ABSTRACT
In this study, a novel method named high-speed homogenization coupled with ultrasound-assisted extraction (HSH-UAE) followed by high-performance liquid chromatography (HPLC) was employed and investigated for the extraction and determination of main flavonoids rutin, quercetin-3-O-glucoside, quercetin, kaempferol and isorhamnetin from Hippophae rhamnoides L. by-products. Optimal conditions for HSH-UAE, proposed by the single factor and the Box–Behnken design (BBD) tests coupled with response surface methodology (RSM), were 68% ethanol concentration, ultrasonic power 250 W, homogenate speed 9000 rpm, liquid/solid ratio 22 mL/g and extraction time 12 min. The extraction yields of five main flavonoids were significantly improved by HSH-UAE than UAE and high-speed homogenization-assisted extraction (HSHAE). Furthermore, the antioxidant activity of HSH-UAE extracts was assessed by 1,1-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays with IC50 value of 0.091 mg/mL and 2.837 mmol FeSO4/g DW. Good linear ranges were obtained for five main flavonoids in the range of 2.5–500 μg/mL with the coefficient higher than 0.99. The recoveries of the five flavonoids were in the range of 97.87–99.26%. The limit of detection (LOD) and the limit of quantification (LOQ) for the main flavonoids were within the ranges of 0.28–0.46 and 0.89–1.74 μg/mL, respectively. The present results showed that the proposed method HSH-UAE could be developed as a fast and efficient method for extracting the active ingredients from medical edible plant materials for potential application.
Funding
The authors gratefully acknowledge the financial supports by Application Technology Research and Development Program of Harbin (2013AA3BS014) and Special Fund of National Natural Science Foundation of China (31270618).