Pretreatment Effect of Alcoholic Olive Leaf Extract on Oxidative and Antioxidative Enzymes Status in Ovariectomized Rats

There is increasing evidence that menopause due to oxidative imbalance will lead to metabolic disorders (1). Menopause also increases food intake and body weight gain and is associated with abnormalities in lipid metabolism (2). More recent experimental studies confirm that ovariectomy cause oxidative stress and cell damage in animals (1,3,4). Steroid hormones, particularly estrogen, are natural antioxidants (5). Hormonal balance is a critical factor for the appropriate activity of the body organs. Any hormonal imbalances lead to impaired metabolic processes. Such an imbalance can be shown by changes in the oxidant/antioxidant status in the liver (1). Estradiol and its derivatives can reduce lipid peroxidation in serum and liver tissue and can also increase expression of antioxidant enzymes such as super oxide dismutase (SOD) and glutathione peroxidase (GPX) (6). Lipid peroxidation in biological membranes is extremely damaging and occurs when reactive oxygen species and free radicals attack the double bonds of unsaturated fatty acids. These compounds are toxic and if not removed, can create a chain of reactions (7). Ovariectomy in rats is a common method to evaluate the effects of estrogen loss in animal models. The lack of estrogen is associated with increased food intake and weight of the animal (6). Research on flavonoids and other polyphenols with antioxidant properties due to their biological activities and their effects on the prevention of the disease is increasing (8). Olive leaf as a rich source of biologically active phenolic compounds have better antioxidant activity, anti-inflammatory power and radical scavenging effects (9,10). Flavonoids are the most widespread polyphenolic compounds that as antioxidant compounds have been identified in various biological systems in recent years. Olive tree leaves as an ancient remedy were used in Europe and the Mediterranean diet in the form of herbal tea and extract. It seems that olive leaf extract with phenolic compounds can be used as natural antioxidants (11). Therefore, the aim of this study was to evaluate the effects of olive leaf extract on antioxidant activity of liver tissue in ovariectomized rats.