The composition of organisms adapted to habitat in the aquatic environment, including fish, is represented by a variety of biologically active compounds. Of particular value are peptides – substances whose molecules are built from two or more amino acid residues. They possess antihypertensive, immunomodulatory, anticoagulant, antioxidant, antitumor, antimicrobial properties. On the basis of fish peptides are synthesized pharmacological preparations and bioactive food supplements.
Fish as a source of peptides
More than 300,000 species of organisms live in the seas, oceans, rivers and lakes, 15,000 of which are predominantly fish. Previously, they were considered solely as a food resource. The inclusion of fish in the diet allows you to provide the body with the necessary substances for life:
• complex carbohydrates;
• polyunsaturated fatty acids;
• dietary minerals;
• fat- and water-soluble vitamins.
Now for the pharmacological industry, fish peptides, their organic compounds which regulate the state of cells are of particular interest. These substances are found in soft tissues, scales, bones, cartilage, gills. To obtain peptides, not only fish tissues are used, but also any fish waste remaining after their processing, which is about 20–50% of all raw materials. Their use for the needs of pharmaceutical factories was the solution to the economic and environmental problems of waste disposal.
Therapeutic effect of peptides
Developed sensory organs are necessary for fish to survive in the aquatic environment, as well as the coordinated work of all vital systems. It is especially worth highlighting the strong immunity of fish for inhibiting and destroying pathogenic microorganisms. Its formation occurs due to the production of specific peptides with a pronounced antimicrobial action. Such peptides contain saliva, mucus, and the blood of fish — the environments in which disease-causing agents are primarily implanted.
Pharmaceuticals in the human body are metabolized, interact not only with the affected tissues, but also with absolutely healthy cells. This leads to malfunction of the liver, kidneys, gastrointestinal tract. Therefore, fish peptides that do not exhibit the aggression characteristic of chemicals are of particular interest to science. Thanks to the biologically active peptides, the cells begin to work properly, stimulating regeneration processes. For peptides, a restoration effect is characteristic – recovery of a damaged organ occurs against the background of increased activity of the immune system.
Peptides application spectrum
Fish bioactive peptides differ from proteins in their amino acid composition and amino acid sequence. Due to the peculiarities of the structure, they exhibit numerous therapeutic properties. The mechanisms of action of peptides vary considerably, so scientists are looking for and successfully find methods whose use increases one or another effect from the use of bioactive substances. It has been proven that peptides have the following pharmacological activity:
The therapeutic effect of peptides is determined by their chemical structure, charge and other structural features. Penetrating into the human body, peptides selectively act on damaged tissue. They stimulate the formation of young and healthy cells that can function for much longer.
Methods for producing peptides from fish
The leading methods for the isolation of peptides from raw materials in the fish industry are liquid extraction using caustic acids, alkalis, enzymes, as well as the precipitation or salting out of high-molecular substances from previously prepared decoctions. Methods of obtaining vary depending on the type of initial products, the technological base of the manufacturer, and the quality standards of the finished product.
Enzymatic hydrolysis is especially in demand – the extraction of bioactive peptides using proteolytic enzymes: protease, a-chymotrypsin, trypsin, papain, bromelain. These are enzymes of natural origin contained in the original microbial, plant and animal raw materials.
The advantage of enzymatic hydrolysis is the high integrity of amino acids. They are practically not destroyed and do not enter into additional reactions that may adversely affect therapeutic efficacy. Such hydrolysis is also:
• ecologically safe;
• carried out in “mild” conditions (at a temperature of 35-50 degrees and atmospheric pressure);
• does not require high energy costs.
It should be noted that in fish proteins peptides are in inactive forms. They are activated by creating a number of favorable conditions, including during enzymatic hydrolysis. When proteins interact with water and enzymes, their decomposition occurs with the formation of biologically active substances.
Molecular weight, structure and sequence of amino acids determine the physico-chemical properties of peptides. To isolate a peptide with a specific pharmacological effect, the raw materials undergo stepwise enzymatic hydrolysis. In the production process, specific enzymes are used. As a result, hydrolysates with different molecular weights are obtained. To separate them into fractions, membrane ultrafiltration is used. To set the structure of a peptide with a specific effect allows changing the conditions at a certain stage of production. For this, technologists lower or increase the temperature of the raw material or determine the time of extraction and precipitation.