Evaluation of EndoTrap® blue for removing endotoxin contamination from Echinacea extracts

Endotoxins (lipopolysaccharides, LPS) are part of the outer membrane of the cell wall of Gram-negative bacteria. It is known that LPS causes cytokine production in immune cells. Therefore contamination of plant extracts with traces of LPS severely influences measurements of immune reactions in cell based assays. For that reason efficient endotoxin removal is necessary before studying immunmodulating actions of plant extracts.

We determined the ability of EndoTrap® blue (Profos) to remove LPS from an extract of Echinacea angustifolia roots (60% ethanol), and checked whether the content of active plant constituents like alkamides, caffeic acid-derivatives and polysaccharides is influenced. EndoTrap® blue is an endotoxin removal system based on high affinity chromatographic separation. The content of active constituents was determined before and after endotoxin removal: alkamides and caffeic acid-derivatives by a HPLC method [1] and polysaccharides with a colorimetric method [2]. The efficiency of endotoxin removal was measured by the Limulus-Amebocyte-Lysat Test (Charles River Endosafe®).

EndoTrap® blue removed 76% of the LPS. From the active compounds only the polysaccharides could be recovered by 99.0%. Alkamides and caffeic acid-derivatives were retrieved only by 7.4% and 13.6% respectively. According to these results EndoTrap® blue seems to be an inappropriate tool for endotoxin removal from Echinacea extracts.

References: 1. Turner, R.B., et al. (2005), NEJM 353: 341–348 (Supp. Materials). 2. Dubois, M. et al. (1956), Anal. Chem. 28: 350–356.