Vasorelaxant Alkaloids from Spirospermum penduliflorum (Menispermaceae), a Plant Used to Treat Hypertension in Malagasy Traditional Medicine

Abstract

Spirospermum penduliflorum Thouars (Menispermaceae) is widely used on the eastern coast of Madagascar to treat hypertension. The aim of the present study was to analyse the vasorelaxant properties of different leaf extracts. The activity of the n-hexane, dichloromethane and methanolic extracts was tested on phenylephrine-contracted aorta. The dichloromethane extract was shown to be the most effective. Further fractionation of this extract led to the isolation of an active fraction relaxing phenylephrine-contracted aorta with an IC50 of 0.18 μg/mL {log IC50 (μg/mL) −0.74 ± 0.03} but was much less effective on KCl induced contractions. Bioassay-guided fractionation of this fraction led to the isolation of two aporphinoid alkaloids, neolitsine and dicentrine, which at concentrations of 0.1 μM and 1 μM displaced to the right the phenylephrine concentration-contraction curve. Our results show that Spirospermum penduliflorum extracts possess vasorelaxant activity in vitro that could be related to the presence of dicentrine in the extracts having an α1 antagonist activity. This finding is not in accord with the previous studies by Rasoanaivo et al where no alkaloids were detected in the leaves of Spirospermum penduliflorum.

Preliminary evidences of the direct and indirect antimicrobial activity of 12 plants used in traditional medicine in Africa

“…Spirospermum penduliflorum was mainly studied for its antiplasmodial alkaloids content but also for its vasorelaxant activity (Raoelison et al 2013;Ratsimamanga-Urverg et al 1992). However, this plant was never studied for its antimicrobial activity.…”

“…Two vasorelaxant aporphine alkaloids were isolated from the leaves of S. penduliflorum namely dicentrine and néolitsine (Raoelison et al 2013). Those two compounds are antihelmintic and a dicentrine derivative (dicentrine methane) has a MIC comprised between 50 and 300 mg/L on Staphylococcus aureus strains.…”