LAUSR

Abstract The spice Syzygium aromaticum L. (clove buds) exerts topical anesthetic and analgesic effects. Since GABA A receptors are an emerging drug target for pain treatment, the effects of aqueous clove extracts on the human α1β2-GABA A receptor were tested by two-electrode voltage clamp technique applying a three-step test system. The extract significantly and specifically potentiated the GABA-induced currents by an allosteric mechanism in concentration-dependent manner (0.5–5 µg/mL; up to 426 ± 23%). HPLC-based activity-guided fractionation revealed eugenol as main determinant of this GABAergic activity. Acetyleugenol, an important component of clove bud oil, showed even higher activity than eugenol (1 µg/mL; 308 ± 26% versus 234 ± 29%), but was detected in the aqueous extract only in trace amounts. Thus, the analgesic effects of clove might be partially mediated by positive modulation of the GABA A receptor and eugenol is a major contributor to this activity.