Counter-current fractionation-assisted bioassay-guided separation of active composition from the edible medicinal insect Blaps rynchopetera Fairmaire

An efficient strategy for the selection of active components based on counter-current fractionation and bioassay-guided separation was established in the present work. Blaps rynchopetera Fairmaire was an edible medicinal insect. Its extract showed the potential RAW264.7 macrophage cell inhibitory activity. After extraction with different solvents, the active components were enriched in ethyl acetate. In order to further track the active compounds, the ethyl acetate extraction was divided into 14 fractions by means of HSCCC. The results showed that the activities of F6 and F7 were significant higher than the others. Two compounds, hydroxytyrosol and 4-ethylbenzene-1,3-diol, were separated from the mixture of F6 and F7 by column chromatography and their chemical structures were confirmed by MS, 1H NMR and 13C NMR. The IC50 of hydroxytyrosol and 4-ethylbenzene-1,3-diol against RAW264.7 macrophage cell were 38.24 ± 0.26 μg/mL and 103.26 ± 0.29 μg/mL, respectively, indicating that hydroxytyrosol was the major active ingredient responsible for the RAW264.7 inhibitory activity of Blaps rynchopetera Fairmaire.