Chemistry, analysis and immunological investigations of Echinacea phytopharmaceuticals

Echinacea phytopharmaceuticals represent the most popular group of herbal immunostimulants in Europe and in the USA [1, 2]. According to a recent report, Echinacea products have been the best selling herbal products in natural food stores in the USA in 1997 with 11.93% (1996: 9.6%) of herbal supplement sales [3]. Including homeopathic preparations, more than 800 Echinacea-containing drugs are currently on the market in Germany. Most of the preparations contain the expressed sap of Echinacea purpurea aerial parts, or hydroalcoholic tinctures of E. pallida or E. purpurea roots. They are mainly used for the treatment of colds and infections [4]. Clinical effects have been demonstrated for the expressed sap of the aerial parts of Echinacea purpurea in the adjuvant therapy of relapsing infections of the respiratory and urinary tracts, as well as for alcoholic tinctures of E. pallida and E. purpurea roots as adjuvants in the therapy of the common cold and flu [5, 6]. In the USA, it is mostly encapsulated powders from roots and aerial parts, but also tinctures from the roots and aerial parts that are used. Many investigations of the constituents of Echinacea have been undertaken. So far, compounds from the classes of caffeic acid derivatives, flavonoids, polyacetylenes, alkamides, pyrrolizidine alkaloids, polysaccharides and glycoproteins have been isolated [7]. For the main interest of finding the active component, but also for standardization purposes, the question on the chemical composition of Echinacea herbs and preparations is essential. Therefore, the present knowledge on the chemical constituents, analysis, and immunomodulatory effects of Echinacea preparations shall be reviewed.