GA 2018

A successive optimisation of the extraction process for polyphenol recovery from aerial plants of Echinacea purpurea (L.) Moench (Asteraceae) was performed. The ultrasonication-assisted extraction was carried out using water/glycerol as an eco-friendly solvent mixture. The first step of optimization was performed according to a two-factor interaction model intended for selection of independent variables that were critical to the process. The dependent variables were caftaric and cichoric acid, analysed using the HPLC-DAD method. Radical scavenging activity of the extracts was analyzed using the DPPH free radical. Analysis of variance (ANOVA) has shown that the most important extraction factors were glycerol concentration, temperature, ultrasonication power and extraction time. In an attempt to fine-tune the extraction procedure, subsequent Box Behnken analysis was performed by varying those factors. The results have shown that the yield was significantly influenced by glycerol content and temperature of the extraction solvent as linear terms, as well as by all the variables as quadratic terms. In order to confirm the validity of the model, the set of the extraction conditions optimized for the extraction of the phenolic acids (70% glycerol, 60 C, ultrasonication power 72W and 60 min) was chosen for preparation of one extract. The analysis has shown that the actual sum of concentrations of caftaric and cichoric acid in the extract was 1.542 ± 0.228 mg/mL, while the predicted value was 1.525 mg/mL. This infers that the deviation of the experimental result was only 1.1% and confirms the validity of the quadratic model. The prepared extracts were good radical scavengers with IC50 values starting from 3.97 mL extract/mL. The results indicate that the ultrasonication-assisted extraction using water/glycerol mixtures is a promising tool for extraction of bioactive phenolics from E. purpurea suitable for inclusion into cosmetic and pharmaceutical preparations.