Extraction of antioxidant compounds from Aeginetia indica flowers

Optimization of antioxidant extraction from Aeginetia indica flowers has been rarely investigated, despite their traditional use in Thai ethnomedicine and richness in phenolic and flavonoid compounds. This study systematically identified the most influential extraction parameters using a two-step strategy: (i) single-factor experiments to establish preliminary ranges, and (ii) a Plackett–Burman design (PBD) to screen ethanol concentration, solvent-to-material ratio, extraction time, and extraction temperature. Extraction efficiency was evaluated by total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (DPPH and FRAP assays). Single-factor tests indicated that 60% ethanol, a 40 mL/g solvent ratio, and 60°C with extraction times exceeding 60 min favored maximum recovery. PBD results confirmed extraction temperature as the dominant factor influencing TPC, DPPH, and FRAP, while the solvent-to-material ratio was most critical for TFC. These findings establish validated baseline parameters for antioxidant recovery from A. indica flowers and highlight their potential as natural antioxidant sources for functional foods, nutraceuticals, and phytopharmaceuticals.