Dehydrodieugenol isolated from Ocotea cymbarum induces cell death in human breast cancer cell lines by dysregulation of intracellular copper concentration

In this work, two neolignans - dehydrodieugenol (1) and dehydrodieugenol B (2) - were isolated from leaves of Ocotea cymbarum (H. B. K.) Ness. (Lauraceae). When tested against two human breast cancer cell lines (MCF7 and MDA-MB-231), compound 1 was inactive (IC50 > 500 μM) whereas compound 2 displayed IC50 values of 169 and 174 μM, respectively. To evaluate, for the first time in the literature, the synergic cytotoxic effects of compounds 1 and 2 with ion Cu2+, both cell lines were incubated with equimolar solutions of these neolignans and Cu(ClO4)2·6H2O. Obtained results revealed no differences in cytotoxicity upon the co-administration of compound 2 and Cu2+. However, the combination of compound 1 and Cu2+ increases the cytotoxicity against MCF7 and MDA-MB-231 cells, with IC50 values of 165 and 204 μM, respectively. The activity of compound 1 and Cu2+ in MCF7 spheroids regarding the causes/effects considering the tumoral microenvironment were accessed using fluorescence staining and imaging by fluorescence microscopy. This analysis enabled the observation of a higher red filter fluorescence intensity in the quiescence zone and the necrotic core, indicating a greater presence of dead cells, suggesting that the combination permeates the spheroid. Finally, using ICP-MS analysis, the intracellular copper disbalance caused by mixing compound 1 and Cu2+ was determined quantitatively. The findings showcased a 50-fold surge in the concentration of Cu2+ compared with untreated cells (p > 0.0001) - 18.7 ng of Cu2+/mg of proteins and 0.37 ng of Cu2+/mg of protein, respectively. Conversely, the concentration of Cu2+ in cells treated with compound 1 was similar to values of the negative control group (0.29 ng of Cu2+/mg of protein). This alteration allowed us to infer that compound 1 combined with Cu2+ induces cell death through copper homeostasis dysregulation.

The Impact of Hydroxytyrosol on the Metallomic-Profile in an Animal Model of Alzheimer's Disease

It is undeniable that as people get older, they become progressively more susceptible to neurodegenerative illnesses such as Alzheimer's disease (AD). Memory loss is a prominent symptom of this condition and can be exacerbated by uneven levels of certain metals. This study used inductively coupled plasma mass spectrometry (ICP-MS) to examine the levels of metals in the blood plasma, frontal cortex, and hippocampus of Wistar rats with AD induced by streptozotocin (STZ). It also tested the effects of the antioxidant hydroxytyrosol (HT) on metal levels. The Barnes maze behavior test was used, and the STZ group showed less certainty and greater distance when exploring the Barnes maze than the control group. The results also indicated that the control group and the STZ + HT group exhibited enhanced learning curves during the Barnes maze training as compared to the STZ group. The ICP-MS analysis showed that the STZ group had lower levels of cobalt in their blood plasma than the control group, while the calcium levels in the frontal cortex of the STZ + HT group were higher than in the control group. The most important finding was that copper levels in the frontal cortex from STZ-treated animals were higher than in the control group, and that the STZ + HT group returned to equivalent levels to the control group. The antioxidant HT can restore copper levels to their basal physiological state. This finding may help explain HT's potential beneficial effect in AD-patients.

24-Epibrassinolide alleviates drought effects in young Carapa guianensis plants, improving the hydraulic safety margin, gas exchange and antioxidant defence

Climate change is increasing the frequency of extreme events such as droughts, limiting plant growth and productivity. Exogenous application of plant growth regulators, such as 24-epibrassinolide (EBR), might be a solution as this molecule is organic, eco-friendly, and biodegradable. This is the first research to examine possible roles of EBR on the hydraulic safety margin, physiological behaviour, and metabolism in Carapa guianensis Aubl. (Meliaceae) exposed to drought. C. guianensis is a widely distributed tree in tropical forests of the Amazon. The objective was to determine whether EBR can improve tolerance to water deficit in young C. guianensis by measuring hydraulic traits, nutritional, biochemical and physiological responses, and biomass. The experiment had four randomized treatments: two water conditions (control and water deficit) and two concentrations of EBR (0 and 100 nM EBR). EBR increased the water potential and hydraulic safety margin, increased CO2 fixation, and improved stomatal performance. EBR also stimulated antioxidant defences (SOD, CAT, APX, and POX). Overall, tretreatment with EBR improved drought tolerance of young C. guianensis plants.

Pluronic F-127 Hydrogels Containing Copper Oxide Nanoparticles and a Nitric Oxide Donor to Treat Skin Cancer

Melanoma is a serious and aggressive type of skin cancer with growing incidence, and it is the leading cause of death among those affected by this disease. Although surgical resection has been employed as a first-line treatment for the early stages of the tumor, noninvasive topical treatments might represent an alternative option. However, they can be irritating to the skin and result in undesirable side effects. In this context, the potential of topical polymeric hydrogels has been investigated for biomedical applications to overcome current limitations. Due to their biocompatible properties, hydrogels have been considered ideal candidates to improve local therapy and promote wound repair. Moreover, drug combinations incorporated into the polymeric-based matrix have emerged as a promising approach to improve the efficacy of cancer therapy, making them suitable vehicles for drug delivery. In this work, we demonstrate the synthesis and characterization of Pluronic F-127 hydrogels (PL) containing the nitric oxide donor S-nitrosoglutathione (GSNO) and copper oxide nanoparticles (CuO NPs) against melanoma cells. Individually applied NO donor or metallic oxide nanoparticles have been widely explored against various types of cancer with encouraging results. This is the first report to assess the potential and possible underlying mechanisms of action of PL containing both NO donor and CuO NPs toward cancer cells. We found that PL + GSNO + CuO NPs significantly reduced cell viability and greatly increased the levels of reactive oxygen species. In addition, this novel platform had a huge impact on different organelles, thus triggering cell death by inducing nuclear changes, a loss of mitochondrial membrane potential, and lipid peroxidation. Thus, GSNO and CuO NPs incorporated into PL hydrogels might find important applications in the treatment of skin cancer.

Ionic homeostasis and redox metabolism upregulated by 24-epibrassinolide are crucial for mitigating nickel excess in soybean plants, enhancing photosystem II efficiency and biomass

Nickel (Ni) excess often generates oxidative stress in chloroplasts, causing redox imbalance, membrane damage and negative impacts on biomass. 24-Epibrassinolide (EBR) is a plant growth regulator of great interest to the scientific community because it is a natural molecule extracted from plants, is biodegradable and environmentally friendly. This study aimed to determine whether EBR can improve ionic homeostasis, antioxidant enzymes, PSII efficiency and biomass by evaluating nutritional, physiological, biochemical and morphological responses of soybean plants subjected to Ni excess. The experiment used four randomized treatments, with two Ni concentrations (0 and 200 μm Ni, described as -Ni2+ and +Ni2+ , respectively) and two concentrations of EBR (0 and 100 nm EBR, described as -EBR and +EBR, respectively). In general, Ni had deleterious effects on chlorophyll fluorescence and gas exchange. In contrast, EBR enhanced the effective quantum yield of PSII photochemistry (15%) and electron transport rate (19%) due to upregulation of SOD, CAT, APX and POX. Exogenous EBR application promoted significant increases in biomass, and these results were explained by improved nutrient content and ionic homeostasis, as demonstrated by increased Ca2+ /Ni2+ , Mg2+ /Ni+2 and Mn2+ /Ni2+ ratios.

Exposure to Inorganic Arsenic in Rice in Brazil: A Human Health Risk Assessment

In certain populations, rice is the main source of exposure to inorganic arsenic (iAs), which is associated with cancer and non-cancer effects. Although rice is a staple food in Brazil, there have been few studies about the health risks for the Brazilian population. The objective of this study was to assess the risks of exposure to iAs from white rice and brown rice in Brazil, in terms of the carcinogenic and non-carcinogenic effects, and to propose measures to mitigate those risks. The incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) were calculated in a probabilistic framework. The mean ILCR was 1.5 × 10^-4 for white rice and 6.0 × 10^-6 for brown rice. The HQ for white and brown rice was under 1. The ILCR for white and brown rice was high, even though the iAs concentration in rice is below the maximum contaminant level. The risk for brown rice consumption was lower, which was not expected. Various mitigation measures discussed in this report are estimated to reduce the risk from rice consumption by 5-67%. With the support of public policies, measures to reduce these risks for the Brazilian population would have a positive impact on public health.

Soil Treatment with Nitric Oxide-Releasing Chitosan Nanoparticles Protects the Root System and Promotes the Growth of Soybean Plants under Copper Stress

The nanoencapsulation of nitric oxide (NO) donors is an attractive technique to protect these molecules from rapid degradation, expanding, and enabling their use in agriculture. Here, we evaluated the effect of the soil application of chitosan nanoparticles containing S-nitroso-MSA (a S-nitrosothiol) on the protection of soybeans (Glycine max cv. BRS 257) against copper (Cu) stress. Soybeans were grown in a greenhouse in soil supplemented with 164 and 244 mg kg^-1 Cu and treated with a free or nanoencapsulated NO donor at 1 mM, as well as with nanoparticles without NO. There were also soybean plants treated with distilled water and maintained in soil without Cu addition (control), and with Cu addition (water). The exogenous application of the nanoencapsulated and free S-nitroso-MSA improved the growth and promoted the maintenance of the photosynthetic activity in Cu-stressed plants. However, only the nanoencapsulated S-nitroso-MSA increased the bioavailability of NO in the roots, providing a more significant induction of the antioxidant activity, the attenuation of oxidative damage, and a greater capacity to mitigate the root nutritional imbalance triggered by Cu stress. The results suggest that the nanoencapsulation of the NO donors enables a more efficient delivery of NO for the protection of soybean plants under Cu stress.

Ready-to-use room temperature one-pot synthesis of surface-decorated gold nanoparticles with targeting attributes

Gold nanoparticles (AuNPs) can be used in diagnostic and therapeutic applications. The development of facile and fast synthetic approaches is accordingly desirable towards ready-to-use biomedical materials. We report a practical one-pot method for the synthesis in aqueous media and room temperature of surface-decorated AuNPs with enhanced biological responses. The gold ions could be reduced using only polyethyleneimine (PEI) derivatives containing sugar and-or alkyl chains acting simultaneously as reducing and stabilizing agent, without the aid of any other mediator. The process is possibly potentialized by the presence of the amino groups in the polymer chains which further confer colloidal stability. The kinetics of AuNPs nucleation and growth depends on the chemical nature of the polymer chains. Particularly, the presence of lactose moieties conjugated to the PEI chains conducted to surface-decorated AuNPs with low cytotoxicity that are remarkably faster uptaken by HepG2 cells. These cells overexpress asialoglycoprotein (ASGP-R), a galactose receptor. These findings may kick off significant advances towards the practical and ready-to-use manufacturing of functionalized AuNPs towards cell-targeting since the methodology is applicable for a large variety of other ligands that can be conjugated to the same polymer chains.

Comparative Study on Lead and Copper Biosorption Using Three Bioproducts from Edible Mushrooms Residues

Agricultural waste products can be used as biosorbents for bioremediation once they are low-cost and high-efficient in pollutants removal. Thus, waste products from mushroom farming such as cutting and substrate of Lentinula edodes (popularly known as shiitake) and Agaricus bisporus (also known as champignon) were evaluated as biosorbents for metallic contaminants copper (Cu) and lead (Pb). Shiitake and champignon stalks, and shiitake substrate (medium in which shiitake was cultivated) were dried, grounded, characterized and experimented to remove Cu and Pb from contaminated water. The Sips model was used to establish the adsorption isotherms. Regarding Cu, champignon stalks have the best removal efficiency (43%), followed by substrate and stalks of shiitake (37 and 30%, respectively). Pb removals were similar among three residues (from 72 to 83%), with the champignon stalks standing out. The maximum adsorption capacities (q_max) for Cu in shiitake and champignon stalks were 22.7 and 31.4 mg/g⁻¹, respectively. For Pb, q_max for shiitake and champignon stalks, and shiitake substrate were 130.0, 87.0 and 84.0 mg/g⁻¹, respectively. The surface morphology of the champignon stalks revealed an organized and continuous structure. After an interaction with metals, the stalk of champignon accumulated the metal ions into interstices. Mushroom residues showed a relevant adsorption efficiency, especially for Pb. Mushroom farming waste are a very low-cost and promising alternative for removing toxic heavy metals from aquatic environment.

The applicability of fingernail lead and cadmium levels as subchronic exposure biomarkers for preschool children

Preschool children are exposed daily to metals in their homes and at daycare centers (DCC). Metal exposure and health effects are associated even at low levels, and children comprise a group of public health concern. Nail metals have been studied for exposure biomonitoring and compared to other biological media. The aim of this study was to explore the applicability of preschool fingernail lead and cadmium as subchronic exposure biomarkers. Nail lead and cadmium levels (NLL and NCL) of 602 preschool children (age: 1-4 years) who attended 21 DCC in São Paulo, Brazil, in 2013 were analyzed. Results were compared against blood lead and cadmium levels (BLL and BCL) found in a previous study. Inductively coupled plasma mass spectrometry (ICP-MS) analyses were performed for both samples. DCC and metal contaminated sites (MCS) were georeferencing. Logistic regression tests were applied to verify associations between nail metal levels and risk factors (sex, age, maternal education, secondary smoking, DCC geographic district, vehicle flow density, relative altitude and distance between DCC and nearest MCS) (p < 0.05). BLL was stratified by exposure level (low: <5 μg.dL^-1; high: >13.9 μg.dL^-1; medium: ≥5 μg.dL^-1 and ≤13.9 μg.dL^-1) and also tested the associations in order to verify if nail lead levels are affected by exposure intensity defined by blood metals concentrations. Radius distance and relative altitude of DCC to nearest MCS were associated with high NLL and NCL. Abnormal appearance of nails was associated with high NLL and low NCL. Lead and cadmium exposure magnitude had no significant impact on NLL. NLL should only be used for initial screening, and when financial resources are scarce, especially in areas located near contaminated sites. Preschool children were co-exposed to both lead and cadmium, reinforcing the need for broader studies evaluating exposure to environmental pollutants for more than one chemical element.

Cellular prion protein activates Caspase 3 for apoptotic defense mechanism in astrocytes

The cellular prion protein (PrP^C) is anchored in the plasma membrane of cells, and it is highly present in cells of brain tissue, exerting numerous cellular and cognitive functions. The present study proves the importance of PrP^C in the cellular defense mechanism and metal homeostasis in astrocytes cells. Through experimental studies using cell lines of immortalized mice astrocytes (wild type and knockout for PrP^C), we showed that PrPc is involved in the apoptosis cell death process by the activation of Caspase 3, downregulation of p53, and cell cycle maintenance. Metal homeostasis was determined by inductively coupled plasma mass spectrometry technique, indicating the crucial role of PrP^C to lower intracellular calcium. The lowered calcium concentration and the Caspase 3 downregulation in the PrP^C-null astrocytes resulted in a faster growth rate in cells, comparing with PrP^C wild-type one. The presence of PrP^C shows to be essential to cell death and healthy growth. In conclusion, our results show for the first time that astrocyte knockout cells for the cellular prion protein could modulate apoptosis-dependent cell death pathways.

Anatomical changes in stem and root of soybean plants submitted to salt stress

The soybean is a legume that is widely cultivated in many countries due to the high levels of protein and oil contained in its seed, and is used for human and animal nutrition. However, salinity affects more than 800 million hectares worldwide, limiting global agricultural production. The aim of this research was to evaluate the structural behaviour of the roots and stems under progressive salt stress, detailing the possible anatomical modifications to these organs in soybean plants during this stress. The plants were randomized into five treatments (0, 50, 100, 150 and 200 mm NaCl). All the root regions studied and exposed to 100 mm Na+ exhibited increases in the epidermis and endodermis and formation of lysogenic aerenchyma with increasing salinity, revealing the protective roles of these structures in reducing Na+ influx. In the stem, increases in the cortex and pith in the first internode subject to 100 mm Na+ suggest anatomical responses that aim to minimize oxidative stress. Soybean plants subjected to progressive salt stress (>50 mm Na+ ) avoided cavitation and loss of function linked to vessel elements, reducing the metaxylem in all the root and stem regions analysed. Finally, our results confirm anatomical changes to the roots and stems.

Isolation and characterization of bacteria from a brazilian gold mining area with a capacity of arsenic bioaccumulation

In Paracatu, a city in Minas Gerais State (Brazil), the gold mineral extraction produces wastes that contribute to environmental contamination by arsenic. This work describes the evaluation of arsenic concentration from soil of a gold mining area in Paracatu and the selection of arsenic resistant bacteria. In the process of culturing enrichment, 38 bacterial strains were isolated and the minimum inhibitory concentration (MIC) was determined in solid medium for each strain. Three bacterial strains named P1C1Ib, P2Ic and P2IIB were resistant to 3000 mg L^-1 of arsenite. Analysis of 16S rDNA gene sequences revealed that these bacteria belong to Bacillus cereus and Lysinibacillus boronitolerans species. After cultivation of the strains P1C1Ib, P2Ic and P2IIIb, 69.38%-71.88% of arsenite and 82.39%-85.72% of arsenate concentrations were reduced from the culture medium, suggesting the potential application of theses strains in bioremediation processes.

Evaluation of uptake, translocation, and accumulation of arsenic species by six different Brazilian rice (Oryza sativa L.) cultivars

Rice is a significant source of arsenic (As) exposure. The accumulation of the plant depends on several factors, including environmental conditions and genetic factors. The differences in As uptake, translocation, and grains filling in different cultivars are a focus on studies to mitigate the grains contamination. This study assessed the pattern of As species accumulation in different Brazilian rice cultivars (Oryza sativa L.). Thus, pot experiments were conducted with 6 different cultivars (white rice: EPAGRI 109, EPAGRI 108, BRS Tiotaka SCS, and SCS 114 Andosan and red rice: Maranhão and Cáqui) cultivated in soils at low (As-) (0.65 mg kg^-1) and high (As+) (12.1 mg kg^-1) As levels. All cultivars in As+ group presented total As (t-As) in grains more elevated than the maximum limit of inorganic arsenic (i-As) recommended by Codex Alimentarius Commission. The As speciation disclose that Maranhão, Caqui, and SCS 114 Andosan cultivars presented the lowest % i-As (27%, 25% and 31%, respectively) at the highest As exposure condition. On the other hand, higher i-As concentration and % i-As (91%) were observed in EPAGRI 108. Moreover, EPAGRI 108 and EPAGRI 109 had the highest transference factor soil-to-grain (TFsoil-grain = 0.22 and 0.20, respectively). Interestingly, for the cultivars EPAGRI 108 and Maranhão, the levels of some essential elements (Co and Mn) in grains were modulated by the levels of As in the soil. This study shows that levels of i-As were modulated by the type of Brazilian rice cultivar, the range of As levels in soil, As phytotoxicity and the transference factor of As from soil to root straw and grains. Moreover, SCS 114 Andosan is the promising cultivar that exhibits low t-As and % i-As in grains and low TF soil-grain.

Flow of essential elements in subcellular fractions during oxidative stress

Essential trace elements are commonly found in altered concentrations in the brains of patients with neurodegenerative diseases. Many studies in trace metal determination and quantification are conducted in tissue, cell culture or whole brain. In the present investigation, we determined by ICP-MS Fe, Cu, Zn, Ca, Se, Co, Cr, Mg, and Mn in organelles (mitochondria, nuclei) and whole motor neuron cell cultured in vitro. We performed experiments using two ways to access oxidative stress: cell treatments with H₂O₂ or Aβ-42 peptide in its oligomeric form. Both treatments caused accumulation of markers of oxidative stress, such as oxidized proteins and lipids, and alteration in DNA. Regarding trace elements, cells treated with H₂O₂ showed higher levels of Zn and lower levels of Ca in nuclei when compared to control cells with no oxidative treatments. On the other hand, cells treated with Aβ-42 peptide in its oligomeric form showed higher levels of Mg, Ca, Fe and Zn in nuclei when compared to control cells. These differences showed that metal flux in cell organelles during an intrinsic external oxidative condition (H₂O₂ treatment) are different from an intrinsic external neurodegenerative treatment.

Trace metal levels in serum and urine of a population in southern Brazil

This study aimed to evaluate serum and urine concentrations of several trace metals of a non-directly exposed population in southern Brazil and establish reference values. Serum and urine samples were obtained from 240 volunteers (175 males and 65 females, age ranging from 18 to 74 years old). Levels of arsenic, chromium, cobalt, copper, lead, nickel, manganese and zinc were determined by means of dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS). Comparison between genders resulted in no significant difference for all metals but serum copper, as concentrations are higher in females than males. For most metals assessed, a negative correlation between serum concentrations and age was found, but no significant correlation was found between urine concentrations and age.

Arsenic biotransformation by cyanobacteria from mining areas: evidences from culture experiments

Elucidating the role of cyanobacteria in the biotransformation of arsenic (As) oxyanions is crucial to understand the biogeochemical cycle of this element and indicate species with potential for its bioremediation. In this study, we determined the EC50 for As(III) and As(V) and evaluated the biotransformation of As by Synechococcus sp. through high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and X-ray absorption fine structure spectroscopy (XAFS). Synechococcus sp. exhibited higher sensitivity to As(III) with an EC(50, 96 h) of 6.64 mg L(-1) that was approximately 400-fold lower than that for As(V). Even though the cells were exposed to concentrations of As(III) (6 mg L(-1)) approximately 67-fold lower than those of As(V) (400 mg L(-1)), similar intracellular concentrations of As (60.0 μg g(-1)) were observed after 30 days. As(V) was the predominant intracellular As species followed by As(III). Furthermore, organic As species such as monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were observed in higher proportions after exposure to As(III). The differential toxicity among As oxyanions indicates that determining the redox state of As in the environment is fundamental to estimate toxicity risks to aquatic organisms. Synechococcus sp. demonstrated potential for its application in bioremediation due to the high accumulation of As and production of As organic compounds notably after exposure to As(III).

Arsenic-induced responses in Pityrogramma calomelanos (L.) Link: Arsenic speciation, mineral nutrition and antioxidant defenses

Arsenic (As) hyperaccumulation trait has been described in a limited number of fern species. The physiological basis of hyperaccumulation remains unclear, especially in non-Pteris species such as Pityrogramma calomelanos. Aiming at a better understanding of As-induced responses, P. calomelanos plants were exposed to 1 mM As for 21 days and compared with control plants. Chemical analyses revealed that As accumulation was ten times higher in pinnae then in roots and stipes. In pinnae, As was present mainly as arsenite, whereas arsenate was the dominant form in stipes and roots. Arsenic promoted an increase in antioxidant enzyme activities in both fern parts and several alterations in mineral nutrition, especially with regard to P and K. A higher content of non-protein thiols was observed in pinnae of plants exposed to As, whereas As induced the increase in lipid peroxidation in roots. The results showed that Pityrogramma calomelanos shares with Pteris vittata several aspects of As metabolism. High root-shoot As translocation showed to be essential to avoid toxic effects in roots, since the root is more sensitive to the metalloid. The higher capacity of P. calomelanos to sequester arsenite in the pinna and its efficient antioxidant system maintain the reactive oxygen species at a low level, thus enhancing the continuous accumulation of As. Molecular investigations are needed to elucidate the evolution of As-tolerance mechanisms in Pteridaceae species, especially with regard to membrane transporters and ROS signaling.

Toxic and essential elements in Nigerian rice and estimation of dietary intake through rice consumption

In this study, levels and estimated daily intake (EDI) of two toxic elements, Cd and Pb, and eight essential elements: Ca, P, Zn, Mn, Co, Cu, Se and Mo, were determined in Nigerian rice samples. The mean levels of Cd, Pb and Co were 5.43±0.88, 38.66±5.42, 25.8±3.18 ng/g. The mean levels of Ca, P, Zn, Mn, Cu, Se and Mo were 71.5±7.31, 951±52.0, 10.2±0.63, 8.5±0.47, 3.07±0.18, 40.1±9.2 and 0.39±0.05 µg/g, respectively. The percentage contribution to the reference values for each element was 0.54, 7.71, 0.38, 9.51, 8.97, 31.3, 30.7, 5.1 and 60.7% for Cd, Pb, Ca, P, Zn, Mn, Cu, Se and Mo, respectively. The elemental nutrient levels in Nigerian rice samples are comparable to those obtained from other regions and their consumption does not pose any serious health risk to consumers.

Speciation of arsenic in rice and estimation of daily intake of different arsenic species by Brazilians through rice consumption

Rice is an important source of essential elements. However, rice may also contain toxic elements such as arsenic. Therefore, in the present study, the concentration of total arsenic and five main chemical species of arsenic (As(3+), As(5+), DMA, MMA and AsB) were evaluated in 44 different rice samples (white, parboiled white, brown, parboiled brown, parboiled organic and organic white) from different Brazilian regions using high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The mean level of total arsenic was 222.8 ng g(-1) and the daily intake of inorganic arsenic (the most toxic form) from rice consumption was estimated as 10% of the Provisional Tolerable Daily Intake (PTDI) with a daily ingestion of 88 g of rice. Inorganic arsenic (As(3+), As(5+)) and dimethylarsinic acid (DMA) are the predominant forms in all samples. The percentages of species were 38.7; 39.7; 3.7 and 17.8% for DMA, As(3+), MMA and As(5+), respectively. Moreover, rice samples harvested in the state of Rio Grande do Sul presented more fractions of inorganic arsenic than rice in Minas Gerais or Goiás, which could lead to different risks of arsenic exposure.

Identification and distribution of mercury species in rat tissues following administration of thimerosal or methylmercury

Methylmercury (Met-Hg) is one the most toxic forms of Hg, with a considerable range of harmful effects on humans. Sodium ethyl mercury thiosalicylate, thimerosal (TM) is an ethylmercury (Et-Hg)-containing preservative that has been used in manufacturing vaccines in many countries. Whereas the behavior of Met-Hg in humans is relatively well known, that of ethylmercury (Et-Hg) is poorly understood. The present study describes the distribution of mercury as (-methyl, -ethyl and inorganic mercury) in rat tissues (brain, heart, kidney and liver) and blood following administration of TM or Met-Hg. Animals received one dose/day of Met-Hg or TM by gavage (0.5 mg Hg/kg). Blood samples were collected after 6, 12, 24, 48, 96 and 120 h of exposure. After 5 days, the animals were killed, and their tissues were collected. Total blood mercury (THg) levels were determined by ICP-MS, and methylmercury (Met-Hg), ethylmercury (Et-Hg) and inorganic mercury (Ino-Hg) levels were determined by speciation analysis with LC-ICP-MS. Mercury remains longer in the blood of rats treated with Met-Hg compared to that of TM-exposed rats. Moreover, after 48 h of the TM treatment, most of the Hg found in blood was inorganic. Of the total mercury found in the brain after TM exposure, 63% was in the form of Ino-Hg, with 13.5% as Et-Hg and 23.7% as Met-Hg. In general, mercury in tissues and blood following TM treatment was predominantly found as Ino-Hg, but a considerable amount of Et-Hg was also found in the liver and brain. Taken together, our data demonstrated that the toxicokinetics of TM is completely different from that of Met-Hg. Thus, Met-Hg is not an appropriate reference for assessing the risk from exposure to TM-derived Hg. It also adds new data for further studies in the evaluation of TM toxicity.

A simple method based on ICP-MS for estimation of background levels of arsenic, cadmium, copper, manganese, nickel, lead, and selenium in blood of the Brazilian population

Throughout the world, biomonitoring has become the standard for assessing exposure of individuals to toxic elements as well as for responding to serious environmental public health problems. However, extensive biomonitoring surveys require rapid and simple analytical methods. Thus, a simple and high-throughput method is proposed for the determination of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se) in blood samples by using inductively coupled plasma-mass spectrometry (ICP-MS). Prior to analysis, 200 microl of blood samples was mixed with 500 microl of 10% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 10 min, and subsequently diluted to 10 ml with a solution containing 0.05% w/v ethylenediamine tetraacetic acid (EDTA) + 0.005% v/v Triton X-100. After that, samples were directly analyzed by ICP-MS (ELAN DRC II). Rhodium was selected as an internal standard with matrix-matching calibration. Method detection limits were 0.08, 0.04, 0.5, 0.09, 0.12, 0.04, and 0.1 microg//L for As, Cd, Cu, Mn, Ni, Pb, and Se, respectively. Validation data are provided based on the analysis of blood samples from the trace elements inter-\comparison program operated by the Institut National de Sante Publique du Quebec, Canada. Additional validation was provided by the analysis of human blood samples by the proposed method and by using electrothermal atomic absorption spectrometry (ETAAS). The method was subsequently applied for the estimation of background metal blood values in the Brazilian population. In general, the mean concentrations of As, Cd, Cu, Mn, Ni, Pb, and Se in blood were 1.1, 0.4, 890, 9.6, 2.1, 65.4, and 89.3 microg/L, respectively, and are in agreement with other global populations. Influences of age, gender, smoking habits, alcohol consumption, and geographical variation on the values were also considered. Smoking habits influenced the levels of Cd in blood. The levels of Cu, Mn, and Pb were significantly correlated with gender, whereas Cu and Pb were significantly correlated with age. There were also interesting differences in Mn and Se levels in the population living in the north of Brazil compared to the south.

Evaluation of the use of human hair for biomonitoring the deficiency of essential and exposure to toxic elements

Monitoring the nutritional status of essential elements and assessing exposure of individuals to toxic elements is of great importance for human health. Thus, the appropriate selection and measurement of biomarkers of internal dose is of critical importance. Due to their many advantages, hair samples have been widely used to assess human exposure to different contaminants. However, the validity of this biomarker in evaluating the level of trace elements in the human body is debatable. In the present study, we evaluated the relationship between levels of trace elements in hair and whole blood or plasma in a Brazilian population. Hair, blood and plasma were collected from 280 adult volunteers for metal determination. An ICP-MS was used for sample analysis. Manganese, copper, lead and strontium levels in blood varied from 5.1 to 14.7, from 494.8 to 2383.8, from 5.9 to 330.1 and from 11.6 to 87.3 microg/L, respectively. Corresponding levels in hair varied from 0.05 to 6.71, from 0.02 to 37.59, from 0.02 to 30.63 and from 0.9 to 12.6 microg/g. Trace element levels in plasma varied from 0.07 to 8.62, from 118.2 to 1577.7 and from 2.31 to 34.2 microg/L for Mn, Cu and Sr, respectively. There was a weak correlation (r=0.22, p<0.001) between lead levels in hair and blood. Moreover, copper and strontium levels in blood correlate with those levels in plasma (r=0.64 , p<0.001 for Cu) and (r=0.22, p<0.05 for Sr). However, for Cu, Mn and Sr there was no correlation between levels in hair and blood. Our findings suggest that while the idea of measuring trace elements in hair is attractive, hair is not an appropriate biomarker for evaluating Cu, Mn and Sr deficiency or Pb exposure.

Simultaneous determination of Cd, Cu, Mn, Ni, Pb and Zn in nail samples by inductively coupled plasma mass spectrometry (ICP-MS) after tetramethylammonium hydroxide solubilization at room temperature: comparison with ETAAS

A simple method is described for the determination of Cd, Cu, Mn, Ni, Pb and Zn in nails by using inductively coupled plasma mass spectrometry (ICP-MS) or electrothermal atomic absorption spectrometry (ETAAS). Prior to analysis, 10-20 mg of nail samples were accurately weighed into (15 mL) conical tubes. Then, 1 mL of 25% (w/v) tetramethylammonium hydroxide (TMAH) solution was added to the samples, incubated at room temperature overnight and then further diluted to 10 mL with 1% (v/v) HNO(3). After that, samples were directly analyzed. Rhodium was used as internal standard for ICP-MS analysis. Method detection limits (3 s, n=20) were 0.1, 3.0, 1.0, 4.5, 1.5, 5.0 ng g(-1) for Cd, Cu, Mn, Ni, Pb and Zn, respectively for ICP-MS, and 24, 26, 30, 143, 130 and 1000 ng g(-1), respectively for ETAAS. The key issue addressed here is the elimination of the acid digestion prior to analysis. Moreover, with the use of the proposed method there is a considerable improvement in the sample throughput comparing to the traditional methods using microwave-assisted acid sample digestion prior to analysis. For validation purposes, six ordinary nail samples were solubilized and then directly analyzed by ICP-MS and ETAAS, with no statistical difference between the two techniques at 95% level on applying the t-test.