Fig 8. Echinacea purpurea plants grown from sterilized seeds.

E. purpurea seeds were sterilized following removal of the epidermis and grown under sterile conditions for six weeks. The negative control was prepared using the same reaction vessels and solvents as for the individual plants, but without plant material. The seed used to grow plant 49 was subjected to surface sterilization but with epidermis intact (see S1 Table). Plants were harvested and extracts tested for LPS content (A) and ability to induce production of TNF-α from RAW 264.7 cells after 16–18 h incubation (B). Data show the means ± SD of duplicate experiments measuring TNF-α secretion in panel A, and the mean ± SEM of triplicate measurements of LPS content in panel B. Statistical analysis was performed using the Student’s T test, ***p < 0.001.