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991.
Cerdá B Periago P Espín JC Tomás-Barberán FA 《Journal of agricultural and food chemistry》2005,53(14):5571-5576
Dietary ellagic acid and related polyphenols are metabolized in humans to dibenzopyran-6-one derivatives, and the microbial origin of these metabolites has been suggested. However, this has not been demonstrated so far. Fecal samples donated by six volunteers were incubated under anaerobic conditions, and aliquots were used to evaluate the fecal metabolism of ellagic acid, the ellagitannin punicalagin, and an ellagitannin rich extract from walnuts. The isoflavone daidzein was also incubated with the same fecal samples to follow the production of the microbial metabolites previously reported (dihydrogenistein, O-demethylangolensin, and equol) as a positive control of the system and to evaluate similarities between isoflavone and ellagic acid fecal flora metabolism. After fermentation the metabolite "urolithin A" (3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one) was produced from ellagic acid, punicalagin, and the ellagitannin extract in all the fecal cultures from different volunteers, but with very different production rates and concentrations. This large variability in the concentration of metabolite and kinetics of metabolite production is consistent with the large variability found in the excretion of these metabolites in urine in vivo after human consumption of ellagitannins, and with differences in the composition of the fecal microflora. No correlation between isoflavone and ellagic acid metabolism by fecal microflora was observed. The present study confirms the microbial origin of the recently reported in vivo generated hydroxy-6H-dibenzo[b,d]pyran-6-one derivatives in humans and is a further step in the study of the bioavailability and metabolism of ellagic acid and ellagitannins. 相似文献
992.
Ruiz-Mesia L Ruiz-Mesía W Reina M Martínez-Diaz R de Inés C Guadaño A González-Coloma A 《Journal of agricultural and food chemistry》2005,53(6):1921-1926
Three known Cinchona alkaloids of the quinine type, quinine (1), cupreine (2), cinchonine (3), and the possible artifact cinchonine-HCl (3-HCl), along with two new ones, acetylcupreine (4) and N-ethylquinine (5), have been isolated from the bark of Remijia peruviana (Rubiaceae). Their stereochemical structures were established by high resolution NMR spectroscopy. Alkaloids 2-4 had antifeedant effects on Leptinotarsa decemlineata with varying potencies. Compound 4 was cytotoxic to both insect Sf9 and mammalian CHO cells after 48 h of incubation, while 3-HCl had stronger and selective cytotoxicity to Sf9. Quinine 1 had a moderate to low effect on Trypanosoma cruzi. Tumoral cells were also affected by these alkaloids, with 4 and 3-HCl being the most cytotoxic to all the cell lines tested. Overall, the 8R, 9S configurations, as in 3 and 3-HCl, as well as the C-6'acetylated alkaloid 4, with an 8S, 9R configuration, showed stronger biological effects. 相似文献
993.
Valéria Marino Rodrigues Sala Elke Jurandy Bran Nogueira Cardoso Fabiana Fantinatti Garboggini Neusa de Lima Nogueira Adriana Parada Dias da Silveira 《Biology and Fertility of Soils》2008,44(8):1107-1112
This study reports for the first time the presence of diazotrophic bacteria belonging to the genera Achromobacter and Zoogloea associated with wheat plants. These bacterial strains were identified by the analysis of 16S rDNA sequences. The bacterium
IAC-AT-8 was identified as Azospirillum brasiliense, whereas isolates IAC-HT-11 and IAC-HT-12 were identified as Achromobacter insolitus and Zoogloea ramigera, respectively. A greenhouse experiment involving a non-sterilized soil was carried out with the aim to study the endophytic
feature of these strains. After 40 days from inoculation, all the strains were in the inner of roots, but they were not detected
in soil. In order to assess the location inside wheat plants, an experiment was conducted under axenic conditions. Fifteen
days after inoculation, preparations of inoculated plants were observed by the scanning electron microscope, using the cryofracture
technique, and by the transmission electron microscope. It was observed that all isolates were present on the external part
of the roots and in the inner part at the elongation region, in cortex cells, but not in the endodermis or in the vascular
bundle region. No colonizing bacterial cells were observed in wheat leaves. 相似文献
994.
995.
I. N. Kurganova V. O. Lopes de Gerenyu J. F. Gallardo Lancho C. T. Oehm 《Eurasian Soil Science》2012,45(1):68-79
The processes of the organic matter (OM) mineralization in forest soils developed under temperate continental (Moscow oblast,
Russia), Mediterranean (the central and western parts of Spain), and tropical monsoon (southern Vietnam) climates were studied
under laboratory conditions. The potential and specific rates of the OM mineralization (PR
min and PR
min/Corg, respectively), the ecophysiological parameters of the microbial communities status (Cmic, qCO2, and Cmic/Corg), and the sensitivity of the rate of the OM mineralization to the rise in temperature were evaluated by the temperature coefficients
(Q
10) determined in the humus horizons (0–10 cm, without forest litter). The average values of PR
min for the climatic zones decreased in the following order: Mediterranean (57.1 ± 10.6 mg C/kg per day) > temperate continental
(23.8 ± 7.1 mg C/kg per day) > tropical monsoon (10.4 ± 1.6 mg C/kg per day). The lowest resistance of the soil OM to mineralization
as evaluated by the PR
min/Corg values was found in the Albeluvisol and Phaeozem of the temperate continental climate and in the Acrisol of the Mediterranean
climate. The highest Q
10 coefficients were attributed to the OM mineralization in the forest soils of the temperate continental climate. This allowed
us to conclude that the observed and expected climate changes with an increase in the mean annual air temperature should lead
to the maximum intensification of the OM mineralization processes in the forest soils of northern regions. 相似文献
996.
Sotelo A Argote RM Moreno RI Flores NI Diaz M 《Journal of agricultural and food chemistry》2003,51(9):2821-2825
The nutritive and toxicological values of the dry seeds, germinated seeds, and string beans of Erythrina americana were studied using raw and boiled samples. Raw germinated seeds had a higher protein content and lower fiber content than dry seeds. The whole string bean had lower protein content and higher fiber content. However, the seeds of the green pod showed the same protein concentration as the dry seeds (dry basis). Boiling and elimination of broth was beneficial in diminishing the alkaloid concentration in all the samples. The trypsin inhibitors, lectins, and tannins were also diminished as was expected. The raw string bean showed the lowest LD(50). Although the total essential amino acids content of the boiled germinated seeds was increased, the quality of protein, protein efficiency ratio (PER), was lower than in boiled dry seeds, and in these, the PER was similar to the control (casein). The present results suggest that for the protein quality and low alkaloid content, the boiled dry seeds and string beans could be used for animal feeding. It could be interesting to test the raw string beans in ruminants since in this stage E. americana showed the lowest toxicity. 相似文献
997.
Ochratoxin A is a metabolite produced by Aspergillus and Penicillium species that is nephrotoxic and possibly carcinogenic to humans. The aim of this study was to evaluate ochratoxin A contamination in green coffee obtained by different harvesting and drying operations and from fruits of different ripening stages in order to identify hazards. The research was directed to coffees from the highland area of Rio de Janeiro state (Brazil), which is traded in the domestic market. Twenty-two out of 54 samples contained ochratoxin A at levels ranging from 0.3 to 160 microg/kg. Ochatoxin A contamination levels between different ripe stage fruits were not significant (P > 0.05). "Varri??o" coffee, consisting of fruits that fell from the tree spontaneously and stayed longer on the ground before being harvested, was the most contaminated. Eleven out of 14 samples of varri??o coffee were contaminated. Three out of 10 samples from the northwestern region of the state were positive for ochratoxin at levels ranging from 10.1 to 592 microg/kg. The contaminated samples had in common the fact that they were harvested directly from the soil. 相似文献
998.
Cadahía E Fernández de Simón B Jalocha J 《Journal of agricultural and food chemistry》2003,51(20):5923-5932
The volatile composition (volatile phenols, phenolic aldehydes, furanic compounds, lactones, phenyl ketones, and other related compounds) of Spanish oak heartwood of Quercus robur, Quercus petraea,Quercus pyrenaica, and Quercus faginea was studied by gas chromatography/mass spectrometry, in relation to the processing in barrels cooperage and in relation to the French oak of Quercus robur (Limousin) and Quercus petraea (Allier) and American oak of Quercus alba (Missouri), which are habitually used in cooperage. The volatile composition of seasoned oak woods varied according to individual trees, species, and origins, and the differences were more significant in Spanish species with respect to American species than with respect to French species. The toasting process influenced the volatile composition of wood. It led to high increases in the concentration of volatile phenols, furanic aldehydes, phenyl ketones, and other related structures, but the effect on w-lactones levels depended on species and origin. The volatile composition in Spanish oak species evolved during toasting like in French and American oak, but quantitative differences were found, especially important in American species with respect to European species. 相似文献
999.
1000.
Enio Tarso de Souza Costa Luiz Roberto Guimarães Guilherme Guilherme Lopes Nilton Curi 《Water, air, and soil pollution》2012,223(4):1661-1670
Assessing multielement adsorption of trace metals on materials having potential to be used as soil amendments is an essential
stage for the remediation success, as soil contamination rarely occurs with a single element. This study evaluated mono-/multielement
adsorption of Zn, Cu, Cd, and Pb on aluminum (AMB) and iron mining by-products (IMB, used for comparison). Prior to adsorption,
these products were characterized by X-ray diffraction, isoelectric point, infrared spectroscopy, scanning electron microscopy,
and microwave furnace digestion. Sorption experiments comprised: (1) pH adjustment (5.5, 6.5, and natural suspension pH),
(2) mono- and multielement adsorption, and (3) desorption. Rising pH from 5.5 to natural suspension values (9.5) increased
monoelement adsorption of Zn, Cu, Cd, and Pb on AMB up to 3.8-, 1.4-, 6.2-, and 1.1-fold, whereas multielement adsorption
was increased up to 17.3-, 2.0-, 20.3-, and 1.2-fold, respectively. Zinc and Cd were less adsorbed than Cu and Pb and more
affected by competition. Multielement adsorption at 5.5 pH in AMB resulted in smaller adsorption of Zn (up to 4.6-fold), Cu
(1.4-fold), Cd (3.3-fold), and Pb (1.1-fold) when compared with monoelement adsorption. The lower the pH, the smaller the
adsorption and the higher the desorption. The AMB showed higher capacity to maintain the elements adsorbed than the IMB. 相似文献