1. Antibacterial activity
Antibacterial active peptides are usually derived from animals, plants, and microorganisms, or obtained through immune insects. Most antibacterial peptides are composed of fewer than 50 amino acids, exhibiting basic or positive charge characteristics, primarily consisting of lysine and arginine. They possess both hydrophilic and lipophilic properties.The hydrophilicity allows them to dissolve in body fluids, while the lipophilicity enables them to bind with bacterial cell membranes, forming small pores that lead to the leakage of substances beneath the sensitive bacterial cell membrane, ultimately inhibiting bacterial growth until death. Antibacterial peptides demonstrate strong lethal effects against some bacteria, fungi, protozoa, viruses, and cancer cells. Clinical trials have also shown that antibacterial peptides can enhance the body's ability to resist pathogenic microorganisms, and they are less likely to develop resistance in the body, indicating a wide range of application prospects.
2. Immunoactivity
Many bioactive peptides derived from plants and animals have the function of regulating immunity. Researchers have extracted immune-active peptides from the degradation products of casein, which can activate the phagocytic ability of macrophages. These immune-active peptides can interact with intestinal mucosa-associated lymphoid tissue and can penetrate the intestinal wall to directly affect peripheral lymphocytes. Thymosin, as an immune factor, has been applied in clinical medicine and has achieved significant results in the treatment of infections and immunodeficiency. Soy protein is a food source that can provide immune-active peptides. Studies have shown that Pan Cuiling and others found that the enzymatic hydrolysates of soy protein and casein can stimulate peripheral blood lymphocyte transformation induced by PHA in 10-day-old piglets to varying degrees, with the enzymatic hydrolysates of soy protein showing the most significant promoting effect on lymphocyte transformation. In addition to soy peptides, peptides produced from the degradation of proteins in dairy products also play an important role in immune regulation.
Immunologically active peptides mainly regulate the immune function of the body by modulating the function of lymphocytes, influencing the production of antibodies, affecting the function of mononuclear macrophages, regulating the secretion of cytokines, and impacting the conduction of calcium ions within lymphocytes, the activity of second messengers cAMP and cGMP, as well as the secretion of nitric oxide and inducible nitric oxide synthase in macrophages. They can stimulate the proliferation of lymphocytes, enhance the phagocytic ability of macrophages, and improve the body's ability to resist infections from external pathogens, thereby reducing the disease incidence.
Some peptide fragments with immunostimulatory effects have been found in casein from human milk and cow's milk, which can enhance the phagocytic ability of macrophages. In addition, after appropriate enzymatic treatment, milk proteins, soy proteins, and rice proteins can also produce peptide substances with immune activity.
3.Antioxidant effect
Antioxidant active peptides, when added to meat products as preservatives, can effectively prevent the degradation of oxidized fatty acids, thus having a wide application potential in the food and animal feed industries. Studies have shown that enzymatic hydrolysates of soy protein also contain peptides with antioxidant activity. Chen and others extractedmultiple peptides with antioxidant functions from the enzymatic hydrolysates of soy, and these peptides inhibit the lipid peroxidation of linoleic acid. Currently, a few antioxidant peptides such as carnosine and glutathione have been studied in depth.
Carnosine is a substance found in animal muscle that can inhibit lipid oxidation reactions catalyzed by iron, hemoglobin, lipoxygenase, and singlet oxygen in vitro. Some peptides and protein hydrolysates have the ability to remove heavy metals and promote the decomposition of hydrogen peroxide, thereby reducing the rate of self-oxidation, decreasing the content of hydrogen peroxide in fats, and consequently reducing the generation of free radicals. Antioxidant active peptides, such as carnosine, glutathione, and soy protein hydrolysates, serve as natural antioxidants and have advantages like low toxicity and high efficacy, showing a good prospect for application.
The antioxidant mechanism of peptides includes providing hydrogen to antioxidant enzymes, chelating metal ions, and capturing free radicals. In living organisms, many substances with antioxidant activity are proteins. Due to their excellent emulsifying properties, they can mediate at the oil-water interface, which is of great significance in eliminating excess free radicals in the body and inhibiting lipid oxidation in membranes.
Post time: 2025-09-01