Abstract: Flavonoids from the buds of Sophora japonica Linn. were extracted by three different methods, namely alkali extraction followed by acid sedimentation, ethanol refluxing and ultrasound-assisted extraction. The extraction conditions, including pH value of solvent and the kind of stabilizer were researched as well. Furthermore, with rutin as comparison, the flavonoids content of different extracts from buds of Sophora japonica L. and their FT-IR spectra had been determined. The results showed that both the yield and purity of the products by alkali extracting followed by acid sedimentation with the extract adjusted to pH value 9 containing borax as stabilizer were higher than others. Meanwhile, the typical FT-IR spectra of every sample had specific absorption peak pattern, intensity and location, related to different extracting technology. Among them, the FT-IR spectrum of flavonoids obtained under the above optimum extraction technology was similar to that of standard rutin. Therefore, quantitative analysis along with their FT-IR spectra provide a favorable foundation for quality control of flavonoids from the buds of Sophora japonica Linn..

Key words: buds of Sophora japonica Linn., flavonoids, extracts, rutin