Phenolic Extract fromMoringa oleiferaLeaves Inhibits Key Enzymes Linked to Erectile Dysfunction and Oxidative Stress in Rats’ Penile Tissues

Abstract

This study was designed to determine the antioxidant properties and inhibitory effects of extract from Moringa oleifera leaves on angiotensin-I-converting enzyme (ACE) and arginase activities in vitro. The extract was prepared and phenolic (total phenols and flavonoid) contents, radical (nitric oxide (NO), hydroxyl (OH)) scavenging abilities, and Fe2+-chelating ability were assessed. Characterization of the phenolic constituents was done via high performance liquid chromatography-diode array detection (HPLC-DAD) analysis. Furthermore, the effects of the extract on Fe2+-induced MDA production in rats' penile tissue homogenate as well as its action on ACE and arginase activities were also determined. The extract scavenged NO∗, OH∗, chelated Fe2+, and inhibited MDA production in a dose-dependent pattern with IC50 values of 1.36, 0.52, and 0.38 mg/mL and 194.23 µg/mL, respectively. Gallic acid, chlorogenic acid, quercetin, and kaempferol were the most abundant phenolic compounds identified in the leaf extract. The extract also inhibited ACE and arginase activities in a dose-dependent pattern and their IC50 values were 303.03 and 159.59 µg/mL, respectively. The phenolic contents, inhibition of ACE, arginase, and Fe2+-induced MDA production, and radical (OH∗, NO∗) scavenging and Fe2+-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.

Modulation of some markers of erectile dysfunction and malonaldehyde levels in isolated rat penile tissue with unripe and ripe plantain peels: identification of the constituents of the plants using HPLC

“…Hence, the inhibition of arginase activity can be additional therapeutic targets for the management of ED as this could increase the bioavailability of L-arginine, contribute to the production of NO via reaction catalyzed by NOS, where overall result could facilitate penile erection. Inhibition of arginase activity by the studied extracts is in line with some reports of plant extracts, which are rich in phenolics including epicatechin, quercetin, quercitrin and isoquercitrin and their arginase inhibitory potential (Shin et al 2011;Oboh et al 2015;Akomolafe et al 2016). Hence, the observed high flavonoid content and abundant presence of flavonoid compounds such as (-)-epicatechin, rutin, quercetin and quercitrin in UPP may be responsible for its higher arginase inhibitory activity.…”

“…In the ED, the increased activity of arginase reduces production of NO, as arginase catalyzes the conversion of arginine to urea and ornithine, thereby reducing arginine levels that could be used for NO production by NO synthase (NOs). Arginase competes with NOs for L-arginine substrate, therefore, inhibition of arginase could up-regulate NO production (Sakai et al 2004;Oboh et al 2015). Inhibition of acetylcholinesterase (AChE) is another target for the treatment of ED as it regulates the levels of ACh, which trigger NO-dependent smooth muscle relaxation in erection process (Vargas et al 2004).…”

“…The increase in the production of angiotensin-II as a result of elevated angiotensin-I converting enzyme (ACE) activity induces ED (Bader 2010;Fraga-Silva et al 2013;Oboh et al 2015;Akomolafe et al 2016). Therefore, the inhibition of ACE activity in turn reduces angiotensin-II levels and improves erectile function in ED patients (Dorrance et al 2002).…”

“…The use of antioxidants has been reported to ameliorate oxidative stress via scavenging of free radicals and chelation of transition metals (Adefegha et al 2015;Ademiluyi et al 2015). So far, polyphenols which are abundant in plant-based human diet such as fruits and vegetables have been reported to be efficient in the management of ED and other related diseases such as hypertension with little or no side effects (Ferreira et al 2006;Oboh et al 2015;Akomolafe et al 2016).…”

“…This has motivated a continuous search for herbal/medicinal plant with erectogenic potentials as there are less side effects associated with herbal medications (Saxena et al 2012;Oboh et al 2015;Akomolafe et al 2016). Plantain [Musa sapientum Linn.…”