Comparative phytochemical profiles and bioactivities of two Melicope pteleifolia leaf batches

This study compared phytochemical contents, antioxidant responses, antibacterial activities, and LC–HRMS/MS profiles of the ethanol extract (MPE) and its n-hexane (MPH), ethyl acetate (MPEA), and methanol (MPM) fractions from two Melicope pteleifolia leaf batches collected in May (M5) and October (M9) 2022. Across all four corresponding extracts and fractions, M5 had higher total phenolic content (TPC: 249.360–712.367 mg GAE/g) and total flavonoid content (TFC: 119.571–177.266 mg QE/g) than M9 (TPC: 49.050–117.943 mg GAE/g; TFC: 24.513–79.533 mg QE/g). M5 had lower DPPH IC50 values in MPE, MPH, and MPM, whereas M9-MPEA had a lower IC50 than M5-MPEA (23.013 versus 48.086 µg/mL). All four M9 extracts and fractions had lower reducing-power OD0.5 values than their M5 counterparts. Against Staphylococcus aureus and Escherichia coli, M9 MICs were 1.25–2.50 and 1.25–4.00 mg/mL, respectively, compared with 6.25–50 and 25–50 mg/mL for M5. Manual review of LC–HRMS/MS data retained 52 of 64 features. Selected flavonoid-glycoside and coumarin-related candidate features showed greater within-feature signal contributions in M5, whereas several alkaloid-related candidates were more prominent in M9.