Hypotensive activity of Tacca chantrieri and its hypotensive principles

Abstract

The rhizomes of Tacca chantrieri Andre (Taccaceae) have been used in Chinese medicines for the treatment of various diseases including high blood pressure, burns, gastric ulcers, enteritis, and hepatitis. The rhizomes of this plant have been found to contain a wide array of saponins and other compounds. The aims of the current study were to investigate the hypotensive activity of the ethanol extract (TCE) and both the crude (TCS) and purified saponin extract of T. chantrieri, and thus to characterize the hypotensive principles. TCE and TCS at the dose of 5 mg/kg caused hypotension and bradycardia in normotensive rats under pentobarbital anesthesia. Both TCE and TCS caused a decrease in the force and rate of contractions in isolated rat atria. The vasorelaxant activity of TCE and TCS could be demonstrated when tested on the aortic ring with endothelium intact. It is therefore implied that TCE and TCS exert both their hypotensive effect and bradycardia by affecting the heart as well as blood vessels. Separation of the crude saponin extract of T. chantrieri yielded four fractions with hypotensive activity. Fraction 1 contained diarylheptanoid glucosides, fraction 2 was a mixture of the glucosides and saponins, and fractions 3 and 4 contained spirostanol saponins. It is likely that in addition to the saponins, other constituents (diarylheptanoid glucosides) are involved in the hypotensive activity of T. chantrieri. © 2007 Informa Healthcare.