Identification of phosphorylated components in milk of different species

Milk is a biological fluid well suited for nutritional studies and diagnostic purposes, as it can be collected routinely and noninvasively. 31P high-resolution NMR spectroscopy does not require an extensive chemical manipulation of samples and can easily highlight differences and/or similarities between samples as complex as milk. 31P NMR analysis using detergents, a method already used for the analysis of plasma and erythrocyte membrane phospholipid composition, showed the presence, in all milk samples analyzed, of hydrolysis products of phosphatidylcholine and phosphatidylethanolamine: glycerophosphorylcholine (GPC), known for its neuroprotection effect on age-related oxidative damage, glycerophosphorylethanolamine (GPE) and phosphorylcholine (PC). Phosphocreatine is also present except in human and cow milk. In addition, minor phosphorylated sugars, that probably are metabolic intermediates of biochemical pathways, were identified (galactose-1-phosphate, N-acetylglucosamine-1-phosphate) in greater amounts in donkey milk than in human, cow, goat and camel milk. These data confirm the natural variability of milk samples among different species. Moreover, this simplified method could be proposed to carry on a comparative study of phosphorylated components, used as membrane stabilizers in the antioxidant therapy.