Structure-Based Identification of Small-Molecule Angiotensin-Converting Enzyme 2 Activators as Novel Antihypertensive Agents

Abstract

Abstract-Angiotensin-converting enzyme 2 (ACE2) is a key renin-angiotensin system enzyme involved in balancing the adverse effects of angiotensin II on the cardiovascular system, and its overexpression by gene transfer is beneficial in cardiovascular disease. Therefore, our objectives were 2-fold: to identify compounds that enhance ACE2 activity using a novel conformation-based rational drug discovery strategy and to evaluate whether such compounds reverse hypertension-induced pathophysiologies. We used a unique virtual screening approach. In vitro assays revealed 2 compounds (a xanthenone and resorcinolnaphthalein) that enhanced ACE2 activity in a dose-dependent manner. Acute in vivo administration of the xanthenone resulted in a dose-dependent transient and robust decrease in blood pressure (at 10 mg/kg, spontaneously hypertensive rats decreased 71Ϯ9 mm Hg and Wistar-Kyoto rats decreased 21Ϯ8 mm Hg; PϽ0.05). Chronic infusion of the xanthenone (120 g/day) resulted in a modest decrease in the spontaneously hypertensive rat blood pressure (17 mm Hg; 2-way ANOVA; PϽ0.05), whereas it had no effect in Wistar-Kyoto rats. Strikingly, the decrease in blood pressure was also associated with improvements in cardiac function and reversal of myocardial, perivascular, and renal fibrosis in the spontaneously hypertensive rats. We conclude that structure-based screening can help identify compounds that activate ACE2, decrease blood pressure, and reverse tissue remodeling. Administration of ACE2 activators may be a valid strategy for antihypertensive therapy. T he recent discovery of angiotensin-converting enzyme (ACE) 2 1,2 and its role in the control of renin-angiotensin system activity is relevant as a potentially valuable target for antihypertensive therapies. ACE2 is a zinc-dependent monocarboxypeptidase that plays a central role in balancing vasoconstrictor and proliferative actions of angiotensin (Ang) II with the vasodilatory and antiproliferative effects of Ang-(1-7). 3 Altered expression of this enzyme is associated with cardiac, vascular, and renal dysfunctions. 4,5 In addition, blocking the synthesis of Ang II by Ang-converting enzyme inhibitors or its actions by Ang II receptor blockers has been shown to increase cardiac ACE2 expression. 6,7 Furthermore, overexpression of ACE2 by gene transfer 8 protects the heart from hypertension-induced cardiac remodeling. It was demonstrated that ACE2 is an effective enzyme in attenuating fibrosis and structural remodeling. 8 Based on these observations, we hypothesize that pharmacological enhancement of ACE2 activity would have beneficial effects on the cardiovascular system and would protect against hypertensioninduced pathophysiology. Therefore, our objectives in this study were 2-fold: to identify compounds that enhance ACE2 activity and to determine the effects of ACE2 enhancers on hypertension and associated pathophysiology. Materials and MethodsSynthesis of xanthenone, measurement of ACE2 activity, histological analysis, and statistical analysis are described in the sup...

Angiotensin-converting enzyme 2, angiotensin-(1–7) and Mas: new players of the renin–angiotensin system

“…Accordingly, Ang-(1-7) elicits relaxation in several vascular beds (see Santos et al (2000) for review). In line with these observations, activation of endogenous ACE2 provokes reductions in arterial blood pressure of normal and hypertensive rats (Hernandez Prada et al 2008). However, contradictory effects of Ang-(1-7) have been reported in human vessels.…”

“…Importantly, deletion of Mas produced impairment of cardiac function associated with a significant increase in collagen type I, III and fibronectin content in the heart (Santos et al 2006, Gava et al 2012. On the other hand, ACE2 activation using XNT decreased cardiac fibrosis induced by high blood pressure through a mechanism involving reduction of ERK1/2 expression (Hernandez Prada et al 2008. Altogether, these findings indicate that the ACE2/Ang-(1-7)/Mas axis is a functional cardioprotective arm of the RAS (Fig.…”

Evidence for Angiotensin-converting Enzyme 2 as a Therapeutic Target for the Prevention of Pulmonary Hypertension

“…Collectively, these observations led us to propose that activation of endogenous ACE2 could have a protective effect against PH. We have used the monocrotaline (MCT) rat model of PH and a recently identified ACE2 activator (18) to provide evidence in support of this hypothesis. Administration of MCT, a plant-derived toxin, causes pulmonary endothelial cell injury, infiltration of mononuclear cells, and muscularization of pulmonary arteries resulting in PH (19).…”

Peptidases and the Renin-Angiotensin System: The Alternative Angiotensin-(1-7) Cascade

“…In turn, overexpression of ACE2 or administration of the soluble form of the peptidase, which retains full enzymatic activity, attenuates the Ang II-dependent increase in blood pressure and indices of target organ injury [77][78][79][80][81][82][83][84][85]. In regard to the benefits of an activated ACE2 pathway, several compounds have been identified that may act as allosteric activators of ACE2 including xanthenone (XNT) and diminazene aceturate (DIZE) to promote a higher ratio of Ang-(1-7) to Ang II [86]. Chronic treatment with DIZE ameliorated the extent of pulmonary hypertensin and fibrosis, renal tissue injury, and myocardial infarction consistent with enhanced levels of Ang-(1-7) and a reduction in Ang II [84,[87][88][89][90].…”