71 research outputs found
Chain-breaking antioxidant activity of hydroxylated and methoxylated magnolol derivatives: The role of H-bonds
No full textChemical modification of magnolol, an uncommon dimeric neolignan contained in Magnolia genus trees, provides a unique array of polyphenols having interesting biological activity potentially related to radical scavenging. The chain-breaking antioxidant activity of four new hydroxylated and methoxylated magnolol derivatives was explored by experimental and computational methods. The measurement of the rate constant of the reaction with ROO center dot radicals (k(inh)) in an apolar solvent showed that the introduction of hydroxyl groups ortho to the phenolic OH in magnolol increased the k(inh) value, being 2.4 x 10(5) M-1 s(-1) and 3.3 x 10(5) M-1 s(-1) for the mono and the dihydroxy derivatives respectively (k(inh) of magnolol is 6.1 x 10(4) M-1 s(-1)). The di-methoxylated derivative is less reactive than magnolol (k(inh) = 1.1 x 10(4) M-1 s(-1)), while the insertion of both hydroxyl and methoxyl groups showed no effect (6.0 x 10(4) M-1 s(-1)). Infrared spectroscopy and theoretical calculations allowed a rationalization of these results and pointed out the crucial role of intramolecular H-bonds. We also show that a correct estimation of the rate constant of the reaction with ROO center dot radicals, by using BDE(OH) calculations, requires that the geometry of the radical is as close as possible to that of the parent phenol
Nanosponges based on self-assembled starfish-shaped cucurbit[6]urils functionalized with imidazolium arms
No full textA new porous material based on the first supramolecular cucurbituril-based nanosponge was synthesized by the functionalization of cucurbit[6]uril with twelve 1-(2-bromoethyl)-3-methyl-1H-imidazol-3-ium arms. The porous structure and the high adsorption capacity were demonstrated through surface area measurements and carbon dioxide adsorption. The new supramolecular sponge showed attractive properties such as (i) a highly porous structure that allowed CO2capture, (ii) the possibility to reuse the adsorbed CO2for organic synthesis, and (iii) an exciting thermal stability up to around 800 °C, with the potential use of this material in high temperature reactions. Finally, the reuse of CO2was successfully investigated in the carboxylation reaction of phenylacetylene
A heterotetrameric alpha-amylase inhibitor from emmer (Triticum dicoccon Schrank) seeds
No full textPlants have developed a constitutive defence system against pest attacks, which involves the
expression of a set of inhibitors acting on heterologous amylases of different origins.
Investigating the soluble protein complement of the hulled wheat emmer we have isolated and
characterized a heterotetrameric α-amylase inhibitor (ETI). Based on mass spectroscopy data, it is
an assembly of proteins highly similar to the CM2/CM3/CM16 found in durum wheat. Our data
indicate that these proteins can also inhibit exogenous α-amylases in binary assemblies. The
calculated dissociation constants (Ki) for the pancreatic porcine amylase- and human salivary
amylase-ETI complexes are similar to those found in durum and soft wheat. Homology modeling of
the CM subunits indicate structural similarities with other proteins belonging to the cereal family of
trypsin/α-amylase inhibitors; a possible homology modeled structure for a tetrameric assembly of
the subunits is proposed
Dimeric inhibitors of human salivary alpha-amylase from emmer (Triticum dicoccon Schrank) seeds
No full textPoppea's bath liquor: The secret proteome of she-donkey's milk
No full textDonkey's milk is today categorized among the best mother's milk substitute for allergic newborns, due to its much reduced or absent allergenicity, coupled to excellent palatability and nutritional value. However, up to the present, only a handful of proteins had been characterized, just about the std. eight to ten major ones known in all types of milk. By exploiting the combinatorial peptide ligand library technol., and treating large vols. (up to 300 mL) of defatted, de-caseinized (whey) milk, we have been able to identify 106 unique gene products, by far the largest description so far of this precious nutrient. Due to poor knowledge of the donkey's genetic asset, only 10% of the proteins could be identified by consulting the data base of Equus asinus; the largest proportion (70%) could be identified by homol. with the proteins of Equus caballu
Review: Applications of HPLC–MS for food analysis
No full textHPLC–MS applications in the agrifood sector are among the fastest developing fields in science and industry. The present tutorial mini-review briefly describes this analytical methodology: HPLC, UHPLC, nano-HPLC on one hand, mass spectrometry (MS) and tandem mass spectrometry (MS/MS) on the other hand. Analytical results are grouped together based on the type of chemicals analyzed (lipids, carbohydrates, glycoproteins, vitamins, flavonoids, mycotoxins, pesticides, allergens and food additives). Results are also shown for various types of food (ham, cheese, milk, cereals, olive oil and wines). Although it is not an exhaustive list, it illustrates the main current directions of applications. Finally, one of the most important features, the characterization of food quality (including problems of authentication and adulteration) is discussed, together with a future outlook on future directions
A preliminary investigation of the emmer (Triticum dicoccon Schrank) seed soluble proteome
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