Lactoferrin and its protein degradation product, lactoferrin peptide, have a wide range of biological activities, including broad-spectrum antibacterial action, anti-inflammatory, inhibiting the growth of tumor cells and regulating the immune response of the body. It is considered as a new antibacterial and anticancer drug and a food and cosmetic additive with great development potential. For example, the US Food and Drug Administration has long allowed lactoferrin to be used as a food additive in sports and functional foods. In recent ten years, laboratories all over the world have conducted extensive research on the functions of lactoferrin, especially its biological functions, and many new functions are being discovered. Many experiments in vivo and in vitro have proved that lactoferrin does have the functions of anti-microorganism, immunomodulation, anti-infection and tumor growth inhibition. The possible biological functions of lactoferrin are shown in the figure below.
Biological functions are as follows:
First, participate in iron metabolism and promote iron absorption.
Lactoferrin can improve the bioavailability of iron by intestinal cells, stabilize reduced iron ions and reduce the stimulation of iron ions on gastrointestinal tract. Lactoferrin can maintain the iron balance in the body by regulating the absorption of iron by intestinal mucosal cells according to the body's demand for iron.
Second, the anti-microbial function.
Among the many biological functions of lactoferrin, the antimicrobial activity is the most striking. Lactoferrin has different degrees of inhibition and killing effects on many microorganisms, including G+ and G- aerobic bacteria, anaerobic bacteria and some fungi.
Third, antiviral effect.
Lactoferrin is a member of non-specific immune system, which has unique antiviral activity, mainly by binding with the surface proteins of virus or host cells or both, and plays an antiviral role in the process of virus adsorption and invasion.
Fourth, immune regulation and anti-infection.
Studies have shown that lactoferrin is a component of human innate nonspecific immune system, which plays an anti-microbial role by inhibiting microbial reproduction, adsorption or (and) killing microorganisms on the surface of secretion and epithelial cells, and participates in the anti-inflammatory process of the body.
Fifth, anti-tumor.
Although iron-saturated lactoferrin can promote the proliferation of normal cells, it can prevent rather than stimulate cancer cells.
Sixth, the antioxidant effect.
Under normal circumstances, the intracellular antioxidant defense system keeps the generation and elimination of free radicals in a dynamic balance state and will not cause damage to tissues and cells of the body.
Seven, as a cell growth factor.
With the research on the effect of lactoferrin on osteoblasts, it was found that lactoferrin can not only promote the proliferation and differentiation of primitive osteoblasts at physiological concentration, but also reduce the apoptosis of osteoblasts, inhibit the proliferation of osteoclasts and promote the survival opportunity of osteoblasts.
Eight, other physiological functions
1, inhibit the accumulation of cholesterol and participate in lipid metabolism: Lactoferrin can decrease cholesterol and triacylglycerol in liver and blood by increasing the concentration of high-density lipoprotein (HDL) and decreasing the concentration of low-density lipoprotein (LDL), and participate in lipid metabolism.
2. Regulation of gene transcription: After lactoferrin binds to some cell surface receptors, such as nucleolin, it enters the cell by endocytosis and is transmitted to the nucleus, and then binds to specific DNA and RNA sequences to regulate the transcription process of these genes.
3. Antithrombotic effect: Lactoferrin receptor is expressed on platelet membrane, which can prevent platelet aggregation after adenosine diphosphate (ADP) treatment; Lactoferrin can prevent fibrinogen from combining with ADP-activated platelets; Lactoferrin can prevent platelet aggregation, thrombosis, release of serotonin and expression of α -granule membrane protein.
4. Analgesic effect: Under natural conditions, exogenous lactoferrin is usually derived from mammalian milk, which is not easy to produce tolerance, and lactoferrin itself has a significant anti-injury effect. Therefore, it is suggested that lactoferrin may become a natural drug for treating pain.