Study on different extracting methods and antioxidant activity of flavonoids from water chestnut

The best extraction method and process of flavonoids from water chestnut were investigated using ethanol extraction and microwave extraction respectively. Antioxidant activity, qualitative, and quantitative analysis of extract were tested with DPPH, HPLC and spectrophotometry. The optimum conditions of two methods were obtained by orthogonal test respectively. Ethanol concentration, stuff -liquid ratio, power of extraction, and time of extraction were acted as several influential factors of orthogonal test, then the flavonoids extraction rate as an indicator. The extraction rate of ethanol extraction and microwave extraction were 2.25% and 3.43%, with IC50 values of 4.60 μg/mL and 4.34 μg/mL, respectively. Compared with ethanol extraction, microwave extraction had some advantages include high efficiency and short time. The maximum yield of flavonoids with microwave extraction was obtained by dual extraction with 60% ethanol, 1/40 stuff-liquid ratio, 400 W power, and 2 minutes. In these conditions, the antioxidant activity of the extract was similar to Vc.