RESUMO
Background Gongronema latifolium Benth. (family Apocynaceae) leaves (GL) has interesting medicinal properties. The effects of extracts from G. latifolium on blood pressure (BP) and the possible mechanisms of action were also investigated. Methods The ultrahigh resolution liquid chromatography orbitrap MS analysis was used to identify the phytochemicals present. Normotensive Wistar rats were anesthetized with sodium pentobarbitone (40 mg/kg) intraperitoneally, and the jugular vein was cannulated for infusion of drugs while the carotid artery was cannulated for direct BP measurement. GL extract (5-20 mg) alone or with nifedipine (10 mg/kg), atropine (2 mg/kg), L-NAME (5 mg/kg), methyl blue (3 mg/kg) and propranolol (1 mg/kg) were administered intravenously to Wistar rats and direct BP measurements were carried out. Results Systolic and diastolic BP levels (128/90 mm Hg; MAP 103 ± 3 mm Hg) and heart rates were all significantly (p < 0.01) decreased after GL administration. Raised mean arterial pressure (MAP) and heart rate by atropine, L-NAME and methyl blue were significantly (p < 0.01) reduced after GL administration, while propranolol significantly (p < 0.01) inhibited hypotension caused by GL. Infusion of GL reduced MAP (95 ± 3 mm Hg) comparable with nifedipine (93 ± 2 mm Hg), a calcium channel blocker. The phytochemicals identified were 34 compounds, including oleanolic acid derivatives, flavonoids, antioxidant fatty acids, 2 coumarins and 2 iridoids. Conclusions These results suggest that G. latifolium has hypotensive properties mediated by the synergistic activity of the compounds, probably via the ß-adrenergic blockade mechanism.