Characterization of Antiviral Activities in Echinacea. Root Preparations

Abstract

The roots of three commonly used taxa of Echinacea.—E. purpurea., E. pallida. var. pallida., and E. pallida. var. angustifolia.—were extracted and fractionated by means of accelerated solvent extraction to reflect the most commonly used methods for commercial preparations. These fractions were analyzed by HPLC for their content of caffeic acid derivatives and alkamides and for antiviral activities against three viruses often implicated in colds and influenza. Aqueous extracts of E. purpurea. root contained a relatively potent activity against herpes simplex virus (HSV) and influenza virus (FV) but not against rhinovirus (RV). These fractions had low amounts of caffeic acids and alkamides. The ethyl acetate fraction contained significant but weak activity against both HSV and FV and contained significant levels of cichoric acid. In contrast, E. pallida. var. angustifolia. gave no water-soluble antiviral activity, but the ethanolic and ethyl acetate fractions contained significant activity against all three viruses, and this activity correlated with the presence of alkamides. E. pallida. var. pallida., however, gave no antiviral activity in any of the fractions, and this observation accorded well with the near absence of the marker compounds. Thus, we have detected a relatively potent water-soluble antiviral activity in E. purpurea. root, together with the weaker antiviral cichoric acid; an antiviral alkamide fraction in E. pallida. var. angustifolia.; but no antiviral activity in E. pallida. var. pallida.. Therefore, different types of Echinacea. root preparations, such as tinctures, tablets, and teas, based on different species and extraction methods, would be expected to offer quite different antiviral profiles.