Microwave-Assisted Extraction and Composition Analysis of Flavonoids from Perilla frutescens Leaves

Response surface methodology was used to optimize conditions for the microwave-assisted extraction of flavonoids from Perilla frutescens leaves.The effects of raw material particle size,extraction time,temperature,ethanol concentration and solid-to-solvent ratio on extraction efficiency were investigated.The optimal conditions for extracting flavonoids from Perilla frutescens leaves were found to be extraction at 71 ℃ for 70 min with 61% ethanol at a solid-to-solvent ratio of 1:20(g/mL) and a raw material particle size of 20 mesh.Under these conditions,the maximum extraction yield of flavonoids was 59.28 mg/g.The obtained extract was purified by D152 macroporous resin column chromatography and the purified product mainly consisted of lutin and luteolin as demonstrated by UV absorption spectrometry and HPLC.