Characterization of the vasodilator effect of eugenol in isolated human umbilical cord arteries

Eugenol (EUG) is a phenylpropanoid widely used in the food and cosmetic industries. It is commonly referred to in the literature by its biological activities such as antioxidant, anti-inflammatory, antimicrobial, and relaxing in organs of laboratory animals, especially in rodent vessels. However, its vasorelaxant potential in human tissue, has not been investigated. Thus, this study characterizes the vasodilatory effect of EUG in the human umbilical artery (HUA). HUAs were isolated, cleaned, sectioned (3-4 mm) and placed in an organ bath (10 mL Krebs Henseleit, 37 °C; and carbogenic mixture). EUG (100-1400 μM), obtained total relaxation of electromechanical contractions induced by KCl (60 mM), and pharmacomechanical contractions (30-1200 μM), induced by serotonin (10 μM) and by histamine (10 μM), showing statistically significant concentrations: 600 μM, 400 μM and 200 μM, and EC₅₀ values: 759.8 ± 6.5 μM, 229.9 ± 7.9 and 279.0 ± 3.4 μM, respectively. EUG (1200 and 1400 μM) prevented the contraction promoted by BaCl₂ (0.1-30 mM), similar to the effects of nifedipine (10 μM), sugesting the involvement of EUG in blocking VOCCs. In the presence of tetraethylammonium (10 μM), EUG (30-1200 μM) did not produce a total relaxation (88.6%), suggesting that an alternative pathway where potassium channels, may partially mediate EUG effect. In the presence of 4-aminopyridine (1 mM), glibenclamide (10 μM), and tetraethylammonium (1 mM), EUG relaxed HUAs 100%, although the pharmacological potency was statistically altered, demonstrating the participation of K⁺ channels (Kv, KATP, BKCa). Our data indicates that EUG has a vasorelaxant effect on HUAs, had a greater pharmacological potency in the serotoninergic pathway, showing effective participation of VOCCs and a partial modulation of K⁺ channels. These data suggest new possibilities for the use of EUG in human vascular dysfunctions, such as preeclampsia. More studies are necessary to confirm the safety and effectivity in future treatments.