Characterization of Echinacea fractions obtained by an ultrafiltration process

Echinacea extracts are widely used in Romania accordingly or in combination with other plant extracts, usually as ethanolic extracts. The main objective of the present study was to obtain an Echinacea purpurea extract with a high content of polymeric compounds using an ultrafiltration process. The second target was to characterize the fractions obtained by this process. E. purpurea roots were extracted with 30 percent ethanol (1: 10 w/v), and polymers of 10 kDa or more were collected as ultrafiltration retentates. The ultrafiltration process was performed using two types of membranes with a cut off 5000 Da and 1000 Da. Permeates were collected in two stages in order to follow the process of polyphenol concentrations. We obtained a concentration report 1.5:1 (v/v). The content of bioactive compounds (another than polysaccharides) and free radical scavenging activity of retentates and permeates was determined and compared with those of initial extracts. The total phenolic content was determined using the Folin-Ciocalteu method [1] and the free radical scavenging activity was evaluated using DPPH and ABTS scavenging methods and the results were expressed as Trolox equivalent antioxidant capacity (TEAC) [2]. Chemical constituents of all the samples were analysed by an RP HPLC–DAD method. The results show that even low molecular mass compounds like polyphenols pass through membranes, the content of polyphenols in retentate (2.8±0.02mg/ml) was higher than all the permeates (1.7±0.023mg/ml). The data were sustained by TEAC values obtained for retentates (11.89mM/L TEAC by DPPH method and 26.77mM/L TEAC by ABTS method) and permeates (8.83 mM/L TEAC by DPPH method and 9.36 mM/L TEAC by ABTS method). Small differences were observed between the two permeates collected. The same results were obtained by HPLC determinations.

Acknowledgements: This work was financially supported by Romanian Project CEEX 70/2006

References: 1. Waterhouse, A.L. (2002) Current Protocols in Food Analytical Chemistry. John Wiley & Sons. New York. 2. Litescu, S.C. et al. (2001) Electroanal. 13:804:806