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61.
Tokalov SV Kind B Wollenweber E Gutzeit HO 《Journal of agricultural and food chemistry》2004,52(2):239-245
The biological effects of epicuticular substances in farinose exudates accumulated on inflorescence shafts and calyces of Primula denticulata on human acute myeloid leukemia cells (HL-60) were analyzed. The crude material possessed little antioxidative capacity but strong cytostatic properties. Some of its known components (5-hydroxyflavone, 2'-hydroxyflavone, 5,2'-dihydroxyflavone, and 5,8-dihydroxyflavone) were further tested to identify the biologically active compounds. The effects of these flavones on cell cycle progression, mitochondrial membrane potential, and reactive oxygen species have been investigated by flow cytometry. The flavonol quercetin was included in the study as reference compound because of its known cytostatic properties and its activity as radical scavenger. Compared to quercetin the flavones induced little apoptosis (up to 40 microM), but despite their low toxicity, the Primula flavonoids possessed strong cytostatic properties even at low concentrations. The cell cycle distribution showed a characteristic time-dependent shift, giving evidence of a generally short-lived effect of the test compounds in the exposed cells. The antioxidative properties quantified according to two different methods correlated with the number of hydroxyl groups. Whereas quercetin strongly affected the mitochondrial membrane potential, none of the Primula flavones showed a comparable effect. 相似文献
62.
Does long-term farmyard manure fertilization affect short-term nitrogen mineralization from farmyard manure? 总被引:2,自引:0,他引:2
Leif Nett Sven Averesch Silke Ruppel Jörg Rühlmann Carmen Feller Eckhard George Matthias Fink 《Biology and Fertility of Soils》2010,46(2):159-167
One of the challenges in organic farming systems is to match nitrogen (N) mineralization from organic fertilizers and crop
demand for N. The mineralization rate of organic N is mainly determined by the chemical composition of the organic matter
being decomposed and the activity of the soil microflora. It has been shown that long-term organic fertilization can affect
soil microbial biomass (MB), the microbial community structure, and the activity of enzymes involved in the decomposition
of organic matter, but whether this has an impact on short-term N mineralization from recently applied organic substances
is not yet clear. Here, we sampled soils from a long-term field experiment, which had either not been fertilized, or fertilized
with 30 or 60 t ha−1 year−1 of farmyard manure (FYM) since 1989. These soil samples were used in a 10-week pot experiment with or without addition of
FYM before starting (recent fertilization). At the start and end of this experiment, soil MB, microbial basal respiration,
total plant N, and mineral soil N content were measured, and a simplified N balance was calculated. Although the different
treatments used in the long-term experiment induced significant differences in soil MB, as well as total soil C and N contents,
the total N mineralization from FYM was not significantly affected by soil fertilization history. The amount of N released
from FYM and not immobilized by soil microflora was about twice as high in the soil that had been fertilized with 60 t ha−1 year−1 of FYM as compared with the non-fertilized soil (p < 0.05). 相似文献
63.
Sawalha H den Adel R Venema P Bot A Flöter E van der Linden E 《Journal of agricultural and food chemistry》2012,60(13):3462-3470
In this study, water-in-oil emulsions were prepared from water containing different salt concentrations dispersed in an oil phase containing a mixture of β-sitosterol and γ-oryzanol. In pure oil, the β-sitosterol and γ-oryzanol molecules self-assemble into tubular microstructures to produce a firm organogel. However, in the emulsion, the water molecules bind to the β-sitosterol molecules, forming monohydrate crystals that hinder the formation of the tubules and resulting in a weaker emulsion-gel. Addition of salt to the water phase decreases the water activity, thereby suppressing the formation of sitosterol monohydrate crystals even after prolonged storage times (~1 year). When the emulsions were prepared with less polar oils, the tubular microstructure was promoted, which significantly increased the firmness of the emulsion-gel. The main conclusion of this study is that the formation of oryzanol and sitosterol tubular microstructure in the emulsion can be promoted by reducing the water activity and/or by using oils of low polarity. 相似文献
64.
Koch Eckhard Enders Melanie Ullrich Cornelia Molitor Daniel Berkelmann-Löhnertz Beate 《植物病害和植物保护杂志》2013,120(1):26-33
Journal of Plant Diseases and Protection - The paper describes in vitro and in vivo experiments with extracts from Primula root and Hedera helix aimed at characterizing their effect on Phyllosticta... 相似文献