L-type Ca2+ channel (Cav1.2) blocking by Z. zerumbet (L., SM) and its major compound sesquiterpene: in vitro, in vivo and in silico approaches

Abstract

Hypertension is the primary chronic illness around the world. Some drugs available for treating hypertension are ineffective and can present numerous side effects. In this context, medicinal herbs have a long history in the management of hypertension, leading to a reduction in the blood pressure with least side effects. Zingiber zerumbet is a common plant in Northern Brazil, and is usually used for medicinal purposes. The present study aimed to evaluate the biological activity of the essential oil of Z. zerumbet (OEZz) and its main constituent, zerumbone (Zer), on the vascular function of Wistar rats. Vascular reactivity studies together with cell culture assays, histological analysis by stereology and computation molecular docking were performed. Male Wistar rats (220–250 g) from the central animal facility of the Federal University of Amazonas (UFAM) were used in this study. All experiments were carried out in accordance with the Animal Research Ethical Committee of the UFAM (protocol:001/2015). The extraction of the essential oil from the rhizomes of Zingiber zerumbet was carried out by the hydrodistillation method. From the extraction of the oil, Zerumbone undergoes the recrystallization process, giving crystals with a melting point of 65–65.7 °C, density: 0.887 ± 0.06 g/cm 3 and 97% purity. The quantitative and qualitative method of obtaining Zer was patented by our research group (PI 0505343-9). For the in vivo experiments, the rats received OEZz (50 or 100mg/kg/day) for 21 days. In vitro, OEZz and Zer demonstrated a concentration-dependent vasodilator effect that were independent of the presence of the endothelium in phenylephrine (10−7M) pre-constricted vessels, Zer was more potent but with a lower efficacy than OEZz (p <0.05). Pre-incubation of aortas with OEZz or Zer (103μg/mL) were able to inhibit phenylephrine-induced vasoconstriction (p <0.0001). OEZz and Zer showed to reduce the potency and efficacy of calcium influx-mediated vasoconstriction in rings estimulated with phenylephrine (10−7M) or KCl (60mM). OEZz also demonstrated vasodilator potential in vivo, as observed by enlargement of the thoracic aorta. No hypertrophic responses were observed. The molecular docking studies showed that zerumbone may cause a stabilizing or destabilizing influence on the both closed and open states of L-type Ca 2+ channel by interacting with hydrophobic residues of the P-loops and inner helices. Additionally, OEZz and Zer demonstrated anti-inflammatory activity by inhibiting NO production in macrophages, and antioxidant properties by inhibiting the production of ROS. Thus, OEZz and Zer could be potential therapeutic tools for the treatment of cardiovascular disorders, such as hypertension, which is associated with inflammation, oxidative stress and impairment of vascular function.