Production of a novel neuromelanin at the sevoflurane–water interface

Roberts, Ryan D.; Fibuch, Eugene E.; Heal, M. Elisabeth; Seidler, Norbert W.

doi:10.1016/j.bbrc.2007.08.150

Cited by 13 publications

(27 citation statements)

References 19 publications

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“…In addition to the catecholamines mentioned above, serotonin ( (7) in Fig.1) has been investigated as a potential precursor for the formation of NMs. [4][5][6] Allomelanins are nitrogen-free MNs found in plants derived from precursors like catechol ((1) in Fig.1) or pyrogallol ((2) in Fig.1). 1 Some MNs produced by fungi or bacteria are referred to as pyomelanin.…”

Section: Introductionmentioning

confidence: 99%

Dark- or Light-Colored Melanins: Generating Pigments Using Fe2+ and H2O2

Vercruysse

Russell²,

Knight³

et al. 2017

Preprint

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We have studied the formation of melanin-like pigments from catechol or pyrogallol and a wide range of other phenolic compounds using Fe 2+ and H 2 O 2 . Combining UV_Vis spectroscopic measurements and size-exclusion chromatography analyses we evaluated the impact of the intensity of the oxidation reaction by varying the concentration of H 2 O 2 present in the reaction mixtures. All compounds tested, except tyrosine, reacted readily leading to mixtures that were black, brown or yellow-orange in color. For many compounds tested, the use of increasing concentrations of H 2 O 2 resulted in either precipitation of the pigment or the formation of a soluble, lighter-colored pigment. With catechol or pyrogallol as model compounds, and using different concentrations of H 2 O 2 , several materials were synthesized, purified and dried. The physic-chemical properties of these materials were compared to the properties of melanin-like pigments synthesized from the same precursors using air-oxidation in an alkaline environment. For both precursors, a distinct chemical change, as judged from FT-IR spectroscopy, was introduced in the melanin structures when using H 2 O 2 as the oxidizing agent and the relative intensity of this distinct signal strengthened with increasing concentration of H 2 O 2 used in the reaction. In general, our results suggest that depending on the precursor molecule and the intensity of the oxidizing reaction conditions involved, light-or dark-colored melanin-like pigments can be generated. This may be an important factor when evaluating the visible outlook of histological or archeological specimens: the presence of a lighter color or the absence of a dark color may not necessarily mean the absence of melanin-like biomolecules.

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Section: Introductionmentioning

confidence: 99%

Dark- or Light-Colored Melanins: Generating Pigments Using Fe2+ and H2O2

Vercruysse

Russell²,

Knight³

et al. 2017

Preprint

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“…Serotonin forms higher order structures in an oxidizing environment that in addition to depleting serotonin levels may generate side products that are neurotoxic [10,11]. We previously observed that serotonin reacts with acrolein [7], which is a lipid peroxidation 3-carbon fragment that accumulates in aging [12] and plays a role in substantia nigra pathology [13]. Interestingly, sevoflurane, a commonly used inhaled anesthetic, sequesters acrolein [7] and enhances the formation of a serotoninderived melanoid (SDM), which may act to deplete serotonin and thus contribute to POCD.…”

Section: Introductionmentioning

confidence: 96%

“…While serotonin's reactive nature with various agents (i.e. acrolein, copper ions) may result in localized depletion thus promoting cognitive impairment, serotonin metabolites like bitryptamine [11] or SDM [7,14,15] appear to be have noxious properties, suggesting a cytotoxic mechanism for POCD.…”

Section: Introductionmentioning

confidence: 97%

“…We previously observed that serotonin reacts with acrolein [7], which is a lipid peroxidation 3-carbon fragment that accumulates in aging [12] and plays a role in substantia nigra pathology [13]. Interestingly, sevoflurane, a commonly used inhaled anesthetic, sequesters acrolein [7] and enhances the formation of a serotoninderived melanoid (SDM), which may act to deplete serotonin and thus contribute to POCD. We further showed that SDM exhibits redox properties [14] and disrupts lipid bilayers [15].…”

Section: Introductionmentioning

confidence: 97%

“…We previously proposed an alternate hypothesis that focuses on the role of serotonin [7], which has been implicated in AD. Others have also suggested that inhaled anesthetics may have a negative impact on serotonin signaling [8].…”

Section: Introductionmentioning

confidence: 99%

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Carnosine Protects Against the Neurotoxic Effects of a Serotonin-Derived Melanoid

et al. 2010

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Anesthesia-related postoperative cognitive dysfunction (POCD) leads to morbidity in the elderly. Lipid peroxidative byproducts (i.e. acrolein) accumulate in aging and may play a role. Sevoflurane, an inhaled anesthetic, sequesters acrolein and enhances the formation of a serotonin-derived melanoid (SDM). SDM may be a biologically relevant polymeric melanoid that we previously showed exhibits redox activity and disrupts lipid bilayers. In this study, we examined the toxicity of SDM in cell culture and looked at protection using L-carnosine. SDM's toxic effects were tested on neuronal-like SH-SY5Y cells, causing an exponential decrease in viability, while human dermal fibroblasts were completely resistant to the toxic effects. SDM brought about morphological changes to differentiated SH-SY5Y cells, particularly to neuronal processes. Co- but not pre-treatment with L-carnosine protected differentiated SH-SY5Y cells exposed to SDM. Our mechanism suggests focal sevoflurane-induced sequestration of age-related acrolein leading to SDM synthesis and neuronal impairment, which is prevented by L-carnosine.

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Redox Mechanism of Neurotoxicity by a Serotonin–Acrolein Polymeric Melanoid

et al. 2010

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Postoperative cognitive dysfunction may be associated with the toxic products of lipid peroxidation, such as the α,β-unsaturated aldehyde acrolein, which accumulates in aging. We previously identified an acrolein-mediated, serotonin-derived melanoid product, or SDM. This study further characterizes this putative novel neuromelanin, which is not made from catecholamines. In addition to its strong protein-binding properties, we observed that SDM binds Fe(2+) readily and exhibits complex redox characteristics. SDM may exist as a two-dimensional network of polymers that coalesce into larger entities exhibiting electroactive properties. These observations suggest that SDM may contribute to the decline in cognition due to focal degeneration from SDM-mediated free-radical production. We know that inhalational anesthetics sequester acrolein, which is toxic to neurons, and we propose that the local increase in acrolein depletes serotonin levels and enhances neuronal vulnerability through the production of neuromelanin-like structures, such as SDM.

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Production of a novel neuromelanin at the sevoflurane–water interface

Cited by 13 publications

References 19 publications

Dark- or Light-Colored Melanins: Generating Pigments Using Fe2+ and H2O2

Dark- or Light-Colored Melanins: Generating Pigments Using Fe2+ and H2O2

Carnosine Protects Against the Neurotoxic Effects of a Serotonin-Derived Melanoid

Redox Mechanism of Neurotoxicity by a Serotonin–Acrolein Polymeric Melanoid

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