Flavonoids have been recognised as one of the largest and most widespread groups of plant secondary metabolites, with marked antioxidant properties. The general name flavonoid refers to a class of more than 6500 molecules based upon a 15-carbon skeleton. In this paper a general overview of flavonoids, their classification, structures and analytical methods for their determination is presented.

In order to understand the molecular basis of salt stress response, a proteomic approach, employing two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS), was used to identify proteins affected by salinity in wheat (Triticum durum 'Ofanto'). Identification of proteins, whose levels were altered, was performed by comparing protein patterns of salt-treated and control plants. A set of control plants was grown without NaCl addition under the same conditions as the salt-treated plants. Proteins were extracted from the leaves of untreated and NaCl-treated plants, and resolved using 24-cm immobilized pH gradient strips with a pH 4-7 linear gradient in the first dimension and a 12.5% sodium dodecyl sulphate polyacrylamide gel electrophoresis in the second dimension; the gels were stained with Coomassie and image analysis was performed. Quantitative evaluation, statistical analyses and MALDI-TOF MS characterization of the resolved spots in treated and untreated samples enabled us to identify 38 proteins whose levels were altered in response to salt stress. In particular, ten proteins were downregulated and 28 were upregulated. A possible role of these proteins in response to salinity is discussed. © 2008 Springer-Verlag

The concept that the effective unit of interest in the cell-nanomaterial interaction is the particle and its corona of associated proteins is emerging. Here we investigate the compositional evolution of the protein corona of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) cationic liposomes (CLs) and DOTAP/DNA lipoplexes over a wide range of plasma concentrations (2.5-80%). The composition of the hard corona of lipoplexes is quite stable, but that of CLs does evolve considerably. We show that the protein corona of CLs is made of both low-affinity and competitive-binding proteins whose relative abundance changes with the plasma concentration. This result may have deep biological implications for the application of lipid-based gene vectors both in vitro and in vivo.

A mass spectrometric method for extensive detection and semi-quantitative determination of flavonoid glycosides in stem and leaves of young Triticum durum plants is presented. About 100 g of sample were lyophilized and ground, and the compounds of interest were then extracted, cleaned-up, and fractionated using high-performance liquid chromatography (HPLC). Tandem mass spectrometry analyses were performed using a quadrupole-linear ion trap instrument with an information-dependent data acquisition (IDA) protocol that looped two experiments, enhanced MS scan and enhanced product ion scan. Various glycoconjugates, which are all derivatives of only four flavones, apigenin, luteolin, chrysoeriol and tricin, were identified and belong to the following categories: 7 monoglycosides, 31 diglycosides, 15 triglycosides and 1 tetraglycoside. Among these some acylated glycosides were found. Tricin derivatives are present exclusively as O-glycosides, while apigenin and luteolin are present always as C-glycosides. Semi-quantitative estimation was performed by using the monoglycoside and diglycoside of quercetin as internal standards.

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