Depressor effect of the young leaves of Polygonum hydropiper Linn. in high-salt induced hypertensive mice

A novel chymase inhibitor has been reported to have depressor effect in salt-induced hypertension. Therefore, we examined the hypothesis that chymase inhibitory dried young leaves of Polygonum hydropiper ( PPH) or young leaves extract of Polygonum hydropiper (PHE) could reduce salt-induced hypertension. In this study, 8-wk old wild-type mice were allocated into three experiments and experiment I included groups, I-normal water drinking, II-high salt (2% NaCl) water (HSW) drinking, and III-HSW plus PPH (500 mg kg(-1), orally) for 12-wk. Blood pressure (BP) and heart rate (HR) were measured at baseline and weekly up to wk-12. In experiment II, mice were given HSW for 12-wk followed by 8-wk treatment with PPH plus HSW (62.5, 125, 250 and 500 mg kg(-1) for groups I, II, III and IV, respectively). BP and HR were measured at baseline and monthly until wk-12, following weekly for 8-wk. Experiment III comprised of four groups of mice for 12-wk HSW and 8-wk treatment with PHE plus HSW (2.5, 5, 10 and 20 mg kg(-1) for groups I-IV, respectively). BP and HR were measured at baseline and monthly up to wk-12, following weekly for 8-wk. Significant reduction in BP and HR were observed in mice treated with PPH (500 mg kg(-1)) compared to HSW control. PPH reduced BP and HR dose dependently in hypertensive mice and the higher dose showed maximum reduction. PHE at its maximum dose (20 mg kg(-1)) significantly suppressed BP and HR. Over all, we found that the young leaves of Polygonum hydropiper suppressed salt-induced hypertension.