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.
Highlights
Echinacea purpurea L. is frequently used to alleviate colds, sore throats and other upper respiratory infections
When the total extraction yields were taken into consideration, total phenols content of the two-steps and three-steps sequential extractions were 834.72 mg and 911.63 mg, respectively
When the total extraction yields were taken into consideration, the contents of alkamide 8/9 of the two-steps and three-steps sequential extractions were 2469.74 and 2724.24 μg, respectively
Summary
Echinacea purpurea L. is frequently used to alleviate colds, sore throats and other upper respiratory infections. The immuno-stimulating properties of Echinacea products are mainly attributed to its bioactive phytochemicals including caffeic acid derivatives, alkamides, polysaccharides, and glycoproteins. Alkamides are reported to be a new class of cannabinomimetics modulating tumor necrosis factor α (TNF-α) gene expression via the cannabinoid type 2 (CB2) receptor [5] [6]. They have exhibited a strong stimulating effect on phagocyte function and on lipoxygenase-inhibiting activity [1] [5]-[8]. The objectives of this study were to investigate the effects of multi-steps extraction and multi-batches extraction methods on the extraction yields, active compounds and antioxidant properties of the 50% ethanolic extracts of freeze-dried E. purpurea flower
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