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Human milk is extremely complex secretion rich in biologically active glycoconjugates including free oligosaccharides, glycoproteins, glycolipids, and glycosaminoglycans. Alpha1-2-fucosylated glycoconjugates of human milk are component of the innate immune system and provide an additional defense for infants. Participation of fucosylated glycotopes in the inhibition of infections caused by some bacteria and/or viruses rely on blocking of lectin-receptors of pathogen. Free fucosylated glycoconjugates present in milk are recognized and bound by the lectin-receptors of bacteria and/or viruses, and prevent pathogens adhesion to host epithelial cells and development of infection. So far, the efficacy of fucosylated glycoconjugates of human milk in the inhibition of adhesion has been confirmed for Escherichia coli, Campylobacter jejuni, Salmonella enterica, Rotaviruses, HIV, and Noroviruses. In this process the secretor/nonsecretor status of mother plays an important role. This is particularly important for the women who are nonsecretors and whose milk does not contain α1-2-fucosylated glycoconjugates and has reduced anti-microbial properties. Fucosylated glycoconjugates of milk are also one of the energy sources for physiological bacterial flora (Bifidobacterium), and have a positive impact on the intestinal peristalsis, and indirectly stimulate the central nervous system of infants. Furthermore, compared to human milk, the content of fucosylated glycoconjugates of cow’s milk is very low and does not provide adequate protection. This fact is particularly important in terms of nutrition and should be taken into consideration when artificial mixtures based on cows’ milk are used. The paper presents the current state of knowledge on human milk glycoconjugates, particularly on α1-2-fucosylated free oligosaccharides and glycoproteins, and discusses the significance of fucosylated glycoconjugates of human milk in the nutrition of newborns and infants.

Human milk contains a lot of components (i.e. proteins, carbohydrates, lipids, inorganic elements) which provide basic nutrients for infants during the first period of their lives. Qualitative composition of milk components of healthy mothers is similar, but their levels change during lactation stages. Colostrum is the fluid secreted during the first days postpartum by mammary epithelial cells. Colostrum is replaced by transitional milk during 5-15 days postpartum and from 15 days postpartum mature milk is produced. Human milk, apart from nutritional components, is a source of biologically active molecules, i.e. immunoglobulins, growth factors, cytokines, acute phase proteins, antiviral and antibacterial proteins. Such components of human milk are responsible for specific biological activities of human milk. This secretion plays an important role in growth and development of newborns. Bioactive molecules present in the milk support the immature immune system of the newborn and also protect against the development of infection. In this article we describe the pathways involved in the production and secretion of human milk, the state of knowledge on the proteome of human milk, and the contents of components of milk during lactation. Moreover, some growth factors and proteins involved in innate and specific immunity, intercellular communication, immunomodulation, and inflammatory processes have been characterized.

Fucose is a deoxyhexose that is present in the L-configuration of many N- and O-linked oligosaccharide structures of membrane as well as soluble glycoproteins and glycolipids produced by mammalian cells. The fucose molecule is present in ABH blood group antigens and in some oligosaccharide structures belonging to the Lewis(x), Lewis(y), Lewis(a), and Lewis(b) antigens. Characteristic of fucose is its almost exclusive presence at a terminal position, i.e. not inserted in an oligosaccharide chain. Fucose can be alpha 1,2, alpha 1,3, alpha 1,4, and alpha 1,6 linked to the glycans of glycoconjugates. This predisposes fucose to play a crucial role in biological recognition events, such as cell-cell and cell-matrix interactions. In the present review the influence of fucose on the properties and biological functions of glycoproteins is described. The state of current knowledge on the role of fucosylglycotopes, fucose-containing glycans, in many physiological processes, such as fertilization, embryogenesis, fetal development, neuron transmission, leukocytes adhesion, signal transduction, and apoptosis, as well as in diseases, such as rheumatoid arthritis, cystic fibrosis, peptic ulcer disease, inflammatory process, and cancer, is summarized. Finally, some examples of changes in fucose expression and its possible determination as a marker for diseases diagnosis and monitoring are shown.

Objectives: Sialic acid is a negatively charged monosaccharide attached to non-reducing end of N- and O-linked carbohydrate chains of glycoconjugates. The claimed biological functions of sialic acid include its participation in cell to cell recognition and interaction as well as affecting the function of receptors by providing binding sites for ligand. Increased sialic acid concentration have been observed in several diseases e.g. malignancies, diabetes, inflammatory disorders, rheumatoid arthritis and alcoholism., Design: The aim of the present work was to determine if the amount of sialic acid attached to glycoconjugates of amniotic fluid changes during pregnancy., Materials and Methods: The sialic acid content in 47 samples of amniotic fluid derived from pregnant women with gestational age between 13 and 42 was studied by sialic acid specific lectins immunosorbent assay. The patient samples were divided into seven groups., Results: Time dependent changes in the degree of sialylation of glycoconjugates in amniotic fluid during pregnancy, particularly in advanced pregnancy were observed. Moreover, the highest sialic acid content on glycoconjugates in pregnancies complicated by premature rupture of membranes and is prolonged pregnancy were also detected., Conclusions: Sialic acid content determination in amniotic fluid could be a potentially useful marker of inflammation process of amniochorion during pregnancy.