Kalanchoe pinnata aqueous extract possesses vasorelaxant activities contributing to its antihypertensive effects in a model of rat-induced hypertension and myocardial infarction

Abstract

Background and aim: Kalanchoe pinnata is an herbal medicine used in Cameroon against cardiovascular diseases. Hypertension and myocardial infarction are among key risk factors of cardiovascular diseases. This research aimed to investigate antihypertensive effect of Kalanchoe pinnata in salt loaded myocardial infarcted rats and possible mechanism of action on vascular smooth muscle. Experimental procedure: Thirty rats were equally distributed into six groups: neutral, negative and positive controls and three test groups (administered extract 50, 100 and 150 mg/kg). Hypertension was induced by salt loading (18%) meanwhile myocardial infarction was by injection of 100mg/kg isoproterenol. The 28 day-In vivo treatment was followed by evaluation of systolic and diastolic arterial pressures, and troponin level. Ten untreated rats were used for the in vitro study, to investigate vasorelaxant mechanism. Results and conclusion: Treated rats showed significant increase of systolic (46.3%) and diastolic (73.5%) pressures. Troponine level increased by 400%. Extract at highest dose (150mg/kg) reduced these increases by 29.1%, 41.3% and 52% respectively. Extract (1.5mg/mL) caused a vasorelaxation (62.79%) in the presence of endothelium. Endothelium removal did not significantly modify the effect of the extract in KCl pre-contracted rings. In the same way, in rings pre-contracted with phenylephrine, the extract (1.5mg/mL) did not significantly modify the relaxation induced by sodium nitroprusside. However, methylene blue, a NO-cGMP inhibitor significantly reduced (P<0.001) the vasorelaxant effect of K. pinnata extract (1.5mg/mL). This indicated that the extract exhibits its antihypertensive activity by relaxing vascular smooth muscle, partially through endothelium mediators.

Kalanchoe pinnata aqueous extract efficacy against myocardial infarction and effects on three cardio-metabolic biomarkers in NaCl-overloaded rat

“…Wistar rats were raised in the Animal House of the Department of Animal Biology and Conservation, University of Buea, under the same conditions previously described by Tom et al [17]. A total of 30 adult rats aged 3-4 months, weighting 155-190g, were randomly distributed, as previously [17], into five groups of six animals each (Table 1). The dose of 100mg/kg/day of K. pinnata aqueous extract has been considered, from our previous findings [14], as the "therapeutic dose" [17].…”

“…A total of 30 adult rats aged 3-4 months, weighting 155-190g, were randomly distributed, as previously [17], into five groups of six animals each (Table 1). The dose of 100mg/kg/day of K. pinnata aqueous extract has been considered, from our previous findings [14], as the "therapeutic dose" [17].…”

“…Fresh leaves of Kalanchoe pinnata were harvested in Buea (Cameroon), in April 2018 and authenticated (at Southwestern Cameroon Herbarium, Limbe, Voucher Number SCA 2770). From 3kg of plant material, extraction was carried out as previously described [17], and 0.99% yields powder was obtained. The stock solution (1g/mL) was prepared [17] for subsequent experiments.…”

“…From 3kg of plant material, extraction was carried out as previously described [17], and 0.99% yields powder was obtained. The stock solution (1g/mL) was prepared [17] for subsequent experiments.…”

“…Previously, we demonstrated that in addition to being antihypertensive [13], the above extract could induce cardioprotection of the heart against MI in Isoproterenol (a beta-agonist)-treated normotensive rat [16]. We have recently demonstrated that the plant extract, when administered to concurrent salt overloaded and myocardial infarcted animal model, is still able to lower blood pressure, through vasodilation [17]. In the current research, we have investigated the effects of the aqueous extract in NaCloverloaded rat with concomitant Isoproterenol infarcted heart.…”