Echinacea complex--chemical view and anti-asthmatic profile.

BACKGROUND

Echinacea purpurea (L.) Moench is one of the mostly used herbs in the traditional medicine for the treatment of respiratory diseases. Modern interest in Echinacea is directed to its immunomodulatory activity. Recent studies have shown that secretion of asthma-related cytokines in the bronchial epithelial cells can be reversed by Echinacea preparations.

OBJECTIVE

To examine the pharmacodynamics profile of Echinacea active principles, a complex has been isolated from its flowers by alkaline extraction and has been tested using an animal model of allergic asthma.

METHODS

The structural features of Echinacea purpurea complex was determined using chemical and spectroscopic methods. Allergic inflammation of the airways was induced by repetitive exposure of guinea pigs to ovalbumin. Echinacea complex was then administered 14 days in 50mg/kg b.w. daily dose perorally. Bronchodilatory effect was verified as decrease in the specific airway resistance (sRaw) in vivo and by reduced contraction amplitude (mN) of tracheal and pulmonary smooth muscle to cumulative concentrations of acetylcholine and histamine in vitro. The impact on mucociliary clearance evaluated measurement of ciliary beat frequency (CBF) in vitro using LabVIEW™ Software. Anti-inflammatory effect of Echinacea complex was verified by changes in exhaled NO levels and by Bio-Plex® assay of Th2 cytokine concentrations (IL-4, IL-5, IL-13 and TNF-alpha) in serum and bronchoalveolar lavage fluid (BALF).

RESULTS

Chemical and spectroscopic studies confirmed the presence of carbohydrates, phenolic compounds and proteins, as well as the dominance of rhamnogalacturonan and arabinogalactan moieties in Echinacea complex. The significant decrease in sRaw values and suppressed histamine and acetylcholine-induced contractile amplitude of isolated airways smooth muscle that were similar to effects of control drug salbutamol confirmed Echinacea complex bronchodilatory activity. The anti-inflammatory effect was comparable with that of control agent budesonide and was verified as significantly reduced exhaled NO levels and concentration of Th2 cytokines in serum and BALF. The values of CBF were changed only insignificantly on long-term administration of Echinacea complex suggested its minimal negative impact on mucociliary clearance.

CONCLUSIONS

Pharmacodynamic studies have confirmed significant bronchodilatory and anti-inflammatory effects of Echinacea complex that was similar to effects of classic synthetic drugs. Thus, results provide a scientific basis for the application of this herb in traditional medicine as a supplementary treatment of allergic disorders of the airways, such as asthma.