Paullinia pinnata L. (Sapindaceae) is an African tropical plant whose roots and leaves are used in traditional medicine for many purposes, especially for erectile dysfunction, but its action mechanism is unknown. P. pinnata root and leaf methanolic extracts are rich in phenolic compounds. This study shows that both extracts are highly antioxidative and induce a slight transcriptional activity of peroxisome proliferator activated receptor-alpha. They also increased and decreased endothelial nitric oxide synthase and endothelin-1 mRNA levels in bovine aortic endothelial cells, respectively. In this study P. pinnata methanolic extracts in cumulative doses elicited in a dose-dependent manner the relaxation of phenylephrine precontracted isolated rat aortic rings. N-nitro-L-arginine methyl ester significantly attenuated the capacity of both extracts to induce arterial relaxation, indicating that this arterial relaxation was mediated by endothelial nitric oxide release. It could be suggested that the arterial relaxation induced by both extracts could be mainly linked to their capacities to inhibit nitric oxide oxidation through their antioxidant properties.
There is increasing evidence that oxidized low-density lipoproteins (Ox-LDL) might be involved in the pathogenesis of atherosclerosis and it has been reported that polyphenols inhibit LDL peroxidation and atherosclerosis. Endothelin-1 (ET-1) is a potent vasoconstrictor peptide isolated from endothelial cells and it induces smooth muscle cell proliferation. ET-1 secretion is increased in atheroma and induces deleterious effects such as vasospasm and atherosclerosis. The goal of this study was to test the effect of four natural phenolic compounds against copper-oxidized LDL (Cu-LDL)-induced ET-1 liberation by bovine aortic endothelial cells (BAEC). The tested compounds were phenylpropanoid glycosides previously isolated from the aerial parts of Marrubium vulgare L. (acteoside 1, forsythoside B 2, arenarioside 3 and ballotetroside 4). ET-1 secretion increased when cells were incubated with Cu-LDL but the compounds 1-4 inhibited this increase. These results were confirmed by quantitative-polymerase chain reaction (QPCR) analysis. Since ET-1 plays an important role in atherosclerosis development, our work suggests that the tested phenylpropanoids could have a beneficial effect in inhibiting atherosclerosis development.
La dysfonction érectile est un phénomène de santé relativement important dont les conséquences sont néfastes pour l'homme et son entourage. De nombreux traitements par des molécules de synthèse sont actuellement proposés pour pallier ces troubles, mais leur coût élevé, ainsi que les effets secondaires qu'ils engendrent, redonnent un nouvel élan aux substances naturelles. Certaines préparations d'origine végétale n'ont pourtant aucun effet et ne sont pour la plupart que légendes. D'autres, peu nombreuses, ont une activité réelle prouvée sur le plan scientifique. Par ailleurs, de nombreuses plantes prometteuses dans le traitement des dysérections n'ont fait l'objet que de rares investigations et mériteraient une étude pharmacologique plus approfondie.Abstract: Erectile dysfunction is a major health problem, the consequences of which can affect both the man and his family. Many synthetic drugs are available to treat this problem but, as they are expensive and can provoke important adverse effects, effective natural treatments are still in demand. Even if many of these plants or natural products have absolutely no effect, some of them show real biological activity, proven by scientific data. Moreover, many plants which are used in traditionnal medicine for treating erectile dysfunction have been studied little and deserve deeper pharmacological studies.
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