Composição química dos frutos de Campomanesia xanthocarpa Berg-Myrtaceae

Frutos in natura de C. xanthocarpa (Myrtaceae), coletados em diferentes estádios de amadurecimento na Floresta Estadual de Assis, município de Assis - SP, foram avaliados por meio de métodos tradicionais de análise, técnicas cromatográficas e de espectrometria de massas e de emissão ótica quanto à composição nutricional, ao perfil químico do óleo volátil e ao teor de elementos inorgânicos. Os resultados mostraram alto teor de água (81,4%); lipídios (1,9%); carboidratos totais (8,9%); fibra alimentar (6,3%); além de quantidades razoáveis de ácido ascórbico (17,8 mg.100 g-1); e traços de riboflavina (0,09 mg.100 g-1). No óleo volátil (0,2%), pôde-se identificar 62 componentes, correspondendo a 100% dos constituintes do óleo, destacando-se dentre eles os monoterpenos α-pineno (15%), o-cimeno (10,8%), β-pineno (10,5%). Entre os minerais (16), os principais elementos foram o K (2084 mg.kg-1), P (149 mg.kg-1), Mg (135 mg.kg-1) e, como microelementos, o Fe (6,4 mg.kg-1), Cu (93,3 mg.100 g-1) e Pb (1,3 mg.kg-1). O valor energético do fruto (57,3 kcal.100 g-1) deve-se quase que exclusivamente aos teores de carboidratos totais (8,9%).

Fontes orgânicas e inorgânicas de zinco e cobre como melhoradores de desempenho em leitões desmamados

Foram conduzidos dois experimentos para avaliar fontes orgânicas e inorgânicas de zinco e cobre nas dietas e seus efeitos no desempenho de leitões desmamados aos 21 dias de idade. Em cada experimento, foram utilizados 90 leitões em delineamento experimental de blocos ao acaso, com cinco dietas, seis repetições e três animais por parcela. As dietas utilizadas nos experimentos 1 e 2 continham 120 ppm de zinco e 10 ppm de cobre na forma de sulfato. No experimento 1, foram suplementadas com 0, 300, 600 e 900 ppm de zinco na forma orgânica ou 2.400 ppm na forma de óxido (ZnO) e, no experimento 2, com 0, 50, 100 e 150 ppm de cobre na forma orgânica ou 240 ppm de cobre na forma de sulfato (CuSO4 H2O). No experimento 1, os níveis de zinco de fonte orgânica tiveram efeito linear no consumo de ração e no ganho de peso nos períodos de 0 a 15 dias e de 0 a 21 dias pós-desmame. O ganho de peso nas fases de 0 a 35 dias e de 0 a 42 dias pós-desmame e o consumo de ração dos leitões que receberam a dieta com 900 ppm de zinco de fonte orgânica não diferiram dos valores observados naqueles que receberam a dieta com 2.400 ppm de zinco na forma inorgânica. A suplementação da dieta com zinco na forma orgânica (900 ppm) ou inorgânica (2.400 ppm) aumentou o consumo de ração e o ganho de peso de leitões nas primeiras três semanas após o desmame. A suplementação da dieta com 2.400 ppm de zinco na forma inorgânica reduziu a incidência de diarreia nas primeiras três semanas pós-desmame. No experimento 2, os níveis de cobre de fonte orgânica tiveram efeito quadrático no consumo de ração dos leitões nos períodos de 0 a 31 e de 0 a 40 dias pós-desmame. A suplementação da dieta com cobre, tanto de fonte orgânica (90 ppm) como inorgânica (240 ppm), aumenta o consumo de ração e o ganho de peso de leitões nos primeiros 40 dias pós-desmame.

Fontes de minerais orgânicos e inorgânicos para leitões desmamados

A presente pesquisa foi realizada com o objetivo de comparar os efeitos de fontes orgânicas e inorgânicas de microminerais sobre o desempenho, os parâmetros sanguíneos e a deposição de minerais em tecidos e órgãos de leitões desmamados. Foram utilizados 54 leitões de genética comercial, desmamados com idade média de 24 dias e peso médio de 7,35±0,88kg, num delineamento experimental de blocos ao acaso, com dois tratamentos, nove repetições e três animais por parcela. Os tratamentos foram representados pelo uso de rações suplementadas com minerais de fontes orgânicas ou inorgânicas (Cu, Zn, Fe, Mn e Se) no período dos 24 aos 57 dias de idade. Foram avaliados o consumo diário de ração, o ganho diário de peso, a conversão alimentar, os parâmetros hematológicos e a deposição de minerais em tecidos e órgãos. As fontes orgânicas de minerais nas rações fornecidas dos 24 aos 57 dias de idade melhoraram o ganho diário de peso (P=0,06) e a conversão alimentar (P=0,05) e aumentaram o número de hemáceas (P=0,10), contudo não influenciaram a deposição de minerais no músculo masseter, fígado, coração, baço e rim. Portanto, o suplemento de minerais de fontes orgânicas foi mais eficiente para o desempenho dos leitões na fase de creche.

The inducing NO-vasodilation by chemical reduction of coordinated nitrite ion in cis-[Ru(NO(2))L(bpy)(2)](+) complex

The synthesis of [Ru(NO(2)) L(bpy)(2)](+) (bpy = 2,2'-bipyridine and L = pyridine (py) and pyrazine (pz)) can be accomplished by addition of [Ru(NO) L(bpy) 2](PF(6))(3) to aqueous solutions of physiological pH. The electrochemical processes of [Ru(NO2) L(bpy) 2]+ in aqueous solution were studied by cyclic voltammetry and differential pulse voltammetry. The anodic scan shows a peak around 1.00 V vs. Ag/AgCl attributed to the oxidation process centered on the metal ion. However, in the cathodic scan a second peak around-0.60 V vs. Ag/AgCl was observed and attributed to the reduction process centered on the nitrite ligand. The controlled reduction potential electrolysis at-0.80 V vs. Ag/AgCl shows NO release characteristics as judged by NO measurement with a NO-sensor. This assumption was confirmed by ESI/MS(+) and spectroelectrochemical experiment where cis-[Ru(bpy)(2)L(H(2)O)](2+) was obtained as a product of the reduction of cis-[Ru(II)(NO(2)) L(bpy)(2)](+). The vasorelaxation observed in denuded aortic rings pre-contracted with 0.1 mu mol L(-1) phenylephrine responded with relaxation in the presence of cis-[RuII(NO2) L(bpy) 2]+. The potential of rat aorta cells to metabolize cis-[RuII(NO(2)) L(bpy)(2)](+) was also followed by confocal analysis. The obtained results suggest that NO release happens by reduction of cis-[RuII(NO(2)) L(bpy)(2)](+) inside the cell. The maximum vasorelaxation was achieved with 1 x 10(-5) mol L(-1) of cis-[RuII(NO(2)) L(bpy)(2)](+) complex.

Reactivity, photolability, and computational studies of the ruthenium nitrosyl complex with a substituted cyclam fac-[Ru(NO)Cl(2)(kappa(3)N(4),N(8),N(11)(1-carboxypropyl)cyclam)]Cl center dot H(2)O

Chemical reactivity, photolability, and computational studies of the ruthenium nitrosyl complex with a substituted cyclam, fac-[Ru(NO)Cl(2)(kappa(3)N(4),N(8),N(11)(1-carboxypropyl)cyclam)]Cl center dot H(2)O ((1-carboxypropyl) cyclam = 3-(1,4,8,11-tetraazacyclotetradecan-1-yl) propionic acid)), (I) are described. Chloride ligands do not undergo aquation reactions (at 25 degrees C, pH 3). The rate of nitric oxide (NO) dissociation (k(obs-NO)) upon reduction of I is 2.8 s(-1) at 25 +/- 1 degrees C (in 0.5 mol L(-1) HCl), which is close to the highest value found for related complexes. The uncoordinated carboxyl of I has a pK(a) of similar to 3.3, which is close to that of the carboxyl of the non coordinated (1-carboxypropyl) cyclam (pK(a) = 3.4). Two additional pK(a) values were found for I at similar to 8.0 and similar to 11.5. Upon electrochemical reduction or under irradiation with light (lambda(irr) = 350 or 520 nm; pH 7.4), I releases NO in aqueous solution. The cyclam ring N bound to the carboxypropyl group is not coordinated, resulting in a fac configuration that affects the properties and chemical reactivities of I, especially as NO donor, compared with analogous trans complexes. Among the computational models tested, the B3LYP/ECP28MDF, cc-pVDZ resulted in smaller errors for the geometry of I. The computational data helped clarify the experimental acid-base equilibria and indicated the most favourable site for the second deprotonation, which follows that of the carboxyl group. Furthermore, it showed that by changing the pH it is possible to modulate the electron density of I with deprotonation. The calculated NO bond length and the Ru/NO charge ratio indicated that the predominant canonical structure is [Ru(III)NO], but the Ru-NO bond angles and bond index (b.i.) values were less clear; the angles suggested that [Ru(II)NO(+)] could contribute to the electronic structure of I and b.i. values indicated a contribution from [Ru(IV)NO(-)]. Considering that some experimental data are consistent with a [Ru(II)NO(+)] description, while others are in agreement with [Ru(III)NO], the best description for I would be a linear combination of the three canonical forms, with a higher weight for [Ru(II)NO(+)] and [Ru(III)NO].

A possible role of ground-based microorganisms on cloud formation in the atmosphere

The formation of clouds is an important process for the atmosphere, the hydrological cycle, and climate, but some aspects of it are not completely understood. In this work, we show that microorganisms might affect cloud formation without leaving the Earth's surface by releasing biological surfactants (or biosurfactants) in the environment, that make their way into atmospheric aerosols and could significantly enhance their activation into cloud droplets. In the first part of this work, the cloud-nucleating efficiency of standard biosurfactants was characterized and found to be better than that of any aerosol material studied so far, including inorganic salts. These results identify molecular structures that give organic compounds exceptional cloud-nucleating properties. In the second part, atmospheric aerosols were sampled at different locations: a temperate coastal site, a marine site, a temperate forest, and a tropical forest. Their surface tension was measured and found to be below 30 mN/m, the lowest reported for aerosols, to our knowledge. This very low surface tension was attributed to the presence of biosurfactants, the only natural substances able to reach to such low values. The presence of strong microbial surfactants in aerosols would be consistent with the organic fractions of exceptional cloud-nucleating efficiency recently found in aerosols, and with the correlations between algae bloom and cloud cover reported in the Southern Ocean. The results of this work also suggest that biosurfactants might be common in aerosols and thus of global relevance. If this is confirmed, a new role for microorganisms on the atmosphere and climate could be identified.

Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O(3), NO, NO(2), CO, VOC, CO(2), and H(2)O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h(-1). Within the plume core, aerosol concentrations were strongly enhanced, with Delta CN/Delta CO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. Delta CN/Delta CO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large fraction of the total particle number served as CCN (about 60-80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16 +/- 12 %) of the plume particles were CCN. The fresh plume aerosols showed relatively weak light scattering efficiency. The CO-normalized CCN concentrations and light scattering coefficients increased with plume age in most cases, suggesting particle growth by condensation of soluble organic or inorganic species. We used a Single Column Chemistry and Transport Model (SCM) to infer the urban pollution emission fluxes of Manaus City, implying observed mixing ratios of CO, NO(x) and VOC. The model can reproduce the temporal/spatial distribution of ozone enhancements in the Manaus plume, both with and without accounting for the distinct (high NO(x)) contribution by the power plants; this way examining the sensitivity of ozone production to changes in the emission rates of NO(x). The VOC reactivity in the Manaus region was dominated by a high burden of biogenic isoprene from the background rainforest atmosphere, and therefore NO(x) control is assumed to be the most effective ozone abatement strategy. Both observations and models show that the agglomeration of NO(x) emission sources, like power plants, in a well-arranged area can decrease the ozone production efficiency in the near field of the urban populated cores. But on the other hand remote areas downwind of the city then bear the brunt, being exposed to increased ozone production and N-deposition. The simulated maximum stomatal ozone uptake fluxes were 4 nmol m(-2) s(-1) close to Manaus, and decreased only to about 2 nmol m(-2) s(-1) within a travel distance >1500 km downwind from Manaus, clearly exceeding the critical threshold level for broadleaf trees. Likewise, the simulated N deposition close to Manaus was similar to 70 kg N ha(-1) a(-1) decreasing only to about 30 kg N ha(-1) a(-1) after three days of simulation.

Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity

Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. We have measured and characterized CCN at water vapor supersaturations in the range of S=0.10-0.82% in pristine tropical rainforest air during the AMAZE-08 campaign in central Amazonia. The effective hygroscopicity parameters describing the influence of chemical composition on the CCN activity of aerosol particles varied in the range of kappa approximate to 0.1-0.4 (0.16+/-0.06 arithmetic mean and standard deviation). The overall median value of kappa approximate to 0.15 was by a factor of two lower than the values typically observed for continental aerosols in other regions of the world. Aitken mode particles were less hygroscopic than accumulation mode particles (kappa approximate to 0.1 at D approximate to 50 nm; kappa approximate to 0.2 at D approximate to 200 nm), which is in agreement with earlier hygroscopicity tandem differential mobility analyzer (H-TDMA) studies. The CCN measurement results are consistent with aerosol mass spectrometry (AMS) data, showing that the organic mass fraction (f(org)) was on average as high as similar to 90% in the Aitken mode (D <= 100 nm) and decreased with increasing particle diameter in the accumulation mode (similar to 80% at D approximate to 200 nm). The kappa values exhibited a negative linear correlation with f(org) (R(2)=0.81), and extrapolation yielded the following effective hygroscopicity parameters for organic and inorganic particle components: kappa(org)approximate to 0.1 which can be regarded as the effective hygroscopicity of biogenic secondary organic aerosol (SOA) and kappa(inorg)approximate to 0.6 which is characteristic for ammonium sulfate and related salts. Both the size dependence and the temporal variability of effective particle hygroscopicity could be parameterized as a function of AMS-based organic and inorganic mass fractions (kappa(p)=kappa(org) x f(org)+kappa(inorg) x f(inorg)). The CCN number concentrations predicted with kappa(p) were in fair agreement with the measurement results (similar to 20% average deviation). The median CCN number concentrations at S=0.1-0.82% ranged from N(CCN,0.10)approximate to 35 cm(-3) to N(CCN,0.82)approximate to 160 cm(-3), the median concentration of aerosol particles larger than 30 nm was N(CN,30)approximate to 200 cm(-3), and the corresponding integral CCN efficiencies were in the range of N(CCN,0.10/NCN,30)approximate to 0.1 to N(CCN,0.82/NCN,30)approximate to 0.8. Although the number concentrations and hygroscopicity parameters were much lower in pristine rainforest air, the integral CCN efficiencies observed were similar to those in highly polluted megacity air. Moreover, model calculations of N(CCN,S) assuming an approximate global average value of kappa approximate to 0.3 for continental aerosols led to systematic overpredictions, but the average deviations exceeded similar to 50% only at low water vapor supersaturation (0.1%) and low particle number concentrations (<= 100 cm(-3)). Model calculations assuming aconstant aerosol size distribution led to higher average deviations at all investigated levels of supersaturation: similar to 60% for the campaign average distribution and similar to 1600% for a generic remote continental size distribution. These findings confirm earlier studies suggesting that aerosol particle number and size are the major predictors for the variability of the CCN concentration in continental boundary layer air, followed by particle composition and hygroscopicity as relatively minor modulators. Depending on the required and applicable level of detail, the information and parameterizations presented in this paper should enable efficient description of the CCN properties of pristine tropical rainforest aerosols of Amazonia in detailed process models as well as in large-scale atmospheric and climate models.

Design of 1D and 2D molecule-based magnets with the ligand 4,5-dimethyl-1,2-phenylenebis(oxamato)

Three new bimetallic oxamato-based magnets with the proligand 4,5-dimethyl-1,2-phenylenebis-(oxamato) (dmopba) were synthesized using water or dimethylsulfoxide (DMSO) as solvents. Single crystal X-ray diffraction provided structures for two of them: [MnCu(dmopba)(H(2)O)(3)]n center dot 4nH(2)O (1) and [MnCu(dmopba)(DMSO)(3)](n center dot)nDMSO (2). The crystalline structures for both 1 and 2 consist of linearly ordered oxamato-bridged Mn(II)Cu(II) bimetallic chains. The magnetic characterization revealed a typical behaviour of ferrimagnetic chains for 1 and 2. Least-squares fits of the experimental magnetic data performed in the 300-20 K temperature range led to J(MnCu) = -27.9 cm(-1), g(Cu) = 2.09 and g(Mn) = 1.98 for 1 and J(MnCu) = -30.5 cm(-1), g(Cu) = 2.09 and g(Mn) = 2.02 for 2 (H = -J(MnCu)Sigma S(Mn, i)(S(Cu, i) + S(Cu, i-1))). The two-dimensional ferrimagnetic system [Me(4)N](2n){Co(2)[Cu(dmopba)](3)}center dot 4nDMSO center dot nH(2)O (3) was prepared by reaction of Co(II) ions and an excess of [Cu(dmopba)](2-) in DMSO. The study of the temperature dependence of the magnetic susceptibility as well as the temperature and field dependences of the magnetization revealed a cluster glass-like behaviour for 3.

Chemical and in vitro study of the potential of 3-(aryl)-2-sulfanylpropenoic acids and their Zn(II) complexes as protective agents against cadmium toxicity

The free H(2)xspa ligands [xspa = pspa, Clpspa, tspa or fspa where p = 3-(phenyl), Clp = 3-(2-chlorophenyl), t = 3-(2-thienyl), f = 3-(2-furyl) and spa = 2-sulfanylpropenoato], their Zn(II) complexes of formula [HQ](2)[Zn(xspa)(2)] (HQ=diisopropylammonium) and the Cd(II) equivalents were prepared and characterized by elemental analysis and by IR, Raman and NMR ((1)H, (13)C) spectroscopy. X-Ray studies of the crystal structures of [HQ](2)[Zn(pspa)(2)], [HQ](2)[Zn(Clpspa)2], [HQ](2)[Zn(tspa)(2)] and [HQ](2)[Zn(fspa)(2)] show that the zinc atom is coordinated to two O atoms and two S atoms of the ligands in a distorted tetrahedral ZnO(2)S(2) environment. In the structures of [HQ](2)[Cd(pspa)(2)] and [HQ](2)[Cd(Clpspa)(2)] the cadmium atom is coordinated to three S atoms and two carboxylato O atoms of the ligands in a distorted trigonal bipyramidal environment. The interchange of ligands between Zn( II) and Cd( II) was studied by (113)Cd NMR spectroscopy. The in vitro protective effect of H(2)xspa and their Zn( II) complexes against Cd toxicity was investigated using the human hepatocarcinoma HepG2 cell line and the pig renal proximal tubule LLC-PK1 cell line. The incorporation of Zn( II) was found to be relevant in the case of H(2)pspa, with an increase observed in the cell viability of the LCC-PK1 cells with respect to the value for the free ligand.

Synthesis, electrochemical studies and anticancer activity of ferrocenyl oxindoles

A series of (E) and (Z)-ferrocenyl oxindoles were prepared by coupling substituted oxindoles to ferrocenylcarboxyaldehyde in the presence of morpholine as a catalyst. The redox behavior of these isomers was determined by cyclic voltammetry. The effects of the oxindole derivatives on the migration of human breast cancer cells were evaluated using the wound-healing assay and the Boyden chamber cell-migration assay. The most potent Z isomers 11b (IC(50) = 0.89 mu M), 12b (IC(50) = 0.49 mu M) and 17b (IC(50) = 0.64 mu M) could represent attractive new lead compounds for further development for cancer therapy.

DNA oxidation, strand-breaks and etheno-adducts formation promoted by Cu, Zn-superoxide dismutase-H(2)O(2) in the presence and absence of bicarbonate

Biomolecule oxidation promoted by Cu, Zn-superoxide dismutase (SOD1) has been studied because of its potential role in neurodegenerative diseases. We studied the mechanism of DNA damage promoted by the SOD1-H(2)O(2) system. The system promoted the formation of strand breaks in plasmid DNA and the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in calf thymus DNA. We were also able to detect, for the. first time, 1,N(2)-etheno-2'-deoxyguanosine (1,N(2)-epsilon dGuo) in calf thymus DNA exposed to SOD1-H(2)O(2). The addition of a copper chelator caused a decrease in the frequency of 8-oxodGuo and 1,N(2)-epsilon dGuo, indicating the participation of copper ions lost from SOD1 active sites. The addition of bicarbonate increased the levels of both DNA lesions. We conclude that copper liberated from SOD1 active sites has a central role in the mechanism of DNA damage promoted by SOD1 in the presence of H(2)O(2), and that bicarbonate can modulate the reactivity of released copper.

Direct evidence of singlet molecular oxygen generation from peroxynitrate, a decomposition product of peroxynitrite

The decomposition of peroxynitrite to nitrite and dioxygen at neutral pH follows complex kinetics, compared to its isomerization to nitrate at low pH. Decomposition may involve radicals or proceed by way of the classical peracid decomposition mechanism. Peroxynitrite (ONOOH/ONOO(-)) decomposition has been proposed to involve formation of peroxynitrate (O(2)NOOH/O(2)NOO(-)) at neutral pH (D. Gupta, B. Harish, R. Kissner and W. H. Koppenol, Dalton Trans., 2009, DOI: 10.1039/b905535e, see accompanying paper in this issue). Peroxynitrate is unstable and decomposes to nitrite and dioxygen. This study aimed to investigate whether O(2)NOO(-) formed upon ONOOH/ONOO(-) decomposition generates singlet molecular oxygen [O(2) ((1)Delta(g))]. As unequivocally revealed by the measurement of monomol light emission in the near infrared region at 1270 nm and by chemical trapping experiments, the decomposition of ONOO(-) or O(2)NOOH at neutral to alkaline pH generates O(2) ((1)Delta(g)) at a yield of ca. 1% and 2-10%, respectively. Characteristic light emission, corresponding to O(2) ((1)Delta(g)) monomolecular decay was observed for ONOO(-) and for O(2)NOOH prepared by reaction of H(2)O(2) with NO(2)BF(4) and of H(2)O(2) with NO(2)(-) in HClO(4). The generation of O(2) ((1)Delta(g)) from ONOO(-) increased in a concentration-dependent manner in the range of 0.1-2.5 mM and was dependent on pH, giving a sigmoid pro. le with an apparent pK(a) around pD 8.1 (pH 7.7). Taken together, our results clearly identify the generation of O(2) ((1)Delta(g)) from peroxynitrate [O(2)NOO(-) -> NO(2)(-) + O(2) ((1)Delta(g))] generated from peroxynitrite and also from the reactions of H(2)O(2) with either NO(2)BF(4) or NO(2)(-) in acidic media.

DNA damage by sulfite autoxidation catalyzed by cobalt complexes

DNA damage was investigated in the presence of sulfite, dissolved oxygen and cobalt(II) complexes with glycylglycylhistidine, glycylhistidyllysine, glycylglycyltyrosylarginine and tetraglycine. These studies indicated that only Co(II) complexed with glycylglycylhistidine (GGH) induced DNA strand breaks at low sulfite concentrations (1-80 mu M) via strong oxidants formed in the reaction. In the presence of the other complexes, some damage occurred only in the presence of high sulfite concentrations (0.1-2.0 mM) after incubation for 4 h. In the presence of GGH, Co(II) and dissolved O(2), DNA damage must involve a reactive high-valent cobalt complex. The damaging effect was increased by adding S(IV), due to the oxysulfur radicals formed as intermediates in S(IV) autoxidation catalyzed by the complex. SO(3)(center dot)-S-, HO(center dot) and H(center dot) radicals were detected by EPR-spin trapping experiments with DMPO (5,5-dimethyl-1-pyrroline N-oxide). The results indicate that Co(II) binds O2 in the presence of GGH, and leads to the formation of a DMPO-HO(center dot) adduct without first forming free superoxide or hydroxyl radical, supporting the participation of a reactive high-valent cobalt complex.

A hybrid material assembled by anthocyanins from acai fruit intercalated between niobium lamellar oxide

Organic-inorganic hybrid materials can be prepared dispersing organic species into well-defined inorganic nanoblocks. This paper describes the immobilization of natural dyes from the extract of the Brazilian acai-fruit into two types of layered hexaniobate precursors derived from H(2)K(2)Nb(6)O(17): (i) colloidal dispersion of niobate exfoliated nanoparticles and (ii) niobate pre-intercalated with tetraethylammonium cations (TEA(+)). The restacking of exfoliated particles in the presence of acai anthocyanins promotes their intercalation and produces stacked layers showing large basal spacing (ca. 50 angstrom). The TEA(+) pre-intercalated niobate provides particles with lower content of dye species than the exfoliated precursor but with higher degree of organization and regularity according to X-ray diffraction data and images obtained by electron microscopies. Vibrational (FTIR and Raman) and (13)C NMR spectroscopies indicate the presence of flavylium cations in the hybrid materials and spectral profiles characteristic of glycosylated anthocyanidins. According to thermal analysis results, the purplish hybrids materials are more stable than the free acai-dyes. One hybrid sample was heated under air up to 170 degrees C and maintained at this temperature for 240 min. No weight loss events were observed and the sample retained its original color, indicating that the intercalation of anthocyanin into hexaniobate increases its thermal stability. Considering the structural, chemical, optical and thermal properties of the synthesized hybrid materials, they might be good candidates to be investigated for future specialized applications.