Stable isotope characterization of the ortho-oxygenated phenylpropanoids: coumarin and melilotol

The natural abundance 2H NMR spectra of extractive coumarin 10 and of its dihydroderivative melilotol 11 produced by baker's yeast reduction has been compared with synthetic materials. Diagnostic for the differentiation of 10 are the (D/H)beta values, which are in the 128.1-133.6 ppm interval for the natural compounds but 258.5 and 189.8 ppm for the synthetic materials. Such a dramatic difference is also found for methyl cinnamate 12, which shows (D/H)beta values of 127.2 and 515.8 ppm, respectively. In extractive 10, the ratio (D/H)4para/(D/H)6ortho = 1.24 is similar to that observed in structurally related salicin and methyl salicylate. Coumarin 10 is transformed in salicyl alcohol 9, providing diacetate 14, showing in the natural series the trend (D/H)3meta > (D/H)4para > (D/H)5meta approximately (D/H)6ortho. A similar trend is shown also by the synthetic 10. A clear distinction between extractive and synthetic 10 is obtained through delta18O determinations on 10 and on chroman 13. The bulk delta18O values in the extractive series of 10 are 20.3, 23.6, and 22.6 per thousand, while those of the aromatic oxygen are 2.3, 0.5, and -0.5 per thousand. In the synthetic sample, the values are 12.6 and 5.6 per thousand, respectively. As a final product, the reduction of 10 leads to the dihydroderivative 11. Both the baker's yeast reduction and the catalytic hydrogenation lead to a marked decrease of the deuterium content of 11, which is stronger for the beta-position than for the alpha-position.     

Fast determination of catechins and xanthines in tea beverages by micellar electrokinetic chromatography

Antioxidant properties and stimulating effects of green tea are related to its content of cathechins and xanthines; tea quality evaluation is based on organoleptic tests and on the presence of those components. In this work, by a MEKC method, eight cathechins and three xanthines were quantified in some tea-based beverages. The best separation was realized using a phosphate-borate running buffer, with sodium dodecyl sulfate as micellar agent. A 40 cm capillary, a temperature of 29 degrees C, a voltage of 30 kV, and UV detection at 200 nm were used. The method showed a very good sensitivity (limit of detection ranging from 0.0011 to 0.0051 microg/mL) and was applied to real tea samples to characterize their antioxidant content. Statistical studies were performed and showed a satisfactory reliability of the data.     

Stable isotope labeling pattern of resveratrol and related natural stilbenes

The stable isotope characterization of resveratrol 1 from Polygonum cuspidatum and of related natural stilbenes 11 and 12 obtained by hydrolysis of the corresponding glucosides 2 and 3 from Rheum is reported. The C(6)-C(2)-C(6) framework of suitably protected derivatives of 1, 2, and 3 has been degraded with ozone to the C(6)-C(1) aldehydes 4, 5, 9, and 10, retaining all hydrogen atoms of the precursors. The natural and synthetic derivatives are characterized and distinguished by natural abundance deuterium nuclear magnetic resonance studies. In the case of anisaldehyde 4 the two series show, as expected, the characteristic difference of the aromatic labeling. The formyl deuterium contents of 4 and 5 from resveratrol are remarkably different, seemingly reflecting the different enrichments existing between positions 3 and 2, respectively, of the phenylpropanoid precursor. The positional delta(18)O values of the extractive materials 1-3 were also determined. In this instance a selective deoxygenation procedure was adopted, leading from 1 to the products 6, 7, and 8. The delta(18)O values of the latter compounds reveal, respectively, those at position 4' and positions 3 and 5 of 1. Similarly, the phenolic products 11 and 12 were converted into 13 and 14. From the delta(18)O values of the single components it is possible to design a detailed map of the oxygen fractionations which characterizes the stilbenes 1-3. In particular, the oxygen present at position 4' of the phenylpropanoid moiety of 1-3 shows delta(18)O values of +11.5, +1.8, and +6.7 per thousand, respectively. Moreover, the phenolic oxygen atom at position 3' of rhapontin 3 shows a value of +11.7 per thousand. The data are compared with those previously obtained on structurally related compounds. These results show the utility of simple chemical degradations in the stable isotope characterization of structurally complex food components.     

Compositional shifts of bacterial groups in a solarized and amended soil as determined by denaturing gradient gel electrophoresis

Soil solarization is a widespread, nonchemical agricultural practice for disinfesting soils, which is often used in combination with organic amendment, and whose action represents an important factor impacting on soil bacterial communities structure and population dynamics. The present study was conducted to investigate whether and to which extent a 72-day plot-scale soil solarization treatment, either combined or not with organic amendment, could stimulate compositional changes in the genetic structure of indigenous soil bacterial communities. Soil solarization with transparent polyethylene film, in combination or not with farmyard manure addition, was carried out during a summer period on a clay loam agricultural soil located in Southern Italy. Soils from a four-treatment (NS, nonsolarized control soil; S, solarized soil; MA, manure-amended nonsolarized soil; MS, manure-amended and solarized soil) plot block were sampled after 0, 8, 16, 36 and 72 days. Compositional shifts in the genetic structure of indigenous soil bacterial communities were monitored by denaturing gradient gel electrophoresis (DGGE) fingerprinting of 16S rRNA gene fragments amplified from soil-extracted community DNA using primers specific for Bacteria, Actinomycetales, α- and β-Proteobacteria. Changes in soil temperature, pH, and electrical conductivity (EC_1:1) were also monitored from 0 to 72 days. Beneath the polyethylene film the average soil temperature at 8-cm depth reached 55 °C compared to 35 °C in nonsolarized soil. In general, without amendment both soil pH and EC_1:1 were not significantly affected by solarization, whereas in manured plots either variables were greatly increased (from 7.0 to 8.0 pH and from 271 to 3021 μS cm⁻¹ EC_1:1), and both showed long-lasting effects due to soil solar heating. The eubacterial DGGE profiles revealed that soil solarization was the main factor inducing strong time-dependent population shifts in the community structure either in unamended or amended soils. Conversely, the addition of organic amendment resulted in an altered bacterial community, which remained rather stable over time. A similar behaviour was also observed in the DGGE patterns of β-proteobacterial and actinomycete populations, and also, albeit to a lesser extent, in the DGGE profiles of α-Proteobacteria. An increased bacterial richness was evidenced by DGGE fingerprints in 16- and 36-day samplings, followed by a decrease appearing in 72-day samplings. This could be explained, other than by a direct thermal effect on soil microflora, by solarization-induced changes in the physico-chemical properties of soil microbial habitats or by other ecological factors (e.g. decreased competitiveness of dominating bacterial species, reduced grazing pressure of microfaunal predators, increased nutrient availability).     

Anthracene influence on (15NH4)2SO4 fertilization of wheat seedlings

The influence of the addition of anthracene (1 μg anthracene g^?1 soil) in N transformations following (¹⁵NH₄)₂SO₄ fertilization (200 mg N g^?1 soil) was investigated in wheat pots by quadrapole mass-spectrometry. The dry matter yield at harvesting (after 16 days) was not statistically affected (P=0.05) by anthracene addition. The total amount of N from the fertilizer taken up by wheat seedings in 16 days was 29 and 26.8% of the added N in the absence and in the presence of anthracene, respectively, but the difference was not significantly different at level P=0.05. In order to investigate more deeply the effect of anthracene on the N cycle in the soil-plant system, the first-order rate constants of N mineralization, N immobilization, nitrification and N plant uptake have been determined according to a ¹⁵N + ¹⁴N soil-plant model. The comparison of the constants showed that organic N mineralization, nitrification and plant uptake proceeded at the same rate, while a small different rate (P=0.05) was shown by N immobilization. In fact, the N immobilization constant increased from 0.14±0.012 to 0.21±0.014 day^?1 as a consequence of anthracene addition.     

A SCAR marker for the sex types determination in Colombian genotypes of Carica papaya

Sex type determination in papaya (Carica papaya L.) is very important for crop improvement processes because it accelerates the identification of the fruitful plants. The use of molecular technology provides a quick and reliable identification of sex types in plantlets growing in seedbeds. Random amplified polymorphic DNA (RAPD) markers were used to determine the sex types of Colombian cultivars of dioecious papaya genotypes. This species has three sex types (male, female and hermaphrodite) determined by a multiallelic locus. There are no morphological differences at the chromosome level; therefore the identification of sex types by chromosomal dimorphism is not possible. A RAPD marker of 900 bp was found in male plants, but not in females or hermaphrodites. From this RAPD marker a sequence characterized amplified region (SCAR) was developed and it was possible to amplify fragments from the genomes of male and hermaphrodite plants, but not the female ones. The results indicate that this new SCAR marker will be valuable to determine the sex type of papaya plants.     

Evaluation of Weaning Strategies for Intensively Reared Australian Freshwater Fish, Murray Cod, Maccullochella peelii peelii

The Australian Murray cod supports a growing national industry. However, with regard to the process of weaning fry, there is a lack of information and optimal procedures need to be developed. The aim of the present investigation was to test the biological and economic efficacy of different weaning strategies for Murray cod. Three weaning strategies were tested on triplicate groups of fish: (1) only Artemia for 5 d, 7 d on Artemia plus starter diet, and 14 d on dry diet only; (2) 12 d on Artemia plus starter diet and 14 d on dry diet only; and (3) directly to dry diet for the entire experimental period. No significant differences were recorded in the growth and feed efficiency, while significantly higher mortality (38.4 ± 0.35%) was recorded in fish weaned directly onto dry diet. Fish subjected to the first 5 d on Artemia only showed a growth reduction during this period, which was compensated by a phase of enhanced growth during the dry‐diet phase. No significant differences were noted in the proximate composition of fish under the different treatments. The economic evaluation suggested that the treatment with the simultaneous supply of Artemia and starter diet is preferable.     

Copper complexes grafted to functionalized silica gel as wood preservatives against the brown rot fungus <Emphasis Type="Italic">Coniophora puteana</Emphasis>

Wood modification with siloxanes bearing amino groups with copper-linking function was carried out by a sol–gel process. Tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) were the main components. Two different procedures were followed: a two-step process (impregnation with the TEOS/APTES mixture followed by dipping into a copper sulphate solution) and a one-step process (impregnation with a homogeneous sol mixture of TEOS, APTES and copper (II) chloride). The obtained materials were characterized by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis. The determination of copper content before and after leaching was performed by atomic absorption spectroscopy. The efficacy against the brown rot fungus Coniophora puteana was tested by an accelerated procedure. SEM analyses showed that silicon penetrated into wood, while copper is effectively drawn into wood only in the one-step treatment. Copper fixation to the silica gel proved to be adequately strong. Both sol–gel treatments gave good protection against Coniophora puteana.