Exploratory compositional profiling of metabolite and antioxidant properties in green perilla (Perilla frutescens) seeds at maturation stages

Green perilla has been utilized as food and medicinal resources in East Asia. This research employed an exploratory compositional profiling approach to investigate variations in metabolite constituents and antioxidant capacities of green perilla seeds at three maturation stages: unripe (UR), mid-ripe (MR), and full ripe (FR). Twelve phytochemicals identified by UPLC-Q-Orbitrap-MS showed distinct stage dependent patterns. Six isolated phenolics exhibited significant differences, with the highest level at MR (28,697.8 μg/g), followed by UR (16,132.6 μg/g) and FR (7820.0 μg/g). Specifically, luteolin-7- O -glucoside exhibited remarkable fluctuations with decreasing levels (13,161.9 → 28,192.6 → 152.9 μg/g). Protein and oil contents increased progressively, with oil content rising 13.5 → 46.1%, accompanied by marked increases in linolenic acid (31.0 → 60.8%) and γ-tocopherol contents (10.4 → 265.4 μg/g). Antioxidant properties were highest at MR, demonstrating 87.6% (DPPH), 100% (ABTS), 5.64 OD 593nm (FRAP) at 200 μg/mL, and 87.6% (DNA protection) at 250 μg/mL, followed by UR > FR. Additionally, chemometric analysis (PCA and heatmap) revealed clear stage-associated differences in the metabolic profiles. These findings provide preliminary yet insightful data on the maturation-related chemical shifts in green perilla seeds, establishing a descriptive baseline for optimizing harvest times based on desired functional constituents.