Natl. J. Physiol. Pharm. Pharmacol. (2025), Vol. 15(3): 253-257

Research Article

10.5455/NJPPP.2025.v15.i3.6

Vasorelaxant effects of methanolic fraction leaves powder extract of Elaeis guineensis in porcine coronary arteries: Possible involvement of Nitric Oxide

Mbaye Sene^1*, Ibrahima Diouf², Mamadou Ndiaye³, Awa Ba⁴, Awa Ndiaye³, Modou Oumy Kane¹, Mamadou Sarr¹, Valérie Schini-Kerth⁵ and Madieye Sene³

¹Laboratoire de Physiologie Pharmaceutique, Faculté de Médecine, de Pharmacie et d’Odontologie, Université Cheikh Anta Diop, Dakar, Senegal

²Unit of Training and Research in Health Sciences, Assane Seck University of Ziguinchor, Ziguinchor, Senegal

³Laboratoire de Pharmacologie et Pharmacodynamie, Faculté de Médecine, de Pharmacie et d’Odontologie, Université Cheikh Anta Diop, Dakar, Senegal

⁴Faculty of Health and Sustainable Development, Alioune Diop University, Bambey, Senegal

⁵Translational Cardiovascular Medicine, Strasbourg Biomedical Research Centre, Strasbourg University, Strasbourg, France

*Corresponding Author: Mbaye Sene. Laboratoire de Physiologie Pharmaceutique, Faculté de Médecine, de Pharmacie et d’Odontologie, Université Cheikh Anta Diop, Dakar, Senegal. Email: mbaysen [at] yahoo.fr

Submitted: 24/10/2024 Accepted: 02/02/2025 Published: 31/03/2025

---

Abstract

Background: Elaeis guineensis is a plant of the Arecaceae family that is used in traditional medicine in Senegal to treat high blood pressure. However, to our knowledge, there is no scientific evidence supporting its ability to lower blood pressure in hypertensive patients.

Aim: The objective of this study was to provide a scientific basis for the use of this plant as a remedy for high blood pressure in traditional medicine.

Methods: We in vitro evaluated the endothelium-dependent vasorelaxant capacity of a methanolic fraction of E. guineensis leaf powder (MSEG01). To achieve this, rings of pig coronary arteries with and without endothelium are mounted in isolated organ chambers. After stabilization for approximately 1 hour, the rings were precontracted with U46619 and then exposed to a range of increasing concentrations of MSEG01 ranging from 1 to 100 μg/ml. For some experiments, the rings were incubated with different inhibitors (L-NA, INDOMETHACIN, TRAM-34 +UCL) to determine the cell signaling pathways involved in MSEG01-induced relaxation.

Results: The results showed that MSEG01 causes relaxation in a model of coronary arteries in pigs previously contracted with U46619. For rings with endothelium, a relaxation start was noted at 3 μg/ml, and the maximum relaxation (90%) was obtained at 100 μg/ml. Without endothelium, MSEG01 does not induce relaxation.

Conclusion: This study explains the use of E. guineensis for the management and prevention of high blood pressure and cardiovascular complications in traditional medicine in Senegal. However, additional research is needed to ensure its safety for human health.

Keywords: Elaeis guineensis, Vasorelaxant effects, Porcine coronary.

---

Introduction

Cardiovascular disease is one of the leading causes of death and is increasingly recognized as a public health problem. High blood pressure alone is responsible for nearly 8 million deaths per year worldwide and almost 100 million days of disability in the working population. It is the cause of almost half of all strokes and heart attacks worldwide (Krzesinski 2002; Lawes et al. 2002; Kearney et al. 2005). The management of these diseases remains a real challenge in developing countries; although the effectiveness of existing treatments has been widely proven, their affordability remains problematic in view of poverty. Therefore, the World Health Organization encourages the use of traditional medicine (Walker et al. 2000; Seck et al. 2013; Organisation mondiale de la Santé. 2013). Such a situation would justify the pharmaceutical industry’s interest in these pathologies, with the treatment costs of treatments especially for populations in Senegal. Therefore, an alternative that consists of developing new therapeutic approaches using plants from the traditional pharmacopoeia is necessary. This is the whole meaning of this in vitro study with the objective of highlighting the vasorelaxant effects of the methanolic fraction of the leaf powder of Elaeis guineensis in a model of the coronary arteries of pigs. The cellular signaling pathways will also be characterized.

---

Materials and Methods

Plant material

Elaeis guineensis leaves were harvested in Casamance, a region in southern Senegal, in June 2022. We carried out identification at the Laboratory of Pharmacognosia and Botany of the Faculty of Medicine of Cheikh Anta Diop University of Dakar by Pr Alioune Dior FaLL. Leaves were dried for 15 days, protected from light, before being pulverized. The resulting powder was stored at room temperature (25°C–30°C) in a well-ventilated room until transport to the Laboratory of Translational Cardiovascular Medicine, UR 3074, FMTS, Strasbourg, France, where vascular reactivity experiments were conducted. Extraction and fractionation were performed in the Laboratory of Pharmacognosia and Botany of the Faculty of Medicine of Cheikh Anta Diop University, Dakar, Senegal (Gomis 2023).

Chemical material

L-NA, indomethacin, UCL, and Tram-34 were obtained from Sigma Chemical Co. (St. Louis, MO, U.S.A.). U46619 and bradykinin were purchased from Calbiochem.

Vascular reactivity studies

Pig coronary artery rings are suspended between two metal hooks in 10 ml insulated organ vessels that are thermostatically controlled at 37°C and oxygenated with carbogen (95% O₂ and 5% CO₂) containing Krebs solution. Each ring is connected to an isometric voltage sensor that measures variations. The contractile voltage was recorded by a computer with an amplifier connected to the sensors. To measure the isometric voltage changes, each ring was held at a basal tension of 5 g. After precontracting with U46619, the rings are contacted after obtaining the contraction plate with a concentration range of MSEG01, ranging from 10^-4 to 10^-1 mg/ml. In some experiments, the endothelium was removed by luminal abrasion with forceps. Cell signaling pathways were determined by incubating the rings with L-NA (an endothelial NO synthase inhibitor), Indometacin (a cyclooxygenase inhibitor), or the combination of Tram-34 + UCL (inhibitors of potassium channels IKca and SKca) before applying the MSEG01 concentration range. The measured voltages were collected and plotted as curves using GraphPad. Prism version 6.01^®.

Fig. 1. Effect–concentration curves of MSEG01 in isolated porcine coronary arteries precontracted with U46619, with or without functional endothelium. Results are shown as means ± SEM of 6 different experiments. **** p < 0.0001 for inhibitory effect versus control.

Fig. 2. Effect–concentration curves of MSEG01 in isolated porcine coronary arteries preincubated with L-NA (300 μM) for 30 minutes before the addition of U46619. Results are shown as means ± SEM of 6 different experiments. **** p < 0.0001 for inhibitory effect versus control.

Fig. 3. Effect–concentration curves of MSEG01 in isolated porcine coronary arteries preincubated with indomethacin (10 μM) for 30 minutes before the addition of U46619. Results are shown as means ± SEM of 6 different experiments. n=6.

Statistical analysis

Results are expressed as means, followed by the standard error to the mean (SEM average of 6–8 experiments). The statistical analysis of data and graphical representations were performed using GraphPad Prism version 6.01^®. The significance of differences observed in comparisons was determined by analysis of variances. The values of p < 0.05 are considered significant.

---

Results

Role of the endothelium in MSEG01-induced relaxation

A range of concentrations of MSEG01 from 1 to 100 μg/ml administered on the coronary artery rings of pigs with functional endothelium pre-contracted to U46619 resulted in dose-dependent relaxation, as shown in Figure 1. Without endothelium, there is no relaxation.

Characterization of cellular signaling pathways

Incubation of endothelium rings with L-NA (300 μM)) inhibited the relaxation induced by MSEG01, resulting in the involvement of NO (Fig. 2). However, incubation with indomethacin (10 μM) and the combination of Tram-34 (100 nM) + UCL (100 nM) did not affect MSEG01-induced relaxation, suggesting that prostacyclin and endothelium-derived hyperpolarizing factor (EDHF) are not involved (Figs. 3 and 4).

Fig. 4. Effect–concentration curves of MSEG01 in isolated porcine coronary arteries preincubated with UCL (100 nM) + TRAM (100 nM) for 30 minutes before the addition of U46619. Results are shown as means ± SEM of 6 different experiments. n=6.

---

Discussion

The results obtained in this study show that in a model of coronary artery pigs previously contracted with U46619, the metabolic fraction of the leaves powder of E. guineensis (MSEG01) causes vascular relaxation. The peak of relaxation was noted at 3 μg/ml, and the maximum relaxation (91.91%) occurred at 100 μg/ml.

The relaxation requires the presence of functional endothelium. Without endothelium, MSEG01 does not induce relaxation. This shows that the methanolic fraction of the leaves powder of E. guineensis has dose-dependent vasodilatory properties in porcine coronary arteries with an endothelium-dependent character. These results are in line with those reported by many studies demonstrating the predominant role of the vascular endothelium in the mechanisms of vasorelaxation induced by polyphenols (Furchgott and Zawadzki 1980; Sene et al. 2019; Sene et al. 2020). It is generally accepted that endothelium-dependent vasorelaxation is caused by three major relaxant factors, namely NO, prostacyclins, and EDHF. These different relaxing factors are produced by endothelial NOS, cyclooxygenase, and a source that has not yet been determined for EDHF (Félétou et al. 2003). Our results showed that the relaxation induced by MSEG01 was due to the activation of endothelial NOS with the production of NO. In addition, Ndiaye et al. (2004) showed that polyphenols induce relaxation of the coronary vessels of pigs by stimulating NO production through eNOS activation (Ndiaye et al. 2004).

The phytochemical analysis of the methanolic fraction of the leaves powder of E. guineensis provides an indication of the nature of compounds involved in the vasorelaxant activity of these arteries. Gomis B showed that this fraction contains polyphenolic compounds, mainly flavonoids and tannins. However, alkaloids and sterols/triterpenes have not been identified (Gomis 2023). These results show that polyphenols, mainly flavonoids, and tannins are responsible for the vasorelaxant endothelium-dependent activity of the methanolic fraction of the leaves powder of E. guineensis. Several studies have also shown the presence of polyphenols in the methanolic extract of the leaves of E. guineensis. This fraction has a broad medical value. It has vasorelaxant, antibacterial, antioxidant, anti-hypertensive, antidiabetic, healing, and anticancer properties (Soha et al. 2019). Epidemiological studies have shown a correlation between the consumption of plant polyphenols and a low incidence of cardiovascular disease, probably due to their ability to modify many factors that cause these diseases (Gomis 2024). These results are consistent with previously published studies showing that sources rich in polyphenols (e.g., grape juice, red wine, and a Crataegus extract) induce endothelium-dependent relaxation and mediate the NO redox-sensitive and EDHF pathway (Auger et al. 2009). Therefore, our results follow the same logic as those reported by these studies demonstrating the predominant role of the endothelium in vasorelaxation induced by polyphenols.

---

Conclusion

Elaeis guineensis exhibits vasorelaxant properties in porcine coronary arteries, supporting its potential use in the treatment of arterial hypertension. This effect requires the presence of a functional endothelium and is mediated through the redox-sensitive eNOS pathway.

---

References

Auger, C., Chataigneau, T. and Schini-Kerth, V. 2009. Vascular protection by grape-derived polyphenols. Mol Nutr Food Res. 20, 38–40.

Félétou, M., Busse, R., Edwards, G., Fleming, I., Weston, A.H. and Vanhoutte, P.M. 2003. Dialogue entre cellules endothéliales et cellules musculaires lisses. 19(12), 1242–1250.

Furchgott, R.F. and Zawadzki, J.V. 1980. The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine. Nature 288(5789), 373–376.

Gomis, B. 2023. Etude in-vitro de l’activité antiinflammatoire de la fraction méthanolique des feuilles de Elaeis guineensis Jacq. (Arecaceae). Thèse Pharma. UCAD, Dakar, Senegal.

Gomis, A. 2024. Effets vasorelaxants d’un extrait de feuilles d’Adansonia digitata sur un modèle d’artères mésentériques principales de rat. Thèse Pharma. UCAD, Dakar, Senegal.

Kearney, P.M., Whelton, M., Reynolds, K., Muntner, P., Whelton, P.K. and He, J. 2005. Global burden of hypertension: analysis of worldwide data. Lancet 365(9455), 217–223.

Krzesinski, J.M. 2002. Épidémiologie de l’hypertension artérielle. Rev. Med. Liège 57(3), 142–147.

Lawes, C., Vander, H.S. and Rodgers, A. 2002. Global burden of blood-pressure-related disease. Lancet 371, 1513–1518.

Ndiaye, M., Chataigneau, T., Chataigneau, M. and Schini-Kerth, V.B. 2004. Red wine polyphenols induce EDHF-mediated relaxations in porcine coronary arteries through the redox-sensitive activation of the PI3-kinase/Akt pathway. Br. J. Pharmacol. 142, 1131–1136.

Seck, S.M., Guéye, S., Tamba, K. and Ba, I. 2013. Prevalence of chronic cardiovascular and metabolic diseases in Senegalese workers: a cross-sectional study, 2010. Prev. Chronic Dis. 10, 110339; doi:10.5888/pcd10.110339.

Sene, M., Diouf, I., Toure, M., Auger, C., Senecheau, C.V., Sarr, M., Schini-Kerth, V. and Kane, M.O. 2019. Vasoactive properties of Ceiba pentandra in porcine coronary artery and different conductance and resistance vessels from rats : a role of nitric oxide. Natl. J. Physiol. Pharm. Pharmacol. 9(10), 1027–1033.

Sene, M., Lee, H., Diouf, I., Toure, M., Senecheau, C.V., Auger, C., Sarr, M., Schini-Kerth, V. and Kane, M.O. 2020. Terminalia avicennioides causes redox-sensitive endothelium-dependent relaxation involving nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing in porcine coronary artery and different conductance and resistance vessels from rats. Natl. J. Physiol. Pharm. Pharmacol. 10(09), 804–812.

Soha, S.A.S., Dougnon, T.J., Ohouko, F.H.O., Kpodekon, M.T.T. and Youssao, A.K.I. 2019. Activités biologiques et utilisations de Elaeis guineensis (Jacq) et de Khaya senegalensis (Desr) en médecine traditionnelle humaine et vétérinaire. Int. J. Biol. Chem. Sci. 13(1), 525–542.

Organisation mondiale de la Santé. 2013. Stratégie de l’OMS pour la médecine traditionnelle pour 2014-2023. Organisation mondiale de la Santé, Geneva, Switzerland.

Walker, R.W., McLarty, D.G. and Kitange, H.M. 2000. Stroke mortality in urban and rural Tanzania. Lancet 355, 1684–1687.