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61.
Over forty-five complex free oligosaccharides (of which several are novel) have been isolated and chemically characterized by gas chromatography and high resolution and high mass accuracy matrix-assisted laser desorption/ionization mass spectrometry (MALDI-FTICR MS) in red and white wines, Grignolino and Chardonnay, respectively. Oligosaccharides with a degree of polymerization between 3 and 14 were separated from simple monosaccharides and disaccharides by solid-phase extraction. The concentrations of free oligosaccharides were over 100 mg/L in both red and white wines. The free oligosaccharides-characterized for the first time in the present study-include hexose-oligosaccharides, xyloglucans, and arabinogalactans and may be the natural byproduct of the degradation of cell wall polysaccharides. The coupled gas chromatography and accurate mass spectrometry approach revealed an effective method to characterize and quantify complex functional oligosaccharides in both red and white wine.  相似文献   
62.
The in vitro antimicrobial activity of commercial coffee extracts and chemical compounds was investigated on nine strains of enterobacteria. The antimicrobial activity investigated by the disc diffusion method was observed in both the extracts and tested chemical compounds. Even though pH, color, and the contents of trigonelline, caffeine, and chlorogenic acids differed significantly among the coffee extracts, no significant differences were observed in their antimicrobial activity. Caffeic acid and trigonelline showed similar inhibitory effect against the growth of the microorganisms. Caffeine, chlorogenic acid, and protocatechuic acid showed particularly strong effect against Serratia marcescens and Enterobacter cloacae. The IC(50) and IC(90) for the compounds determined by the microtiter plate method indicated that trigonelline, caffeine, and protocatechuic acids are potential natural antimicrobial agents against Salmonella enterica. The concentrations of caffeine found in coffee extracts are enough to warrant 50% of the antimicrobial effect against S. enterica, which is relevant to human safety.  相似文献   
63.
64.
Rice fields represent important production rates in Portugal. However, the intensive soil management and the exploitation of agrochemicals may pose a threat to nontarget organisms. Hence, the present work regards the toxicity screening of surface waters and sediment elutriates collected during the drainage of fields in the vicinity of a rice paddy (Quinta do Seminário, Soure, Portugal): 1. in River Pranto (RP), the river from which the field irrigation water is canalized; 2. inside the rice paddy, from the main drainage channel – Vala de Enxugo (VE). For that purpose, it was used a combination of physico-chemical analyses and bioassays with two green algae species – Pseudokirchneriella subcapitata and Chlorella vulgaris. The chemical screening showed an apparent absence of xenobiotics in sediment samples, while no pesticides were found within the chemical contaminants detected in water samples. The nutrient load reflected low levels of inorganic contamination. Bioassays revealed that P. subcapitata was more sensitive to the overall physico-chemical conditions in natural samples than C. vulgaris, being its growth inhibited under water samples from both sites. On a whole, water samples, mainly those from the main irrigation/drainage channel of the rice fields (VE), were more deleterious to microalgae than those from RP or any of the elutriates.  相似文献   
65.
The antiradical activity of dry beans was evaluated in order to assess the validity of this test and to correlate the results with those achieved with the Folin-Ciocalteu method and with a rapid spectrophotometric method for the analysis of total flavonoids. Four landraces (12 samples) of common beans (Phaseolus vulgaris L.), collected in two regions of Italy (Tuscany and Basilicata) in three different years, were analyzed. The EC50 values ranged from 39 to 2810 mg sample/mg 1,1-diphenyl-2-picrylhydrazil radical. The phenolic content of each sample was expressed as gallic acid equivalents; it changed from 1.17 to 4.40 mg/g. The flavonoid content, expressed as mg of (+)-catechin per g of dry seeds, ranged from 0.24 to 1.43 mg/g. The qualiquantitative composition of polyphenols has been also elucidated by means of high-performance liquid chromatography (HPLC)-diode array detection and HPLC/MS. These investigations showed that rapid tests can contribute to assessing the quality of functional food.  相似文献   
66.
This study describes the purification of an N-acetylglucosamine-binding lectin from Koelreuteria paniculata seeds and its effects on the larval development of Callobruchus maculatus and Anagasta kuehniella. The lectin (KpLec) was characterized and isolated by gel filtration, affinity column, and reverse phase chromatography. SDS-PAGE indicated that this lectin is a dimer composed of subunits of 22 and 44 kDa. The N terminus exhibited 40% similarity with Urtiga dioica agglutinin. KpLec was tested for anti-insect activity against C. maculatus and A. kuehniella. With regard to C. maculatus, an artificial diet containing 0.7 and 1% KpLec produced LD(50) and ED(50) value, respectively. However, for A. kuenhiella, an artificial diet containing 0.65% KpLec produced an LD(50), whereas 0.2% KpLec produced an ED(50). The transformation of genes coding for this lectin could be useful in the development of insect resistance in important agricultural crops.  相似文献   
67.
To obtain information about the extent of the early Maillard reaction between the N-termini of peptides and lactose, alpha-N-(2-furoylmethyl) amino acids (FMAAs) were quantified together with epsilon-N-(2-furoylmethyl)lysine (furosine) in acid hydrolyzates of hypoallergenic infant formulas, conventional infant formulas, and human milk samples using RP-HPLC with UV-detection. FMAAs are formed during acid hydrolysis of peptide-bound N-terminal Amadori products (APs), and furosine is formed from the Amadori products of peptide-bound lysine. Unambiguous identification was achieved by means of LC/MS and UV-spectroscopy using independently prepared reference material. The extent of acid-induced conversion of APs to FMAAs was studied by RP-HPLC with chemiluminescent nitrogen detection (CLND). Depending on the corresponding alpha-N-lactulosyl amino acid, between 6.0% and 18.1% of FMAAs were formed during hydrolysis for 23 h at 110 degrees C in 8 N HCl. From epsilon-N-lactulosyllysine, 50% furosine is formed under these conditions. Whereas furosine was detectable in all assayed samples, five different FMAAs, alpha-FM-Lys, alpha-FM-Ala, alpha-FM-Val, alpha-FM-Ile, and alpha-FM-Leu, were exclusively detected in acid hydrolyzates of hypoallergenic infant formulas in amounts ranging from 35 to 396 mumol/100 g protein. Taking the conversion factors into account, modification of N-terminal amino acids in peptides by reducing carbohydrates was between 0.3% and 8.4%. This has to be considered within the discussion concerning the nutritional quality of peptide-containing foods.  相似文献   
68.
Complexes of β-cyclodextrin (β-CD) and caffeine (Caf) with biophenols present in olive and olive oil (tyrosol, hydroxytyrosol, homovanillic acid, 3,4-dihydroxyphenylacetic acid, and protocatechuic acid) were investigated by NMR spectroscopy and thermodynamical-molecular dynamic studies to verify the formation of supermolecular aggregates. The obtained results indicated that the investigated biophenols form inclusion complexes with β-CD in a molar ratio of 1:1 in aqueous solution having binding constant values from 10- to 40-fold bigger than those of the corresponding complexes with Caf. Then, β-CD preferentially encloses the biophenol molecule, decreasing its bitter taste and, at the same time, preserving it against chemical and physical decomposition reactions that occur during storage.  相似文献   
69.
Agricultural herbicides are among the most commonly used pesticides worldwide, posing serious concerns for both humans, exposed to these chemicals through many routes, and the environment. To clarify the effects of three herbicides as commercial formulations (namely, Pointer, Silglif, and Proper Energy), parameters related to oxidative issues were investigated on an autochthonous wine yeast strain. It was demonstrated that herbicides were able to affect the enzymatic activities of catalase and superoxide dismutase, as well as to induce carbonylation and thiol oxidation as post-translational modifications of proteins. Saccharomyces cerevisiae is an optimal model system to study responses to xenobiotics and oxidative stress. Thus, the results obtained could further the understanding of mechanisms underlying the toxicity of herbicides.  相似文献   
70.
Flavonoids and hydroxycinnamic derivatives of turnip tops (Brassica rapa L. subsp. sylvestris L.) were characterized for the first time in four samples from different origins. Turnip tops exhibit a high polyphenols content (ranging from 107 to 191 mg/100 g, fresh weight) and a good antiradical activity, determined with the DPPH* test. After a liquid-liquid extraction and fractionation procedures, most flavonoids (isorhamnetin, kaempferol, and quercetin glycosides) and hydroxycinnamic derivatives were identified by means of HPLC-DAD/MS techniques. Isorhamnetin glycosides were the main flavonoid derivatives, differing from that found in the vegetables belonging to the Brassica oleracea group.  相似文献   
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