Covalent adduct formation between the plasmalogen-derived modification product 2-chlorohexadecanal and phloretin.
Bottom Line: Adduct characterization by high-resolution mass spectroscopy confirmed these results.In contrast to 2-ClHDA, the covalent 2-ClHDA-phloretin adduct was without adverse effects on MTT reduction (an indicator for metabolic activity), cellular adenine nucleotide content, and barrier function of brain microvascular endothelial cells (BMVEC).We here identify a detoxification pathway for a prototypic chlorinated fatty aldehyde (generated via the MPO axis) that compromises BBB function in vitro and in vivo.
Affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.Show MeSH
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Mentions: Hypothetically adduct formation between 2-ClHDA and phloretin could occur via electrophilic aromatic substitution followed by hemiacetal formation on the A-ring. To characterize the structure of the 2-ClHDA-phloretin adduct, NMR analyses and theoretical enthalpy calculations were performed. The isolated product was dissolved in DMSO-d6 and could be completely assigned using a combination of 1D (1H, homodecoupled 1H, 13C, DEPT-135) and 2D (COSY, HSQC, HMBC, INADEQUATE) spectra. Both the HMBC and INADEQUATE spectra were necessary to unambiguously identify the adduct structure. An overlay of the HSQC and HMBC spectra, confirming hemiacetal formation is shown in Fig. 2. In particular, correlations between H-2″ with C-7a″, H-3″ with C-3a″, and H-2″ with C-3a″ in the HMBC, as well as C-3″ with C-3a″ and C-3a″ with C-7a″ in the INADEQUATE were important for structure elucidation. The complete assignment is presented in Table 1. This analysis clearly suggests hemiacetal formation between the aldehyde and the A-ring of phloretin corresponding to the structure shown in Fig. 2B.
Affiliation: Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.