Echinacea: The genus Echinacea

8
Factors Affecting Echinacea
Quality: Agronomy and
Processing
Nigel B. Perry, Ronald B.H. Wills, and Douglas L. Stuart
CONTENTS
Introduction
Bioactive Compounds and Analytical Methods
Phenolics
Alkamides
Quantitative Analytical Methods
Botanical and Cultivation Effects on Bioactive Compounds
Differences between Species and Plant Parts
Cultivation Effects
Proposed Quantitative Standards
Postharvest Handling and Processing Effects on Bioactive Constituents
Handling and Drying
Storage
Extraction
Quality of Commercial Products
Conclusions
Acknowledgments
References
INTRODUCTION
Echinacea preparations, taken as immunostimulants, are among the top 10 selling herbal medicines
in the U.S. and Europe (Bauer, 1998; Brevoort, 1998) with an estimate by Blumenthal (2001) of
US$58 million in retail sales in the U.S. in 2000. The three species used in this trade are Echinacea
purpurea, Echinacea angustifolia, and Echinacea pallida, with the most popular being E. purpurea
followed by E. angustifolia (McGuffin, 2001). For example, in Australia in 2000, 80 MT of E.
purpurea were used compared to 15 to 20 MT of E. angustifolia and less than 1 MT of E. pallida
(Walker, 2000). E. angustifolia is the most difficult of these species to cultivate but has the highest
market value (Binns et al., 2002a; Berti et al., 2002). The scientific literature on Echinacea is
extensive including major reviews by Bauer (1999a), Hobbs (1994a, 1994b), Mahady et al. (2001)
and Wills et al. (2000). In this chapter, the chemistry of the three medicinal Echinacea species is
summarized with particular focus on the phenolics and alkamides, the bioactive compounds most
widely used as quality indicators in Echinacea. Aspects examined are quantitative analytical
methods for these compounds and their retention during growing, postharvest handling, and pro-
© 2004 by CRC Press LLC