In-Peptide Synthesis of Imidazolidin-2-one Scaffolds, Equippable with Proteinogenic or Taggable/Linkable Side Chains, General Promoters of Unusual Secondary Structures

Peptidomimetics containing (S)- or (R)-imidazolidin-2-one-4- carboxylate (Imi) have been obtained by the expedient in-peptide cyclization of (S)- or (R)-\u3b1,\u3b2-diaminopropionic acid (Dap) residues. These Imi scaffolds behave as proline analogues characterized by a flat structure and a transrestricted geometry of the preceding peptide bond and induce well-defined secondary structures in a biomimetic environment. While (S)-Imi peptides adopted a \u3b3\u2032-turn conformation, (R)-Imi induced the contemporary formation of a \u3b3-turn and a rare 11-membered H-bonded structure in the 2\u21924 opposite direction of the sequence, identified as a \u3b5-turn. In order to exploit these Imi scaffolds as general promoters of unusual secondary structures, proteinaceous side chains have been introduced at the N1 position of the five-membered ring, potentially mimicking any residues. Finally, the Imi rings have been equipped with unnatural side chains or with functionalized substituents, which can be utilized as linkers to chemoselectively bind the Imi-peptides onto nanoparticles, biomaterials, or diagnostic probes

Flavonoids and Immune Function in Human: A Systematic Review

Flavonoids, through a modulation of immune function, have been suggested to be involved in the role played by plant foods in disease prevention. We performed a systematic search in the MEDLINE database to review the effect of flavonoid-rich foods and flavonoids supplements on immune function. A total of 58 studies, were identified as suitable: 41 addressed in vivo proinflammatory cytokines and 15 measured ex vivo markers of immune function. According to our findings and on the basis of single food items, the number of studies in humans is limited and, for galenic supplements, only quercetin has been investigated. More evidences are needed to clarify the role of flavonoids as modulator of immune function in humans.

Oxidative stress in atherosclerosis development: the central role of LDL and oxidative burst

The involvement of both oxidative stress and hyperlipaemia in atherosclerosis development is well established. Oxidative burst is an innate immune response to infection, the latter being associated also with marked changes in lipid and lipoprotein metabolism, aimed to neutralize endotoxin toxic effects. On the other hand, lipid overload may increase lipopolysaccharide circulating levels and oxidative stress. Whilst these changes may be beneficial from the perspective of host defense, if they become chronic, they likely increase the risk of atherosclerosis. In particular, oxidation of lipoproteins, resulting from an imbalance of the pro- and antioxidant equilibrium, is involved in the pathologic process of atherosclerosis, changing cellular functions. Lipid oxidation, induced by leukocytes derived reactive oxygen species, can amplify foam cell formation through oxidized low density lipoproteins LDL (oxLDL) formation and uptake. The main enzymes, operating during oxidative burst, involved in LDL oxidation are NADPH oxidase and myeloperoxidase. In vitro studies have shown that oxLDL are able to induce many proatherogenic processes, including modulation of oxidative burst. OxLDL may also induce maturation of dendritic cells and regulate the shift from classical (M1) to alternative (M2) macrophage activation and from T helper 1 to T helper 2 response, suggesting that these could act as a bridge between innate and adaptative immunity, both involved in plaque development. Understanding the relationship between oxLDL and leukocyte oxidative burst helps to explain the involvement of innate immune responses in the early phases of atherosclerosis. The present review focuses on this interplay

Non enzymatic browning during cocoa roasting as affected by processing time and temperature

Non enzymatic browning (NEB) kinetics were studied at 125, 135 and 145 °C during a cocoa beans roasting process aimed to reach a final moisture content of 2 g 100 g-1. Colour lightness and hue angle decreased with roasting time following a first and a zero order kinetic, respectively. Moisture content being equal, high temperature-short time (HTST) roasting processes minimized the extent of browning reaction. Melanoidins increased with roasting time following an asymptotic kinetic. Moisture content being equal, HTST processes maximized the melanoidins formation. The energy of activation of melanoidin formation (132 kJ mol-1) was higher than those of colour changes and polyphenol oxidation (between 60 and 80 kJ mol-1), thus NEB during roasting is not solely dependent on Maillard reaction occurrence. Hydroxymethylfurfural (HMF) increased exponentially with roasting time but its final content was low (0.1-0.8 g kg-1). HTST processes minimized the HMF formation, which was not temperature dependent and was influenced by concentration

Flavanols, proanthocyanidins and antioxidant activity changes during cocoa (Theobroma cacao L.) roasting as affected by temperature and time of processing

The effect of roasting on the content of flavanols and proanthocyanidins and on the antioxidant activity of cocoa beans was investigated. Cocoa beans were roasted at three temperatures (125, 135 and 145 C), for different times, to reach moisture contents of about 2 g 100 g1. Flavanols and proanthocyanidins were determined, and the antioxidant activity was tested by total phenolic index (TPI), ferric reducing antioxidant power (FRAP) and total radical trapping antioxidant parameter (TRAP) methods. The rates of flavanol and total proanthocyanidin loss increased with roasting temperatures. Moisture content of the roasted beans being equal, high temperature-short time processes minimised proanthocyanidins loss. Moisture content being equal, the average roasting temperature (135 C) determined the highest TPI and FRAP values and the highest temperature (145 C) determined the lowest TPI values. Moisture content being equal, low temperature-long time roasting processes maximised the chainbreaking activity, as determined by the TRAP method