Solanum indicum ssp distichum extract is effective against l-NAME-induced hypertension in rats

Solanum indicum ssp. distichum is used as a vegetable in some parts of Africa and claimed in folk medicine to guard against cardiovascular disorders. It was of interest to study the potential blood pressure lowering effects of a standardized extract of the fruit. An ethanolic extract of the fruit, standardized to contain > 0.15% chlorogenic acids, was tested orally in both normotensive rats and in those rendered hypertensive by twice daily intraperitoneal injection of N(W)-nitro-l-arginine methylester (l-NAME) for 1 week. The extract was either given at the same time as l-NAME or after the establishment of hypertension. The systolic blood pressure (SBP) was measured non-invasively using a tail cuff computer-aided monitoring device. Treatment of normotensive rats with the extract (30-300 mg/kg) for 4 weeks showed no hypotensive effect. Giving the extract (100 and 300 mg/kg) orally once daily during the 1 week hypertension induction period with l-NAME prevented the development of hypertension. Administration of the extract orally for 1 week after the establishment of hypertension tended to normalize the blood pressure. Pharmacological evidence for the antihypertensive activity of S. distichum is hereby reported for the first time. The extract showed good prophylactic as well as curative effect against l-NAME-induced hypertension, whereby its content of chlorogenic acids may play a minor role. Other constituents may be responsible for the antihypertensive action. The findings support further development of the extract as a potential therapeutically useful antihypertensive agent.