RESUMEN
The aim of the current study was to investigate the vasorelaxant effect of several extracts from Laelia speciosa and Laelia anceps, on an ex vivo method using aorta rat rings with and without endothelium pre-contracted with norepinephrine (0.1 μM), in order to establish them as a real source for the isolation of bioactive compounds with potential use as antihypertensive agent. All extracts caused concentration-dependent relaxation in -precontracted aortic rings with and without endothelium; the most active extracts were the hexanic and dichlorometanic extracts from roots of L. anceps and L. speciosa (HERLanc, DERLanc, HERLspec and DERLspec, respectively), and were less potent than positive controls used (carbachol and sodium nitroprusside). These results suggest that secondary metabolites, responsible for the vasorelaxant activity, belong to a group of compounds of medium and low polarity, and the roots were the main tissues of the plant where the vasorelaxant compounds are stored. In conclusion, both orchids represent an ideal source for obtaining lead compounds for designing new therapeutic agents, with potential vasorelaxant and antihypertensive effects.