Abstract:

The aim of this experiment is to study the optimum extraction technique of total flavonoids from leaves of Broussonetia papyrifera by using the method of heating reflux. A single factor experimental design was used to study the optimum reaction time, reaction temperature, liquid to solid ratio and ethanol concentration of the extraction of total flavonoids from leaves of the tree. The above four factors were set at five levels, respectively. The extraction amount of total flavonoids was used as the evaluation index to screen the optimal reaction condition. On this basis, orthogonal experiment was used to design the optimal extraction process, and the optimal extraction process was further verified by repeated validation test and process amplification test. The results showed that the optimum ethanol concentration was 70%, reaction time was 2.5 h, solid-liquid ratio was 1:30 and reaction temperature was 70℃. The optimum extraction condition was determined by orthogonal test as follows: ethanol concentration of 70%, reaction time of 2.5 h, solid-liquid ratio of 1:30, and reaction temperature of 80℃. The yield was 23.11 mg/g in repeated validation test and 23.13 mg/g in process amplification test, respectively. This process has good stability and operability, and is suitable for the extraction of total flavonoids from leaves.

Key words: Broussonetia papyrifera leaf, total flavonoids, extraction technique, heating reflux method, ethanol