Enhanced production of cichoric acid in cell suspension culture of Echinacea purpurea by silver nanoparticle elicitation

This study was conducted to optimize callus induction, cell suspension culture, and enhance cichoric acid production in Echinacea purpurea. For this purpose, leaf and root explants were grown in ½ MS medium supplemented with different concentrations of plant growth regulators. The highest percentage of callus induction (100%) was obtained with different concentrations of Kin in combination with 2,4-D and or NAA, in both explants. Then interaction slicing method was applied to analyze the effects of different concentrations of Kin in combination with 2,4-D and or NAA on total phenol contents. The maximum amount of total phenol was observed in 0.5 mg/L kin and 1 mg/L 2,4-D, in both leaf and root-derived callus. Data from HPLC–UV analysis showed that cichoric, chlorogenic, and caffeic acids are present in the callus. While cichoric acid content was 2.11 and 4.73 mg/g dry weight (DW) in leaf explant and its derived callus, it was 3.47 and 5.67 mg/g DW in root explant and its derived callus, respectively. Cell suspension culture was established and treated by AgNO3 and AgNPs (0, 2 and 4 mg/L). Overall, AgNPs’ elicitation was more effective in cichoric acid production compared to AgNO3. The highest amount of cichoric acid (9.54 mg/g DW) was found in root cell suspension culture after 48 h of exposure to 2 mg/L AgNPs. But leaf cell suspension culture reached the maximum cichoric acid level (8 mg/g DW) 72 h after treatment with 2 mg/L AgNPs. The current protocol can be used for the production of cichoric acid from callus and cell suspension cultures.