Vasorelaxant effect of Dihydrospinochalcone A isolated from Lonchocarpus xull

Lonchocarpus xuul is an endemic tree from the Yucatan Peninsula, Mexico.The present work research was conducted to evaluate the vasorelaxant effect of dihydrospinochalcone A (DECh A), a compound type chalcone, isolated from Lonchocarpus xuul. Activity of DECh A was determined ex vivo on aorta rat rings test with- and without endothelium, and in vivo on spontaneously hypertensive rats (SHR) model. DECh A showed a partially endothelium-dependent and concentration-dependent vasorelaxant effect (Emax=79.67% and EC₅₀=21.46µM E+, Emax=23.58% EC₅₀ =91.8µM). The functional mechanism of action for DECh A was elucidated due to its significant activity. Pre-incubation with L-NAME, atropine, TEA and ODQ produced a significant change in the maximum vasorelaxant effect. Finally, orally DECh A administration (50mg/kg) in rats SHR decreased diastolic and systolic blood pressure up to 30% from the first hour and the effect was sustained during all experimental time. The heart rate was not modified. In conclusion, DECh A functional vasorelaxant mechanism is linked to the NO/GMPc system derived-endothelium, due to the possible muscarinic receptor agonist and the increment in the production of nitric oxide. The release of NO increases cGMP production in smooth muscle, which mediates the opening of potassium channels, and in consequence, the vasorelaxant effect occurs. Finally, the in vivo antihypertensive effect induced by DECh A is directly related with its vasorelaxant activity.