Characterization of phenolic exudates from Phaeodactylum tricornutum and their effects on the chemistry of Fe(II)–Fe(III)

Santana-Casiano, J. Magdalena; González‐Dávila, Melchor; González, Albano; Rico, Milagros; López, Aroa; Martel, Alain

doi:10.1016/j.marchem.2013.11.001

Cited by 44 publications

(48 citation statements)

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“…The role of several polyphenols is related to the availability of Fe(II) in solution and the presence of natural exudates also retards the oxidation of Fe(II) (González et al 2012). Santana-Casiano et al (2014) reported that the phenolic compounds exuded from microalgae, such as sinapic acid and (+) catechin, have an influence in iron redox chemistry by favouring the persistence of Fe(II) for their requirements.…”

Section: Discussionmentioning

confidence: 99%

“…As mentioned above, polyphenolic compounds can act as antioxidants by chelating metal ions such as iron(II)/ copper(I) and iron(III)/copper(II) ions that are involved in the conversion of O 2 −• and H 2 O 2 into highly aggressive HO • through Haber-Weiss/Fenton-type reactions (Munin and Edwards-Levy 2011). Determining how polyphenol concentrations change in response to high metal levels will demonstrate the role of polyphenols in microalgae-defensive tools to avoid poisoning and might be useful to help explain the dynamics of this important class of compounds in seawater (Santana-Casiano et al 2014). Identification and quantification of natural polyphenols excreted by microorganisms are necessary to improve our knowledge about the biogeochemistry of metals in natural waters and the role of these ligands in the chemistry under metallic stress conditions.…”

Section: Introductionmentioning

confidence: 99%

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Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

López

Rico

Santana-Casiano

et al. 2015

Environ Sci Pollut Res

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The present study investigates the phenolic profile of exudates and extracts of the green algae Dunaliella tertiolecta, harvested in natural seawater in the absence (control) and in the presence of Cu(II) (315 and 790 nmol L(-1)) and Fe(III) (900 nmol L(-1)) in order to identify and quantify the phenolic compounds produced under metallic stress conditions. The presence of metal ions modifies the growth of cells and changes cell metabolism by producing phenolic compounds adapted to the solution. The use of reversed-phase high-performance liquid chromatography (RP-HPLC) permitted the identification of 14 phenolic constituents. The concentration and type of polyphenols detected in cell extracts and in solution are directly related with the metal and its concentration during growth cultures, achieving 1.4 times higher levels of polyphenols under 790 nmol Cu(II) L(-1) with respect to the control experiments. Microalga excretes polyphenols to be adapted to the environmental conditions. Gentisic acid, (+) catechin and (-) epicatechin, the most prominent phenolic compounds detected in the algae extracts, showed high antioxidant activity in inhibiting 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. This potent activity may be related to its presence in cells and exudates in high concentrations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

López

Rico

Santana-Casiano

et al. 2015

Environ Sci Pollut Res

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“…The first datapoints were generally in agreement with the initial spike of Fe(II) added, confirming that the later over-estimation of Fe(II) could not consistently be attributed to an erroneous baseline. It remains possible that the residual Fe(II) concentration observed at the end of all experiments by ferrozine, and occasionally luminol B, (Figure 1) represents an Fe(II)-species which is resistant to oxidation, and indeed the presence of organic compounds capable of retarding Fe(II) oxidation in seawater has been widely discussed in prior work (e.g., González et al, 2014;Santana-Casiano et al, 2014). However, it is not expected that such high residual Fe(II) concentrations (2.7-9.1 nM) would remain in aged Mediterranean seawater.…”

Section: Potential Explanations For Inter-methods Differences In Fe(iimentioning

confidence: 82%

A Comparison between Four Analytical Methods for the Measurement of Fe(II) at Nanomolar Concentrations in Coastal Seawater

et al. 2017

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“…Note that, although the bulk solution is buffered at pH 8.6, the pristine pH of the photosynthesizing cell is typically 1 to 2 pH units higher, as is known from in-situ measurements with microelectrodes [39,46]. Second, the cells under light might be able to exudate various organic ligands, as is known in both freshwater and marine phytoplankton species [47][48][49][50][51].…”

Section: Long-term Interaction Of Aunps With Live Diatom Cellsmentioning

confidence: 99%

Interaction of Freshwater Diatom with Gold Nanoparticles: Adsorption, Assimilation, and Stabilization by Cell Exometabolites

et al. 2018

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Abstract:The rising concern about the potential toxicity of synthetic gold nanoparticles (AuNPs) in aquatic environments requires a rigorous estimation of physico-chemical parameters of reactions between AuNPs and major freshwater microorganisms. This study addresses the interaction of 10-nm size, positively charged AuNPs with periphytic freshwater diatoms (Eolimna minima). The adsorption experiments on viable cells were performed in 10 mM NaCl and 5 mM NaCl + 5 mM NaHCO 3 solution at a variable pH (3-10), at an AuNPs concentration from 1 µg/L to 10,000 µg/L, and an exposure time from a few minutes to 55 days. Three types of experiments, adsorption as a function of time (kinetics), pH-dependent adsorption edge, and constant-pH "Langmuirian" type isotherms, were conducted. In addition, long-term interactions (days to weeks) of live diatoms (under light and in the darkness) were performed. The adsorption was maximal at a pH from 3 to 6 and sizably decreased at a pH of 6 to 10. Results of adsorption experiments were modeled using a second order kinetic model, a Linear Programming Model, Freundlich isotherm, and a ligand binding equation for one site competition. The adsorption of AuNPs(+) most likely occurred on negatively-charged surface sites of diatom cell walls such as carboxylates or phosphorylates, similar to previously studied metal cations. Under light exposure, the AuNPs were stabilized in aqueous solution in the presence of live cells, probably due to the production of exometabolites by diatoms. The adsorbed amount of AuNPs decreased after several days of reaction, suggesting some AuNPs desorption. In the darkness, the adsorption and assimilation were stronger than under light. Overall, the behavior of positively charged AuNPs at the diatom-aqueous solution interface is similar to that of metal cations, but the affinity of aqueous AuNPs to cell exometabolites is higher, which leads to the stabilization of nanoparticles in solution in the presence of diatoms and their exudates. During photosynthetic activity and the pH rising above 9 in the vicinity of diatom cells, the adsorption of AuNPs strongly decreases, which indicates a decreasing potential toxicity of AuNPs for photosynthesizing cells. The present study demonstrates the efficiency of a thermodynamic and kinetic approach for understanding gold nanoparticles interaction with aquatic freshwater peryphytic microorganisms.

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Characterization of phenolic exudates from Phaeodactylum tricornutum and their effects on the chemistry of Fe(II)–Fe(III)

Cited by 44 publications

References 50 publications

Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

Phenolic profile of Dunaliella tertiolecta growing under high levels of copper and iron

A Comparison between Four Analytical Methods for the Measurement of Fe(II) at Nanomolar Concentrations in Coastal Seawater

Interaction of Freshwater Diatom with Gold Nanoparticles: Adsorption, Assimilation, and Stabilization by Cell Exometabolites

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