Humic acid model substances with pronounced redox functionality for the study of environmentally relevant interaction processes of metal ions in the presence of humic acid

Sachs, Susanne; Bernhard, Gert

doi:10.1016/j.geoderma.2011.01.012

Cited by 27 publications

(17 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…HSs are known as natural attenuators of pollutant toxicity (Sachs and Bernhard 2011;Zhilin et al 2004;Orlov 1997;Perminova et al 2001). Their ability to detoxify water solutions is a subject of interest for researchers.…”

Section: Humic Substances As Natural Detoxifying Agentsmentioning

confidence: 99%

“…Carboxyl, quinoid, phenolic, SH, and other electrondonating groups of HS are known to be responsible for binding and, hence, decreasing the amount of free metal ions in water ecosystems (Theng 2012;Sachs and Bernhard 2011;AlAbri et al 2010;Havelcová et al 2009;Lorenzo et al 2002). Phenolic, SH, and other groups of HS macromolecules reduce toxic impact of organic and inorganic oxidizers.…”

Section: Humic Substances As Natural Detoxifying Agentsmentioning

confidence: 99%

See 1 more Smart Citation

Pollutant toxicity and detoxification by humic substances: mechanisms and quantitative assessment via luminescent biomonitoring

Kudryasheva

Tarasova

2014

Environ Sci Pollut Res

View full text Add to dashboard Cite

The paper considers mechanisms of detoxification of pollutant solutions by water-soluble humic substances (HSs), natural detoxifying agents. The problems and perspectives of bioassay application for toxicity monitoring of complex solutions are discussed from ecological point of view. Bioluminescence assays based on marine bacteria and their enzymes are of special attention here; they were shown to be convenient tools to study the detoxifying effects on cellular and biochemical levels. The advantages of bioluminescent enzymatic assay for monitoring both integral and oxidative toxicities in complex solutions of model pollutants and HS were demonstrated. The efficiencies of detoxification of the solutions of organic oxidizers and salts of metals (including radioactive ones) by HS were analyzed. The dependencies of detoxification efficiency on time of exposure to HS and HS concentrations were demonstrated. Antioxidant properties of HS were considered in detail. The detoxifying effects of HS were shown to be complex and regarded as 'external' (binding and redox processes in solutions outside the organisms) and/or 'internal' organismal processes. The paper demonstrates that the HS can stimulate a protective response of bacterial cells as a result of (1) changes of rates of biochemical reactions and (2) stabilization of mucous layers outside the cell walls. Acceleration of auto-oxidation of NADH, endogenous reducer, by HS was suggested as a reason for toxicity increase in the presence of HS due to abatement of reduction ability of intracellular media.

show abstract

Section: Humic Substances As Natural Detoxifying Agentsmentioning

confidence: 99%

Section: Humic Substances As Natural Detoxifying Agentsmentioning

confidence: 99%

Pollutant toxicity and detoxification by humic substances: mechanisms and quantitative assessment via luminescent biomonitoring

Kudryasheva

Tarasova

2014

Environ Sci Pollut Res

View full text Add to dashboard Cite

show abstract

“…A 2 ml sample was taken after 24 h and acidified (pH \ 1). This solution was extracted with 0.5 M 2-thenoyltrifluoracetone (TTA) in vented xylol according to Bertrand and Choppin (1982) and Sachs and Bernhard (2011), respectively. Phase separation was done by centrifugation at 4,0009g 10 min.…”

Section: Artificial Depletion Of Cellular Gsh By Chlorodinitrobenzenementioning

confidence: 99%

Impact of uranium (U) on the cellular glutathione pool and resultant consequences for the redox status of U

2011

Self Cite

View full text Add to dashboard Cite

Uranium (U) as a redox-active heavy metal can cause various redox imbalances in plant cells. Measurements of the cellular glutathione/glutathione disulfide (GSH/GSSG) by HPLC after cellular U contact revealed an interference with this essential redox couple. The GSH content remained unaffected by 10 μM U whereas the GSSG level immediately increased. In contrast, higher U concentrations (50 μM) drastically raised both forms. Using the Nernst equation, it was possible to calculate the half-cell reduction potential of 2GSH/GSSG. In case of lower U contents the cellular redox environment shifted towards more oxidizing conditions whereas the opposite effect was obtained by higher U contents. This indicates that U contact causes a consumption of reduced redox equivalents. Artificial depletion of GSH by chlorodinitrobenzene and measuring the cellular reducing capacity by tetrazolium salt reduction underlined the strong requirement of reduced redox equivalents. An additional element of cellular U detoxification mechanisms is the complex formation between the heavy metal and carboxylic functionalities of GSH. Because two GSH molecules catalyze electron transfers each with one electron forming a dimer (GSSG) two UO(2) (2+) are reduced to each UO(2) (+) by unbound redox sensitive sulfhydryl moieties. UO(2) (+) subsequently disproportionates to UO(2) (2+) and U(4+). This explains that in vitro experiments revealed a reduction to U(IV) of only around 33% of initial U(VI). Cellular U(IV) was transiently detected with the highest level after 2 h of U contact. Hence, it can be proposed that these reducing processes are an important element of defense reactions induced by this heavy metal.

show abstract

“…The HS have been evaluated in different studies, such as in agriculture, transport of contaminants in the environment, metal complexation and drinking water treatment (Araújo et al, 2002;Samios et al, 2007;Campos et al, 2007;Rigobello et al, 2011;Sachs and Bernhard, 2011;Muscolo et al, 2013). When using chlorine, HS lead to a high demand of the disinfectant, as well as the formation of toxic halogenated byproducts as trihalomethanes (Pascoalatto et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

Rigobello¹,

Campos²,

Azevêdo³

et al. 2017

Rev. ambiente água

View full text Add to dashboard Cite

This paper compares the structural characteristics of aquatic humic substances (AHS) with humic substances from peat (HSP) through different analytical techniques, including elemental analysis, solid state 13 C cross polarization/magic-angle-spinning nuclear magnetic resonance spectroscopy ( 13 C CP-MAS NMR), ultraviolet/visible (UV/Vis) spectroscopy and Fourier transform infrared (FTIR) spectroscopy and total organic carbon (TOC). The AHS were extracted from water collected in a tributary of the Itapanhaú River (Bertioga/SP) using XAD 8 resin, and the HSP were extracted from peat collected in the Mogi Guaçu River bank (Luis Antonio/SP) with a KOH solution. After dialysis, both AHS and HSP extracts were filtered in membrane of 0.45 µm pore size (Fraction F1: < 0.45 µm) and fractioned by ultrafiltration in different apparent molecular sizes (AMS) (F2: 100 kDa-0.45 μm; F3: 30 kDa-100 kDa and F4: < 30 kDa). The extracts with the lowest AMS (F3 and F4) showed a higher number of aliphatic carbons than aromatic carbons, a higher concentration of groups containing oxygen and a higher percentage of fulvic acids (FA) than humic acids (HA) for both AHS and HSP. However, the AHS presented higher FA than HA content in relation to the HSP and distinct structural properties.Keywords: fulvic acid, humic acid, humic substances, ultrafiltration. 775Comparative characterization of humic substances … Rev. Ambient. Água vol. 12 n. 5 Taubaté -Sep. / Oct. 2017 Caracterização comparativa de substâncias húmicas extraídas de água e de turfa de diferentes tamanhos moleculares aparentes RESUMOEste artigo compara as características estruturais das substâncias húmicas aquáticas (SHA) com substâncias húmicas de turfa (SHT) usando diferentes técnicas analíticas, incluindo análise elementar, espectro de polarização cruzada de estado sólido 13 C/ espectroscopia de ressonância magnética nuclear ( 13 C CP-MAS RMN), espectroscopia no ultravioleta/visível e infravermelho com transformada de Fourier e carbono orgânico total (COT). As SHA foram extraídas de água coletada em um afluente do rio Itapanhaú (Bertioga/SP), utilizando resina XAD 8 e as SHT foram extraídas de turfa coletadas na margem do rio Mogi-Guaçu (Luis Antonio/SP) com uma solução de KOH. Após a diálise, ambos extratos de SHA e SHT foram filtrados em membrana com 0,45 m de tamanho de poro (Fração F1: < 0,45 m) e após fracionados através de ultrafiltração em diferentes tamanhos moleculares aparentes (F2: 100 kDa-0,45 m; F3: 30 -100 kDa e F4: < 30 kDa). Os extratos de menor tamanho (F3 e F4) apresentaram um maior número de átomos de carbono alifáticos do que de carbonos aromáticos, uma maior concentração de grupos contendo oxigênio e uma percentagem mais elevada de ácidos fúlvicos do que os ácidos húmicos para ambas as frações de SHA e de SHT. No entanto, as SHA apresentaram maior quantidade de ácidos fúlvicos que ácidos húmicos em relação às SHT e propriedades estruturais distintas.Palavras-chave: ácidos fúlvicos, ácidos húmicos, substâncias húmicas, ultrafiltração.

show abstract

Humic acid model substances with pronounced redox functionality for the study of environmentally relevant interaction processes of metal ions in the presence of humic acid

Cited by 27 publications

References 61 publications

Pollutant toxicity and detoxification by humic substances: mechanisms and quantitative assessment via luminescent biomonitoring

Pollutant toxicity and detoxification by humic substances: mechanisms and quantitative assessment via luminescent biomonitoring

Impact of uranium (U) on the cellular glutathione pool and resultant consequences for the redox status of U

Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

Contact Info

Product

Resources

About