Crystal and molecular structure of piceatannol; scavenging features of resveratrol and piceatannol on hydroxyl and peroxyl radicals and docking with transthyretin     

Rossi M  Caruso F  Opazo C  Salciccioli J 《Journal of agricultural and food chemistry》2008,56(22):10557-10566

The mechanism by which the naturally occurring polyphenolic compounds resveratrol (RES), C(14)H(12)O(3), and its metabolite piceatannol (PIC), C(14)H(12)O(4), scavenge free radicals is studied using experimental and density functional theory (DFT) methods. PIC's crystal structure shows a strong intermolecular hydrogen bond network, which, through a concerted motion of the hydroxyl hydrogen atoms, can produce a second hydrogen bond chain. This reorganization offers a low-energy pathway for the transfer of hydrogen atoms and is a contributing factor to PIC's biological activity. Additionally, DFT calculations describing the entire reaction mechanism of RES, PIC, and 3,3',4',5,5'-pentahydroxystilbene with hydroxyl and peroxyl radicals agree with experimental results, showing that increased hydroxylation aids in scavenging activity. PIC is more efficient than RES because (i) by sharing its 3'-OH hydrogen atom with its adjacent neighbor, O-4', the abstraction and transfer of the 4'-H atom to the free radical becomes easier and (ii) the resulting PIC semiquinone radical is more stable. As a result of the reaction with OH(*), both RES and PIC form water; with the peroxyl radical, both RES and PIC form hydrogen peroxide. Also, docking of PIC onto the protein transthyretin suggests better performance than RES and confirms its possible application in neurodegenerative conditions such as Alzheimer's disease.  相似文献   

Cooking decreases observed perfluorinated compound concentrations in fish   总被引：1，自引：0，他引：1  

Del Gobbo L  Tittlemier S  Diamond M  Pepper K  Tague B  Yeudall F  Vanderlinden L 《Journal of agricultural and food chemistry》2008,56(16):7551-7559

Dietary intake is a major route of exposure to perfluorinated compounds (PFCs). Although fish and seafood contribute significantly to total dietary exposure to these compounds, there is uncertainty with respect to the effect of cooking on PFC concentrations in these foods. Eighteen fish species purchased from markets in Toronto, Mississauga, and Ottawa, Canada were analyzed for perfluorooctanesulfonamide (PFOSAs)-based fluorochemicals and perfluorinated acids (PFAs) in raw and cooked (baked, boiled, fried) samples. Of 17 analytes, perfluorooctanesulfonic acid (PFOS) was detected most frequently; concentrations ranged from 0.21 to 1.68 ng/g ww in raw and cooked samples. PFOSAs were detected only in scallops at concentrations ranging from 0.20 ng/g ww to 0.76 ng/g ww. Total concentrations of PFAs in samples were 0.21 to 9.20 ng/g ww, respectively, consistent with previous studies. All cooking methods reduced PFA concentrations. Baking appeared to be the most effective cooking method; after baking samples for 15 min at 163 C (325 degrees F), PFAs were not detected in any of the samples. The margin of exposures (MOE) between the toxicological points of reference and the dietary intake of perfluorocarboxylates (PFCAs) and PFOS in fish and seafood muscle tissue were greater than 4 orders of magnitude. This indicates that reducing consumption of fish muscle tissue is not warranted on the basis of PFC exposure concerns at the reported levels of contamination, even for high fish consuming populations.  相似文献   

Amylolytic-, trypsin-inhibiting-, and urease-activity in three varieties of soybeans and in soybean plant     

Yehudith Birk  Miriam Waldman 《Plant foods for human nutrition (Dordrecht, Netherlands)》1965,12(2):199-209

Summary A comparative study has been carried out on amylase, urease and trypsin-inhibiting activities in the soybean varieties Adams, Harosoy and Lincoln and in soybean plant material of Harosoy. No significant quantitative difference was found between these activities in the three varieties. Two pH optima, at 5.5 and at 6.4 were found for amylase activity from all three varieties of soybeans. Although the temperature of 60° was most favourable for Adams-, Harosoy-and Lincoln-amylase, the latter lost almost all its activity at 70° whereas that of Adams remained constant.No urease and trypsin-inhibiting activities and only slight amylase activity could be detected in the leaves, stems and empty pods of the soybean plant. Young seeds (three weeks after setting) were compared, on the basis of dry weight, to mature seeds and were found to contain 50% of the trypsin inhibiting activity, 34% of the amylase and only 3% of the urease of the latter.

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Zusammenfassung Eine vergleichende Studie wurde durchgeführt über Amylase-, Urease- und Trypsin-hemmende Wirkung der Sojabohnen-Sorten Adams, Harosoy und Lincoln sowie in Sojabohnenpflanzen der Sorte Harosoy. Keine mengenmäßig-signifikanten Unterschiede in der Wirkung fanden sich bei den drei Sorten. Zwei pH-Optima ergaben sich für die Amylase-Aktivität der drei Sojabohnen-Sorten bei 5,5 und 6,4. Obwohl die Temperatur von 60° sehr günstig für die Amylase der Sorten Adams, Harosoy und Lincoln war, verlor die Amylase der letztgenannten Sorte fast ihre gesamte Wirksamkeit bei 70°, während die der Sorte Adams dabei konstant blieb.Keine Urease- und Trypsin-hemmende Wirkung und eine nur leichte Amylase-Aktivität konnte in den Blättern, Sproßachsen und in den leeren Hülsen der Sojabohnen-Pflanze nachgewiesen werden. Junge Samen (drei Wochen nach der Aussaat) wurden auf Trockengewichtsbasis mit reifen Samen verglichen. Es wurde bei den jungen Samen — im Vergleich zu den reifen — eine nur 50%ige Trypsin-hemmende Wirkung, eine 34%ige der Amylase und eine nur 3%ige der Urease ermittelt.

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Resumen Se ha efectuado un estudio comparativo sobre las actividades de la amilasa, la ureasa y el inhibidor de la tripsina en las variedades de porotos de soya Adams, Harosoy y Lincoln, así como en algunas partes vegetativas de la variedad Harosoy. No se encontraron ningunas diferencias cuantitativas entre las actividades de estas variedades. Se encontraron dos valores optimales del pH, 5.5 y 6.4, para la amilasa de todas las tres variedades de porotos de soya. Aunque la temperatura más favorable para la amilasa de las variedades Adams, Harosoy y Lincoln fuera 60°, esta última perdió casi toda su actividad a 70°, mientras que la actividad de la variedad Adams se quedó sin cambiar.No se pudo demostrar la presencia de ureasa y actividad inhibidora de la tripsina en las hojas, los tallos y las cápsulas vacías de las plantas de soya, y se encontró solamante una ligera actividad de amilasa en estas partes vegetativas. Se compararon, en base seca, semillas nuevas (a las tres semanas de formarse) con semillas maduras. Se encontró que las primeras exhibieron 50% de la actividad inhibidora de la tripsina, 34% de la actividad de amilasa y solo 3% de la actividad de ureasa, en comparación con las actividades de las semillas maduras.

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Resumé Une étude comparative a été faite sur les activités de l'amylase, l'uréase et l'activité inhibitrice de la trypsine, dans les variétés de fèves de soya: Adams, Harosoy et Lincoln ainsi que sur différents stades de l'appareil végatatif du soya Harosoy. Aucune différence quantitative, significative, ne fut trouvée entre les activités dans les trois variétés. Deux pH optima à 5.5 et à 6.4 furent trouvés pour l'activité de l'amylase de toutes les trois variétés de fèves de soya. Bien que la témperature de 60° fut la plus favorable pour l'amylase de Adams, Harosoy et Lincoln, l'amylase de ces 2 derniers perdit presque toute son activité à 70° tandis que l'amylase dAdams resta constante.Ni activité d'urease, ni activité inhibitrice de trypsine ainsi que très peu d'amylase ne furent observés dans les feuilles, tiges et gousses vides de la plante soya. De jeunes semences (trois semaines après la fécondation) furent comparées, sur la base du poids sec, à des semences adultes et furent trouvées contenir 50% de l'activité inhibitrice de la trypsine, 34% de l'amylase et rien que 3% de l'uréase par rapport aux graines adultes.

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with 3 figs.  相似文献   

Mercury Dynamics in the Lahontan Reservoir,Nevada: Application of the QWASI Fugacity/Aquivalence Multispecies Model     

Diamond  Miriam  Ganapathy  Murali  Peterson  Steve  Mach  Carl 《Water, air, and soil pollution》2000,117(1-4):133-156

The Lahontan Reservoir in western Nevada has among the highest mercury (Hg) concentrations recorded in water, sediments and biota. The QWASI fugacity/aquivalence multispecies model was applied to examine Hg dynamics through a steady-state analysis of high loading conditions. The analysis indicated that the Carson River supplies most Hg in the water and upper sediments, with minimal inputs from the atmosphere and the Truckee Canal. Model estimates suggest that more than 90% of Hg entering the system from the Carson River at high flow is retained in the sediment of the reservoir, with export removing the remainder. Losses due to volatilization are negligible. The amount of methylmercury (MeHg) in the reservoir can be accounted for by inputs from the Carson River with minimal methylation occurring in the reservoir. The lack of species conversion and high retention rate appear to be due to the unreactive mineralogy of particulate Hg. Thus, we suggest that Hg dynamics are similar to that of other highly particle-reactive metals where fate is determined by particle movement. Finally, model results suggest an additional source of Hg to the system, which we hypothesize is from deep contaminated sediment that enters the system through sediment mixing caused by seasonal wet and dry cycles and sediment resuspension.  相似文献   

The Phanerozoic record of global sea-level change   总被引：5，自引：0，他引：5  

Miller KG  Kominz MA  Browning JV  Wright JD  Mountain GS  Katz ME  Sugarman PJ  Cramer BS  Christie-Blick N  Pekar SF 《Science (New York, N.Y.)》2005,310(5752):1293-1298

We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 +/- 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 10(4)- to 10(6)-year scale, but a link between oxygen isotope and sea level on the 10(7)-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).  相似文献   

Forecasting fire season severity in South America using sea surface temperature anomalies   总被引：2，自引：0，他引：2  

Chen Y  Randerson JT  Morton DC  DeFries RS  Collatz GJ  Kasibhatla PS  Giglio L  Jin Y  Marlier ME 《Science (New York, N.Y.)》2011,334(6057):787-791

Fires in South America cause forest degradation and contribute to carbon emissions associated with land use change. We investigated the relationship between year-to-year changes in fire activity in South America and sea surface temperatures. We found that the Oceanic Ni?o Index was correlated with interannual fire activity in the eastern Amazon, whereas the Atlantic Multidecadal Oscillation index was more closely linked with fires in the southern and southwestern Amazon. Combining these two climate indices, we developed an empirical model to forecast regional fire season severity with lead times of 3 to 5 months. Our approach may contribute to the development of an early warning system for anticipating the vulnerability of Amazon forests to fires, thus enabling more effective management with benefits for climate and air quality.  相似文献   

The rise of oxygen over the past 205 million years and the evolution of large placental mammals   总被引：2，自引：0，他引：2  

Falkowski PG  Katz ME  Milligan AJ  Fennel K  Cramer BS  Aubry MP  Berner RA  Novacek MJ  Zapol WM 《Science (New York, N.Y.)》2005,309(5744):2202-2204

On the basis of a carbon isotopic record of both marine carbonates and organic matter from the Triassic-Jurassic boundary to the present, we modeled oxygen concentrations over the past 205 million years. Our analysis indicates that atmospheric oxygen approximately doubled over this period, with relatively rapid increases in the early Jurassic and the Eocene. We suggest that the overall increase in oxygen, mediated by the formation of passive continental margins along the Atlantic Ocean during the opening phase of the current Wilson cycle, was a critical factor in the evolution, radiation, and subsequent increase in average size of placental mammals.  相似文献   

Response of Tribolium castaneum (Coleoptera, Tenebrionidae) to Salpichroa origanifolia Withanolides.   总被引：1，自引：0，他引：1  

Graciela Mareggiani  María I Picollo  Adriana S Veleiro  María C Tettamanzi  Miriam O V Benedetti-Doctorovich  Gerardo Burton  Eduardo Zerba 《Journal of agricultural and food chemistry》2002,50(1):104-107

Biological effects on Tribolium castaneum larvae were evaluated for three withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and for several chemically modified analogues. The compounds were incorporated into the larval diet at concentrations of 500 and 2000 ppm. Salpichrolide C (2) produced a significant delay in the development of neonate larvae to adults at the highest concentration (2000 ppm); development delays and lethal effects were produced by salpichrolides A (1) and G (3) at both concentrations assayed. The size of surviving adults was used as a criterion for assessing feedant deterrent effects; the results suggest that these compounds act as feeding inhibitors. Influence of chemical modifications in development delay was analyzed.  相似文献   

Ammonia autointoxication of common carp: case studies     

Zdeňka Svobodová  Jana Máchová  Hana Kroupová  Miriam Smutná  Ladislav Groch 《Aquaculture International》2007,15(3-4):277-286

Three case studies of ammonia autointoxication of the common carp (Cyprinus carpio L.) are described. In the first case, carp yearlings with a full digestive tract were transferred during the growing period from pond water (22°C) to tap water (17°C). In the second case, marketable carp were transferred from the fishing ground of a pond (18°C) to a storage pond (10–12°C). Harvest was performed in late September when the fish were still ingesting natural feed. In the third case, marketable carp after storage for 1 month were transferred to storage ponds with markedly lower water temperature. Stress because of harvest and handling also occurred in this case. In all cases, highly increased concentrations of ammonia were found in the blood plasma of the fish (mean ± SD 1760 ± 350 μmol L⁻¹ in the first case, 870 ± 540 μmol L⁻¹ in the second case, and 880 ± 150 μmol L⁻¹ in the third case). Highly congested, dark-red coloured, oedematous gills were observed for all specimens. We can avoid similar cases of ammonia autointoxication by protection of fish from sudden changes of temperature during rearing, harvesting, and handling.  相似文献   

Age-specific expression of a P450 monooxygenase (CYP6CM1) correlates with neonicotinoid resistance in Bemisiatabaci     

Christopher M. Jones  Miriam Daniels  Melanie Andrews  Russell Slater  Robert J. Lind  Kevin Gorman  Martin S. Williamson  Ian Denholm 《Pesticide biochemistry and physiology》2011,101(1):53-58

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