The Development of a Specific and Sensitive LC-MS-Based Method for the Detection and Quantification of Hydroperoxy- and Hydroxydocosahexaenoic Acids as a Tool for Lipidomic Analysis

Abstract

Docosahexaenoic acid (DHA) is an n-3 polyunsaturated fatty acid that is highly enriched in the brain, and the oxidation products of DHA are present or increased during neurodegenerative disease progression. The characterization of the oxidation products of DHA is critical to understanding the roles that these products play in the development of such diseases. In this study, we developed a sensitive and specific analytical tool for the detection and quantification of twelve major DHA hydroperoxide (HpDoHE) and hydroxide (HDoHE) isomers (isomers at positions 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19 and 20) in biological systems. In this study, HpDoHE were synthesized by photooxidation, and the corresponding hydroxides were obtained by reduction with NaBH4. The isolated isomers were characterized by LC-MS/MS, and unique and specific fragment ions were chosen to construct a selected reaction monitoring (SRM) method for the targeted quantitative analysis of each HpDoHE and HDoHE isomer. The detection limits for the LC-MS/MS-SRM assay were 1−670 pg for HpDoHE and 0.5−8.5 pg for HDoHE injected onto a column. Using this method, it was possible to detect the basal levels of HDoHE isomers in both rat plasma and brain samples. Therefore, the developed LC-MS/MS-SRM can be used as an important tool to identify and quantify the hydro(pero)xy derivatives of DHA in biological system and may be helpful for the oxidative lipidomic studies.

Docosahexaenoic Acid–Derived Fatty Acid Esters of Hydroxy Fatty Acids (FAHFAs) With Anti-inflammatory Properties

“…MS/MS/MS analysis revealed 14-HDHA-specific fragments (205.2 and 161.2 m/z) (39,42) in the corresponding peak. Importantly, oxidized phospholipids containing predominantly the 14-HDHA positional isomer were identified in human platelets (39).…”

Lethal dysregulation of energy metabolism during embryonic vitamin E deficiency

“…Initially, total and free DHA were elevated in E− embryos, but by 48 hpf both were significantly lower than E+ embryos (Fig. 1C, see also Figure 1 and Tables 1 and 2 in [10]); further, the lipid peroxidation products, 7- and 10-hydroxy-DHA [31], as well as 9-HODE, were elevated in E− (Fig. 1C), ranging from 3–7% of the free DHA at 120 hpf, confirming increased DHA peroxidation.…”

Vitamin E deficiency during embryogenesis in zebrafish causes lasting metabolic and cognitive impairments despite refeeding adequate diets

“…Both animal [37] and human [38] studies demonstrate that brain F 4 -NPs are elevated during enhanced oxidative stress and pathological cognitive decline. Higher levels of additional autoxidized DHA products such as 10-HDoHE [39] (Figure 6A) further suggest free radical-induced lipid peroxidation of brain DHA due to inadequate antioxidant (VitE) protection in E− larvae, though the possibility of aberrant enzymatic activity (e.g. of lipoxygenases) warrants attention as well.…”