The effects of a watery extract of Agathosma on the development of hypertension

[摘要] ENGLISH ABSTRACT: Introduction: Obesity is a major risk factor for non-communicable diseases (NCD), a collective term given to type 2 diabetes (T2D), hypertension (HTN) and cardiovascular disease (CVD). Globally, NCDs are the leading cause of death. In recognition of this, untested remedies are flooding the market. Buchu water is one of these herbal remedies advertised as having antihypertensive properties. This water is a by-product of the extraction of the oil from the leaves of Agathosma. Buchu water is already freely available to the public.Aim: The aims of the present study were to test the effect of ingestion of Buchu water on i) the blood pressure (BP) of diet induced hypertensive as well as normotensive rats when given as pre-treatment; ii) HTN in rats when used as treatment; iii) endothelial function using aortic rings from control and hypertensive rats; iv) the expression and/or activation of signalling proteins involved in NO production in the endothelium (PKB/Akt, AMPK, eNOS); v) insulin sensitizing effects in cardiomyocytes prepared from insulin resistant rats to determine possible cardiovascular effects.Methodology: We utilized rat models of obesity induced HTN and diet-induced obesity (DIO). Male Wistar rats were rendered i) hypertensive by feeding a high fat diet (HFD) and ii) insulin resistant after being placed on a high caloric diet for 16 weeks. Half the animals were placed on Buchu water treatment (26% (v/v) Buchu water) for a period of 16 weeks. Blood pressure, urine output, water and food consumption were measured. The animals on the HFD were sacrificed and intraperitoneal fat weight determined, aortas used in aortic ring studies and blood collected for biochemical analyses. Animals in the DIO model were sacrificed after 16 weeks and cardiomyocytes prepared to determine insulin sensitivity.Results: The HFD caused increases in body weight, visceral adiposity and blood pressure. Chronic Buchu water treatment i) reduced body weight gain and visceral adiposity in the HFD animals; ii) affected leptin levels and components of the renin-angiotensin-aldosterone system (RAAS); iii) it both prevented the development of HTN when given in conjunction with the HFD and restored BP when used as treatment while having no effect on the BP of the control animals; iv) it had no effect on endothelial function nor did it activate any signalling proteins involved in the synthesis of NO in the endothelium that may be responsible for vasodilation in the arteries; v) it elevated basal myocardial glucose uptake which can be cardioprotective.Conclusion: Our present study was novel and demonstrated that Buchu water treatment exhibits similar properties to that of antihypertensive medication known as angiotensin-converting enzyme inhibitors. It acts on the whole body RAAS in a similar manner reducing both BP and weight gain. It also reduced metabolic aberrations (HTN, leptin, aldosterone) seen in animals on a HFD, partly through visceral fat remodelling. In addition Buchu water also elicits some cardioprotective properties. Thus we conclude that Buchu water is an alternative, cost effective and ready available means to treat HTN and is beneficial to one's health.

[发布机构] Stellenbosch University