A novel LC-MS/MS method for quantification of unstable endogenous 3,4-dihydroxyphenylacetaldehyde in rat brain after chemical derivatization.

J Pharm Biomed Anal

Key Laboratory of Basic Pharmacology of Ministry of Education & Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, 563003, China. Electronic address:

Published: February 2021

AI Article Synopsis

  • DOPAL is a toxic byproduct of dopamine metabolism that can lead to neurodegeneration, and accurate measurement of its levels is important for studying Parkinson's disease.
  • A novel UPLC-MS/MS method has been developed and validated for measuring DOPAL in rat brain tissue, overcoming challenges related to its instability and poor ionization.
  • The study showed that DOPAL levels significantly increased in the striatum of rats after a 6-OHDA injection, suggesting its potential pathogenic role in Parkinson's disease.

Article Abstract

3,4-dihydroxyphenylacetaldehyde (DOPAL), a toxic intermediary metabolite of dopamine (DA), causes catecholaminergic neurodegeneration via covalent binding with functional proteins or other biomolecules. Accurate quantification of DOPAL is essential to investigate the etiological factors associated with DOPAL and the pathogenetic role of DOPAL in Parkinson's disease (PD). However, no validated quantitative methods are available. Quantification of DOPAL in biosample is challenging since it is a reactive endogenous aldehyde with poor ionization efficiency and chromatographic behavior in the LC-MS system. Here, a sensitive, simple, and robust UPLC-MS/MS method has been established and validated for the determination of DOPAL in rat brain tissue specimens. DOPAL was found to be unstable in biosample due to reactive aldehyde whereas it was stable in acidic condition. The analyte was stabilized by pH and temperature control during the sample preparation and derivatization. Then, a chemical derivatization method that can be readily performed in acidic conditions and at low temperature was employed using 2-hydrazino-4-(trifluoromethyl)-pyrimidine (HTP) to block the reactive aldehyde and improve the detection sensitivity (about 100-fold increase) and chromatographic retention. Bovine serum albumin was used as a surrogate matrix, which was validated by the parallelism assay and post-column infusion experiment. This method was fully validated and the lower limit of quantification (LLOQ) was 0.5 ng/mL. With the method, a significant increase of DOPAL level was found in striatum region of rats received 6-hydroxydopamine (6-OHDA) injection for 12 h, indicating DOPAL may play a pathogenic role in 6-OHDA-induced PD model.

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Source
http://dx.doi.org/10.1016/j.jpba.2020.113822DOI Listing

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