In vitro Effects of Olive Leaf Extract (Oleuropein) on Human Sperm Parameters and Oxidative Stress Induced by Bacterial Lipopolysaccharide (LPS).

Recently, biomolecules from natural products have paved the way for novel drug in the treatment of some diseases in vitro and in vivo models as diabetes, cancer and infertility. As such, we aimed to evaluate the capacity of Oleuropein (OLE), the major bio-phenol in olive leaf, to protect human sperm against bacterial lipopolysaccharide (LPS) inducing sperm oxidative stress and defective sperm functions. The toxic effect of OLE on human sperm was firstly investigated by evaluating sperm parameters after incubation during 60 minutes with different concentrations. Determined non-toxic concentration was then used to evaluate the capacity of OLE to protect sperm against LPS oxidative damages and sperm parameters alterations. Thus, sperms were consecutively incubated with LPS (10 µg/mL) and OLE (40 µg/mL) during 60 minutes, then submitted to sperm parameters analysis and oxidative stress assessment by measuring malondialdehyde (MDA), carbonyl groups (CG) levels and the activity of some antioxidant enzymes: superoxide dismutase (SOD) and catalase (CAT). A significant decrease of sperm parameters as well as a significant increase in MDA levels, CG levels, SOD and CAT activities was found after stimulation by LPS. However, a non-significant difference was shown comparing sperms treated by LPS and OLE with LPS-treated control sperms. Consequently, despite the high antioxidant and anti-inflammatory capacity of OLE reported in diverse cells, this phenolic compound seems to be not appropriate to protect human sperm in vitro against induced LPS oxidative stress and seems to have a "double-edged sword" behavior.