Aqueous extract from Ficus capensis leaves inhibits key enzymes linked to erectile dysfunction and prevent oxidative stress in rats' penile tissue

Context: Ficus capensis Thunb (Moraceae) is a medicinal plant widely grown in tropical and subtropical regions with the leaf decoction commonly taken in traditional folklore as fertility agent in men for ages. Aim: This study investigated the effects of aqueous extract from Ficus capensis leaves on angiotensin-I-converting enzyme (ACE), acetylcholinesterase (AChE) and arginase activities in vitro. The antioxidant properties of the extract as typified by the abilities to scavenge radicals [nitric oxide (NO), hydroxyl (OH)], chelate Fe2+ and inhibit Fe2+ -induced lipid peroxidation were also assessed. Methods: The aqueous extract (1:10 w/v) of Ficus capensis leaves was prepared and the ability of the extract to inhibit arginase, angiotensin I –converting enzyme (ACE), acetylcholinesterase (AChE) and antioxidant properties of the extract in rat’s penile tissue in vitro was investigated using various spectrophotometric methods. Phenolic constituent was carried-out using high performance liquid chromatography coupled with diode array detection (HPLC - DAD). Results: The extract inhibited ACE (IC50 = 52.17), AChE (IC50 = 172.60 μg/mL) and arginase (IC50 = 112.50 μg/mL) activities in a dose-dependent pattern. Gallic acid, quercetin, caffeic acid, ellagic acid, rutin and chlorogenic acid were the most abundant phenolic compounds identified in the sample. Furthermore, extract scavenged NO (IC50 = 0.12 μg/mL) and OH (IC50 = 0.53 μg/mL) radicals, chelated Fe2+ (IC50 = 0.16 μg/mL) and inhibited Fe2+ lipid peroxidation (IC50 = 435.17 μg/mL) dose-dependently. Conclusion: Inhibition of ACE, AChE, arginase, Fe2+ -induced lipid peroxidation as well as radical scavenging and Fe2+ -chelating abilities could be some of the possible mechanisms by which F. capensis leaves could be used in the treatment/management of erectile dysfunction (ED). Keywords: Ficus capensis, Erectile dysfunction, ACE, Arginase, AChE, Polyphenols