Rich sources and diverse bioactivities of marine bioactive peptides
The marine biome, covering nearly 70% of the Earth's surface, is a rich and underexploited source of high-value marine species, estimated to range from 500,000 to 10 million. The aquatic organisms are classified into three main categories: plankton, nekton, and benthos, showcasing the variety of marine life with significant potential for bioactive compound extraction.
Marine bioactive peptides have garnered significant attention in recent years due to their diverse biological activities and potential applications in pharmaceuticals, nutraceuticals, and cosmeceuticals. These peptides are derived from various marine sources such as fish, shellfish, and microorganisms. Their bioactivity stems from their unique amino acid sequences, which enable them to exhibit antioxidant, antimicrobial, antihypertensive, and immunomodulatory properties, among others.
Fig 1. Various marine resources and their representative marine bioactive peptides. [1]
Marine bioactive peptides from Alfa Chemistry
Isolation and purification of marine peptides
- Extraction and initial purification techniques
The extraction of bioactive peptides from marine sources can be achieved using organic solvents such as methanol or ethyl acetate. The extracted peptides are then concentrated and further partitioned with solvents like hexane, carbon tetrachloride, or dichloromethane. Subsequent purification steps may involve techniques such as silica gel or size exclusion chromatography, where solvents of increasing polarity are used to elute the desired peptides.
- Isolation from protein digestion
Alternatively, bioactive peptides can be obtained through the digestion of proteins from marine organisms using enzymes like pepsin, trypsin, α-chymotrypsin, or papain. Following enzymatic digestion, the hydrolysates are screened for bioactivities, fractionated by ultrafiltration based on size, and subjected to purification using reverse-phase HPLC or size exclusion chromatography.
- Industrial-scale production methods
In industrial-scale production, while traditional organic solvent extraction methods have been used, modern approaches such as supercritical fluid extraction, pressurized solvent extraction, microwave-assisted extraction, and enzyme-assisted extraction are preferred for their efficiency and environmental friendliness.
- Membrane filtration and advanced technologies
Following hydrolysis, membrane filtration techniques are utilized to concentrate and separate bioactive peptides based on their molecular weights. Ultrafiltration membranes with specific molecular weight cutoffs are used for peptide separation, while nanofiltration membranes are employed for desalting and purification purposes. The emergence of ultrafiltration membrane bioreactor technology offers a novel approach to fractionate marine hydrolysates based on different molecular weight ranges, enhancing the efficiency of peptide extraction and purification.
In vivo stability of marine peptides
The in vivo stability of marine-derived peptides is influenced by various factors, primarily dependent on the peptides' size, structure, and specific characteristics that distinguish them from peptides obtained from other sources.
The size of the peptide affects its transport from the lumen to enterocytes and influences the mode of transport, whether paracellular, transcellular, or via peptide transporters such as PEPT1 and PEPT2. Additionally, the type of amino acid residues and the peptide's conformation significantly influence its susceptibility to degradation by gastrointestinal proteases. Notably, the presence of proline residues in peptide sequences promotes increased stability towards protease degradation.
Marine-derived peptides exhibit distinct features that contribute to their enhanced in vivo stability compared to peptides from other sources. These characteristics include a high percentage of proline and branched amino acid residues, the presence of both d and l amino acids, cyclic structure, existence as depsipeptides, the presence of unusual amino acid residues such as bromotryptophan, and the presence of secondary structures like alpha helix and beta sheets.
References
- Ishtiaq Ahmed, et al. Mar. Drugs, 2022, 20(3), 208.
- Kellie L. Tuck, et al. Marine Drugs, 2015, 13(7), 4006-4043.
- Milica Pavlicevic, et al. Marine Drugs, 2020, 18(8), 424.
For Research Use Only. Not for use in diagnostic or therapeutic procedures.
