Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels

Abstract

INTRODUCTION:Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensin‐converting enzyme. However, other mechanisms that may contribute to the hypotensive effect have not been studied.OBJECTIVES:To investigate the cardiovascular effects of a butanolic fraction of Gynura procumbens in rats.METHODS:Anaesthetized rats were given intravenous bolus injections of butanolic fraction at doses of 2.5–20 mg/kg in vivo. The effect of butanolic fraction on vascular reactivity was recorded in isolated rat aortic rings in vitro.RESULTS:Intravenous administrations of butanolic fraction elicited significant (p<0.001) and dose‐dependent decreases in the mean arterial pressure. However, a significant (p<0.05) decrease in the heart rate was observed only at the higher doses (10 and 20 mg/kg). In isolated preparations of rat aortic rings, phenylephrine (1×10‐6 M)‐ or potassium chloride (8×10‐2 M)‐precontracted endothelium‐intact and ‐denuded tissue; butanolic fraction (1×10‐6–1×10‐1 g/ml) induced similar concentration‐dependent relaxation of the vessels. In the presence of 2.5×10‐3 and 5.0×10‐3 g/ml butanolic fraction, the contractions induced by phenylephrine (1×10‐9–3×10‐5 M) and potassium chloride (1×10‐2–8×10‐2 M) were significantly antagonized. The calcium‐induced vasocontractions (1×10‐4–1×10‐2 M) were antagonized by butanolic fraction concentration‐dependently in calcium‐free and high potassium (6×10‐2 M) medium, as well as in calcium‐ and potassium‐free medium containing 1×10‐6 M phenylephrine. However, the contractions induced by noradrenaline (1×10‐6 M) and caffeine (4.5×10‐2 M) were not affected by butanolic fraction.CONCLUSION:Butanolic fraction contains putative hypotensive compounds that appear to inhibit calcium influx via receptor‐operated and/or voltage‐dependent calcium channels to cause vasodilation and a consequent fall in blood pressure.

Gynura procumbens: An Overview of the Biological Activities

“…To date, the administration of G. procumbens has been reported to result in significant lowering of systolic blood pressure and mean arterial pressure in hypertensive rats (Hoe and Lam, 2005; Kim et al, 2006; Hoe et al, 2007). Additionally, the treatment with G. procumbens extract has also resulted in significant decrease in heart rate, strong negative chronotropic, and negative ionotropic effects at rats' right atrium and left atrium respectively (Hoe et al, 2011; Kaur et al, 2012; Abrika et al, 2013). …”

“…Vasocontraction caused by phenylephrine, calcium and potassium chloride was shown to be antagonized by G. procumbens extracts. This was probably due to the blocking of receptor-operated and/or voltage dependent calcium channels as well as opening of potassium channel (Hoe et al, 2011; Ng et al, 2013). Therefore, G. procumbens potentially serves as an antihypertensive agent with cardioprotective activity due to its ability to target various mechanisms including the renin-angiotensin system and calcium influx which are crucial players in the pathophysiology of hypertensive conditions.…”

OPTIMIZATION OF CHLOROPHYLL EXTRACTION FROM Gynura procumbens

“…For instance, Rosidah et al [10] maintained that the ethanolic extract of G. procumbens showed anti-hyperglycaemic and anti-hyperlipidaemic activities in diabetic rats [5,9,11,12]. Furthermore, Gynura procumbens has been reported to possess anti-herpes simplex virus, antihyperglycemic, anti-hyperlipidemic [13], anti-hypertensive effects [8], anti-hyperlipidemic [12,13], anti-sterility, anti-oxidative capabilities, and it has been found to be useful for prevention of rheumatism [5 -7,9,12,13]. In addition, ethanol and methanol extracts from the leaves of Gynura procumbens showed anti-diabetic effects in streptozotocin (STZ)-induced diabetic rats [12].…”

Gynura procumbens Improved Fertility of Diabetic Rats: Preliminary Study of Sperm Proteomic

“…One alternative is the herb Gynura procumbens (GP). It is a medicinal plant of the Asteraceae family, known for its beneficial therapeutics effects, such as treating fever, rashes, hypertension, and diabetes mellitus [8]. This evergreen shrub grows extensively in Southeast Asia and is locally known in Malaysia as Sambung Nyawa .…”