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PubMed2004

Arsenic speciation in tissues of the Mediterranean polychaete Sabella spallanzanii.

Arsenic toxicity is strictly related to its chemical form and marine organisms are known to accumulate this element mostly as organoarsenic nontoxic molecules. Contrasting with this general trend, the presence of moderately toxic to toxic arsenic compounds recently has been reported in some polychaete species, showing a completely different profile of represented chemical species. In this work the presence and distribution of arsenic were characterized in the Mediterranean polychaete Sabella spallanzanii, by analyzing total levels in different tissues and subcellular fractions and the occurrence of various arsenical compounds. Further investigations on arsenic accumulation in S. spallanzanii were based on the capability of this species to regenerate the branchial crown both in laboratory and field conditions. Though basal levels of arsenic in the thorax were similar to those already described for most polychaetes and invertebrate species, branchial crown revealed a remarkable accumulation of this element with concentrations higher than 1000 microg/g. Arsenic mainly was localized in a soluble form within the cytosol and dimethyl-arsinate (DMA) appeared the most represented chemical species. Experiments on bioaccumulation of arsenic in regenerating branchial crowns confirmed the environmental origin of this element and the time-dependent appearance of various As compounds suggested a methylation pathway more than a degradation process for the elevated content of DMA. The accumulation of this moderately toxic compound in the more vulnerable tissues of the polychaete might represent an antipredatory strategy, as indicated by some feeding trials where fish ate the thorax but rejected the branchial crowns.

Animals↗
PubMed1991

Comutagenesis of sodium arsenite with ultraviolet radiation in Chinese hamster V79 cells.

Solar ultraviolet radiation has been associated with the induction of skin cancer. Recent studies have indicated that near-ultraviolet, especially UVB, is mutagenic. Exposure to trivalent inorganic arsenic compounds has also been associated with increased skin cancer prevalence. Trivalent arsenic compounds are not mutagenic per se, but are comutagenic with a number of cancer agents. Here, we test the hypothesis that arsenite enhances skin cancer via its comutagenic action with solar ultraviolet radiation. Irradiation of Chinese hamster V79 cells with UVA (360 nm), UVB (310 nm) and UVC (254 nm) caused a fluence-dependent increase in mutations at the hprt locus. On an energy basis, UVC was the most mutagenic and UVA the least. However, when expressed as a function of toxicity, UVB was more mutagenic than UVC. Nontoxic concentrations of arsenite increased the toxicity of UVA, UVB and UVC. Arsenite acted as a comutagen at the three wavelengths; however, higher concentrations of arsenite were required to produce a significant (P less than 0.05) comutagenic response with UVB. The increased mutagenicity of UVB and UVA by arsenite may play a role in arsenite-related skin cancers.

Animals↗
PubMed2004

Uptake and accumulation behaviour of angiosperms irrigated with solutions of different arsenic species.

Uptake and metabolisation of arsenic as a function of both the plant type and the chemical form of arsenic were examined. For this purpose two different plant species (Silene vulgaris and Plantago major) were selected that differed in their vitality and accumulation behaviour on arsenic-loaded substrates. The plants were cultivated on soil and irrigated with aqueous solutions of an inorganic arsenic compound (arsenious acid) and an organic compound (dimethylarsinate). The arsenic species accumulated in the parts of the plants above ground were extracted by PLE and determined using IC-ICP-MS. The concentrations and metabolisation products of arsenic found in the extracts indicate different mechanisms of arsenic uptake and transformation in both angiosperms. The arsenic species pattern showed that S. vulgaris was more arsenic--tolerable than P. major which is attributed to a low arsenate to arsenite concentration ratio in the plant compartments. S. vulgaris was also able to demethylate and reduce dimethylarsinate to form arsenite in a high extent. P. major accumulated only eight times lower concentration of arsenic, and the arsenate to arsenite concentration ratio shifted to higher values. Metabolisation products of dimethylarsinate did not occur under the present experimental conditions. The vitality of the angiosperms seems to be very dependent on the ability of the plant to reduce arsenate to arsenite.

Arsenates↗
PubMed1990

Assessment of occupational exposure to inorganic arsenic based on urinary concentrations and speciation of arsenic.

An analytical speciation method, capable of separating inorganic arsenic (As (V), As (III] and its methylated metabolites (MMAA, DMAA) from common, inert, dietary organoarsenicals, was applied to the determination of arsenic in urine from a variety of workers occupationally exposed to inorganic arsenic compounds. Mean urinary arsenic (As (V) + As (III) + MMAA + DMAA) concentrations ranged from 4.4 micrograms/g creatinine for controls to less than 10 micrograms/g for those in the electronics industry, 47.9 micrograms/g for timber treatment workers applying arsenical wood preservatives, 79.4 micrograms/g for a group of glassworkers using arsenic trioxide, and 245 micrograms/g for chemical workers engaged in manufacturing and handling inorganic arsenicals. The maximum recorded concentration was 956 micrograms/g. For the most exposed groups, the ranges in the average urinary arsenic speciation pattern were 1-6% As (V), 11-14% As (III), 14-18% MMAA, and 63-70% DMAA. The highly raised urinary arsenic concentrations for the chemical workers, in particular, and some glassworkers are shown to correspond to possible atmospheric concentrations in the workplace and intakes in excess of, or close to, recommended and statutory limits and those associated with inorganic arsenic related diseases.

Arsenic↗
PubMed2006

Determination of soluble toxic arsenic species in alga samples by microwave-assisted extraction and high performance liquid chromatography-hydride generation-inductively coupled plasma-atomic emission spectrometry.

A microwave-based procedure for arsenic species extraction in alga samples (Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) is described. Extraction time and temperature were tested in order to evaluate the extraction efficiency of the process. Arsenic compounds were extracted in 8 ml of deionised water at 90 degrees C for 5 min. The process was repeated three times. Soluble arsenic compounds extracted accounted for about 78-98% of total arsenic. The results were compared with those obtained in a previous work, where the extraction process was carried out by ultrasonic focussed probe for 30 s. Speciation studies were carried out by high performance liquid chromatography-hydride generation-inductively coupled plasma-atomic emission spectrometry (HPLC-HG-ICP-AES). The chromatographic method allowed us to separate As(III), As(V), monomethylarsonic acid and dimethylarsinic acid in less than 13 min. The chromatographic analysis of the samples allowed us to identify and quantify As(V) in Hizikia sample and Sargasso material, while the four arsenic species studied were found in Chlorella sample. In the case of Laminaria sample, none of these species was identified by HPLC-HG-ICP-AES. However, in the chromatographic analysis of this alga by HPLC-ICP-AES, an unknown arsenic species was detected.

Arsenic↗
PubMed1999

Uptake of arsenic-betaines by the mussel Mytilus edulis.

Mussels (Mytilus edulis) were exposed to trimethyl(carboxymethyl)arsonium bromide (arsenobetaine, C-1 betaine), trimethyl(2-carboxyethyl)arsonium bromide (C-2 betaine), or trimethyl(3-carboxypropyl)arsonium bromide (C-3 betaine). Arsenic was accumulated by the mussels in all cases but the efficiency of uptake decreased with the number of methylene units in the carboxyalkyl group. Arsenobetaine (C-1 betaine) was the most readily accumulated, followed by the C-2 betaine (70% as efficient as arsenobetaine) and the C-3 betaine (approximately 7%). Chromatographic analysis (HPLC-ICPMS) of extracts of the mussels demonstrated that the arsenic compounds were accumulated unchanged. A 46-day depuration period which followed exposure did not significantly reduce the arsenic concentration in any of the three groups. Comparison with previous data on accumulation of arsenic compounds by M. edulis indicates that uptake may be influenced by the presence of a quaternary arsonium group and the zwitterionic nature of the arsenic-betaines.

Animals↗
PubMedDate not supplied

[Arsenic and respiratory neoplasms, risks, prevention].

Arsine and in general airborne arsenic compounds show the main cancer promoting characteristics. Protection of employees is therefore a question of ventilation speed and arsenic determination in ambient air and, preservated with EDTA, in urine. Meanwhile, the excess of respiratory cancers alone will continue to increase 5% for each microgram of arsenic present per m3 of air breathed in the work area, or excreted in every one-third liter of urine. Eighteen years after occupational lung cancer due to arsenic and arsenic compounds has been recognised in Japan, the presently accepted TLV of arsine, 200 micrograms/m3, unchanged since 1950, thus corresponds to an excess mortality of 1000%.

Arsenic↗
PubMed2004

Microbial metabolite of dimethylarsinic acid is highly toxic and genotoxic.

Dimethylarsinic acid [DMA, (CH(3))(2)AsO(OH)] causes cancer in the urinary bladder of rats. However, its mechanism of cancer or the ultimate carcinogenic form is not yet known. Rats administered dimethylarsinic acid excrete three unknown arsenic compounds (termed M-1, M-2, and M-3) in urine or feces, and these compounds are presumed to be produced by intestinal bacteria. Escherichia coli A3-6 isolated from a rat yielded two unknown arsenic compounds (M-2 and M-3) from dimethylarsinic acid and M-1 from trimethylarsine oxide (TMAO) in the presence of cysteine (Cys). Contents of M-2 and M-3 varied with cysteine concentration. The cytotoxicity and genotoxicity of the bacteria-free solution of dimethylarsinic acid or trimethylarsine oxide metabolized by E. coli A3-6 were studied using V79 cells. Dimethylarsinic acid (1 mM) metabolized by E. coli A3-6 in the presence of cysteine (1 mM) was highly cytotoxic (50% survival reduction concentration; 2.1 microM As) in V79 cells, and the toxic substance appeared to be M-2. The metabolite solution (at 2.5-10 microM total As) induced c-mitosis and tetraploids, and caused mitotic arrest, since it increased mitotic cells at the cytotoxic dose. The metabolite solution also significantly increased sister chromatid exchange (SCE) and chromosomal aberrations, most of which were chromatid gaps and chromatid breaks. A3-6 converted 96.1% of trimethylarsine oxide to M-1 in the presence of cysteine. This metabolite solution did not exhibit cytotoxicity or genotoxicity. The reported M-2 concentration in urine of rats administered levels of DMA via drinking water known to cause bladder tumors was sufficient to exhibit cytotoxic and genotoxic effects in urinary bladder. Thus, we hypothesize that intestinal bacteria play an important role in carcinogenicity of dimethylarsinic acid.

Animals↗
PubMed2003

Raman spectroscopy of selected arsenates--implications for soil remediation.

The contamination of soils with heavy metals such as As, Cr and Cu is of great importance; the remediation of such soils even more so. Arsenic compounds are prevalent in soils either through leaching of mine tailings, the use of Cu/Cr/As as a wood preservative or through the use of arsenic in cattle dips. The arsenic compounds in soils and leachates can be highly reactive and mobile, resulting in the formation of metal arsenate compounds. Of these compounds, one such set of minerals that can be formed is the vivianite arsenate minerals. Raman spectroscopy has been used to characterise the vivianite arsenates and to identify arsenic contaminants in a soil.

Arsenates↗
PubMed2003

In vitro activity of dimethylarsinic acid against human leukemia and multiple myeloma cell lines.

PURPOSE: Arsenic trioxide (As(2)O(3)), an inorganic arsenic compound, has recently been approved for the treatment of relapsed or refractory acute promyelocytic leukemia. However, systemic toxicity associated with As(2)O(3) treatment remains a problem. Inorganic arsenic is detoxified in vivo by methylation reactions into organic arsenic compounds that are less toxic. METHODS AND RESULTS: We investigated the antiproliferative and cytotoxic activity of dimethylarsinic acid (DMAA), an organic arsenic derivative and major metabolic by-product of As(2)O(3), against a panel of eight leukemia and multiple myeloma cell lines. As(2)O(3) was tested in comparison. In clonogenic assay, the average concentration of DMAA that suppressed cell colony growth by 50% was 0.5-1 m M, while for As(2)O(3) it was on average 1-2 microM. At those concentrations DMAA and As(2)O(3) had significantly less effect on colony growth of normal progenitor cells. Cytotoxic doses of DMAA and As(2)O(3) in 3-day trypan blue dye exclusion assay experiments were similar to doses effective in clonogenic assay. Assessment of apoptosis by annexin V assay revealed a high rate of apoptosis in all cell lines treated with DMAA and As(2)O(3), but significantly less effect on normal progenitor cells. DMAA, unlike As(2)O(3), had no effect on the maturation of leukemic cells. CONCLUSIONS: DMAA exerts differential antiproliferative and cytotoxic activity against leukemia and multiple myeloma cells, with no significant effect on normal progenitor cells. However, concentrations of DMAA needed to achieve such efficacy are up to 1000 times those of As(2)O(3). Evaluation of novel organic arsenic that would combine the high efficacy of As(2)O(3) and the low toxicity of DMAA is warranted.

Cacodylic Acid↗
PubMed2003

Tetraarsenic oxide, a novel orally administrable angiogenesis inhibitor.

Arsenic compounds have been used to treat angiogenic diseases such as cancer, psoriasis, and rheumatoid arthritis in traditional oriental medicine. In recent years, arsenic trioxide (As2O3, diarsenic oxide) has been successfully used to treat acute promyelocytic leukemia. We investigated the antiangiogenic properties of tetraarsenic oxide (As4O6), another trivalent arsenic compound. In in vitro studies, tetraarsenic oxide inhibited the proliferation (IC50 = 99.7 nM), migration into the denuded area (IC50 = 27.4 nM), and invasion through a layer of Matrigel (IC50 = 73.5 nM) of basic fibroblast growth factor (bFGF)-stimulated bovine capillary endothelial (BCE) cells in a dose-dependent manner. Tetraarsenic oxide also inhibited the tube formation of human umbilical vein endothelial cells. Tetraarsenic oxide induced cell cycle arrest of bFGF-stimulated BCE cells in the G2/M phase and inhibited the secretion of matrix metalloproteinase-2 from BCE cells. Orally administered tetraarsenic oxide (50 mg/kg/day) inhibited bFGF-induced new-vessel formation in a rat corneal micropocket assay, and reduced by about 54% the number of experimental pulmonary metastatic nodules in mice implanted with B16F10 melanoma cells. Thus, we provide evidence that tetraarsenic oxide has effective antiangiogenic activities.

Administration, Oral↗
PubMed2001

Occurrence of organo-arsenicals in jellyfishes and their mucus.

Water-soluble arsenic compound fractions were extracted from seven species of jellyfishes and subjected to analysis by high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for arsenicals. A low content of arsenic was found to be the characteristic of jellyfish. Arsenobetaine (AB) was the major arsenic compound without exception in the tissues of the jellyfish species and mucus-blobs collected from some of them. Although the arsenic content in Beroe cucumis, which preys on Bolinopsis mikado, was more than 13 times that in B. mikado, the chromatograms of these two species were similar in the distribution pattern of arsenicals. The nine species of jellyfishes including two species treated in the previous paper can be classified into arsenocholine (AC)-rich and AC-poor species. Jellyfishes belonging to Semaostamae were classified as AC-rich species.

Animals↗
PubMedDate not supplied

Modulation of arsenic induced cytotoxicity by tea.

Arsenic, a naturally ocurring chemical element, is considered hazardous to human health. Inorganic arsenic compounds were found to induce cytotoxicity in Chinese hamster V-79 cells in culture. The arsenite form was more toxic than arsenate. Extracts of green and two varieties of black tea, as well as their principal polyphenols, (-)-epigallocatechingallate and theaflavin, efficiently counteracted the cytotoxic effects of arsenic compounds. On the basis of the amount of tea extract that afforded 50% protection to the cells from arsenic induced cytotoxicity, black tea was found to be as effective as green tea. The protective effect was attributable to the contents of not only (-)-epigallocatechingallate but also of theaflavin, the latter being a predominant polyphenol present in black tea.

Animals↗
PubMed1977

Cytopathogenic effects of atoxyl, an ototoxic compound, on human diploid fibroblasts in vitro.

Atoxyl, an arsenic compound, may cause degeneration in vivo of the inner ear including cells of the stria vascularis and hair cells. The mechanism behind the cytotoxic effect is not known. The effects of atoxyl at the subcellular level were investigated in this study using human diploid embryonic lung fibroblasts in monolayer cultures as an in vitro model system. Atoxyl caused a subtle but significant increase in the permeability of the fibroblast plasma membrane, as measured by release of a low molecular weight cytoplasmic marker (alpha-amino isobutyric acid). At higher concentrations or after longer incubation times, protein synthesis was impaired. This effect occurred in parallel with alterations in the cellular morphology as viewed by light microscopy. In the final stages of atoxyl intoxication the cells released also a higher molecular weight marker (nucleotide), indicating a further increased membrane permeability following the primary damage. It is concluded that atoxyl exerts a dual effect on the human fibroblasts, namely on membrane permeability and protein synthesis. Although the concentrations used were higher than those exerting the ototoxic effects in vivo, the prolonged exposure times to low concentrations obtained in whole animals may very well compensate for this fact. The effects observed in the in vitro fibroblast model system may thus be relevant to the mechanism of action of atoxyl during induction of ototoxic effects in vivo.

Aniline Compounds↗
PubMed2005

Methyl arsenic adsorption and desorption behavior on iron oxides.

In virtually all Earth surface environments, methylated forms of arsenic can be found. Because of the widespread distribution and toxicity of methyl-arsenic compounds, their adsorption by soil minerals is of considerable interest. The objective of this study was to compare the adsorption and desorption behavior of methylarsonic acid (MMAsV), methylarsonous acid (MMAsIII), dimethylarsinic acid (DMAsV), dimethylarsinous acid (DMAsIII), arsenate (iAsV), and arsenite (iAsIII) on iron oxide minerals (goethite and 2-line ferrihydrite) by means of adsorption isotherms, adsorption envelopes, and desorption envelopes (using sulfate and phosphate as desorbing ligands). MMAsIII and DMAsIII were not appreciably retained by goethite or ferrihydrite within the pH range of 3 to 11, while iAsIII was strongly adsorbed to both iron oxides. MMAsV and iAsV were adsorbed in higher amounts than DMAsV on goethite and ferrihydrite at all pH values studied. MMAsV and iAsV exhibited high adsorption affinities on both goethite and ferrihydrite from pH 3 to 10, while DMAsV was adsorbed only at pH values below 8 by ferrihydrite and below 7 by goethite. All arsenic compounds were desorbed more efficiently by phosphate than sulfate. MMAsV, iAsV, and DMAsV each exhibited adsorption characteristics suggesting specific adsorption on both goethite and ferrihydrite. Increased methyl substitution resulted in both decreased adsorbed arsenic at low arsenic concentrations in solution and increased ease of arsenic release from the iron oxide surface.

Adsorption↗
PubMed2004

Volatile analytes formed from arsenosugars: determination by HPLC-HG-ICPMS and implications for arsenic speciation analyses.

It is generally accepted that the use of the hydride generation method to produce volatile analytes from arsenic compounds is restricted to the two inorganic forms (As(III) and As(V)) and the three simple methylated species methylarsonate (MA), dimethylarsinate (DMA), and trimethylarsine oxide. We report here that arsenosugars, major arsenic compounds in marine organisms, produce volatile analytes by the hydride generation (HG) method without a prior mineralization/oxidation step and that they can be quantitatively determined using HPLC-HG-ICPMS. The hydride generation efficiency depends on the type of hydride generation system and is influenced by the concentration of HCl and NaBH(4). For the four arsenosugars investigated, the hydride generation efficiencies were approximately 21-28% (or 4-6%, depending on the HG system) that obtained for As(III) under conditions optimized for As(III). This hydride efficiency was less than that shown by MA ( approximately 68% relative to As(III)) and DMA ( approximately 75%) but greater than that displayed by As(V) ( approximately 18%). Analysis of two species of brown algae, Fucus serratus and Hizikia fusiforme, by HPLC-HG-ICPMS produced results comparable with those obtained from other techniques used in our laboratory (HPLC-ICPMS and LC-ESMS for F. serratus) and with results from other laboratories taking part in a round robin exercise (H. fusiforme). This study shows for the first time the quantitative determination of arsenosugars using the hydride generation method without a decomposition step and has considerable implications for analytical methods for determining inorganic arsenic based on the formation of volatile hydrides.

Arsenates↗