Food-derived peptidic antioxidants: A review of their production, assessment, and potential applications

Lipases (triacylglycerol ester hydrolases, EC 3.1.1.3) are ubiquitous enzymes that catalyze the breakdown of fats and oils with subsequent release of free fatty acids, diacylglycerols, monoglycerols and glycerol. Besides this, they are also efficient in various reactions such as esterification, transesterification and aminolysis in organic solvents. Therefore, those enzymes are nowadays extensively studied for their potential industrial applications. Examples in the literature are numerous concerning their use in different fields such as resolution of racemic mixtures, synthesis of new surfactants and pharmaceuticals, oils and fats bioconversion and detergency applications. However, the drawbacks of the extensive use of lipases (and biocatalysts in general) compared to classical chemical catalysts can be found in the relatively low stability of enzyme in their native state as well as their prohibitive cost. Consequently, there is a great interest in methods trying to develop competitive biocatalysts for industrial applications by improvement of their catalytic properties such as activity, stability (pH or temperature range) or recycling capacity. Such improvement can be carried out by chemical, physical or genetical modifications of the native enzyme. The present review will survey the different procedures that have been developed to enhance the properties of lipases. It will first focus on the physical modifications of the biocatalysts by adsorption on a carrier material, entrapment or microencapsulation. Chemical modifications and methods such as modification of amino acids residues, covalent coupling to a water-insoluble material, or formation of cross-linked lipase matrix, will also be reviewed. Finally, new and promising methods of lipases modifications by genetic engineering will be discussed.

Customizing lipases for biocatalysis: a survey of chemical, physical and molecular biological approaches

Bovine whey proteins – Overview on their main biological properties

The first function attributed to lactoferrin (Lf), an iron binding protein belonging to the non-immune natural defences, was antimicrobial activity that depended on its capacity to sequester iron. Iron-independent microbicidal activities, requiring direct interaction between this cationic protein and microbial surface components, were later demonstrated. Many other anti-microbial and anti-viral functions have since been ascribed to Lf. In mucosal secretions, iron and Lf modulate the motility and aggregation of pathogenic bacteria. Lf inhibits bacterial adhesion on abiotic surfaces through ionic binding to biomaterials, or specific binding to bacterial structures or both. Lf inhibition of bacterial adhesion to host cells requires Lf binding to bacteria and/or host cells. Lf hinders microbial internalization by binding to both glycosaminoglycans and bacterial proteins which can be degraded by Lf-mediated proteolysis. Moreover, Lf internalisation and localisation to the host cell nuclei could modulate bacterial entry into cells through gene regulation. Finally, the capability of Lf to exert antiviral activity, through its binding to host cells and/or viral particles, strengthens the idea that it is an important brick in the mucosal wall, effective against both microbial and viral attacks.

Lactoferrin: an important host defence against microbial and viral attack.

Antioxidant properties of ultrafiltration-recovered soy protein fractions from industrial effluents and their hydrolysates

Inhibition from binding of Cholera toxin (CT) to Chinese hamster ovary (CHO)-K1 cells and ganglioside GM1 by lactoferrin (Lf) and K-casein glycomacropeptide (GMP) from cow’s milk was examined. Both Lf and GMP effectively reduced the CT-derived morphological changes in CHO-K1 cells. The competitive binding assay demonstrated that both Lf and GMP inhibited the binding of CT to GMH although their affinity for CT was lower than that of GM1. The inhibitory effect of Lf and GMP seemed to be attributed to their terminal sialic acid, although the sugar chain sequence only partially fitted to the CT-receptor.

Inhibition by Lactoferrin and κ-Casein Glycomacropeptide of Binding of Cholera Toxin to its Receptor

Natto water-soluble fractions, low-molecular-weight viscous substance, and soybean water extract, which had an inhibitory effect on the oxidation of low-density lipoproteins (LDL) in vitro, were fed to rats for 3 weeks. These fractions had no influence on the growth of rats, which were fed a basal diet containing 1% cholesterol, but lowered plasma triglyceride and total cholesterol. Inhibition of copper-oxidation of plasma and LDL ex vivo, and a reduction in lipid peroxidation in liver and aorta in vivo, were also observed. The antioxidant enzymes were not induced in rats fed natto fraction diets. These results demonstrate that ingestion of the natto fractions led to inhibition of LDL oxidation, and that the fractions perform direct antioxidant action in the body. It is suggested that natto fractions might help to prevent arteriosclerosis, as they appear to reduce lipid peroxidation and improve lipid metabolism.

Antioxidative functions of natto, a kind of fermented soybeans: effect on LDL oxidation and lipid metabolism in cholesterol-fed rats

(1993). Inhibition by κ-Casein Glycomacropeptide and Lactoferrin of Influenza Virus Hemagglutination. Bioscience, Biotechnology, and Biochemistry: Vol. 57, No. 7, pp. 1214-1215.

Inhibition by κ-Casein Glycomacropeptide and Lactoferrin of Influenza Virus Hemagglutination

“Delicious peptide” was reported to be as delicious as beef soup. The peptide and its fragments were synthesized to study its taste active sites. “Delicious peptide” was found to produce a umami and a sour taste. By preparing several di- or tripeptides composed of basic or acidic amino acids, we found that the taste of “delicious peptide” was produced by an interaction between the basic and the acidic fragments in the peptide.

The Relationship between Taste and Primary Structure of “Delicious Peptide” (Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala) from Beef Soup

Adherence is an essential and prerequisite step for the colonization of mucosal surfaces by enterotoxigenic Escherichia coli (ETEC). We studied the effect of bovine lactoferrin (BLF) on the adherence of ETEC to human epithelial cells in vitro, and to intestinal mucosa of ICR germfree mice in vivo. In the in vitro study, BLF was found to inhibit the adherence of ETEC. This adhesion-inhibiting activity of BLF was found to lessen with decreasing BLF concentration, but the data obtained suggest a positive inhibitory effect of BLF against the adhesion of ETEC cells. In the in vivo study, the counts of adherent bacteria in various sections of the intestinal tract (duodenum, jejunoileum, and large intestine) were lower in the BLF group than in the control group, suggesting the possible action of BLF as an intestinal tract adherence-blocking agent with regards to ETEC.

Yoshihiro Kawasaki

Papers

Inhibition by Lactoferrin and κ-Casein Glycomacropeptide of Binding of Cholera Toxin to its Receptor

Antioxidative functions of natto, a kind of fermented soybeans: effect on LDL oxidation and lipid metabolism in cholesterol-fed rats

Inhibition by κ-Casein Glycomacropeptide and Lactoferrin of Influenza Virus Hemagglutination

The Relationship between Taste and Primary Structure of “Delicious Peptide” (Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala) from Beef Soup

Inhibitory effects of bovine lactoferrin on the adherence of enterotoxigenic Escherichia coli to host cells.