1936 Scholars Journal of Applied Medical Sciences (SJAMS) ISSN 2320-6691 (Online) Sch. J. App. Med. Sci., 2015; 3(5B):1936-1940 ISSN 2347-954X (Print) ©Scholars Academic and Scientific Publisher (An International Publisher for Academic and Scientific Resources) www.saspublisher.com Research Article Angiotensin Converting Enzyme (ACE): Inhibition of Sheep Kidney and Lung ACE In vitro by Rauwolfia serpentina and Allium sativum Ranjini.H.S*, E.G. Padmanabha Udupa, Jenu Maria Thomas Department of Biochemistry, Kasturba Medical College, Manipal University, Manipal, Udupi, Karnataka-576104, India. *Corresponding author Mrs. Ranjini. H.S Abstract: Regulation of blood pressure is one of the important functions of Angiotensin I converting enzyme (ACE, EC. 3.4.15.1). ACE is widely distributed and appears to have several important physiological functions including its major role in blood pressure regulation. In the treatment of congestive heart failure, coronary artery disease, diabetic nephropathy etc.ACE inhibitors are used. The current study was aimed to find the effect of aqueous extracts of Rauwolfia serpentina leaves and Allium sativum cloves on sheep kidney and lung ACE. The method is Hippuryl-Histidyl-Leucine (HHL) as substrate, sheep kidney and lung ACE activity was measured and the hippuric acid released was measured spectrophotometrically at 228 nm. Aqueous extracts of Rauwolfia serpentina leaves and Allium sativum cloves were used in the enzyme assay to determine their effect on kidney and lung ACE. The results of linearity of ACE activity in kidney and lung was established with HHL as substrate for the incubation period of 30 min at 37°C. ACE activity was confirmed with specific ACE inhibitors like Captopril, Lisinopril, and Enalapril.25 μl of R. serpentina leaf extract reduced ACE activity by 68% and 57% in kidney and lung respectively. 25 μl of A. sativum cloves extract reduced ACE activity by 50% and 60% in kidney and lung respectively. In conclusion, use of medicinal plants is gaining considerable significance as a drug to treat hypertension. The significant inhibition of kidney and lung ACE activity by these two plant products suggests their possible role in controlling blood pressure as a mode of treatment for cardiovascular diseases, when used as supplement medicine. Keywords: Angiotensin Converting Enzyme (ACE), Blood pressure, ACE Inhibitors, Rauwolfia serpentina, Allium sativum. INTRODUCTION Angiotensin Converting Enzyme (EC-3.4.15.1) is a zinc metalopeptidase that hydrolyses carboxyl terminal dipeptide of many oligopeptide substrates, inclusive of angiotensin I (Ang I) and bradykinin [1]. This enzyme is most commonly related with the control of blood pressure [2, 3]. The octapeptide Angiotensin II is one of the most potent vasoconstrictors [4]. ACE is widely distributed in various body tissues, in which predominantly present in kidney epithelium [5, 6]. In Renin – Angiotensin – Aldosterone system (RAS), ACE and angiotensin II are biologically active components of RAS. These components play a key role in maintenance of blood pressure [7, 8]. ACE inhibitors competitively inhibit the angiotensin converting enzyme which is used to treat hypertension, cardiac failure, diabetic nephropathy, acute myocardial infarction [9]. Hypertension is a word used to denote chronic disease i.e., high blood pressure due to the exertion of force of blood against the walls of arteries but sustained hypertension over time is a major risk factor for cerebro vascular, coronary artery and renal diseases. It is considered to be one of the major morbidity and mortality factors due to its association with different organs and its severe consequences including myocardial infarctions, strokes and heart failure [10]. Excessive use of antihypertensive drugs can cause certain side effects like cough, hyperkalemia, headache, dizziness, fatigue, nausea, hypotension and renal impairment was been reported [11]. In such cases, use of herbal drugs as therapeutic agents is helped to prevent hypertension and there will be enhancement of metabolic health [12]. Widely used ACE inhibitors include Captopril, Lisinopril and Enalapril, however show certain side effects as mentioned above. A large number of natural inhibitors are well known for their hypotensive action. Some of these include Gooseberry, Gokshura, Rose petal jam, Turmeric, Ginger, Cinnamon, and Cardamom etc [13]. Allium sativum commanly known as Garlic, is a member of the Alliaceae family, may be one of the known medicinal plant, used since ancient time to cure