Chemodiversity and Antinociceptive Activity of Amorpha fruticosa L. Essential Oil

An essential oil dominated by germacrene D (19.3% by GC) was isolated from the fresh fruit of Amorpha fruticosa L. (Fabaceae). Agglomerative clustering and k-means clustering were employed to compare the composition of the oil with the existing literature data, suggesting that the A. fruticosa used in this study represents a new chemotype. The essential oil was evaluated for its antinociceptive activity using the acetic acid-induced writhing test in rats at doses of 400, 200, and 100 mg/kg. All tested doses reduced the number of writhes induced by the intraperitoneal injection of acetic acid. The 400 mg/kg dose of the oil demonstrated a 54.4% inhibition, which was statistically different from the positive control, aspirin, which showed 90.2% inhibition at a dose of 200 mg/kg. Since the injection of acetic acid produces the release of prostaglandins, such as PGE2α and PGF2α, as well as sympathetic nervous system mediators in peritoneal fluids, the results suggest that the inhibition of prostaglandin release might represent one of the possible mechanisms of action exerted by the oil.