Free radical scavengers, anti-inflammatory and analgesic activity of Acaena magellanica

Extracts of the whole plant Acaena magellanica (Rosaceae) were assessed for anti‐inflammatory, antipyretic and analgesic activity in animal models. At 600 mg kg−1, the global ethanolic extract (GEE), dichloromethane (DCM) and defatted methanol (MeOH) fractions showed a mild anti‐inflammatory effect in the carrageenan‐induced guinea‐pig paw oedema. The GEE, DCM and defatted MeOH fractions significantly reduced inflammation by 43.2, 40.5 and 42.1%, respectively. The GEE did not showed any significant antipyretic activity in doses up to 600 mg kg−1. A 20% w/v infusion administered orally at 16 mL kg−1 presented analgesic effect in the acetic acid‐induced abdominal constriction test in mice. The GEE and MeOH extract of A. magellanica showed free radical scavenging activity in the diphenylpicrylhydrazyl decolouration assay. Assay‐guided isolation led to quercetin, Q‐3‐O‐β‐D‐glucoside, Q‐3‐O‐β‐D‐galactoside, ellagic acid and catechin as the free radical scavengers. The saponins tormentic acid 28‐O‐β‐D‐galactopyranoside and 28‐O‐β‐D‐glucopyranoside were isolated from the polar extract. The structures were determined by spectroscopic methods.