Abstract: To improve the extraction rate of polyphenols from Agrimonia pilosa Ledeb., liquid-to-material ratio (A), ultrasonic time (B), SHMP addition (C), and ultrasonic power (D) were selected as influencing factors based on single-factor experiment results. A four-factor three-level response surface methodology was designed with polyphenol yield as the response value to optimize the extraction process, and the antioxidant capacity of the polyphenols was determined. The results showed that the optimal extraction conditions for polyphenols from Agrimonia pilosa Ledeb. were the liquid-to-material ratio of 25∶1 (mL/g), ultrasonic time of 40 min, SHMP addition of 0.5%, and ultrasonic power of 160 W, with a polyphenol yield of 4.35% under these conditions.When the concentration of polyphenols from Agrimonia pilosa Ledeb. ranged from 0.1 to 1.5 mg/mL, the maximum scavenging rates for superoxide anion radicals, DPPH radicals, and hydroxyl radicals were 59.80%, 43.61%, and 32.72%, respectively. The scavenging capacity increased with polyphenol concentration, demonstrating the antioxidant ability of Agrimonia pilosa Ledeb. polyphenols.

Key words: Agrimonia pilosa ledeb., polyphenols, extraction process, antioxidant activity