Assessment of anxiolytic and panicolytic effects of dichloromethane fraction from stems of Kielmeyera coriacea

Kielmeyera coriacea Mart. (Calophyllaceae) is known popularly as “Pau Santo”. The hydroethanolic extract (HE) of Kielmeyera coriacea stems and its semi-pure dichloromethane (DCM) constituent produced an antidepressant-like effect in rats. The purpose of this study was to investigate the effects of repeated administration (21 days) by gavage of the DCM fraction (5, 10 or 15 mg/kg) in rats submitted to the elevated T-maze (ETM), a model of generalized anxiety and panic disorders. The tricyclic antidepressant imipramine (15 mg/kg) was used as a positive control. Rat locomotion was assessed using the open field test (OFT) following each drug treatment. The 2-hydroxy-1-methoxyxanthone (1), aucuparin (2), swertinin (3), 1,3,7-trihydroxy-2-(3-methylbut-2-enyl)-xanthone (4) and 1,3,5-trihydroxy-2-(3-methylbut-2-enyl)-xanthone (5) were identified in DCM fraction, and suggest that the xanthone (4) is related with the antidepressant-like profile of this plant. Pharmacological evaluation showed that DCM fraction (10 and 15 mg/kg) decreased the inhibitory avoidance latency from the closed arm and increased the one-way escape latency from the open arm in the ETM, which is indicative of anxiolytic and panicolytic effects, respectively, as occurs with the positive control, imipramine (15 mg/kg), when compared to their control group (vehicle). Locomotor activity was not significantly altered by the different treatments. This study suggests that the DCM fraction from stems of Kielmeyera coriacea can be an important therapeutic alternative in the treatment of anxiety disorders, such as generalized anxiety and panic disorders.