Anti-inflammatory activity of Echinacea angustifolia fractions separated on the basis of molecular weight.

Five fractions of an aqueous extract obtained from the roots of Echinacea angustifolia were separated on the basis of molecular weight. The topical anti-inflammatory activity of the fractions has been evaluated in mice using the Croton oil ear test. The fraction with a molecular weight between 30,000 and 100,000 was the most active in inhibiting the oedema; it also reduced the infiltration of inflammatory cells. The activity of this fraction was comparable with that of a raw polysaccharidic extract obtained from E. angustifolia roots by differential solubility. The high-molecular weight polysaccharides are therefore proposed as the anti-inflammatory principles of the plant.