Hypertensive and Sympathomimetic Effects of the Methanol and Aqueous Extracts of Scoparia dulcis in Anaesthetized Male Wistar Rats

Abstract

Objective Scoparia dulcis, a widely used medicinal plant is believed to have antihypertensive effects among traditional medical healers. This study investigates the efficacy of Scoparia dulcis as an antihypertensive agent in Wister rats. Methods Plant specimens were collected from local gardens in Portharcourt and identified in Department of plant Science, University of Portharcourt. Methanol and aqueous extracts were made from the leaves of the plant. Phytochemical screening was done using conventional methods and acute toxicity studies carried out to determine the LD 50 using the Arithmetic method of Karber. Rats were anaesthesized using urethane, and endotracheally-intubated. The rats were then cannulated via the jugular vein and carotid artery. The carotid artery was connected to a pre-calibrated Ugo Basile double channel pen recorder. Adrenaline (0.5µg/kg), Acetylcholine (1.5µg/kg), and 20, 40, 80 and 160mg/kg of the aqueous and methanol extracts were administered through the jugular vein and their effects on the blood pressure (BP) and heart rate (HR) recorded. The mean arterial pressure (MAP) was calculated. This was repeated in four series for each extract and the mean of all experiment ± standard error of mean calculated. Results were analyzed statistically using Kruskal-Wallis, Dunn's and Tukey-Kramer multiple comparisons test and Friedman nonparametric test. Results The phytochemical analysis reveals the presence of Tannins, Phlobatannins, Steroids, Terpenoids, Flavonoids and Cardiac glycosides in the leaves of Scoparia dulcis. There were no Saponins. The LD 50 was 450 and 650mg/kg for the methanol and aqueous respectively. There was significant (P<0.05) hypertensive and sympathomimetic effects at 40, 80 and 160mg/kg dose levels for both extracts. Discussion Though, Scoparia dulcis plant is used traditionally in the treatment of hypertension, scientific research has not demonstrated this property but rather has shown this plant to increase the BP, MAP and HR as revealed by the above results. The plant contains catecholamines which accounts for these effects after parenteral administration. In the traditional medicine system, there are no scientific means of diagnosis of hypertension such as measurement of BP, other than perceived symptoms such as headache, insomnia and malaise. Extracts of Scoparia dulcis plant are reported to have analgesic, anti-inflammatory and sedative effects and it is likely that the improvement in the above symptoms in hypertensive patients that is erroneously believed to be the BP lowering effects among traditional medical healers.

A review on the phytochemistry and pharmacology of the herbScoparia dulcisL. for the potential treatment of metabolic syndrome

“…Review of Freire et al in 1993, Chow et al in 1974and Esume et al 2011 found that dose dependent hypertension produced by the ethanolic extract of S. dulcis and its aqueous fraction is useful for treatment of hypertension. 66,88,91 However, low-dose norepinephrine and epinephrine are easily degraded in the digestive tract aer oral administration and are not absorbed into the blood in signicant amounts.…”

“…Review of Freire et al in 1993, Chow et al in 1974and Esume et al 2011 found that dose dependent hypertension produced by the ethanolic extract of S. dulcis and its aqueous fraction is useful for treatment of hypertension. 66,88,91 However, low-dose norepinephrine and epinephrine are easily degraded in the digestive tract aer oral administration and are not absorbed into the blood in signicant amounts. Nevertheless, the test results of Esume et al 2011 88 also display that the higher doses of the aqueous and methanol extract of S. dulcis leaves signicantly increased blood pressure, heart rate and mean arterial pressure.…”

“…66 The polar extract of the aerial parts of S. dulcis, containing noradrenaline and adrenaline substances, displayed the hypertensive effect in vivo, relaxing the tracheal smooth musculature and increasing inotropism in heart muscle. 11 Nevertheless, the experimental results of Esume et al 2011 88 showed that higher dose of the water and methanol extracts of S. dulcis signicantly increased blood pressure from baseline values of animal tests. Although S. dulcis plant has been widely used in the treatment of hypertension, the effect of treating hypertension needs more scientic research to demonstrate its therapeutic effect.…”

“…The LD 50 values of aqueous and methanol extract of S. dulcis administered intraperitoneally using arithmetic method of karber were measured, which were 535 mg kg −1 and 390 mg kg −1 respectively, indicating the methanol extract was more toxic. 88 …”

Therapeutic potency of saponin rich aqueous extract of Scoparia dulcis L. in alloxan induced diabetes in rats

“…It is a perennial herb widely distributed in tropical and sub-tropical regions. In these regions, fresh or dried S. dulcis plants have been traditionally used as remedies for various ailments such as stomach problems that is, peptic ulcer,[ 9 ] hypertension,[ 10 ] hyperlipidemia,[ 11 ] hepatic injury,[ 12 ] algesia, and inflammation. [ 13 14 ] It has various biologically active secondary metabolites such as carbohydrates, coumarins, phenols, saponins, glycosides, tannins, amino acids, flavonoids, terpenoids, catecholamine, noradrenaline, and adrenaline.…”