Antihypertensive effect of total flavone extracts from Puerariae Radix

Aim of the study

To evaluate the antihypertensive effect of total flavone extracts from Puerariae Radix (FEPR). To explore the hemodynamic profiles and pertinent mechanism of the extracts.

Materials and methods

Acute and chronic antihypertensive effects of FEPR were examined in spontaneous hypertensive rats (SHRs) and reno-hypertensive rats (two kidneys one clip model, 2K1C). Anesthetized dogs were used to evaluate the hemodynamic effects of FEPR. The determination of angiotensin converting enzyme (ACE) activity in vitro and plasma renin activity (PRA) and endothelin (ET) in vivo were used to study the pilot mechanism of FEPR. Moreover, the toxicity study of FEPR was evaluated.

Results

FEPR (100, 200 and 400 mg/kg, i.v.) notably reduced the blood pressure of SHRs in a short time period. A two-week administration of FEPR (45, 90 and 180 mg/kg, p.o.) decreased the blood pressure of both 2K1C rats and SHRs. The results of hemodynamic study in anesthetized dogs showed that, left ventricular end systolic pressure and left ventricular dP/dt_max had shown no significant difference between FEPR-treated dogs and those from the control group, while the cerebral blood flow increased significantly in FEPR-treated groups. FEPR significantly inhibited the ACE activities in vitro dose dependently, and inhibited the PRA in vivo, while the content of ET showed no difference in the FEPR treated group comparing with the control group.

Conclusions

FEPR shows significantly blood pressure lowering and cerebral vascular resistance (CVR) decreasing effect, which can partly be explained by the involvement of the Renin-Angiotensin-System (RAS).     

Pharmacological basis for the medicinal use of muskmelon base (Pedicellus Melo.) for abdominal distention and constipation

Ethnopharmacological relevance

Muskmelon base (Pedicellus Melo.) has a long history (Ming Dynasty) as a Chinese traditional medicine. According to traditional use, it was prepared as rectal suppositories for treating abdominal distention and constipation. The present study was carried out on the pharmacological basis for the medicinal use of muskmelon base.

Aim of the study

The objective of this study was to determine the pharmacological basis for the medicinal use of the ethanol extract from muskmelon base (EMB) for abdominal distention and constipation.

Materials and methods

In this study, we report the gastrointestinal prokinetic action of EMB following single rectal or large intestinal administration. Laxative activity, gastric emptying and small intestinal transit tests were examined in ICR mice. SD rats were used to determine changes in large intestinal transit and contractile effects of the proximal colon in vivo. Guinea pigs were used to evaluate the contractile effects of the proximal colon and the possible mechanism or mechanisms on proximal colon activity ex vivo. Moreover, the acute toxicity of EMB was evaluated.

Results

In the in vivo experiments, the acute toxicity test showed that the maximum tolerated dose (MTD) of EMB was 400 mg/kg. A laxative effect was observed in mice at different dosages (6.5, 13 and 26 mg/kg). EMB showed a dose-dependent acceleration of gastric emptying (13 and 26 mg/kg). It also promoted both small intestinal (6.5, 13 and 26 mg/kg) and large intestinal (4, 8 and 16 mg/kg) transit activity. In the SD rat model, single rectal administration of EMB (8 and 16 mg/kg) showed a significant increase in both the frequency and amplitude of proximal colon smooth muscle contractility. These increases in amplitude and frequency peaked 30–60 min after EMB administration and corresponded with the results of the laxative activity test. The ex vivo experiments showed that varying doses of EMB (11.5, 23 and 46 mg/kg) had a direct prokinetic effect that was sensitive to atropine.

Conclusions

Our results show that EMB is a low dosage, fast acting drug with a large therapeutic window (4–400 mg/kg) and shows significant gastrointestinal prokinetic action after single rectal or large intestinal administration. This gastrointestinal prokinetic effect was stronger in the intestines than in the stomach. This effect was sensitive to atropine, suggesting that EMB acts mainly through cholinergic mechanisms.