Effect of protein fortification on heat damage and occurrence of ß-casomorphins in (un)digested donor human milk intended for nutrition of preterm infants.

Pasteurized donor human milk (PDHM) for preterm infant nutrition is fortified with hydrolyzates of cow's milk proteins, which have been poorly investigated in relation to heat-damage and occurrence of the bioactive peptides ß-casomorphins (BCMs). Therefore, thermal protein modifications of three commercial fortifiers were assessed by measuring well-recognized indexes of heat load. The fortifiers did not contain pyrraline, whereas furosine and lysinoalanine levels roughly overlapped the lowest values reported for liquid formulas addressed to term infant nutrition. Bovine BCMs 3 to 7 and human BCMs 3 to 9 were searched. Bovine BCMs 3, 4, 6 and 7 were found in the undigested fortifiers. Following in vitro digestion simulating the digestive conditions of premature infant, bovine BCMs still occurred in fortified PDHM; the human BCMs 3, 7, 8 and 9 formed. Overall, these results better address the nutritional features of protein fortifiers and fortified PDHM intended for nutrition of preterm infants.

bioNMR-based identification of natural anti-Aß compounds in Peucedanum ostruthium.

The growing interest in medicinal plants for the identification of new bioactive compounds and the formulation of new nutraceuticals and drugs prompted us to develop a powerful experimental approach allowing the detailed metabolic profiling of complex plant extracts, the identification of ligands of macromolecular targets of biomedical relevance and a preliminary characterization of their biological activity. To this end, we selected Peucedanum ostruthium, a plant traditionally employed in Austria and Italy for its several potential therapeutic applications, as case study. We combined the use of NMR and UPLC-HR-MS for the identification of the metabolites present in its leaves and rhizome extracts. Due to the significant content of polyphenols, particularly chlorogenic acids, recently identified as anti-amyloidogenic compounds, polyphenols-enriched fractions were prepared and tested for their ability to prevent Aß1-42 peptide aggregation and neurotoxicity in a neuronal human cell line. STD-NMR experiments allowed the detailed identification of Aß oligomers' ligands responsible for the anti-amyloidogenic activity. These data provide experimental protocols and structural information suitable for the development of innovative molecular tools for prevention, therapy and diagnosis of Alzheimer's disease.

Aspartate biosynthesis is essential for the growth of Streptococcus thermophilus in milk, and aspartate availability modulates the level of urease activity.

We investigated the carbon dioxide metabolism of Streptococcus thermophilus, evaluating the phenotype of a phosphoenolpyruvate carboxylase-negative mutant obtained by replacement of a functional ppc gene with a deleted and inactive version, Deltappc. The growth of the mutant was compared to that of the parent strain in a chemically defined medium and in milk, supplemented or not with L-aspartic acid, the final product of the metabolic pathway governed by phosphoenolpyruvate carboxylase. It was concluded that aspartate present in milk is not sufficient for the growth of S. thermophilus. As a consequence, phosphoenolpyruvate carboxylase activity was considered fundamental for the biosynthesis of L-aspartic acid in S. thermophilus metabolism. This enzymatic activity is therefore essential for growth of S. thermophilus in milk even if S. thermophilus was cultured in association with proteinase-positive Lactobacillus delbrueckii subsp. bulgaricus. It was furthermore observed that the supplementation of milk with aspartate significantly affected the level of urease activity. Further experiments, carried out with a p(ureI)-gusA recombinant strain, revealed that expression of the urease operon was sensitive to the aspartate concentration in milk and to the cell availability of glutamate, glutamine, and ammonium ions.