Preliminary study on flavonoids from fennel by solvent extraction

The extraction of flavonoids from fennel by using solvent method was studied.By orthogonal test,the effect of extraction time,ethanol concentration,extraction temperature and the ratio of feedstock to solvent on extraction was reviewed.The method of NaNO_2-Al(NO_3)_3-NaOH was used to determine the content of flavonoids.The results showed that the optimum extracting conditions of a higher total flavonoids were:the concentration of ethanol was 80%,the ratio of feedstock and solvent was 1:20,the temperature was 75℃and the time of extraction was 2h.Under the condition,the extraction rate was 2.69%.