Targeted Isolation of ω-3 Polyunsaturated Fatty Acids from the Marine Dinoflagellate Prorocentrum lima Using DeepSAT and LC-MS/MS and Their High Activity in Promoting Microglial Functions

In this study, we integrated HSQC-based DeepSAT with UPLC-MS/MS to guide the isolation of omega-3 polyunsaturated fatty acid derivatives (PUFAs) from marine resources. Through this approach, four new (1–4) and nine known (5–13) PUFA analogues were obtained from large-scale cultures of the marine dinoflagellate Prorocentrum lima, with lipidomic profiling identifying FA18:5 (5), FA18:4 (7), FA22:6 (8), and FA22:6 methyl ester (11) as major constituents of the algal oil extract. Structural elucidation was achieved through integrated spectroscopic analyses of IR, 1D and 2D NMR, and HR-ESI-MS data. Given the pivotal role of microglia in Alzheimer’s disease (AD) pathogenesis, we further evaluated the neuroprotective potential of these PUFAs by assessing their regulatory effects on critical microglial functions in human microglia clone 3 (HMC3) cells, including chemotactic migration and amyloid-β42 (Aβ42) phagocytic clearance. Pharmacological evaluation demonstrated that FA20:5 butanediol ester (1), FA18:5 (5), FA18:4 (7), FA22:6 (8), and (Z)-10-nonadecenoic acid (13) significantly enhanced HMC3 migration in a wound-healing assay. Notably, FA18:4 (7) also significantly promoted Aβ42 phagocytosis by HMC3 microglia while maintaining cellular viability and avoiding pro-inflammatory activation at 20 μM. Collectively, our study suggests that FA18:4 (7) modulates microglial function in vitro, indicating its potential to exert neuroprotective effects.