A Sea of Possibilities
Peptides derived from natural sources have been covered in many iterations in the PepTalk. Venoms and toxins, Maillard reaction by-products, and algae, to name a few. Next up is peptides derived from seaweed. Although it resembles a plant, seaweed is technically an algae. Seaweed can be found both in fresh and saltwater, are primitive, and originate from 4 of the kingdoms of organisms. Unlike most plants, seaweed can perform photosynthesis in all of their tissues.1
Seaweed is nutritionally dense and can be both a food source and a fertilizer. It also contains a bounty of beneficial compounds and is a relatively good source of protein and, subsequently, is a wellspring of bioactive peptides. Over the years, researchers have looked into bioactive peptides from seaweed and their potential benefits in treating cardiovascular ailments and diabetes. In cardiovascular diseases, hypertension is often seen. Many treatments focus on inhibiting angiotensin converting enzyme, or ACE, since it plays a role in regulating blood pressure as a part of the Renin-Angiotensin System (RAS). In the kidneys, renin converts angiotensinogen into angiotensin-I (an inactive compound) and then ACE converts angiotensin-I into angiotensin-II, a potent vasoconstrictor. A tetrapeptide, Val-Glu-Gly-Tyr (VEGY), was identified and found to be a potent competitive inhibitor of ACE and also stable against digestive enzymes. A myriad of other sequences that had ACE inhibitory activity were also discovered.
Not only did seaweed algae contain ACE inhibitory peptides, researchers have identified peptides that can inhibit DPPIV and others that have potent antioxidant activity. 2
Currently, most research has focused on isolating bioactive peptides from seaweed. However, there are challenges with this method. Heating that is required for improved shelf life can form bitter compounds, as well as decrease the bioavailability of lysine through Maillard reactions.3 Since several bioactive sequences have been identified, perhaps synthesis and optimization of interesting seaweed peptides is in the near future.
- H. Admassu et al., Journal of Food Science, 83(1), 6 (2018).
- C. Fitzgerald et al., J. Agric. Food Chem., 59, 6829 (2011).
Further reading: P. Cherry et al., Marine Drugs, 17, 327 (2019). Our previous PepTalk on algal blooms and peptides is here.