RESUMEN
Research into the impacts of oxidative stress (OS), and hormonal balance on reproductive potential has increased over the last 40 years possibly due to rising male infertility. Decreased antioxidant levels and increased OS in tissues result from hormonal imbalance, which in turn leads to male infertility. Increased reactive oxygen species (ROS) generation in seminal plasma has been linked to many lifestyle factors such as alcohol and tobacco use, toxicant exposure, obesity, varicocele, stress, and aging. This article provides an overview of the crosslink between OS and gonadal hormone disruption, as well as a potential mode of action in male infertility. Disrupting the equilibrium between ROS generation and the antioxidant defense mechanism in the male reproductive system may affect key hormonal regulators of male reproductive activities. Unchecked ROS production may cause direct injury on reproductive tissues or could disrupt normal regulatory mechanisms of the hypothalamic-pituitary-gonadal (HPG) axis and its interaction with other endocrine axes, both of which have negative effects on male reproductive health and can lead to male infertility.
RESUMEN
Neem (Azadirachta indica) seed protein hydrolysates were investigated for in vitro antioxidant and angiotensin 1-converting enzyme (ACE)-inhibitory activities. Neem seed proteins were hydrolysed using pepsin, trypsin and Alcalase. The degree of pepsin hydrolysis of neem seed protein was significantly higher (p < 0.05) than those of trypsin and Alcalase hydrolysis. Proteolytic hydrolysis of the isolate resulted in hydrolysates with improved Arg/Lys ratio, with pepsin hydrolysates still being able to maintain an acceptable level of essential amino acids comparable to that of the isolate. At 2.5 mg/mL, pepsin neem seed protein hydrolysate (NSPH) demonstrated the strongest antioxidant activity with 67.15 % and 50.07 % DPPH- and superoxide anion radical-scavenging activities, respectively, while trypsin NSPH had the highest ferric-reducing power. Using N-[3-(2-furyl)acryloyl]-L-phenylalanyl-glycyl-glycine (FAPGG) as substrate, NSPHs strongly inhibited ACE (69.20-80.39 %) in a concentration-dependent manner. Pepsin NSPH had higher ACE-inhibitory activity than trypsin and Alcalase NSPHs. Kinetic studies showed the mechanism of ACE inhibition to be mixed-type with Ki values of 0.62, 0.84, 1.5 for pepsin, trypsin and alcalase NSPH, respectively. These results suggest that NSPH can be used as a potential nutraceutical with antioxidant capacity and inhibitory activity against ACE.