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The vasorelaxant and phosphodiesterases inhibition activities of extract and fraction from Lannea microcarpa were investigated in this study. The cumulative additions of aqueous extract from L. microcarpa (AELM) caused concentration-dependent relaxation response, in both aortas with endothelium-intact and endothelium-denuded one. While dichloromethane fraction is deprived of relaxant effect, (LMFl), ethyl acetate (LMF2) inhibits phenylephrine-induced vasoconstriction.
Effects of AELM and the two fractions were examined on PDEs inhibition. The order of power of plant extracts with respect to PDEs inhibition is asfollows: LMF2 > AELM> LMFI.
It is concluded that AELM and LMF2 possesses endothelium-independent vasorelaxant activity. These properties on vascular smooth muscle relaxation may involve PDEs activities inhibition.
INTRODUCTION
Many traditional medicine herbs from Burkina Faso that are used to treat hypertension are documented (Nacoulma 1996, Belemtougri et al. 2001). For exemple aqueous extract from Mitragyna inermis and odontonema strictum has been show to diminish basal blood pressure and dilate vascular smooth muscle (Ouedraogo et al 2004; 2005). Extract from Tapinanthus dodoneifolius have been reported to dilate blood vessels in endothelium-dependent andnitric oxide-mediated manner (Ouedraogo et a1,2005). For some of theme, active compounds were identified and their vasodilatory effects were demonstrated; Dodoneine isolated from Tapinanthus dodoneifolius has been show to dilate rat aorta (Ouedraogo et al. 2007) and odontine was isolated from Odontonema strictum and their structures were elucidated (K.ini. 2008).
Lannea microcarpa is not as well known as these medicinal plants mentioned above, but this plant has also been widely used in Burkina traditional medicine, as a single herb or in combination with Anogeissus leiocarpus and Slerocarya birrea (Nacoulma, 1996; Ouedraogo et al unpublish data). The antioxidant effect of its seeds is established (LamienMeda et al. 2008). Little information is known about its effect on bloods vessels. In this work we assessed whether L. microcarpa bark extract, being antihypertensive would exert relaxation of isolated arteries ex vivo. If so we would examine the nature of the relaxation and its possible mechanism of action.
MATERIAL AND METHODS
Plant and extract
The bark of trunk L. microcarpa was collected from the region of Ouagadougou, Burkina Faso (zone of savannah) during July 2008. Voucher specimen (N°361) was deposited at the herbarium, Department of Forest Production, National Centre for Scientific and Technological Research, Ouagadougou Burkina Faso.
The...