Aly B. Okab1 and Mostafa A. Ayoub2
1 Department of Environmental Studies, Institute of Graduate Studies and Research, Alex. Univ., Egypt.
2Department of Animal Production, Faculty of Agriculture, Suez Canal Univ., Ismaillia, Egypt
A free radical is defined as any atom or molecule that contains one or more unpaired electron. It can be anionic, cationic, or neutral. The generation of reactive oxygen species, such as peroxide anion, and the hydroxyl radical can result in peroxidative damage to cell membranes. Free radicals are continually produced by the body, mostly by biochemical redox reactions involving oxygen which occur as part of normal cell metabolism. Elevated Reactive Oxygen Species (ROS) levels in the ejaculates are one of the main causes of sterility reduced sperm motility as well as decreased sperm-oocyte fusion capability in vitro. Mammalian spermatozoa are coated by a membrane rich in polyunsaturated fatty acids. These fatty acids are extremely susceptible to oxidative damage by free radicals or ROS by a process called lipid peroxidation (LPO). Lipid peroxidation damages the sperm cell membrane and is considered to be the key mechanism of this ROS-induced sperm damage leading to loss of motility, abnormal morphology and reduced capacity for sperm oocyte penetration and infertility. To protect sperm from this damage, the body depends on powerful antioxidant enzymes in the body such as superoxide dismutase (SOD), catalase, and glutathione peroxidase/reductase (GPX/GRD). The GPX/GRD enzymes play a central role in the defense against oxidative damage in human sperm. Seminal plasma and spermatozoa possess several antioxidant enzymes, glutathione peroxidase, glutathione reductase, superoxide dismutase. Many natural antioxidant defenses either are, or are dependent on, essential micronutrients. Vitamins C and E, for example, are essential vitamins, whereas the antioxidants, enzymes SOD and GPX are dependent on the essential micronutrients zinc and selenium, respectively, for their activity. The presence of vitamins and minerals in fruits and vegetables increase erythrocyte glutathione peroxidase activity and resistance of plasma lipoproteins to oxidation (Dragsted, 2004).
