RESUMO
Aims: To evaluate preparation herbal mixed of Pouteria campechiana, Chrysophyllum cainito, Citrus limonum and Annona muricata (PCCA) on vasorelaxant and hypotensive effect on rat model and toxicological data after acute oral administration to give scientific support to the use ethnomedical and to explore their potential damaging on oral intake. Study Design: Experimental. Place and Duration of Study: Sample female and male Wistar rats. Pharmacology laboratory of Chemistry School and Department of Clinical and Epidemiological Research of Medicine School, Autonomous University of Yucatán. Between October 2014 and July 2016. Methodology: An ethanolic extract of PCCA was prepared at a ratio of 1:1:1:1 of each plant plus individual extracts were prepared. Vasorelaxant effect was assessed (3.03 to 100 μg/mL), hypotensive effect ((100, 200, 300 mg/Kg) and median lethal dose (LD50) by oral acute toxicity method (OECD 423 guide). Results: PCCA extract induced a significant vasorelaxation (medium effective concentration (EC50)=463.43 μg/mL) in a concentration-dependent manner in aorta’s endothelium-intact rings and this effect was partially endothelium-dependent. Acute oral administration of 200 and 300 mg/kg of PCCA exhibited significant decrease in systolic blood pressure in normotensive rats. PCCA did not show clinical toxicity of acute oral administration. Only 2000 mg/kg show histopathological inflammatory responses on gut and liver. Conclusion: PCCA induces a significant cardiovascular effect and was not toxic for rodents. The results support the popular use of some Mayan Medicinal plants as antihypertensive agents; however, clinical studies are necessary.
RESUMO
The aim of current study was to determinate ex vivo and chromatographic fingerprint by HPLC of four extracts of Euphorbia furcillata K. Ethyl acetate extract of Euphorbia furcillata (EaEEf) was the most effective and potent extract (Emax=98.69±1.24%) and its effect was partially endothelium-dependent. Functional vasorelaxant mechanism of action of EaEEf was determinate, EaEEf showed efficient relaxation of KCl [80 mM]-induced contraction and norepinephrine and CaCl2 contraction curves showed diminution of maximal contraction in the presence of EAEEf and EaEEf-relaxation curve was shifted to the right in the presence of L-NAME (nitric oxide synthase inhibitor) and ODQ (guanylate cyclase inhibitor). Chromatographic fingerprints analysis suggests presence of diterpenoid such as abietane, tigliane, and ingenane skeletons. Our experiments suggest the EaEEf vasorelaxant activity could be attributed to diterpenoid molecules whose mechanism involves nitric oxide production and calcium channel blockade.
Se determinoÌ el efecto vasorrelajante ex vivo y los perfiles cromatograÌficos mediante HPLC de cuatro extractos de Euphorbia furcillata K.. El extracto de acetato de etilo de E. furcillata (EaEEf) fue el maÌs eficaz y potente en la contraccioÌn inducida por norepinefrina (Emax=98.69±1.24%) y el efecto fue parcialmente dependiente del endotelio vascular. Se determinoÌ el mecanismo de accioÌn vasorrelajante para EaEEf, este mostroÌ ser eficaz sobre la contraccioÌn inducida por KCl [80 mM] y la curva de contraccioÌn en respuesta a norepinefrina y CaCl2 en presencia de EaEEf mostroÌ disminucioÌn en la contraccioÌn maÌxima, mientras que la curva de relajacioÌn de EaEEf en presencia de L-NAME (inhibidor de oÌxido niÌtrico sintasa) y ODQ (inhibidor de guanilato ciclasa) se desplazoÌ hacia la derecha. El anaÌlisis cromatograÌfico de EaEEf sugiere la presencia de moleÌculas diterpenoides como abietano, tigliano y esqueletos de ingenano. Nuestros resultados sugieren que el efecto vasorrelajante de EaEEf podriÌa atribuirse a moleÌculas diterpenoides, cuyo mecanismo de accioÌn involucra la produccioÌn de oÌxido niÌtrico y bloqueo de canales de calcio.
Assuntos
Animais , Masculino , Ratos , Vasodilatadores/farmacologia , Extratos Vegetais/farmacologia , Euphorbia/química , Bloqueadores dos Canais de Cálcio/metabolismo , Cromatografia Líquida de Alta Pressão , Ratos Wistar , GMP Cíclico/metabolismo , Óxido Nítrico/metabolismoRESUMO
Current work was conducted in order to determine the underlying mode of relaxant action of 7-ethoxy-4-methyl- 2H-chromen-2-one (1), a coumarin obtained by semisynthesis from umbelliferone (2), with significant relaxant effect in a concentration-dependent manner on tracheal rat rings pre-contracted with carbachol (1 μM). In a previous study it was demonstrated that compound 1 and 2 showed significant relaxant effect, being 1 the most active compound (Emax= 100% and EC50= 83 μM) even more active than theophylline an unspecific phosphodiesterases (PDE’s) inhibitor used as positive control. Moreover, pretreatment with 1 significantly shifted to the right the carbachol-induced contraction. On the other hand, compound 1 (83 μM) produces significant (100%) relaxant effect on the contraction induced by KCl (80 mM) and the CaCl2-induced contraction was significantly reduced by the coumarin 1 as nifedipine does (a L-type calcium channel blocker), used as positive control. Indomethacin (10 μM, unspecific COX inhibitor) significantly reduced 1-relaxation. Meanwhile, in the presence of isoproterenol (a -adrenergic agonist), and K+ channel blockers glibenclamide (10 μM) and 2- AP (100 μM) the relaxant curve was not modified. Compound 1 was docked on an outer cavity located on the extracellular side of the human L-type calcium channel model (affinity energy -6.8 kcal/mol). However, compound 1 was also found on the same location as nifedipine with the same affinity energy (-6.3 kcal/mol) as previously described. Both conformations were stabilized by aliphatic interactions on both binding sites, primordially by a π-π interaction between FIVS6.7 and aromatic rings from compound 1. In conclusion, 7-ethoxy-4- methyl-2H-chromen-2-one (1) induces a significant relaxant action on rat trachea rings, through L-type calcium channel blockade and, as a second mechanism of action, by a possible intracellular cyclic AMP increasing.