Jundishapur J Nat Pharm Prod. 2015 May; 10(2): e17255. DOI: 10.17795/jjnpp-17255 Published online 2015 May 20. Research Article Angiotensin I Converting Enzyme Inhibitory Activities of Hydroalcoholic Extracts of Nardostachys jatamansi , Prangos ferulacea and Marrubium vulgare Foroogh Namjoyan 1 ; Mohammad Ebrahim Azemi 2,* ; Elahe Abdollahi 3 ; Niloufar Goudarzi 3 ; Khadijeh Nikan 3 1 Department of Pharmacognosy, Marine Pharmaceutical Research, Ahvaz Jundishapur University of Medical Sciences, IR Iran 2 Department of Pharmacognosy, Medicinal Herbs and Natural Products Research Center, Ahvaz Jundishapur University of Medical Sciences, IR Iran 3 School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran *Corresponding author: Mohammad Ebrahim Azemi, Department of Pharmacognosy, Medicinal Herbs and Natural Products Research Center, Ahvaz Jundishapur University of Medical Sciences, IR Iran. Tel: +98-6133738380, Fax: +98-6133738381, E-mail: fazemi@yahoo.com Received: December 29, 2013; Revised: April 10, 2015; Accepted: April 18, 2015 Background: Hypertension is one of the major risk factors for cardiovascular diseases. Lifestyle changes, physical exercise and intake of healthy diet are some common issues associated with reducing the risk of hypertension. There are several classes of pharmacological agents used in the treatment of hypertension. Angiotensin I converting enzyme (ACE) cleaves angiotensin I to angiotensin II and inactivates bradykinin. The synthetic ACE inhibitors are used widely to treat cardiovascular disorders. They may cause many adverse efects, including dry cough, allergic reactions and skin rashes, so investigation for new natural sources could be helpful. Objectives: The aim of the present study was to evaluate angiotensin I converting enzyme inhibitory activities of hydroalcoholic extracts of Nardostachys jatamansi, Prangos ferulacea and Marrubium vulgare. Materials and Methods: ACE inhibitory activity was measured according to the methods of Cushman & Cheung with some modifcations. Captopril was used as positive control. Results: The ACE inhibitory activities of hydroalcoholic extracts were as follows; M. vulgare > N. Jatamansi > P. ferulacea. The least IC 50 value was related to the hydroalcoholic extract of M. vulgare (0.791 mg/mL). The IC 50 values of N. Jatamansi and P. ferulacea were 2.147 and 4.057 mg/mL, respectively. Conclusions: The results supported the traditional antihypertensive use of these plants, especially M. vulgare, by inhibitory efects on ACE enzyme. Keywords: Angiotensin-Converting Enzyme Inhibitors; Hypertension; Nardostachys jatamansi; Marrubium vulgare Copyright © 2015, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the mate- rial just in noncommercial usages, provided the original work is properly cited. 1. Background Hypertension is an important public health challenge because of its high prevalence. Its prevalence is esti- mated to be 29% until 2025 (1). High blood pressure is a main risk factor for cardiovascular disease. It is known as a major cause of coronary heart disease, cerebrovascular diseases, peripheral vascular disease and heart failure (2). There are diferent drug classes for hypertension treat- ment. The inhibitors of angiotensin-converting enzyme (ACE) are one of the most important ones. ACE is a key component in the renin angiotensin aldosterone system (RAAS), which regulates blood pressure (3). However, most patients require two or more drugs to control high blood pressure (4). ACE is a Nardostachys jatamansi with a zinc ion. The en- zyme has a less substrate specifcity in vitro. ACE consists of a single polypeptide chain containing two domains of N and C. There are two catalytic sites in each of these domains. ACE plays an important role in the regulation of blood pressure, by acting on the renin–angiotensin system (RAS) and the kallikrein-kinin system (KKS) (5). ACE converts angiotensin I to angiotensin II, which is a potent vasoconstrictor and stimulates adrenal cortex to secret aldosterone, leading to retention of sodium ions. In addition, ACE is responsible for deactivation of bra- dykinin as a vasodilator substance. Because of the dual efects of ACE in the maintenance of blood pressure and fuid and electrolyte homeostasis, inhibition of ACE has been verifed in the treatment of hypertension and congestive heart failure status (6). Synthetic ACE inhibi- tors such as captopril and enalapril have some adverse efects such as cough, allergic reactions, taste disorders and skin rashes (7, 8). There are incentives for further researches to fnd cheaper and more efective drugs, including plants. Cur- rently, natural products and their derivatives include more than 50% of all medicines in clinical use (9). The plants have formed the basis of the traditional medicine introduced from thousands of years ago. Even in modern times, plant-based medications continue to play a major role in health care systems. The World Health Organiza-