Comparative Profiling of Fat-Soluble Nutrients and Antioxidant Indices in Seeds of Six Maple (Acer) Types

Maple (Acer spp.) seeds are potential sources of fat-soluble nutrients and bioactive compounds, yet they remain comparatively understudied. This study compared six market-derived Acer seed types by quantifying phospholipids (PLs), fatty acids, carotenoids, and phytosterols, and by evaluating total phenolic content (TPC) and DPPH radical scavenging activity in methanolic extracts. Total phospholipid contents varied markedly among samples (17.94–295.87 mg/100 g), with phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI) as the predominant classes. Fatty acid profiles were dominated by oleic acid (C18:1) and linoleic acid (C18:2), and nervonic acid (NA; C24:1) was consistently detected in all samples at 0.17–1.88 g/100 g (4.55–7.89% of total fatty acids). β-Sitosterol ranged from 16.58 ± 1.41 to 37.46 ± 1.62 mg/100 g. Carotenoid composition varied among the tested samples, and Jeju red maple showed the highest provitamin A potential, including the exclusive detection of α-carotene and the highest retinol activity equivalent. Antioxidant indices also differed significantly among samples (TPC: 317.89–897.12 mg GAE/100 g; DPPH: 81.37–93.27%), but TPC was not consistently proportional to DPPH activity, suggesting contributions from non-phenolic constituents. Pearson correlation analysis further showed exploratory co-variation patterns among the measured variables across the tested samples. Overall, the tested market-derived Acer seed materials exhibited marked compositional diversity and antioxidant potential, supporting their further evaluation as candidate functional food, nutraceutical, and value-added plant lipid resources.