COMPARATIVE EFFECT OF DIFFERENT EXTRACTS AND FRACTIONS FROM LOPHIRA LANCEOLATA TIEGH. EX KEAY (OCHNACEAE) LEAVES ON ARTERIAL BLOOD PRESSURE AND HEART RATE IN ANAESTHETIZED CATS
Oussou N. Jean-Baptiste*, Eric Boakye-Gyasi, Kouakou K. Léandre, N’guessan B. Benoit, Patrick Amoateng, Yapo A. Francis, Asiedu-Gyekye I. Julius, Ehilé E. Etienne
ABSTRACT
Lophira lanceolata has been used in folk medicine for the treatment of many ailments especially hypertension. The aqueous extract of this medicinal plant reduced blood pressure according to previous research. In order to find the metabolites or group of metabolites involved in the hypotensive effects of L. lanceolata, different leaf extracts and fractions of this herb were evaluated on two cardiovascular parameters: blood pressure (BP) and heart rate (HR). Seven extracts and fractions were obtained by successive use of different solvents. Increasing doses (1 to 20 mg / kg b.w.) of various extracts were administered through cat’s femoral vein; while the carotid artery was connected to a transducer and an oscillograph to determine respectively the BP and the HR. Results showed that the aqueous extract (LLAQ) and the methanol crude extract (LLCE) reduced the blood pressure by 24.7% (158 ± 5.85 to 119 ± 3.75 mmHg) and by 31.8% (151 ± 6.07 to 103 ± 4.33 mmHg) respectively. However, LLAQ have no bradycardia effect but LLCE decreased significantly (p˂0.05) heart rate by 26.43%. The Petroleum ether fraction (LLFPE), dichloromethane fraction (LLFDCM), ethyl acetate fraction (LLFEA), butanol fraction (LLFB) and residual aqueous fraction (LLFA) decreased the arterial blood pressure by 4.06 ± 0.99; 0± 0; 49.5 ± 3.91; 14.6 ± 0.87and 5.53 ± 0.87% respectively. Hypotension induced by LLFEA (ED50=4.61 mg/kg b.w.) was greater than those induced by the other fractions. Among these fractions, only LLFEA exhibited a significant (p˂0.05) decrease of cats’ heart rate from 177 ± 5.20 to 146 ± 5.68 beats/min (17.8 ± 1.05 %). The others have no effect. Phytochemical analysis of LLFEA revealed the presence of phenols, tannins and flavonoids. In conclusion, the secondary metabolites involved in the hypotensive effects and possible bradycardia caused by L. lanceolata are soluble in ethyl acetate.
Keywords: Blood pressure, heart rate, Lophira lanceolata.
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