Relevance of leaf surface contamination for assessing chemical composition of bromeliads in a restinga forest

Resuspended soil and other airborne particles adhered to the leaf surface affect the chemical composition of the plant. A well-defined cleaning procedure is necessary to avoid this problem, providing a correct assessment of the inherent chemical composition of bromeliads. To evaluate the influence of a washing procedure, INAA was applied for determining chemical elements in the leaves of bromeliads from Vriesea carinata species, both non-washed and washed with Alconox, EDTA and bi-distilled water. Br, Ce, Hg, La, Sc, Se, Sm and Th showed higher mass fractions in non-washed leaves. The washing procedure removed the exogenous material without leaching chemical elements from inside the tissues.     

Soil-leaf transfer of chemical elements for the Atlantic Forest

Soil analysis could improve environmental studies since soil is the main source of chemical elements for plants. In this study, soil samples collected at 0–10 cm depth under tree crown projection were analyzed by INAA. Using the chemical composition of the leaf previously determined, the leaf-soil transfer factors of chemical elements could be estimated for the Atlantic Forest. Despite the variability of the intra-species, the transfer factors were specific for some plant species due to their element accumulation in the leaves. Similar Br-Zn combined transfer factors were obtained for the species grouped according to habitats in relation to their position (understory or dominant species) in the forest canopy.     

Seasonal variations in the chemical composition of vine-grape leaf surface

Surface leaf metabolites of two seedlings of a Bulgarian winemaking cultivar Storgozia I(1) were analyzed in two seasons - summer (July) and autumn (October). The resistance towards some fungal pathogens of one of the plants was estimated as superior to the resistance of the other one. Significant seasonal variations in the chemical constituents of the two seedlings were observed. The main metabolites of the summer samples were sterols, terpenes, fatty acids and heterocyclic compounds. In autumn, sterol and fatty acid contents decreased, mono- and diterpenes and heterocyclic compounds disappeared and instead of them hydrocarbons and alcohols were detected. Some individual components - stearic acid, alpha-amyrin, lupeol and squalene - correlated with the estimated resistance and were therefore proposed as biomarkers for the fungal resistance in grape-vine leaves.     

Variability in the chemical contamination effects of gun shot

This is a contribution to a larger study aimed at development of a technique to determine the origins of waterfowl from their feather chemistry, using automated X-ray fluorescence spectrometry. Since feather samples commonly come from shot birds, an effort was made to measure the contamination effects of shot using cotton cloth to simulate feathers. At pointblank ranges contamination can include the elements Ba, Sb, Pb, Cu, S and likely others depending on the exact composition of both gun powder and shot. At greater ranges (12.5 to 50 yards – 14.4 to 45 m) significant contamination resulting from 12 gauge No. 2 shot came only from lead, with some zinc contamination probable at the extreme range used. Lead contamination increased with increasing range, and apparently has a curvelinear relationship with pellet velocity. This knowledge might permit prediction, after the fact, of ranges from which shot has been fired.     

Atlantic Forest: A natural reservoir of chemical elements

The accumulation of chemical elements in biological compartments is one of the strategies of tropical species to adapt to a low-nutrient soil. This study focuses on the Atlantic Forest because of its eco-environmental importance as a natural reservoir of chemical elements. About 20 elements were determined by INAA in leaf, soil, litter and epiphyte compartments. There was no seasonality for chemical element concentrations in leaves, which probably indicated the maintainance of chemical elements in this compartment. Considering the estimated quantities, past deforestation events could have released large amounts of chemical elements to the environment.     

Status of chemical elements in Atlantic Forest tree species near an industrial complex

Environmental quality assessment studies have been conducted with tree species largely distributed in the Atlantic Forest. Leaf and soil samples were collected in the conservation unit Parque Estadual da Serra do Mar (PESM) nearby the industrial complex of Cubatão, São Paulo State, Brazil, and analyzed for chemical elements by instrumental neutron activation analysis. Results were compared to background values obtained in the Parque Estadual Carlos Botelho (PECB). The higher As, Fe, Hg and Zn mass fractions in the tree leaves of PESM indicated anthropogenic influence on this conservation unit.     

Surface desorption atmospheric pressure chemical ionization mass spectrometry for direct ambient sample analysis without toxic chemical contamination

Ambient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is used as a reagent to generate primary ions such as H(3)O(+), which is then directed to impact the sample surface for desorption and ionization. Under experimental conditions, protonated or deprotonated molecules of analytes present on various samples are observed using positive or negative corona discharge. Fast detection of trace amounts of analytes present in pharmaceutical preparations, viz foods, skins and clothes has been demonstrated without any sample pretreatment. Taking the advantage of the gasless setup, powder samples such as amino acids and mixtures of pharmaceutical preparations are rapidly analyzed. Impurities such as sudan dyes in tomato sauce are detected semiquantitatively. Molecular markers (e.g. putrescine) for meat spoilage are successfully identified from an artificially spoiled fish sample. Chemical warfare agent stimulants, explosives and herbicides are directly detected from the skin samples and clothing exposed to these compounds. This provides a detection limit of sub-pg (S/N > or = 3) range in MS2. Metabolites and consumed chemicals such as glucose are detected successfully from human skins. Conclusively, surface desorption atmospheric pressure chemical ionization (DAPCI) mass spectrometry, without toxic chemical contamination, detects various compounds in complex matrices, showing promising applications for analyses of human related samples.     

Surface curvature effects on the NMR chemical shift for molecules trapped in microporous solids

It is shown that the chemical shifts characteristic of molecules trapped in zeolites (¹²⁹Xe, and ¹³C for (CH₃)₄N⁺ ions) correlate directly with the surface curvature effects influencing the physisorption (dispersion) energy. Pore size is the determining parameter and other factors have negligible effect.     

Surface structure and composition effects on electrochemical reduction of carbon dioxide

Carbon dioxide electrochemical reduction has attracted significant attention due to its great potential in environmental protection and energy storage. In this mini-review, some recent progress in heterogeneous electrochemical reduction of carbon dioxide is summarized, with a particular emphasis on the effects of catalyst surface modification. Several structural (metal overlayers, particle size adjustment, roughness creation, special 2D or 3D structure patterning) and compositional (alloy, doping, oxide, and composite) modification techniques are reviewed and discussed. Research directions towards more advanced catalysts design are proposed.     

Effect of seasonal variation on the chemical composition and antioxidant and antifungal activities of Convolvulus althaeoides L. leaf extracts

The composition of polyphenols, chlorophylls and carotenoids of eight extracts of Convolvulus althaeoides L. leaves, harvested in two different seasons, winter and spring, and extracted by hot extraction method using four solvents (dichloromethane, chloroform, ethyl acetate and ethanol) with increasing polarity, were evaluated along with their antioxidant and antifungal activities. Qualitative and quantitative variations were observed in the composition based on two different high performance liquid chromatography systems, liquid chromatography-photodiode array detection coupled to either atmospheric pressure chemical ionization mass spectrometry or to electrospray ionization mass spectrometry, permitting the identification of 22 polyphenols, 11 chlorophyll derivatives and 10 carotenoid compounds. Polyphenolic compounds were predominant in extracts from leaves collected in winter, whereas pigments were predominant in the spring collections. Antioxidant activities of the extracts were determined by DPPH radical scavenging method, revealing a half inhibition concentration (IC₅₀) ranging from 0.1369 ± 0.0272 mg g⁻¹ to 0.432 ± 0.0018 mg g⁻¹, with no correlation to seasonal fluctuation. Concerning antifungal assays, ethyl acetate and ethanol extracts have been shown to be the most active against dermatophytes (T. rubrum, T. menthagrophytes, M. canis), with inhibiting percentages reaching 100% with 50 mg mL⁻¹. Moreover, ethyl acetate and ethanol extracts showed a maximum inhibition potential with minimum inhibitory/fungicidal concentrations ranging from 0.78 to 6.25 mg mL⁻¹ on Candida spp. cultures. The winter collect of these extracts showed an inhibitory effect of 90% on Candida albicans germ tubes formation, at a concentration of 3.1 mg mL⁻¹. In conclusion, seasonality seems to influence the quality and the quantity of natural substances from leaves of C. althaeoides L., which have major importance on the antioxidant and the antifungal effectiveness.     

In vitro antioxidant potential and in vivo effects of Schinus terebinthifolia Raddi leaf extract in diabetic rats and determination of chemical composition by HPLC-ESI-MS/MS

The present study investigated the in vitro and in vivo antioxidant potential and phytochemical composition of Schinus terebinthifolia, which is widely used in folk medicine for various therapeutic purposes. The in vitro analyses indicated that the hydroethanolic extract (HE) had 312.50 ± 0.50 mg GAE/g of total phenols. It also presented anti-DPPH? and anti-ABTS?⁺ activity, reduced phosphomolybden and metal ions and blocked the bleaching of β-carotene. The HE at concentrations of 3.0 and 2.0 μg/mL had TRAP values of 2.223 ± 0.018 and 1.894 ± 0.026 μM Trolox, respectively. The HE increased the availability of antioxidants in plasma in treated animals in vivo. HPLC-ESI-MS/MS indicated the presence of 11 phenols: cumaric acid, (+)-catechin, myricetin-3-O-glicuronide, kaempferol-3-O-glucoside, myricetin, myricitrin, quercetin, gallic acid, methyl galate, pentagalloyl glucose and ethyl galate. Thus, S. terebinthifolia has potential for the prevention or treatment of diseases that are related to oxidative stress, such as diabetes mellitus.     

Essential oil composition and acaricidal activity of Schinus terebinthifolius from Atlantic Forest of Pernambuco, Brazil against Tetranychus urticae

The compositions of the essential oils from unripe (UFr) and ripe (RFr) fruits of Schinus terebinthifolius were analyzed by GC and GC/MS. The major compound identified in both oils was limonene (UFr = 44.1 +/- 1.3%; RFr = 31.8 +/- 1.2%), followed by alpha-phellandrene (15.7 +/- 0.4%) in the UFr oil and thujene (21.7 +/- 0.9%) in the RFr oil. Repellent and toxicity activities of the two oils were also evaluated, and the results compared with eugenol. The UFr oil was more active in the fumigation tests (LC50 = 1.46 microL/L of air), whereas the RFr oil was more active in the sealed dishes (SD) than open dishes (OD) contact assay (LC50 = 3.04 microL/cm2) and not significantly different from eugenol. Both oils exhibited significant repellent activity comparable with that of eugenol. The results suggest that the repellent activity of these oils in association with its toxicity could be a great advantage for the integrated management of T. urticae.     

Ruta chalepensis L. (Rutaceae) leaf extract: chemical composition,antioxidant and hypoglicaemic activities

Ruta chalepensis L. (Rutaceae) leaf extract was investigated for its chemical profile and antioxidant and hypoglycaemic properties. The antioxidant effects were investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene bleaching, and metal chelating activity assays. The carbohydrate-hydrolysing enzymes inhibition assay was used to test the hypoglycaemic potential. R. chalepensis showed a high content of hesperidin and rutin with values of 591.9 and 266.7 mg/g dry extract, respectively. The extract exhibited a promising protection of lipid peroxidation (IC₅₀ value of 16.9 μg/mL) and inhibited both α-amylase and α-glucosidase enzymes in a concentration-dependent manner. The highest activity was found against α-amylase (IC₅₀ value of 69.0 μg/mL). The obtained results support the use of R. chalepensis leaves as healthy food ingredients.     

Surface chemical composition and fibrinogen adsorption-retention of fluoropolymer films deposited from an RF glow discharge

Fluoropolymer films have been deposited in the glow and afterglow regions of radio frequency glow discharges fed with C₂F₆−H₂ mixtures. Structure, growth rate, composition, and wettability of the films have been investigated by means of atomic force microscopy, electron spectroscopy for chemical analysis, secondary ion mass spectrometry, and water contact angle measurements.¹²⁵I labeled baboon fibrinogen in baboon plasma has been used to study the adsorption of the protein onto the films. Protein retention, i.e., the binding affinity of the adsorbed protein, has been examined by elution with a sodium dodecyl sulfate solution. Adsorption and retention of fibrinogen were correlated using multivariate statistical methods with the wettability, the degree of film fluorination, and the CF _x (1≤x≤3) group distribution of the coatings. This correlation identified the influence of each variable on the adsorption and retention of fibrinogen onto these substrates. These variables or surface properties can be easily balanced by properly tuning the experimental conditions of the glow discharge deposition process.     

Solvent effects on chemical processes. 3. Surface tension of binary aqueous organic solvents

The surface tension of binary solvents is modelled by analogy to solvation effects arising from solvent-solute interactions. Competitive exchange equilibria are postulated between solvent component I (water) and solvent component 2 (organic cosolvent) for solute, which in this case is air; the solvation shell is thus the surface phase. A quantitative relationship is given between surface tension and mole fractions x₁ and x₂, the model parameters being exchange equilibrium constants K₁ and K₂. The equation is analyzed, it is applied to literature surface tension data, and it is compared with an earlier model from this laboratory. Curve-fits are very good, and the parameters appear to possess physical significance.     

Bioactivity and chemical composition of the leaf essential oils of Zanthoxylum rhoifolium and Zanthoxylum setulosum from Monteverde, Costa Rica

The leaf essential oils of Zanthoxylum rhoifolium and Zanthoxylum setulosum (Rutaceae) from Monteverde, Costa Rica have been obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The principal constituents of Z. rhoifolium leaf oil were germacrene D (14.6%), limonene (12.5%), trans-2-hexenal (11.3%), beta-elemene (9.2%), 2-undecanone (9.2%), myrcene (7.9%), bicyclogermacrene (7.5%), and germacrene A (5.2%). The leaf oil of Z. setulosum was composed largely of beta-phellandrene (37.5%), beta-caryophyllene (13.7%), alpha-pinene (11.9%), germacrene D (10.9%), myrcene (5.9%), and nerolidol (5.4%). The essential oils were screened for in-vitro cytotoxic activity against Hep G2, MCF-7, and PC-3 human tumor cell lines; antibacterial activity against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli; and for Artemia salina (brine shrimp) lethality. Neither Z. rhoifolium nor Z. setulosum leaf oils exhibited cytotoxicity or antibacterial activity. Both oils showed activity against A. salina.     

Fractionation and composition of the carbohydrates of leaf vegetables

The qualitative and quantitative compositions of the carbohydrates of the leaf vegetables Lactuca sativa L., Spinacea oleracea L., and Rumex acetosa L. have been studied.M. V. Lomonosov Odessa Technological Institute of the Food Industry. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 349–351, May–June, 1993.     

Fractionation and composition of the carbohydrates of leaf vegetables

The qualitative and quantitative compositions of the carbohydrates of the leaf vegetables Lactuca sativa L., Spinacea oleracea L., and Rumex acetosa L. have been studied.