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Anti-hypertensive and angiotensin-converting enzyme inhibitory effects of Radix Astragali and its bioactive peptide AM-1

Authors Wu, Jing-Shan; Li, Jung-Miao; Lo, Hsin-Yi; Hsiang, Chien-Yun; Ho, Tin-Yun

Journal JOURNAL OF ETHNOPHARMACOLOGY , MAY 23 2020,:254

DOI 10.1016/j.jep.2020.112724 PubMed 32119952

Abstract Ethnopharmacological relevance: Hypertension is one of the common chronic health problems in the world. Astragalus membranaceus root (AM), also known as Huangqi, is a popular medicinal herb traditionally used to reinforce vital energy and modulate hypertension.Aim of the study: This study was to reveal the anti-hypertensive activities and mechanisms of AM in spontaneously hypertensive rats (SHRs). Moreover, the presence of bioactive components in AM was further identified.Materials and methods: We analyzed the effects of aqueous extract of AM (AME) on the regulation of blood pressure and angiotensin converting enzyme (ACE), the major target of anti-hypertensive drugs. Proteomic, bioinformatics, and docking analyses were performed to identify the anti-hypertensive bioactive peptides in AME.Results: Our data showed that AME inhibited ACE activities in a dose-dependent manner, with an IC50 of 1.85 +/- 0.01 mu g/ml. In comparison with mock, oral administration of AME reduced systolic blood pressure (SBP) levels in SHR5, and the level of SBP was decreased by 22.33 +/- 3.61 mmHg at 200 mg/kg AME. Proteomic analysis identified that an abundant 152-amino-acid putative protein kinase fragment accounted for approximately 11.7% of protein spots in AME. AM-1 (LVPPHA), a gastrointestinal enzyme-resistant peptide cleaved from putative protein kinase fragment, inhibited ACE activities, with an IC50 value of 414.88 +/- 41.88 mu M. Moreover, oral administration of AM-1 significantly decreased SBP levels by 42 +/- 2.65 mmHg at 10 mu mol/kg. Docking analysis further showed that AM-1 docked into the active site channel of ACE and interacted with Ala354 in the active site pocket of ACE.Conclusions: the ACE inhibitory effect of AM and the presence of ACE inhibitory phytopeptide in AME supported the ethnomedical use of AM on hypertension.

Species covered 黄芪 Astragalus membranaceus