resistant to proteolysis by gastrointestinal proteases, which presents an advantage over other peptide sources. Because of heterogeneity, amino acid sequences as well as preferred mechanisms of peptides showing specific bioactivities differ compared to their animal-derived counterparts. This review offers insights on the extreme diversity of bioactivities, effects, and structural features, analyzing 253 peptides, mainly from marine food sources. Similar to peptides in food of non-marine animal origin, a significant percentage (52.7%) of the examined sequences contain one or more proline residues, implying that proline might play a significant role in the stability of bioactive peptides. Additional problems with analyzing marine-derived bioactive peptides include their accessibility, extraction, and purification; this review considers the challenges and proposes possible solutions.
Highlights
Marine peptides have only fairly recently garnered deserved attention, their potential to generate classes of peptides with interesting properties such as antiaging, antituberculosis, anticoagulant, and antidiabetic makes them promising agents in medicine and pharmacy [1,2,3], and in the cosmetic industry [4,5,6].Because of the beneficial interactions of the marine peptides with phenolic compounds [7], and to the improved emulsifying and foaming properties [8], their usage in the food industry has proven to be valuable
Since the majority of antimicrobial peptides included in this analysis are isolated from fish and bivalves (Figure 3) this could be an additional factor accounting for a large difference in content of positively charged and polar amino acids among antimicrobial peptides from marine and animal sources
Given that ACE inhibitors isolated from marine fish and algae show non-competitive inhibition as a mechanism of action [131,132] this could explain a slightly higher ratio of aromatic and aliphatic amino acid residues in peptides isolated from marine sources compared to animal sources
Summary
Marine peptides have only fairly recently garnered deserved attention (especially compared to peptides from other plant/animal sources), their potential to generate classes of peptides with interesting properties such as antiaging, antituberculosis, anticoagulant, and antidiabetic makes them promising agents in medicine and pharmacy [1,2,3], and in the cosmetic industry [4,5,6]. Reason why BIOPEP was chosen for peptide selection is two-fold: first, it is currently the most inclusive database, since it encompasses all bioactive peptides, regardless of their origin, effect, or length, with 4031 entries as of August 2020. It provides additional information, such as in cases of ACE inhibitors, EC50 value, and type of organism from which peptide(s) were extracted. We included peptides ranging from 2 to 40 amino acid (AA) residues in length, reporting their sequence, the source from which they were isolated, their bioactive effect, and their EC50 value (where available) (Table S1). We compared results for marine peptides with results for peptides from food of non-marine animal origin (taken from 30) to see if there are differences between sequences of peptides exhibiting the same effect in different types of food sources
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