ABSTRACT
Objective To optimize extraction technology and evaluate the stability of anthocyanins from Duchesnea indica by response surface methodology. Methods Based on single factor experiment, the ethanol concentration, liquid-material ratio, extraction time, and extraction temperature were selected as independent variables, and the anthocyanin extraction ratio was selected as response value. The Box-Behnken design method and response surface methodology were used to optimize the extraction technology. Additionally, the effects of pH, temperature, organic acid, and oxidizer on the stability of anthocyanins were investigated. Results The optimized extraction technology: ethanol concentration was 80%, liquid-material ratio was 10:1, extraction time was 93 min, and extraction temperature was 36 ℃. The ratio of the extraction of anthocyanins with the optimal technology was 1.126%. The stability experiments results showed that the anthocyanins should keep in acid and low temperature conditions. Adding citric acid and gallic acid enhanced its stability, but glycine and H2O2 decreased stability. Conclusion The extraction technology optimized by response surface methodology was scientific, reasonable, and feasible, and it can be applicable for the extraction of anthocyanins from D. indica. Moreover, the condition should be paid attention to in order to maintain the stability of anthocyanins from D. indica.
ABSTRACT
AIM To establish an HPLC method for the simuhaneous content determination of five flavonoids in Duchesnea indica (Andr.) Focke at five picking time (April,May,June,July and August).METHODS The analysis of D.indica methanol extract was performed on a 25 ℃ thermostatic Agilent ZORBAX SB-C18 column (250 mm×4.6 mm,5 μm),the mobile phase comprising of acetointrile-0.1％ methanoic acid flowing at 1.0 mL/min in a gradient elution manner,and the detection wavelength was set at 350 nm.RESULTS Rutin,hyperoside,isoquercitrin,celereoin and kaempferol showed good linear relationships within their own ranges (R2 ≥0.998 6),whose average recoveries were 97.1％-101.5％ with the RSDs of 1.37％-2.37％.The contents of five constituents in samples at different picking time exhibited obvious differences,among which lutin and hyperoside contents were the highest in June,isoquercitrin content was the highest in July,and celereoin and kaempferol contents were the highest in August.CONCLUSION The suitable picking time of D.indica is June and July.