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Gliadins, the major proteins of the wheat flour, are a family of monomeric and disulphide‐bonded proteins formed by a non‐repetitive domain rich in α‐helix structures and heterogeneous repetitive domains rich in β‐reverse turns. Gliadins may be strong food allergens, and many studies have explored the mechanisms of gluten allergenicity, with the final aim to properly modify gluten proteins in order to decrease allergen immunoreactivity. In the present study, Raman spectroscopy was used to gain more insights into the conformational changes of gliadins upon interaction with different anthocyanins (kuromanin, callistephin, oenin, cyanin, pelargonin, malvin). Anthocyanins are powerful antioxidant molecules with anti‐carcinogenic properties and largely widespread natural colorants present in vegetables and flowers. Raman spectroscopy demonstrated that the anthocyanins under study induce in gliadins conformational changes of different extents. The treatment with malvin, kuromanin and callistephin induced significant changes in the tyrosine environment, while pelargonin, oenin and cyanin did not. The treatment with any of the anthocyanins altered the distribution of the disulphide conformations: the gauche‐gauche‐trans conformation increased at the expenses of the gauche‐gauche‐gauche conformation. Malvin and pelargonin provoked a significant decrease of the β‐turns content. Since both the latter structural elements have been related to gluten allergenicity, anthocyanins appeared interesting molecules, in the context of the attempts to modify gliadins with the aim to decrease allergen immunoreactivity. Copyright © 2013 John Wiley & Sons, Ltd.

The reactions between strongly electron-rich aromatic substrates (1,3,5-tris(N,N-dialkylamino)benzenes, neutral carbon super nucleophiles) and diazonium salts produce moderately stable sigma complexes (Wheland complexes). The reactivity of Wheland complexes with electrophiles (other diazonium salts, or 4,7-dinitrobenzofuroxan) produces exchange reactions in the electrophilic part: the better electrophile replaces the less powerful electrophile. In the same way, in Wheland complexes with the 1,3,5-tris(morpholinyl)benzene, the 1,3,5-tris(piperidinyl)benzene replaces the less powerful nucleophile 1,3,5-tris(morpholinyl)benzene. Evidence is reported here indicating that for the title system the reaction of the attack of the electrophilic reagent producing Wheland complexes is a reversible process. The final products of the diazo-coupling reactions undergo a further attack of some diazonium salts. From the final products of the double diazo-coupling reactions (diazo compounds), we collected evidence that is a clear instance of complete reversibility of the diazo-coupling reaction.

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A decoction of Capparis spinosa L. roots, widely used in the traditional folk medicine of southern Italy, was prepared and submitted to antibacterial activity tests, which showed an interesting bacteriostatic activity on the growth of Deinococcus radiophilus. Heterocyclic compounds were also recovered from the chloroformic extract of the roots.

Reactions of DNBF with a series of 2-aminothiazoles (1 a-f) to afford thermodynamically stable C-bonded sigma-adducts have been investigated in acetonitrile. A most significant finding emerged on recording NMR spectra immediately after mixing of equimolar amounts of DNBF and the unsubstituted 2-aminothiazole (1 a) in Me2SO: namely, that the formation of 9 a is preceded by that of a short-lived intermediate species X. From the 1H NMR parameters characterizing this intermediate, as well as the dependence of its lifetime on the experimental conditions-the presence of excess DNBF over 1 a increases the lifetime of X while an excess of base (1 a) accelerates its conversion into 9 a--it is convincingly demonstrated that the structure of X combines the presence of a positively charged Wheland complex moiety (with regard to the thiazole ring) with that of a negatively charged Meisenheimer complex moiety (with regard to the benzofuroxan system). So far, only one intermediate of this type (noted WM) has been successfully characterized, in the reactions of DNBF with 1,3,5-tris(N,N-dialkylamino)benzenes. Among the key features supporting the intermediacy of X along the reaction coordinate leading to 9 a is the fact that the reactions of DNBF with 1 a in the presence of an alcohol (MeOH, EtOH, nPrOH) produce new adducts arising from the addition of an alcohol molecule to the thiazole moiety of WM-1 a. Reflecting the presence of three chiral centres, these species are formed as mixtures of several diastereomers that could all be characterized in their racemic forms in ethanol. These findings generalize the previous report on the formation of Wheland-Meisenheimer carbon-carbon complexes in homocyclic series.

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