Fatiany Pierre Ruphin, Fiatoa Barthelemy, Raoelson Guy, Randrianirina Aubin Oscar, Randriantsoa Adolphe, Andrianjara Charles, MinjiÃ© Zhao, Eric Marchioni, Robijaona Baholy, Solofoniaina Marcelin, Koto â€“te- Nyiwa Ngbolua
The aerial part of Cymbopogon pruinosus
is widely used in the Southern part of Madagascar for the treatment of hypertension. The aims of the present study were to analyze the vasorelaxant properties of different extracts from C. pruinosus
and to isolate and characterize bioactive secondary metabolites. An ethno-pharmacological survey was conducted in the south of Madagascar about medicinal plants used in folk medicine to treat hypertension. The vasorelaxant activity of various extracts (n-Hexane, Dichloromethane, Ethyl acetate and Ethanol) from the most cited plant C. pruinosus
1 was carried out on rat aorta ring. The chemical structures of the pure compounds were determined by LC/MS/NMR. The ethyl acetate extract was the most effective. The ethyl acetate extract inhibited phenylephrine contraction in isolated rat thoracic aorta. Bioassay-guided fractionation of this extract led to the isolation and structural characterization of two bioactive pure compounds (named PY-1 and PY-2) which exhibited very good vasorelaxant activities with the EC50
values of 0.0125 Â± 0.006 mgml-1
and 0.00731 Â± 0.0018 mgml-1
respectively. The bioactive compounds were attributed respectively to Scopoletin (PY-1) and Bis(2-ethyl hexyl)phthalate (DEHP). The vasorelaxant potency of the bioactive extract was diminished in the absence of endothelium and by a pre-treatment with propranolol, a Î²2
adrenergic receptor blocker, which was however not affected by indomethacin pre-treatment. These findings indicated that the vasorelaxant effect of Cymbopogon pruinosus
may be partially endothelium dependent, mediated by nitric oxide and that vasoactive prostanoids might not be contributing to the vasorelaxation effect. C. pruinosus
possess vasorelaxant activity on isolated organs. The ability of plant extracts and its isolates in this study to cause relaxation of the aortic rings pre-contracted with phenylephrine may represent a rational explanation for the use of the plant species to treat hypertension by Malagasy traditional healers.
Fatiany Pierre Ruphin, Fiatoa Barthelemy, Raoelson Guy, Randrianirina Aubin Oscar, Randriantsoa Adolphe, Andrianjara Charles, MinjiÃ© Zhao, Eric Marchioni, Robijaona Baholy, Solofoniaina Marcelin, Koto â€“te- Nyiwa Ngbolua. Vasodilator effects of Cymbopogon pruinosus (Poaceae) from Madagascar on isolated rat thoracic aorta and structural elucidation of its two bioactive compounds. J Pharmacogn Phytochem 2016;5(1):46-55.