Comprehensive Screening for EPA/DHA-Structured Phospholipids in Aquatic Products by a Specific Precursor Ion Scanning-Based HILIC-MS/MS Method

Comprehensive screening for functional substances from natural resources is always a hot research topic. Eicosapentaenoic acid- (EPA) and docosahexaenoic acid (DHA)-structured phospholipids (PLEPA/DHA) have versatile cardiovascular benefits as well as superior bioavailability. Herein, the abundance of PLEPA/DHA in 16 aquatic products was specifically and selectively screened using a recently developed precursor ion scan-driven hydrophilic interaction chromatography–mass spectrometry (PreIS-HILIC/MS) method with the fatty acyl moieties of EPA (m/z 301.6) and DHA (m/z 327.6) locked. The aim focused on the characteristics and differences in the varieties and contents of EPA/DHA-structured phosphatidylcholine (PCEPA/DHA) and EPA/DHA-structured phosphatidylethanolamine (PEEPA/DHA) molecular species. A total of 80 PLEPA/DHA molecules were identified in these natural sources, including 47 PCEPA/DHA and 33 PEEPA/DHA. After analysis, PC 16:0/20:5 and PC 16:0/22:6 are present in all aquatic products and at high levels. Antarctic krill was found to be the best resource of PLEPA/DHA in total (2574.69 μg·g–1), followed by mackerel (2330.11 μg·g–1), salmon (2109.91 μg·g–1), and Farrer's scallop (1883.59 μg·g–1), while abalone contained the lowest level of PLEPA/DHA (310.44 μg·g–1). Besides, sea cucumber and sea bass contained the highest contents of EPA-structured and DHA-structured ether phospholipids, respectively, which could be highly recommended as dietary sources of special functional phospholipids. Finally, the multiple discrepancies between the 16 aquatic products were revealed by multivariate statistical analysis. These findings improve the awareness of the composition and content of PLEPA/DHA contained in aquatic products, providing a reference for their integrated development.