Spasmolytic and anti-inflammatory effects of Aloysia triphylla and citral, in vitro and in vivo studies

Aloysia triphylla is traditionally utilized for the treatment of menstrual colic (primary dysmenorrhea) in Mexico. Citral is the main chemical component found in Aloysia triphylla leaves extract. Primary dysmenorrhea is a very frequent gynecological disorder in menstruating women, affecting 30-60% of them. It is usually treated with non-steroidal antiinflammatory drugs (NSAIDs); although their effect is rapid, they possess many side effects. Due to these shortcomings, Mexican folk therapy is considered as a feasible alternative. The effects of the hexane extract of Aloysia triphylla and citral on uterine contractions were evaluated in vitro as well as their anti-inflammatory properties and gastric wound capabilities were assessed in vivo. The inhibitory effects on the contractions were analyzed using isolated uterus strips from estrogen primed rats. Contractions were induced by KCl 60 mM, oxytocin 10 mIU/mL, charbacol 10 μM and PGF_2a 5 μM. The anti-inflammatory effect was assessed on carrageenan-induced rat hind paw edema model. The inhibitory concentration-50 (IC₅₀) of the hexane extract of Aloysia triphylla upon each contractile response was for KCl 44.73 ± 2.48/μg/mL, oxytocin 42.16 ± 3.81/μg/mL, charbacol 41.87 ± 1.73/μg/mL and PGF_2α 28.70 ± 2.40/μg/mL in a concentration-dependent way. The extract of Aloysia triphylla produced a significant inhibitory effect on PGF_2c-induced contraction compared to its inhibitory actions on the others. Citral exhibited the same inhibitory effect on the contraction induced by PGF_2α. The oral administration of the extract (100-800 mg/kg) and citral (100-800 mg/kg) showed anti-inflammatory activity; furthermore, the maximal dose utilized did not produce gastric injury. These results were compared with anti-inflammatory effects and gastric damage produced by 30 mg/kg of indomethacin p.o. The spasmolytic and anti-inflammatory effects support the traditional use of Aloysia triphylla leaves in the treatment of the primary dysmenorrhea in Mexican communities.