Preparative separation of four individual flavonoids in Scutellaria barbata D. Don based on high selectivity polymeric adsorbents with different polarities

The individual flavonoid component, scutellarin, scutellarein, luteolin and apigenin, in Scutellaria barbata plant was isolated based on the macro porous adsorbent with high adsorption selectivity. These adsorbents were synthesized based on the copolymerization of methyl acrylate and divinylbenzene (MA-co-DVB). So the polarity and the adsorption affinity of these adsorbents can be adjusted through changing MA content in the adsorbents. And then the ability of the adsorbent with different MA contents for isolation of these four individual flavonoid was also investigated. Adsorbents M2 and M4, with MA content of 25% and 45%, respectively, demonstrated the best separation ability. Complete separation of the four flavone compounds was achieved in a continuous process based on combination of adsorbents with different polarities (M2 and M4). Gradient elution using adsorbent M4 separated the four flavonoids into three fractions, which were determined to contain scutellarin, scutellarein and a mixture of luteolin and apigenin. The latter was separated completely by adsorbent M2 subsequently. All four compounds were obtained at high resolution and high recovery yield (96.7%, 94.1%, 95.8% and 93.8%, respectively), suggesting the efficiency of sequentially combined columns with different segregation patterns.