Acute immune modulatory effects of bioavailable Echinacea alkamides

Abstract

Echinacea preparations have been extensively used to both boost the immune system and to treat colds and minor infections. The current utilisation of echinacea is largely based on its historical use, with most echinacea preparations made from 'Echinacea angustifolia' or 'Echinacea purpurea'. These two species are phytochemically distinct and yet they are often used interchangeably with similar results expected therapeutically. Recent data has indicated that alkamides are the bioavailable compounds in Echinacea preparations [1,2] and that variations in the phytochemical mixture in the preparations can have different effects on immune cells in vitro [3,4]. In this study, we have examined the cytotoxicity of eight pure alkamides in P388 and HepG2 cells at concentrations shown to be present in plasma [1]. No cytotoxicity was observed at these concentrations. The acute effect of different combinations of alkamides on the phagocytic activity of granulocytes and monocytes in whole blood as well as their effect on freshly isolated natural killer (NK) cells was also examined. Alkamides were found to modulate healthy human granulocyte and monocyte phagocytosis and NK cell activity. Echinacea is able to influence the activity of the immune system and this activity is due to the alkamides. Modulation of the immune system by 'Echinacea' alkamides varies according to the individual, the concentration and the mix of alkamides that is present. There is a complex interaction between the alkamides that appears to influence the immune system and this still needs to be further elucidated.