薬理と治療

Abstract

The general pharmacological effects of the extract from the leaf and stem of yacon（Smallanthus sonchifolius, Compositae）, a novel food resource, were investigated in mice, rats and guinea pigs. The doses and concentration−range of the extract used in this study were 100, 300 and 1000 mg／kg, p. o. in vivo, and 0.001−0.1％ in vitro, respectively. The extract had no effect on the general behavior, spontaneous motor activity, pentobarbital−induced sleep, pentetrazol−induced convulsion and acetic acid−induced writhing in mice, and body temperature in rats. In the isolated guinea pig ileum, the extract caused a transient contraction at a concentration of 0.1％, and showed non−specific inhibition on acetylcholine−, histamine−and barium chloride−induced contraction. The extract slightly attenuated the tension of resting state at a concentration of 0.1％, and slightly suppressed norepinephrine−induced contraction at concentrations of ＞0.03％ in the isolated guinea pig aorta. In the isolated guinea pig right ventricular papillary muscles and right atria, the extract exerted weak positive inotropic and chronotropic effects at concentrations of ＞0.03％, respectively. The extract did not substantially prolong the effective refractory period in the isolated guinea pig right ventricular papillary muscles. In conscious rats, the extract did not affect the respiration, heart rate and blood pressure. The extract had no effect on the intestinal transport of charcoal meal in mice. In rats, the extract at a dose of 1000 mg／kg decreased the urine volume and increased the urinary electrolyte（Na＋, K＋and Cl−）excretion at 0−6 hr after oral administration, although it had no effect on the urine volume and the urinary electrolyte excretion at 6−24 hr after administration. These results suggest that the extract from the leaf and stem of yacon has no notable general pharmacological effects, except that it causes non−specific inhibition of agonistinduced contraction in the isolated smooth muscles and weak cardiotonic action in the isolated cardiac muscles at high concentrations, and the decrease in urine volume and the increase in urinary electrolyte excretion at a high dose in rats.（Jpn Pharmacol Ther 2009；37：411−22）KEY WORDS Yacon, General pharmacology, Mouse, Rat, Guinea pig