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Pharmacol Biochem Behav. 2013 Sep;110:255-64. doi: 10.1016/j.pbb.2013.07.020. Epub 2013 Aug 7.

Ursolic acid from Agastache mexicana aerial parts produces antinociceptive activity involving TRPV1 receptors, cGMP and a serotonergic synergism.

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Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias del Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz. México-Xochimilco 101, Col. Sn Lorenzo Huipulco, 14370 México, D.F., Mexico; Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Col. Santo Tomás, 11340 México, D.F., Mexico.


Agastache mexicana is a plant that has long been used in large demands in Mexican folk medicine to treat anxiety, insomnia and pain, among others affections. Chromatographic technique was used to identify ursolic acid (UA), 130.7 mg/g and 20.3 mg/g, as an antinociceptive active compound identified in ethyl acetate and methanol extracts of A. mexicana aerial parts, respectively. Temporal course curves of the antinociceptive response demonstrated a dose-dependent and significant activity of UA (1 to 100 mg/kg, i.p.) with an ED50=2 mg/kg in comparison to the efficacy of diclofenac (1 or 30 to 100 mg/kg, i.p.), a non-steroidal anti-inflammatory drug, with an ED50=11.56 mg/kg. The antinociceptive response consisted in the reduction of abdominal constrictions induced with 1% acetic acid in mice. Similarly, UA at 2 mg/kg produced significant antinociception in the intracolonic administration of 0.3% capsaicin (a TRPV1 agonist) in mice. It has been reported the inhibition produced by UA on the calcium-flux induced by capsaicin on TRPV1 receptor suggesting the antagonistic activity of this receptor. Finally, an ED50=44 mg/kg was calculated in the neurogenic and inflammatory nociception induced in the formalin test in rats. The antinociceptive response of UA in the formalin test was not modified in presence of naloxone, flumazenil or L-arginine. Nevertheless, it was reverted in presence of 1-H-(1,2,4)-oxadiazolo(4,2-a)quinoxalin-1-one (ODQ, an inhibitor of soluble guanylyl cyclase) and increased in presence of N(G)-L-nitro-arginine methyl ester (L-NAME, inhibitor of nitric oxide synthase), theophylline (inhibitor of phosphodiesterase) and WAY100635 (an antagonist of 5-HT1A receptors). Current results provide evidence that the antinociceptive response of A. mexicana depends in part on the presence of UA. Moreover, this triterpene may exerts its antinociceptive effect mediated by the presence of cGMP and an additive synergism with 5HT1A receptors, but also an antagonistic activity towards TRPV1 receptors may be involved.


Agastache mexicana; Antinociception; Serotonin; TRPV1; Ursolic acid; cGMP

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