Properties of filmogenic solutions of gliadin crosslinked with 1-(3-dimethyl aminopropyl)-3-ethylcarbodiimidehydrochloride/N-hydroxysuccinimide and cysteine

In this study gliadin solutions were crosslinked with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) and cysteine. The filmogenic solutions were studied through rheological, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and FTIR analysis. Gliadin modified by EDC/NHS showed lower viscosity values when compared with the gliadin/cysteine system and the non-modified gliadin system. Determination of amino groups in gliadin modified by EDC/NHS was carried out through the trinitrobenzenesulfonic acid (TNBS) method. The cast films were evaluated by FTIR analysis in order to detect structural changes in the secondary structure of protein. SDS-PAGE showed the formation of higher protein aggregates, indicating that cysteine promotes gliadin polymerization through covalent bonds (disulfide bonds). The TNBS analysis showed that non-chemically modified gliadin had higher amounts of ε-amino groups when compared with gliadin treated with EDC/NHS; however, both systems revealed similar amounts of amino groups for the whole range of glycerol content. The FTIR spectra for the films showed that the two crosslinking agents act by different mechanisms, promoting changes in the secondary structure of gliadin.     

A signature protein-based method to distinguish Mediterranean water buffalo and foreign breed milk

A novel genetic variant at the α_s1-casein locus of water buffalo (WB), 8-residue shorter than its wild-type has been found and sequenced. The internal deletion of the peptide E³⁵KVNELsT⁴² was confirmed by the isolation of the junction peptide. The 8-residue deletion mutant has a molecular weight that is 919 Da less than that of the wild-type. The novel isoform with a unique f35-42 deletion could be the result of the skipping of exon 6, generating an exon 6-deleted variant of α_s1-casein. The wild-type and its shortened α_s1-casein forms were found to co-exist in many individual milk samples. In contrast, the 8-residue, internally deleted α_s1-casein variant did not occur in water buffaloes of the Mediterranean breed reared in Italy. Wild-type α_s1-casein has 6 to 8 phosphate groups (P) while the internally deleted form 6 and 7P per molecule.     

Evaluation of heat and oxidative damage during storage of processed tomato products. I. Study of heat damage indices

The evolution of heat damage during storage of tomato pulp, puree and paste was studied by accelerated aging tests. Heat damage indices—5‐hydroxymethyl‐2‐furfural (HMF), furosine and colour changes (ΔE)—were evaluated for tomato products stored at 30, 40 and 50 °C for up to 90 days. Furosine and ΔE values increased following pseudo‐zero‐order kinetics, and the higher the solid content of the products, the higher were the rate constant values. HMF formation followed pseudo‐first‐order kinetics in tomato pulp and pseudo‐zero‐order kinetics in puree and paste samples. Data show that heat damage reactions in tomato products proceed even at room temperature, and the kinetic model provided can be used to predict changes occurring during shelf‐life. © 2002 Society of Chemical Industry     

4-Hydroxynonenal and cholesterol oxidation products in atherosclerosis

4-Hydroxynonenal (HNE) is by far the most investigated aldehydic end-product of oxidative breakdown of membrane n-6 polyunsaturated fatty acids. Its potential involvement in the pathogenesis of atherosclerosis has been corroborated by its consistent detection in both oxidized LDL and fibrotic plaque in humans. HNE has been shown to activate both macrophage and smooth muscle cells, i.e. the two key cell types in chronic inflammatory processes characterized by excessive fibrogenesis. By signalling to the nucleus, the aldehyde may up-regulate in these cells both expression and synthesis of monocyte chemotactic protein 1 (MCP-1) and transforming growth factor beta1 (TGFbeta1). Oxysterols, namely 27 carbon atoms oxidation products of cholesterol, are found in relatively high amount in LDL from hypercholesterolemic individuals and are consistently detectable in foam cells and necrotic core of human atherosclerotic lesion. As for HNE, the challenge of cells of the macrophage lineage with a mixture of oxysterols like that detectable in hypercholesterolemic individuals led to a marked overexpression of TGFbeta1 and MCP-1. Both HNE and oxysterols then appear to be candidates for a primary role in the progression of the atherosclerotic process.     

Identification of four alcohol oxidases from methylotrophic yeasts

Three yeast strains capable of utilizing methanol as sole carbon and energy source were isolated. Two were classified as Candida boidinii, while the third belonged in the genus Pichia. From these three strains, four alcohol oxidases genes were identified and the sequences of the coding regions were determined: one from each Candida boidinii (aox0673 and aox0680) and two from Pichia sp. 159 (aoxA and aoxB). Methanol induces both alcohol oxidases in Pichia sp. 159: the levels of aoxA and aoxB mRNA reach about 100% and 300%, respectively, of that of his4 mRNA. aoxA, but not aoxB, is expressed at a low level in the presence of glucose. The newly described alcohol oxidases have proper dinucleotide binding sites and PTS1-like C-terminal tripeptides, identified as important elements for peroxisomal localization.     

Isolation of red wine components with anti-adhesion and anti-biofilm activity against Streptococcus mutans

Red wine is a widely consumed beverage with multiple beneficial effects on human health. In the present paper, the anticaries properties of red wine were studied in vitro and ex vivo. Our in vitro findings shows that dealcoholised red wine, besides exerting antibacterial activity, strongly interferes with Streptococcus mutans adhesion to saliva-coated hydroxyapatite (sHA) beads, promotes its detachment from sHA, and powerfully inhibits in vitro biofilm formation. The main components responsible for such activities were found to be proanthocyanidins. The ability of red wine to inhibit ex vivoS. mutans biofilm formation on the occlusal surface of natural human teeth also was demonstrated.     

Bowman-Birk inhibitors in lentil: Heterologous expression,functional characterisation and anti-proliferative properties in human colon cancer cells

A full-length cDNA, encoding a Bowman-Birk protease inhibitor (BBI), was isolated from lentil immature seeds. The deduced amino acid sequence was longer than that of the BBI extracted from lentil seeds and contained two binding sites; the first inhibitory site inhibits trypsin whereas the second one inhibits chymotrypsin. In order to characterize this lentil BBI, a longer (complete) and its C-terminally processed (mature) form were heterologously expressed in the yeast Pichia pastoris. The recombinant BBI proteins proved to be active against trypsin and chymotrypsin, showing K_i values at nanomolar levels. Mass spectrometry analysis revealed that complete BBI was composed of an array of molecular masses, whereas mature BBI showed the presence of a major peak of the expected size. The effects of mature BBI on the growth of human colon adenocarcinoma HT29 and colonic fibroblast CCD-18Co cells were evaluated. Lentil BBI was able to inhibit the growth of such cells at concentrations higher than 19 μM, in a concentration-dependent manner; by contrast, the CCD18-Co cells were unaffected. These data broaden our knowledge of the beneficial biological activities of naturally-occurring BBI proteins and address the need for systematic evaluation of natural variants in order to design novel strategies in preventive medicine.     

Polyphenol compounds in artichoke plant tissues and varieties

Polyphenol compounds, particularly caffeoylquinic acids and flavonoids, were measured in different tissues and developmental stages of 6 artichoke varietal types diffused in the Mediterranean region. Flower heads were subdivided into external, intermediate, internal bracts, and receptacle, while leaves were collected at the vegetative and productive stages. The main polyphenols detected were chlorogenic acid, cynarin, luteolin 7-O-rutinoside, and luteolin 7-O-glucoside. "Violet de Provence" artichoke proved to retain the highest content of total phenols. Single polyphenols accumulated preferentially in specific parts of capitula. In leaves, most polyphenols were detected in the productive stage of the plant. Altogether, results provide useful indications for the promotion of artichoke as nutraceutical food and for the extraction of health-promoting substances in particular tissues/stages of the artichoke plant. PRACTICAL APPLICATION: We describe the content of phenolic compounds in various artichoke tissues, developmental stages, and varieties. Results indicate that artichoke leaves represent an important source of these health-promoting compounds, also useful for phytopharmaceutical applications. A wider utilization of specific artichoke types should be strongly encouraged not only as a food for the fresh market, as they are now used, but also for the pharmaceutical industry, since the content of phenolic compounds is abundant both in the heads and in the leaves.