The conditions for extraction of the total flavonoids from Flos pueraria was optimized and the\r\npurification and separation process were conducted to identify the main constituents of the total\r\nflavonoids as well. The solvent for extraction and its concentration, the solid-to-liquid ratio, extraction\r\nduration, temperature and ultrasonic frequency were investigated through a single-factor experiment.\r\nAn orthogonal design (L9 (34) was constructed to achieve the best extraction conditions. The crude\r\nextract was then purified sequentially by petroleum ether, ethanol and chloroform, n-butyl alcohol, and\r\neluted gradually with mixed mobile phase of methanol-chloroform solution in the silica gel column\r\nsystem. The ingredients were further separated by color reaction, ultraviolet spectrophotometry, high\r\nperformance liquid chromatography, infrared and mass spectral analysis. The optimum extraction\r\ncondition for the total flavonoids from F. pueraria was as follows: extraction by 50% (v/v) methanol\r\nsolution, the solid-to-liquid ratio at 1:30, extraction duration 2.0 h, the temperature of 70�°C, ultrasound 3\r\ntimes and 30 min each time. Five isoflavones were separated and identified as irisolidone, genistein,\r\ndaidzein, kakkalide and puerarin, respectively. Under these optimal conditions, the yield of total\r\nflavonoids in the extracts was up to 17.5%, while the output rate previously reported is about 8% in\r\ngeneral. Our study provided means for further development and utilization of the bioactive components\r\nfrom F. pueraria.
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