Research Article Phenolic Extract from Moringa oleifera Leaves Inhibits Key Enzymes Linked to Erectile Dysfunction and Oxidative Stress in Rats’ Penile Tissues Ganiyu Oboh, 1 Adedayo O. Ademiluyi, 1 Ayokunle O. Ademosun, 1 Tosin A. Olasehinde, 2 Sunday I. Oyeleye, 1 Aline A. Boligon, 3 and Margareth L. Athayde 3 1 Functional Foods and Nutraceuticals Unit, Department of Biochemistry, Federal University of Technology, PMB 704, Akure 340001, Nigeria 2 Nutrition and Toxicology Division, Food Technology Department, Federal Institute of Industrial Research, Oshodi, PMB 21023, Lagos 10001, Nigeria 3 Phytochemical Research Laboratory, Department of Industrial Pharmacy, Federal University of Santa Maria, Building 26, Room 1115, 97105-900 Santa Maria, RS, Brazil Correspondence should be addressed to Tosin A. Olasehinde; tosinolasehinde26@yahoo.com Received 28 July 2015; Accepted 9 September 2015 Academic Editor: Emanuel Strehler Copyright © 2015 Ganiyu Oboh et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. his study was designed to determine the antioxidant properties and inhibitory efects of extract from Moringa oleifera leaves on angiotensin-I-converting enzyme (ACE) and arginase activities in vitro. he extract was prepared and phenolic (total phenols and lavonoid) contents, radical (nitric oxide (NO), hydroxyl (OH)) scavenging abilities, and Fe 2+ -chelating ability were assessed. Characterization of the phenolic constituents was done via high performance liquid chromatography-diode array detection (HPLC- DAD) analysis. Furthermore, the efects of the extract on Fe 2+ -induced MDA production in rats’ penile tissue homogenate as well as its action on ACE and arginase activities were also determined. he extract scavenged NO ∗ , OH ∗ , chelated Fe 2+ , and inhibited MDA production in a dose-dependent pattern with IC 50 values of 1.36, 0.52, and 0.38 mg/mL and 194.23 g/mL, respectively. Gallic acid, chlorogenic acid, quercetin, and kaempferol were the most abundant phenolic compounds identiied in the leaf extract. he extract also inhibited ACE and arginase activities in a dose-dependent pattern and their IC 50 values were 303.03 and 159.59 g/mL, respectively. he phenolic contents, inhibition of ACE, arginase, and Fe 2+ -induced MDA production, and radical (OH ∗ , NO ∗ ) scavenging and Fe 2+ -chelating abilities could be some of the possible mechanisms by which M. oleifera leaves could be used in the treatment and/or management of erectile dysfunction. 1. Introduction Previous reports have revealed that erectile dysfunction (ED) is prevalent in over 150 million men all over the world and has been predicted to afect about 250 million men by 2025 [1]. Normal erectile function is stimulated through a series of actions involving the relaxation of cavernosal arteries and sinuses which leads to increase in blood low to the penis [2]. hese actions are mediated by nitric oxide via the activation of nitric oxide- (NO-) cyclic guanosine monophosphate (cGMP) dilator pathway and can be impaired by diferent factors thereby causing ED [2]. Increased arginase activity has been implicated in ED. Arginase is a metalloenzyme that converts arginine to urea and ornithine in a number of cells. here are also growing evidences that ED can be induced by high blood pressure via inveterate changes in blood pressure which can alter the low of blood in penile vessels [3]. Moreover, angiotensin II which is obtained from angiotensin I in a reaction catalysed by angiotensin-I-converting enzyme is a potent vasoconstrictor capable of inducing vascular hypertrophy and endothelial dysfunction via decrease in the release of NO [4]. Likewise, ACE deactivates bradykinin, a vasodilator which has been implicated in erectile function via the release of NO and relaxation of corpus cavernosum [5]. Hindawi Publishing Corporation Biochemistry Research International Volume 2015, Article ID 175950, 8 pages http://dx.doi.org/10.1155/2015/175950