No abstract

A soy protein isolate was hydrolyzed with Alcalase®, Flavourzyme® and their combination, and the resulting hydrolysates (A, F and A + F) were ultrafiltered and analyzed through SDS-PAGE. Fractions with MW < 1 kDa were investigated for their ACE-inhibitory activity, and the most active one (A < 1 kDa) was purified by semi-preparative RP-HPLC, affording three further subfractions. NMR analysis and Edman degradation of the most active subfraction (A1) enabled the identification of four putative sequences (ALKPDNR, VVPD, NDRP and NDTP), which were prepared by solid-phase synthesis. The comparison of their ACE-inhibitory activities suggested that the novel peptide NDRP might be the main agent responsible for A1 fraction ACE inhibition (ACE inhibition = 87.75 ± 0.61%; IC50 = 148.28 ± 9.83 μg mL−1). NDRP acts as a non-competitive inhibitor and is stable towards gastrointestinal simulated digestion. The Multiple Reaction Monitoring (MRM) analysis confirmed the presence of NDRP in A < 1 kDa.

A library of alkyl galactosides was synthesized to provide the “polar head” of sugar fatty acid esters to be tested as non‐ionic surfactants. The enzymatic transglycosylation of lactose resulted in alkyl β‐D‐galactopyranosides, whereas the Fischer glycosylation of galactose afforded isomeric mixtures of α‐ and β‐galactopyranosides and α‐ and β‐galactofuranosides. n‐Butyl galactosides from either routes were enzymatically esterified with palmitic acid, used as the fatty acid “tail” of the surfactant, giving the corresponding n‐butyl 6‐O‐palmitoyl‐galactosides. Measurements of interfacial tension and emulsifying properties of n‐butyl 6‐O‐palmitoyl‐galactosides revealed that the esters of galactopyranosides are superior to those of galactofuranosides, and that the enantiopure n‐butyl 6‐O‐palmitoyl‐β‐D‐galactoside, prepared by the fully enzymatic route, leads to the most stable emulsion. These results pave the way to the use of lactose‐rich cheese whey as raw material for the obtainment of bio‐based surfactants.

Sugar fatty acid esters are a relevant class of surfactants. Base catalyzed transesterification of lower esters may be carried out on an industrial level. Direct esterification of fatty acids with sugars over heterogeneous catalysts should be more environmental friendly, however this approach is quite challenging. The activity of montmorillonites has been investigated in the acylation of d‐glucose with palmitic acid and the number of Lewis acid sites on the catalyst surface measured through FTIR of adsorbed pyridine. The use of a ketone, namely acetylacetone, as solvent allows the formation of an acetal between the sugar and the solvent itself, increasing the solubility of the substrate, with a maximum of conversion when using FeIII exchanged montmorillonite K10 as the catalyst. The main reaction product was the dipalmitate ester with an acetal group at the 1,2 position of d‐glucose. This product with a hydrophilic lipophilic balance (HLB) of 4.9 shows interesting properties as surfactant with a CMC value close to 0.036% wt/v measured in sunflower oil.

Inositol phosphates and inositol phospholipids are ubiquitous in biochemistry and play a central role in cell signaling and regulation events. For this reason, their synthesis has attracted widespread interest. This paper describes the preparation of a new optically active inositol phosphate derivative, 2‐O‐acetyl‐3,4,5,6‐tetra‐O‐benzyl‐d‐myo‐inosityl diphenylphosphate (6), and its characterization by spectroscopic methods. Compound (6) represents a useful intermediate for the preparation of inositol phosphate and phospholipids, in particular of glycerophosphoinositol (GPI), a natural anti‐inflammatory agent.

Umami taste is elicited predominantly by monosodium glutamate (MSG) and purine 5'-ribonucleotides, in particular guanosine and inosine 5'-monophosphates (GMP and IMP). A significant peculiarity of umami compounds is their capacity to interact synergistically. A possible explanation of such phenomenon is that both l-glutamate and ribonucleotides may interact simultaneously with the "Venus flytrap" domain of T1R1/T1R3 umami receptor, but at different sites. Starting from this model, we reasoned that hybrid compounds, containing the two umami moieties covalently connected through flexible linkers of variable length, could be able to reach both umami receptor sites through a single molecule, thus giving an insight into the mechanism of synergism. MD simulations suggested that a chain of at least eight carbon atoms is requested to allow the interaction of both l-glutamate and 5'-ribonucleotide with their respective binding sites. We report here the synthesis of such hybrids starting from 2',3'-O-isopropylidene-5'-O-t-butyldimethylsilylguanosine.

Polyglycerol fatty acid esters (PGFAEs) are gaining interest in several industrial sectors due to their excellent surfactant properties and their wide range of hydrophilic−lipophilic balance (HLB) values. Moreover, they can be prepared from renewable resources, i.e., fatty acids and glycerol. In this study, polyglycerol-2 stearic acid esters (PG2SAEs) were synthesized by the enzymatic esterification of polyglycerol-2 (PG2) and stearic acid (SA) using the immobilized lipase Novozym 435 as a biocatalyst in a solventfree system. Reaction conditions, i.e., temperature (80 °C), reactant ratio (1:1.8), and enzyme loading (2.7% w/w), were finely optimized; furthermore, biocatalyst recycling was studied by assessing the residual activity of the lipase after each reaction cycle, up to 20 times. The composition of the enzymatically synthesized products (E) was roughly evaluated by chromatographic methods and mass spectrometry and compared with that of the esters obtained by acid-catalyzed esterification (C). Then, the surfactant properties of the prepared polyglycerol-based surfactants were investigated by interfacial tension studies. Specifically, the emulsifying capacity and stability and the rheological behavior of O/ W emulsions prepared in the presence of E were deeply investigated in comparison with those of the chemically synthesized and commercially available product C.