Extraction Optimization by Response Surface Methodology and Physicochemical Properties of Total Flavonoids from Rostellularia procumbens (L.) Ness

Objective: To optimize the reflux extraction technology by the response surface methodology and evaluate the stability and antioxidant activity of the total flavonoids from Rostellularia procumbens (L.) Ness. Methods: The best conditions of extracting total flavonoids from Rostellularia procumbens (L.) Ness were screened by the response surface methodology based on single factor experiments with the ratio of materials to liquid, ethanol volume fraction, extraction times and extraction temperature as factors with the yield of total flavonoids as index. Meanwhile, the stability was evaluated at different temperatures, light, pH and metal ions and the antioxidant activity was measured by scavenging of DPPH. Results: The results showed that optimal process obtained were as follows: Materials to liquid was 1:23 g/mL, ethanol volume fraction was 55%, extraction time was 20 min and extraction temperature was 70 ℃. The yield of total flavonoids was 9.02 mg/g. The total flavonoids from Rostellularia procumbens (L.) Ness under the optimal extraction process was stable at 30~90 ℃ and pH4~9 and not stable in metal ions of Cu²⁺, Fe²⁺, Zn²⁺, Al³⁺, Ba²⁺. IC₅₀ of total flavonoids from Rostellularia procumbens (L.) Ness to DPPH free radical was 0.079 mg/mL. Conclusion: The reflux extraction technology by the response surface methodology was rational and feasible and the extract exhibited good stability and antioxidant activity.