Studies on vasoconstrictor activity of Curculigo pilosa extract and of its isolated compounds

The Curculigo pilosa total extract, its butanolic fraction (0.5 microg-100 mg/kg) and the most active in vitro compound structurally similar to adrenaline, pilosidine (10 ng-l mg/kg), caused a reversible and dose-dependent increase in blood pressure in anaesthetized rat. This hypertensive effect is partially reversed (90%) by the prior administration of phentolamine (1 mg/kg) and abolished by pre-treatment with phentolamine (1 mg/kg) and atenolol (100 microg/kg). Neither tachiphylaxis nor any toxic effects were observed. These experimental findings suggest an interaction between C. pilosa and the peripheral adrenergic system (particularly with alpha1 and beta1 receptors); the structure of the bioactive glucosides could be important in evoking this effect.