Abstract
The pharmacologic activities of Pistia stratiotes were studied. Calcium channel blocking activity of a methanol extract of the whole plant was demonstrated using isolated segments of rabbit jejunum and confirmed via inhibition by pretreatment with verapamil. Additionally, the plant extract exhibited dose-related bronchodilating activity on isolated guinea pig trachea and neuromuscular blocking action, which was also dose-related. The plant extract caused a decrease in blood pressure in anaesthetised rats. After a 10 μg dose of the extract, systolic and diastolic blood pressures fell by 18% and 10%, respectively. Further doses of the plant extract produced slight decreases in blood pressures in anaesthetised rats. The systolic, diastolic and mean blood pressures before the extract were all significantly higher (P < 0.001) than those following the administration of the extract.