INVESTIGADORES
CONFORTI Paula Andrea
artículos
Título:
The spasmolytic effect of Alloysia citriodora Palau (South American cedrón) is partially due to its vitexin but not to isovitexin on rat duodenums
Autor/es:
MARÍA I. RAGONE, MARIANA SELLA, PAULA CONFORTI, MARÍA G. VOLONTÉ, ALICIA E. CONSOLINI
Revista:
JOURNAL OF ETHNOPHARMACOLOGY
Editorial:
ELSEVIER IRELAND LTD
Referencias:
Año: 2007 vol. 113 p. 258 - 266
ISSN:
0378-8741
Resumen:
The spasmolytic effects of an acqueous extracto
of cedrón (AEC) were studied on rat isolated duodenums. This plant (Aloysia
citriodora Palau, Verbenaceae) is widely used for gastrointestinal
disorders and as eupeptic in South America. AEC non-competitively inhibited the
dose-response curve (DRC) of Ach (IC50 of 1.34 ± 0.49 mg lyophilized/mL) and
the DRC of Ca2+ in high-[K]0(IC50 of 2.64 ± 0.23 mg/mL).
AEC potentiated the non-competitive inhibition of either 30µmol/L W-7 (a
calmodulin blocker) and 5-15 µmol/L papaverine on the Ca2+-DRC. Also,
AEC relaxed the contracture produced by high-[K]0(IC50 of 2.6 ± 0.2
mg/mL) until 81.0 ± 3.2% of the maximal effect of papaverine and 78.1 ± 5.0% of
the quercetin, the most selective inhibitor of PDE. The AEC relaxation was
non-competitively inhibited by 10-30 µmol/L methylene blue and competitively
antagonized by 40 µmol/L TEA. The relaxation of 1 mg/ml AEC was inhibited by
hypoxia, but not that of 2 mg/ml. Two flavonoids were identified by HPLC in the
AEC: vitexin and isovitexin. Vitexin non-competitively inhibited the Ach-DRC
(pD2´ of 5.7 ± 0.4) but significantly run leftward the DRC of Ca2+.
Isovitexin did not significantly inhibit the DRC of Ach nor Ca2+.
The results suggest that the spasmolytic effect of AEC could be mostly
associated to the increase in cGMP (target shared with the PDE inhibitors) and
the activation of K+-channels. At low concentrations, AEC also
inhibits the aerobic metabolism. The flavonoid vitexin is partially responsable
for the effect, since it non-competitively inhibits Ach but not the Ca2+
influx. Isovitexin was devoid of activity on duodenums.