ABSTRACT
The extraction yields, active compounds and antioxidant properties of 50%-aqueous-ethanolic extracts of freeze-dried Echinacea purpurea flower with multi-steps and multi-batches extraction methods were assessed. In multi-steps extraction, the extraction yields of 1st, 2nd, and 3rd extracts were 21.52%, 9.33%, and 2.90%, and their total phenols contents were 182.08, 176.33, and 177.08 mg CAE/g, respectively, with cichoric acid (62.07 - 66.57 mg/g) being the main phenolic compound. No differences in the contents of individual and total caffeic acids derivates existed among 1st, 2nd, and 3rd extracts. The dodeca-2E, 4E, 8Z, 10(E/Z)-tetraenoic acid isobutylamide (alkamide 8/9) contents of 1st, 2nd, and 3rd extracts were 505.38, 598.61, and 585.99 µg/g, respectively. In multi-batches extraction, the extracted dry weight increased with increasing the sample batches, with the extraction yields and alkamide 8/9 contents of samples decreased from 19.93% to 12.98% and 534.36 to 269.76 µg/g, respectively. The total phenol (177.25 - 186.92 mg CAE/g), individual and total caffeic acid derivatives (85.99 - 95.06 mg/g) contents of extracts among different sample batches were not significantly different, with cichoric acid (63.66 - 70.31 mg/g) being the main phenolic compound. All the prepared extracts also exhibited potent antioxidant properties. Overall, the two-step sequential extraction is desirable for extracting bioactive compounds from freeze-dried E. purpurea flower.