New glycosides from Capsicum annuum L. var. acuminatum. Isolation, structure determination, and biological activity

Investigation of polar extracts from ripe fruits of Capsicum annuum L. var. acuminatum yielded three new glycosides, capsosides A (1) and B (2) and capsianoside VII (3), along with seven known compounds (4-10). The chemical structures were elucidated mainly by extensive nuclear magnetic resonance methods and mass spectrometry, and the biological activities of icariside E(5) (4) were tested by different assays. Icariside E(5), in contrast to capsaicin, neither induces an increase in the intracellular levels of reactive oxygen species nor affects the mitochondria permeability transition, and it does not signal through the vanilloid receptor type 1. Interestingly, this compound protects Jurkat cells from apoptosis induced by the oxidative stress mediated by serum withdrawal. These results suggest that icariside E(5) may have antioxidant properties that strengthen the importance of peppers in the Mediterranean diet.     

Testing the Aluminium Toxicity Hypothesis: A Field Manipulation Experiment in Mature Spruce Forest in Norway

Aluminium (Al) has been considered to be a central element for risk evaluation of forest damage due to acidification. It has been hypothesized that Al reduces root growth, nutrient uptake and forest vitality. However, forest monitoring studies fail to show correlations between soil acidification and forest health. In general, no direct relation between Al concentration and forest health has been established. Here, Al concentrations in soil solution were manipulated by weekly additions of dilute AlCl₃ to levels that are believed to be unfavorable for plant growth. Four treatments (in triplicate), including a reference and three Al addition levels, were established. Effects of enhanced Al concentrations on fine root growth, nutrient uptake and crown condition in a mature Norway spruce forest in Norway were tested (1996–1999). After three years of manipulation, crown condition, tree growth and fine root growth were not affected by potentially toxic Al concentrations. However, the Mg content in current year's needles decreased at the highest Al addition treatment. The Mg/Al ratio of fine roots of the same treatment had declined too, which suggests that Al blocked Mg uptake at the root surface. The manipulation will be continued for two more years.     

Uncertainties in long-term predictions of forest soil acidification due to neglecting seasonal variability

Soil and soil solution response simulated with a site-scale soil acidification model (NUCSAM) was compared with results obtained by a regional soil acidification model (RESAM). RESAM is a multi-layer model with a temporal resolution of one year. In addition to RESAM, NUCSAM takes seasonal variability into account since it simulates solute transport and biogeochemical processes on a daily basis. Consequently, NUCSAM accounts for seasonal variation in deposition, precipitation, transpiration, litterfall, mineralization and root uptake. Uncertainty caused by the neglect of seasonal variability in long-term predictions was investigated by a comparison of long-term simulations with RESAM and NUCSAM. Two deposition scenarios for the period 1990–2090 were evaluated. The models were parameterized and validated by using data from an intensively monitored spruce site at Solling, Germany. Although both the seasonal and the interannual variation in soil solution parameters were large, the trends in soil solution parameters of RESAM and NUCSAM corresponded quite well. The leaching fluxes were almost similar. Generally it appeared that the uncertainty due to time resolution in long-term predictions was relatively small.     

Oxygen profiles and methane turnover in a flooded rice microcosm

Summary Dissolved O₂ was depleted within the top 3.5-mm surface layer of flooded rice soil microcosms without plants. In planted microcosms, however, O₂ was detectable down to at least 40 mm in depth. O₂ concentrations in the uppermost soil layers of microcosms with rice plants were higher in the light than in the dark, indicating O₂ production by photosynthesis. The CH₄ emission rates were nearly identical for illuminated and for darkened microcosms, demonstrating that the photosynthetically produced O₂ did not increase CH₄ oxidation in the rhizosphere. In contrast, CH₄ emission rates increased when the microcosms were incubated under an N₂ atmosphere, indicating that transport of O₂ from the atmosphere into the rhizosphere was important for CH₄ oxidation. CH₄ emission under air accounted for only 10%–20% of the cumulative CH₄ production determined in cores taken from the microcosms. Apparently, 80%–90% of the CH₄ produced was oxidized in the rhizosphere and thus was not emitted.     

Zur statistischen Abhängigkeit der Adsorption verschiedener Herbizidwirkstoffe vom Anteil der organischen Substanz in Böden

On the relation of herbicide adsorption and soil organic fraction Freundlich adsorption isotherms were measured for four herbicides (atrazine, terbuthylazine, chlorotoluron, isoproturon) and 24 soil horizons, which are typical of Schleswig-Holstein, northern Germany. The relationship between the adsorption constant (K_Fr) of a chemical and the fraction of organic carbon (f_OC) of the soil horizons was evaluated. Chemical specific K'_OC-values, that are independent of soil organic carbon fraction varied considerably for each herbicide (CV about 50%); therefore these values as well as K_OC-values, that are determined by linear regression of K_Fr and f_OC should be evaluated critically before application. K'_OC- and K_OC-values derived from experiments showed decreasing affinity of the herbicides to soil horizons in the order terbuthylazine > chlorotoluron > atrazine ? isoproturon. Calculation of K_OC from K_OW or water solubility of each herbicide, however, led to changes in the above mentioned ranking. Hence, especially K_OW or water solubility based K_OC-values may lead to false conclusions concerning chemical mobility. For atrazine, terbuthylazine and isoproturon Freundlich adsorption constants increased overproportionally with increasing organic carbon content of soils. The relationships between K_Fr and f_OC therefore were described better by a non-linear equation (second order polynom) than by a linear approach. Contrary, for chlorotoluron a linear relation between K_Fr and f_OC holds at least for the range of f_OC investigated in this study.     

Isoflavonoids isolated from Cuban propolis

Chemical investigation of a red-type Cuban propolis sample has led to the isolation of 11 isoflavonoids (2 isoflavones, 3 isoflavans, and 6 pterocarpans), together with gallic acid, isoliquiritigenin, and (-)-liquiritigenin. Structural determination, including the absolute stereochemistry, was accomplished by spectroscopic analysis, particularly CD and 2D NMR techniques. The fragmentation behavior of pterocarpans was studied by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) using an ion-trap analyzer, and a generalized fragmentation pathway, useful in the identification and structural characterization of pterocarpans, is proposed. Isoflavonoids are reported for the first time from propolis samples.     

Identification of alpha-tocopherol oxidation products in triolein at elevated temperatures

The effect of high-temperature treatment on the stability of alpha-tocopherol (1) in triolein was assessed under a reduced-pressure atmosphere (4-40 mbar) simulating the deodorization step of the refining of vegetable oils. A marked degradation of 1 was observed, which increased with increasing temperature (180-260 degrees C) and heating time (20-80 min). The degradation of 1 in triolein at 240 degrees C was inhibited by the addition of the synthetic antioxidant TBHQ or when heating was performed under nitrogen atmosphere, indicating oxidative degradation. The oxidation products were isolated and identified as alpha-tocopherolquinone (2), 4a,5-epoxy-alpha-tocopherolquinone (3), and 7,8-epoxy-alpha-tocopherolquinone (4).     

Comparison of measured and simulated changes in base cation amounts using a one-layer and a multi-layer soil acidification model

Biogeochemical processes describing nutrient cycling strongly affect the development of different soil horizons and soil acidification. However, in many soil acidification models these processes are not directly simulated, and spatially distributed soil properties are lumped into average values. This paper describes the extension of a one-layer soil acidification model (SMART) to a multi-layer model (SMARTEX) by including nutrient cycling, and the performance of both models regarding their ability for the assessment of the effects of acid deposition on forest soil. This was done by comparing simulation results of the two models with respect to changes in base cation amounts to historical data from sites in south Sweden. The results showed that the multi-layer model gives better results for the top soil, whereas the one-layer model gives better results for the rootzone and the total profile. Since the top soil is most important, the extended model is more suited to relate acid deposition to forest growth than the more general results of the one-layer model. However, the sensitivity of the multi-layer model to some parameters is large. A change in these parameters had strong effects on the separate layers, whereas the effects were cancelled out over the total profile. This sensitivity requires a careful parameterization of the model which might be troublesome to lack of data.     

Influence of critical storage temperatures on degradative pathways of pigments in green beans (Phaseolus vulgaris cvs. Perona and boby)

In this work a study of critical storage temperatures on pigment degradation of green beans (Phaseolus vulgaris, cvs. Perona and Boby) was conducted. In this way, green beans kept better quality at 4 degrees C than either 8 or 12 degrees C, maintaining a bright green color and good texture. Nevertheless, temperatures of 4 degrees C induced chilling injury (CI) after eight days of storage, which became evident when the pods were transferred to 20 degrees C. Cold storage temperatures, 12, 8, and 4 degrees C, produced different changes on the green beans chlorophyll profile. Green beans of both cultivars, Perona and Boby, stored at 4 and 12 degrees C showed a continuous degradation of chlorophyll pigments during storage, while samples stored at 8 degrees C showed an increase of chlorophyll content at the first 15 days. Carotenoid pigments also suffered different changes during cold storage. Perona was the green beans cultivar which maintained the higher level of lutein, mainly when samples were stored at the most suitable temperature (8 degrees C).