Pharmacological Screening of Species from the Lippia genus, Content in Terpenes and Phenylpropanoids, and their Vasorelaxing Effects on Human Umbilical Artery

Background: Naturally occurring bioactive compounds have a plethora of biological effects. Objective: In this study, we examined a pharmacological screening of natural products on the human umbilical artery (HUA). Methods: HUA preparations were used to follow contractions by KCl (60 mM) and tested at different concentrations (1-5000 μg/mL and μM) of the Lippia alba (EOLa) and Lippia origanoides (EOLo) essential oils, terpenes (citral, limonene perilic alcohol) and phenylpropanoids (eugenol, methyl eugenol). Results: The reduction corresponded to approximately 100%, except for limonene (80 ± 1.2%). When evaluating the concentration of the natural product that promotes 50% relaxation of the HUA contracted by KCL, EC50 values were: 424.3 μg/mL (EOLa); 468.7 ± 6.7 μg/mL (EOLo); 264.2 ± 8.2 μM (citral); 677.8 ± 5.4 μM (limonene); 186.3 ± 6.4 μM (peryl alcohol); 986.4 ± 7.9 μM (eugenol); and 279.1 ± 4.4 μM (methyl-eugenol). Perillyl alcohol had a lower EC50 (consequently it has a higher pharmacological potency). Conclusion: The plant extracts have a promising vasorelaxing effect in HUAs, paving the way for future investigations: as applications in diseases related to these vessels, such as preeclampsia.