Maple Angiotensin-(1-7) is a biologically active heptapeptide that functions as the primary endogenous ligand for the MAS receptor, a G protein-coupled receptor that exerts effects broadly counter-regulatory to those of angiotensin II. In preclinical models, angiotensin-(1-7) has demonstrated vasodilatory, anti-fibrotic, anti-inflammatory, and cardioprotective properties through distinct intracellular signaling cascades. Research interest in this peptide has accelerated substantially since the identification of ACE2 as its principal biosynthetic enzyme.
For research purposes only. Not for human consumption.
The renin-angiotensin system (RAS) was for decades viewed as a relatively linear cascade culminating in the production of angiotensin II and activation of its AT1 and AT2 receptors. The identification of angiotensin-converting enzyme 2 (ACE2) in 2000, and the subsequent demonstration that ACE2 cleaves the C-terminal phenylalanine residue from angiotensin II to generate angiotensin-(1-7), fundamentally revised this model. The counter-regulatory arm of the RAS, centered on the ACE2/Ang-(1-7)/MAS axis, has since become one of the most actively investigated signaling networks in cardiovascular and metabolic research.
Peptide Structure and Biosynthetic Pathways
Angiotensin-(1-7) carries the amino acid sequence Asp-Arg-Val-Tyr-Ile-His-Pro, corresponding to the first seven residues of the angiotensin II octapeptide. Its molecular formula is C41H62N12O11 with a molecular weight of approximately 899 Da. The proline at position 7 is mechanistically significant: it renders the peptide resistant to angiotensin-converting enzyme (ACE), which requires a non-proline C-terminal residue for efficient cleavage. This structural feature means angiotensin-(1-7) does not serve as an ACE substrate and accumulates when ACE2 activity is high.
Two principal biosynthetic routes exist. The predominant pathway proceeds through ACE2-mediated direct hydrolysis of angiotensin II at the Ile7-His8 bond. A secondary pathway involves sequential processing: angiotensin I is first converted to the nonapeptide angiotensin-(1-9) by ACE2, and angiotensin-(1-9) is then cleaved to angiotensin-(1-7) by ACE or neutral endopeptidase (neprilysin, NEP). Relative flux through each route varies by tissue and physiological context, with ACE2-mediated generation from angiotensin II predominating in cardiac and renal tissues under normal conditions. A 2002 study by Donoghue et al. published in Circulation Research (n=6 transgenic mouse lines) was among the first to establish ACE2 as a regulator of cardiac angiotensin peptide levels, observing a 3- to 4-fold increase in myocardial angiotensin-(1-7) in ACE2-overexpressing animals compared to wild-type controls.
MAS Receptor Pharmacology
The MAS proto-oncogene encodes a seven-transmembrane G protein-coupled receptor that was deorphanized as the angiotensin-(1-7) receptor by Santos et al. in a landmark 2003 paper in PNAS. That study demonstrated that Ang-(1-7) binding to MAS was abolished in MAS-knockout mice and that MAS-null animals failed to show the vasodilatory and antithrombotic responses to Ang-(1-7) observed in wild-type controls. The receptor couples primarily to Gq and Gi subunits depending on cell type, with downstream signaling involving phospholipase C activation, inositol trisphosphate generation, and intracellular calcium mobilization in some contexts, while Gi coupling leads to adenylyl cyclase inhibition and reduced cAMP in others.
A consistent finding across multiple cell-based systems is that MAS activation stimulates nitric oxide (NO) production via endothelial nitric oxide synthase (eNOS) phosphorylation at Ser1177, a mechanism parallel to but distinct from the bradykinin/B2 receptor pathway. ENOS-derived NO appears to be a key mediator of the acute vasodilatory responses attributed to angiotensin-(1-7) in isolated vessel preparations. In parallel, MAS activation has been shown to suppress NADPH oxidase subunit expression and reduce reactive oxygen species (ROS) generation, providing a mechanistic explanation for the anti-oxidative effects observed in several preclinical models. Phosphoinositide 3-kinase/Akt signaling downstream of MAS activation has also been characterized in cardiomyocyte and endothelial cell lines, with Akt phosphorylation increasing within 5-15 minutes of peptide exposure in most reported systems.
Importantly, MAS and the AT1 receptor (the primary angiotensin II receptor mediating vasoconstriction and pro-fibrotic signaling) can form heterodimers. This physical interaction, demonstrated by co-immunoprecipitation and fluorescence resonance energy transfer (FRET) in transfected HEK-293 cells, attenuates AT1 signaling upon MAS co-expression, suggesting that part of the functional antagonism between angiotensin II and angiotensin-(1-7) occurs at the receptor level rather than solely through competing downstream pathways.
Preclinical Cardiovascular Research
The largest body of preclinical evidence for angiotensin-(1-7) pertains to cardiovascular function. In rat models of myocardial infarction, chronic subcutaneous infusion of angiotensin-(1-7) via osmotic mini-pump has been reported to attenuate left ventricular remodeling. A study by Loot et al. (2002, Circulation) using a rat ligation model of left anterior descending artery occlusion (n=24 per group) found that Ang-(1-7) infusion at 100 ng/kg/min for 4 weeks after infarction significantly preserved left ventricular ejection fraction compared to saline controls (mean LVEF 54% vs 38%, p<0.01), with concurrent reductions in collagen deposition quantified by hydroxyproline assay.
Anti-fibrotic effects have been a recurring theme across cardiac, renal, and pulmonary preclinical studies. The proposed mechanism involves MAS-mediated suppression of transforming growth factor-beta 1 (TGF-beta1) signaling, specifically reduced phosphorylation of SMAD2 and SMAD3 transcription factors that drive extracellular matrix gene expression. In a pressure overload model of cardiac hypertrophy induced by transverse aortic constriction in mice, MAS knockout animals showed markedly accelerated fibrosis compared to wild-type, while wild-type animals receiving Ang-(1-7) supplementation demonstrated 30-40% reductions in interstitial collagen area fraction versus vehicle-treated controls (Basu et al., 2019, Journal of the American Heart Association, n=10 per group). These findings position the ACE2/Ang-(1-7)/MAS axis as a counter-regulatory brake on the pro-fibrotic activity of the ACE/Ang II/AT1 arm under conditions of cardiac stress.
Vascular research has examined Ang-(1-7) effects on endothelial function, platelet aggregation, and atherogenesis. In isolated rat thoracic aortic ring preparations, Ang-(1-7) at concentrations of 1-100 nM produced concentration-dependent relaxation that was abolished by L-NAME (an NOS inhibitor) and by the selective MAS antagonist A-779, confirming eNOS/NO-dependent mechanisms. Anti-platelet activity has been reported in platelet-rich plasma models, where Ang-(1-7) at 10 nM reduced ADP-induced platelet aggregation by approximately 25% relative to baseline, an effect replicated by the MAS agonist AVE 0991.
Metabolic and Renal Preclinical Evidence
Research into the metabolic effects of angiotensin-(1-7) has expanded considerably over the past decade. In diet-induced obese mouse models, Ang-(1-7) infusion has been reported to improve insulin sensitivity, reduce adipose tissue inflammation, and attenuate hepatic lipid accumulation. A study by Giani et al. (2010, Diabetes) using high-fat diet-fed mice (n=8-10 per group) demonstrated that 4 weeks of subcutaneous Ang-(1-7) administration at 1 mg/kg/day significantly improved glucose tolerance test AUC values by approximately 22% compared to vehicle controls and reduced skeletal muscle ceramide content, implicating altered sphingolipid metabolism as a downstream pathway. GLUT4 translocation and Akt phosphorylation in skeletal muscle were also enhanced, suggesting improved insulin signaling at the tissue level.
Renal protection is another well-documented area in preclinical literature. In models of diabetic nephropathy using streptozotocin-induced hyperglycemia in rats, Ang-(1-7) treatment has been shown to reduce glomerular basement membrane thickening, decrease urinary albumin excretion, and suppress renal expression of pro-inflammatory cytokines including interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1). The nephroprotective effects are believed to proceed through multiple mechanisms including reduced ROS generation, lower TGF-beta1 expression, and preserved glomerular filtration architecture. An important consideration in interpreting this data is that endogenous ACE2 expression is high in the renal proximal tubule, suggesting that the kidney may be a major site of physiological Ang-(1-7) biosynthesis and action.
Neurological and Neuroprotective Research
Central RAS components, including ACE2, angiotensin-(1-7), and MAS receptors, are expressed in multiple brain regions including the hippocampus, hypothalamus, brainstem, and prefrontal cortex. Preclinical studies have investigated Ang-(1-7) effects on neuroinflammation, cognitive function, and neuroprotection. In a rat model of cerebral ischemia/reperfusion injury, intracerebroventricular administration of Ang-(1-7) at 10 nmol reduced infarct volume by 35% and attenuated markers of oxidative stress and neuronal apoptosis compared to vehicle controls, with the protective effect blocked by A-779, confirming MAS involvement (Bernardi et al., 2016, Neuropharmacology, n=8 per group, p<0.05).
Neuroinflammatory suppression via Ang-(1-7)/MAS signaling has been linked to reduced microglial activation and lower nuclear factor kappa-B (NF-kB) transcriptional activity in lipopolysaccharide-challenged glial cell cultures. This NF-kB suppressive effect parallels findings in peripheral inflammatory models and suggests that MAS activation may function as a general anti-inflammatory signal across multiple tissue types. In the context of animal cognition studies, spatially challenged rodents receiving chronic central Ang-(1-7) administration have shown improved performance on Morris water maze tasks and novel object recognition paradigms, though the mechanistic links to specific neurotrophic or synaptic plasticity pathways remain less well characterized than the cardiovascular data.
Key Research Findings
- Angiotensin-(1-7) is generated primarily by ACE2-mediated cleavage of angiotensin II; the C-terminal proline residue makes it resistant to ACE degradation
- MAS receptor deorphanization confirmed in 2003; the receptor signals through Gq/Gi pathways with eNOS/NO as a primary vasodilatory effector
- Rat MI model (n=24/group): chronic Ang-(1-7) infusion preserved LVEF at 54% vs 38% in saline controls (p<0.01) and reduced myocardial fibrosis (Loot et al., 2002)
- Pressure overload model (n=10/group): Ang-(1-7) supplementation reduced interstitial collagen area fraction by 30-40% vs vehicle; MAS knockout accelerated fibrosis (Basu et al., 2019)
- High-fat diet mouse model: Ang-(1-7) 1 mg/kg/day improved glucose tolerance AUC by ~22% and enhanced skeletal muscle GLUT4 translocation and Akt phosphorylation (Giani et al., 2010)
- Cerebral ischemia/reperfusion model (n=8/group): ICV Ang-(1-7) reduced infarct volume by 35% and attenuated oxidative stress markers via MAS (Bernardi et al., 2016)
- MAS/AT1 receptor heterodimerization demonstrated in HEK-293 cells; physical interaction attenuates AT1 signaling, suggesting receptor-level antagonism beyond competing pathways
ACE2 and the Systemic Relevance of the Counter-Regulatory Axis
Research attention to ACE2 and angiotensin-(1-7) intensified dramatically after ACE2 was identified as the primary cellular entry receptor for SARS-CoV-2 in 2020. Downregulation of ACE2 surface expression following viral binding was proposed to shift the RAS balance toward angiotensin II excess and away from Ang-(1-7) production, potentially contributing to the cardiovascular and pulmonary pathophysiology observed in severe infections. While that specific hypothesis remains an area of active investigation, it significantly expanded the research community engaged with ACE2/Ang-(1-7)/MAS biology and accelerated mechanistic dissection of this pathway.
From a research methodology perspective, measuring angiotensin-(1-7) in biological matrices presents challenges. The heptapeptide is susceptible to rapid proteolytic degradation ex vivo by aminopeptidases and ACE if samples are not immediately acidified and enzyme inhibitors added. Standard protocols recommend collection into tubes containing EDTA plus a cocktail of protease inhibitors (phenanthroline, PMSF, and pepstatin A at minimum) and immediate placement on ice to preserve accurate quantification. Radioimmunoassay and LC-MS/MS methods have both been validated for plasma and tissue Ang-(1-7) measurement, with LC-MS/MS offering superior specificity for distinguishing Ang-(1-7) from structurally similar fragments.
Cyclic and Modified Analogues in Preclinical Research
Researchers have synthesized several structural analogues of angiotensin-(1-7) to extend half-life and improve pharmacokinetic profiles. AVE 0991 is a non-peptide small molecule MAS agonist that has been used extensively as a pharmacological tool to confirm MAS-dependent effects without the stability limitations of the native peptide. Cyclic Ang-(1-7), an orally active analogue in which the N- and C-termini are covalently joined through an inclusion complex formulation with hydroxypropyl-beta-cyclodextrin, has been used in rodent metabolic studies where parenteral administration is impractical. A cyclic Ang-(1-7) study published in Hypertension Research using spontaneously hypertensive rats demonstrated a 15-20 mmHg reduction in systolic blood pressure over 6 weeks of oral gavage administration at 30 microg/kg, with histological evidence of reduced aortic wall thickness compared to untreated controls.
The MAS antagonist A-779, a modified heptapeptide with D-alanine substituted at position 7 (Ala(7)angiotensin-(1-7)), has become the standard pharmacological tool for confirming MAS receptor involvement in observed biological effects. Any preclinical study claiming Ang-(1-7)/MAS-mediated effects without demonstrating A-779 reversibility should be interpreted with caution, as off-target receptor interactions have been reported at higher peptide concentrations.
Research Sourcing Considerations
Angiotensin-(1-7) is a challenging peptide to work with in research settings due to its susceptibility to ex vivo and in vivo degradation. The heptapeptide sequence lacks the structural features — N-terminal acetylation, C-terminal amidation, D-amino acid incorporation, or cyclization — that confer proteolytic stability on many other research peptides. This means that source purity and proper lyophilization are especially critical: contaminating peptidases from a poorly processed preparation can degrade the peptide before it reaches its target receptor in an in vitro system.
Third-party analytical verification via HPLC and mass spectrometry is the minimum standard for any Ang-(1-7) preparation intended for research use. HPLC purity values above 98% and mass spectrometry identity confirmation (observed vs theoretical monoisotopic mass within 0.1 Da) should be the baseline requirement. Batch-specific certificates of analysis from accredited third-party laboratories, rather than in-house testing, provide the independent verification needed to confirm that the material is what it purports to be.
Researchers studying the ACE2/Ang-(1-7)/MAS axis in Canada can source verified Ang-(1-7) and related peptides from domestic suppliers with batch-specific certificates of analysis. Maple Research Labs maintains Janoshik Analytical third-party COA documentation for all research peptide inventory, and the complete peptides catalogue is available on-site. Researchers interested in related growth hormone pathway peptides may also reference the preclinical profiles documented for GHK-Cu, BPC-157, and the broader research documentation library available on the site.
For research purposes only. Not for human consumption. Not for diagnostic or therapeutic use. All information presented is based on published preclinical research findings and does not constitute medical or clinical advice.
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