INTRODUCTION: Natural products with vasoactive characteristics have relevant contributions in the cure and control of numerous pathologies, such as blood pressure disorders. The vessels of the human umbilical cord are targets of changes related to contraction and relaxation, when gestational hypertensive syndromes occur. In this sense, the essential oil of Lippia origanoides (OELo), despite having a relaxing effect on the smooth muscles of animals, there remains a lack of reports regarding its activity on the human vasculature. AIMS: Thus, this study aims to evaluate the vasodilatory effect of OELo in human umbilical arteries (AUH). METHODS: The project was approved by the Human Research Ethics Committee of the Universidade Regional do Cariri-URCA (nº 3,832,881). Fragments of human umbilical cord were obtained with the consent of donors over 18 years of age, normotensive and without pre-delivery complications. After collection, the AUH were isolated, sectioned into 3 to 4 mm rings, nourished with Krebs-Henseleit solution and subjected to isometric tension recordings in an organ bath, with controlled conditions of temperature, pH and aeration. RESULTS AND DISCUSSION: OELo (1-3000 µg/mL) promoted a vasodilatory effect in AUH preparations, affecting basal tone and inhibiting the electromechanical coupling induced by 60 mM KCl (EC50: 468.7 ± 6.7 µg/mL), and pharmacomechanical induced by 10 ?M 5-HT (EC50: 641.3 ± 4.3 µg/mL). In the presence of tetraethylammonium (1 mM), a BKCa blocker, OELo demonstrated vasodilatory potency (EC50: 652.9 ± 4.7 µg/mL). Furthermore, it exhibited a relaxing effect, possibly enhanced, when compared to serotonergic control in the presence of glibenclamide (10 µM), a KATP blocker, (EC50: 98.1 ± 6.6 µg/mL) and 4-aminopyridine (1 mM), KV blocker, (EC50: 304 ± 4.7 µg/mL). These findings in human umbilical vessels are the first reported for OELo. However, other studies involving the Lippia genus have already demonstrated vasorelaxant activity, such as: endothelium-independent vasorelaxant activity in the mesenteric artery of rats (MAYNARD et al., 2011); tocolytic activity in the uterus of rats, with possible interaction in blocking VOOCs (PEREIRA DE MORAIS, et al., 2019) and in the thoracic artery of rats, with an effect that acts through a myogenic mechanism enhanced by substances released from the endothelium. We can suggest that the relaxing effect of OELo may be involved in a mechanism for altering transmembrane potential. Menezes (2017), in turn, indicated that the K+ channel pathway operated by voltage and Ca2+ can influence the relaxing effect of OELo on the smooth muscles of guinea pigs, a fact that corroborates our data. CONCLUSION: OELo had a vasodilatory effect on AUH, being able to change its basal tone, as well as suppress electro- and pharmacomechanical stimuli through a possible modulation of different potassium channels (BKCa, Kv and KATP). ACKNOWLEDGMENTS: The development of this research was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil (CAPES); Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (FUNCAP); and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). REFERENCES: MAYNARD, L. G. et al. Chemical composition and vasorelaxant effect induced by the essential oil of Lippia alba (Mill.) NE Brown.(Verbenaceae) in rat mesenteric artery. Indian journal of pharmacology, v. 43, n. 6, p. 694, 2011; PEREIRA, D.-M. L. et al. Differences between umbilicals arteries contractions patterns of normotense parturients and with diagnosed pre-eclampsia. Anais da Academia Cearense de Ciencias, v. 5, n. 1, p. 83–88, 2021; MENEZES, N. M. PEDRO. Atividade espasmolítica e antitussígena do óleo essencial de Lippia origanoides (VERBENACEA). SILVA, F. S. 2017. 146. Dissertação. Programa de pós-graduação em Recursos Naturais do Semiárido. Universidade Federal do Vale do São Francisco. 2017.
Comissão Organizadora
Francisco Mendonça Junior
Pascal Marchand
Teresinha Gonçalves da Silva
Isabelle Orliac-Garnier
Gerd Bruno da Rocha
Comissão Científica
Ricardo Olimpio de Moura
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