Abstract: We studied the total flavonoids extraction from leaves of Calamus simplicfoilius using ultrasonic-assisted extraction technology. A 3-factor, 3-level central composite design involving the three independent variables followed by response surface analysis was performed for the further optimization of the extraction parameters. The optimal extraction conditions were 72.74% of ethanol volume fraction, 22.5 mL·g^-1 of liquid-solid ratio, and 30 min of extraction time. Under these conditions, the experimental extraction of total flavonoids yield was 19.67 mg·g^-1. Ultrasonic-assisted extraction could reach more flavonoids and less time and energy comparing with traditionally extraction methods including macerate extraction and heat reflux extraction. By IR spectrums, the extracts contained amounts of flavonoids which had similar structure with lutein. Additionally, the DPPH free radical scavenging activity, reducing power and iron reduction activity of total flavonoids extracted using ultrasonic-assisted technology were a little lower than vitamin E, and the superoxide anions scavenging activity was significantly higher than vitamin E.

Key words: Calamus simplicfoilius, flavonoids, ultrasound-assisted extraction, RSM, antioxidant activity