Antihypertensive effect of the stem bark aqueous extract of Garcinia lucida Vesque (Clusiaceae) in L-NAME-treated rats: Contribution of endothelium-dependent and -independent vasorelaxation

Elvine Pami Nguelefack-Mbuyo; Christelle Stéphanie Sonfack; Christian Kuété Fofié; Chamberlin Fodem; Magloire Kanyou Ndjenda Ii; Alain Bertrand Dongmo; Télesphore Benoît Nguelefack

doi:10.1016/j.heliyon.2023.e21896

Antihypertensive effect of the stem bark aqueous extract of Garcinia lucida Vesque (Clusiaceae) in L-NAME-treated rats: Contribution of endothelium-dependent and -independent vasorelaxation

Heliyon. 2023 Nov 8;9(11):e21896. doi: 10.1016/j.heliyon.2023.e21896. eCollection 2023 Nov.

Authors

Elvine Pami Nguelefack-Mbuyo¹, Christelle Stéphanie Sonfack^{1

2}, Christian Kuété Fofié¹, Chamberlin Fodem¹, Magloire Kanyou Ndjenda Ii¹, Alain Bertrand Dongmo², Télesphore Benoît Nguelefack¹

Affiliations

¹ Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
² Department of Animal Biology and Physiology, Faculty of Sciences, University of Douala, P.O. Box 24157, Cameroon.

Abstract

Garcinia lucida is used in Cameroonian folk medicine to handle a variety of ailments, including arterial hypertension. This study aimed at determining the phytochemical profile and the antihypertensive effect of the stem bark aqueous extract of G. lucida (AEGL). AEGL was subjected to LC-MS analysis, and its effect (75, 150, and 300 mg/kg/day; by gavage) was evaluated against Nω-nitro-L-arginine methyl ester (L-NAME; 40 mg/kg)-induced hypertension in adult male Wistar rats for four consecutive weeks. Blood pressure and heart rate were monitored weekly using tail-cuff plethysmography. The vasorelaxant effect of cumulative concentrations (3-10-30-100-300 μg/mL) of AEGL was examined on endothelium-intact and denuded thoracic aorta rings which were precontracted with KCl (90 mM) or norepinephrine (NE; 10^-5 M), and in the absence or presence of L-NAME (10^-4 M), indomethacin (10^-5 M), methylene blue (10^-6 M), tetraethylammonium (TEA, 5 × 10^-6 M), glibenclamide (10 × 10^-6 M) or propranolol (5 × 10^-6 M). The influence of AEGL on the response to NE, KCl, and CaCl₂ was also investigated. Six compounds, including Garcinia biflavonoids GB1 and GB2, were identified. AEGL prevented the development of hypertension (p < 0.01 and p < 0.001) without affecting the heart rate. AEGL induced a concentration-dependent relaxation of aortic rings precontracted with NE (EC₅₀ = 7.915 μg/mL) that was significantly inhibited by the removal of the endothelium, L-NAME, or methylene blue (p < 0.05-0.001). Indomethacin, propranolol, TEA, and glibenclamide did not affect AEGL-evoked vasorelaxation. Preincubation of aortic rings with AEGL reduced the magnitude of contraction elicited by CaCl₂ but did not alter that of KCl or NE. AEGL possesses an antihypertensive effect that is mediated by both endothelium-dependent and endothelium-independent mechanisms. The activation of the NO/sGC/cGMP pathway accounts for the endothelium-dependent vasorelaxation. These pharmacological effects of AEGL could be attributed to the presence of the Garcinia biflavonoids GB1 and GB2.

Keywords: Antihypertensive effect; Garcinia biflavonoids; Garcinia lucida; LC-MS analysis; Vasorelaxant effect.