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Characterization of Catecholaldehyde Adducts with Carnosine and L-Cysteine Reveals Their Potential as Biomarkers of Catecholaminergic Stress
Journal article   Open access   Peer reviewed

Characterization of Catecholaldehyde Adducts with Carnosine and L-Cysteine Reveals Their Potential as Biomarkers of Catecholaminergic Stress

Rachel A Crawford, Ettore Gilardoni, T. Blake Monroe, Luca Regazzoni, Ethan J Anderson and Jonathan A Doorn
Chemical research in toxicology, Vol.34(10), pp.2184-2193
10/18/2021
DOI: 10.1021/acs.chemrestox.1c00153
PMCID: PMC8527522
PMID: 34506109
url
https://doi.org/10.1021/acs.chemrestox.1c00153View
Published (Version of record) Open Access

Abstract

Monoamine oxidase (MAO) catalyzes the oxidative deamination of dopamine and norepinephrine to produce 3,4-dihydroxyphenylacetaldehyde (DOPAL) and 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL), respectively. Both of these aldehydes are potently cytotoxic and have been implicated in pathogenesis of neurodegenerative and cardiometabolic disorders. Previous work has demonstrated that both the catechol and aldehyde moieties of DOPAL are reactive and cytotoxic via their propensity to cause macromolecular cross-linking. With certain amines, DOPAL likely reacts via a Schiff base before oxidative activation of the catechol and rearrangement to a stable indole product. Our current work expands on this reactivity and includes the less-studied DOPEGAL. Although we confirmed that antioxidants mediated DOPAL's reactivity with carnosine and N-acetyl-L-lysine, antioxidants had no effect on reactivity with L-cysteine. Therefore, we propose a non-oxidative mechanism where, following Schiff base formation, the thiol of L-cysteine reacts to form a thiazolidine. Similarly, we demonstrate that DOPEGAL forms a putative thiazolidine conjugate with L-cysteine. We identified and characterized both L-cysteine conjugates via HPLC-MS and additionally identified a DOPEGAL adduct with carnosine, which is likely an Amadori product. Furthermore, we were able to demonstrate that these conjugates are produced in biological systems via MAO after treatment of the cell lysate with norepinephrine or dopamine along with the corresponding nucleophiles (i.e., L-cysteine and carnosine). As it has been established that metabolic and oxidative stress leads to increased MAO activity and accumulation of DOPAL and DOPEGAL, it is conceivable that conjugation of these aldehydes to carnosine or L-cysteine is a newly identified detoxification pathway. Furthermore, the ability to characterize these adducts via analytical techniques reveals their potential for use as biomarkers of dopamine or norepinephrine metabolic disruption.
Physical Sciences Toxicology Chemistry Chemistry, Medicinal Chemistry, Multidisciplinary Life Sciences & Biomedicine Pharmacology & Pharmacy Science & Technology UIOWA OA Agreement

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