Peptide Frontiers: Marine, Cardiovascular, and Nutritional Innovations

by Dr. James Ross

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Marine-Derived Peptides: Structures, Functions, and Emerging Therapeutic Promise

Over the past decades, a growing number of peptides have been identified from marine organisms. Considering that oceans cover more than two-thirds of Earth’s surface and marine species account for more than half of global biodiversity, the ocean represents an immense reservoir of bioactive molecules. Many of these peptides serve as ancient components of innate immunity, participating in processes essential to survival such as defense, reproduction, growth, and homeostasis.

These peptides have attracted the attention of pharmaceutical, nutraceutical, and cosmeceutical industries due to their broad spectrum of biological actions. Reported activities include antibacterial, antifungal, antiviral, antitumor, antioxidant, antihypertensive, antiatherosclerotic, anticoagulant, antidiabetic, analgesic, immune-regulatory, and neuroprotective effects.

Cyanobacteria

Cyanobacteria, a group of Gram-negative microorganisms, synthesize diverse secondary metabolites. Some compounds influence autophagy-related protein expression by enhancing AMPK phosphorylation and suppressing mTOR signaling. Studies on gastropod-derived acyclic molecules revealed a novel type of biotransformation involving ring opening and deletion of amino acid residues, a mechanism not previously described.

Marine Fungi

Investigations have reported 131 peptides isolated from 17 different marine fungal genera. These peptides display wide-ranging effects, including cytotoxicity against tumor cells, antimicrobial and antiviral actions, anti-inflammatory activity, and improved insulin sensitivity.

Jellyfish

Proteomic analysis of nematocysts from Rhopilema esculentum (flame jellyfish) and Sanderia malayensis identified putative toxins grouped into eight functional families. More than 60% were classified as proteases or molecules impairing hemostasis. This was the first detailed proteomic characterization of nematocysts from these jellyfish species.

Mollusks

Bioactive peptides have been identified in the immune, neuroendocrine, and digestive systems of mollusks. One notable compound, Dolastatin-10 (Dol-10), triggers apoptosis in lung cancer and other tumor cells at nanomolar concentrations. Dol-10 has progressed to commercial drug development for the treatment of specific lymphomas.

Polychaete Worms

Polychaetes are a relatively underexplored class of marine invertebrates for host defense peptides. Research has described arenicins from Arenicola marina and capitellacin from Capitella teleta, demonstrating significant biological activity.

Spanish Mackerel

Bioactive peptides have also been extracted from the skin and bones of Spanish mackerel. Among them, antioxidant peptides such as GPY, GPTGE, PFGPD, and YGPM have shown promising activity, highlighting the value of fish-derived byproducts as functional ingredients.

In total, 253 peptides were reviewed, mainly from edible marine sources, providing an informative overview of their structures and biomedical relevance.

Novel Antihypertensive Peptides Isolated from Wine Lees Hydrolysate

Hypertension, or elevated blood pressure, is a major global health concern that increases the risk of stroke, cardiovascular disease, and kidney failure. While synthetic angiotensin-converting enzyme (ACE) inhibitors are effective therapeutic agents, they are associated with undesirable side effects in some patients. As a result, natural ACE-inhibitory peptides are being investigated as alternative interventions, particularly for individuals with prehypertension who are not typically prescribed pharmacological treatments.

Wine production generates substantial quantities of byproducts, including pomace, stems, seeds, and lees. Wine lees, representing approximately 2–6% of the wine volume and up to 25% of winery waste, are a rich source of proteins and phenolic compounds. Enzymatic treatment with Flavourzyme has been used to release peptides with potential antihypertensive properties from lees.

In this study, peptides were fractionated by ultrafiltration and RP-HPLC, and those with the strongest ACE inhibitory activity were identified. Three of six peptides demonstrated IC50 values below 20 μM. Their antihypertensive effects were confirmed in spontaneously hypertensive rats after oral administration at 10 mg/kg body weight.

Among the identified sequences, FKTTDQQTRTTVA, NPKLVTIV, TVTNPARIA, LDSPSEGRAPG, and LDSPSEGRAPGAD showed significant blood pressure-lowering potential. These findings indicate that wine lees hydrolysate represents a sustainable source of bioactive peptides for managing hypertension.

Sweet-Tasting and Bioactive Peptides Derived from Mulberry Seed Proteins

With the rising global population and the increasing demand for cost-effective protein sources, plant-derived proteins have gained considerable importance. Consumers are becoming more aware of the nutritional and functional potential of plant proteins, further increasing their value in both food and health applications.

Mulberries (Morus species) are widely cultivated for their leaves, the primary diet of silkworms, as well as for their berries. The fruits are consumed fresh or processed into juice, tea, jam, and wine. Mulberry seeds, which constitute a byproduct of fruit processing, are particularly rich in protein (25–40% after defatting) and essential amino acids (nearly 29% of the total amino acid content).

In recent research, defatted mulberry seed protein hydrolysates were prepared using multifrequency countercurrent ultrasonic technology (MFCUT). This method improved protein extraction efficiency compared to single-frequency ultrasound treatment. The resulting sweet-flavored peptides exhibited antioxidant activity and suppressed the proliferation of HepG2 liver cancer cells in vitro.

Although these findings highlight the dual potential of mulberry seed peptides as natural flavor enhancers and functional bioactive ingredients, further studies are required. Specifically, the relationship between flavor characteristics and biological activity, as well as in vivo bioavailability, should be explored.

REFERENCES:

1. Bravo, F.I., Mas-Capdevila, A., López-Fernández-Sobrino, R., Torres-Fuentes, C., Mulero, M., Alcaide-Hidalgo, J.M., Muguerza, B. Identification of novel antihypertensive peptides from wine lees hydrolysate. Food Chemistry, 2021. https://doi.org/10.1016/j.foodchem.2021.130690
2. Ovchinnikova, T.V. Marine Peptides: Structure, Bioactivities, and a New Hope for Therapeutic Application. Mar. Drugs 2021, 19, 407. https://doi.org/10.3390/md19080407
3. Bian, Y-R., Li, W-J., Pan, L-H., Peng, Q-M., You, S., Sheng, S., Wang, J., Wu, F-A., Sweet-flavored peptides with biological activities from mulberry seed protein treated by multifrequency countercurrent ultrasonic technology, Food Chemistry (2021), doi: https://doi.org/10.1016/j.foodchem. 2021.130647