Chemical composition and vasorelaxant effect induced by the essential oil of Lippia alba (Mill.) N.E. Brown. (Verbenaceae) in rat mesenteric artery

Abstract

Objectives : To investigate the chemical composition and vasorelaxant effect of the essential oil of Lippia alba (EOLA) in rat mesenteric artery. Material and Methods : Chemical composition of EOLA was investigated by gas chromatography-mass spectrometry (GC/MS). Vasorelaxant effect was evaluated in vitro in rat superior mesenteric artery rings. Results : GC/MS analysis revealed the presence of 19 compounds, with geranial (48.58%) and neral (35.42%) being the major constituents. In intact rings precontracted with phenylephrine (Phe: 1 μM), EOLA (100-1000 μg/mL) induced relaxation, where the maximal effect (Emax) was 110.8 +- 10.8%. This effect was not modified after endothelium removal (Emax = 134.8 +- 16.5%), after tetraethylammonium (TEA) (Emax = 117.2 +- 4.96%), or in rings precontracted with KCl (80 mM) (Emax = 112.6 +- 6.70%). In addition, EOLA was able to inhibit the contraction caused by CaCl 2 and produced a small but significant (P<0.05) additional effect (from 70.5 +- 3.4 to 105.3 +- 13.5%, n = 5) on the maximal relaxation of nifedipine (NIF: 10 μM). Conclusions : The results demonstrated that EOLA induces endothelium-independent vasorelaxation, which appears to be caused, at least in part, by blocking Ca 2+ influx through voltage-operated Ca 2+ channels. [PUBLICATION ABSTRACT]