Antioxidant activity of oral administration of Rosmarinus officinalis leaves extract on rat's hippocampus which exposed to 6-Hydroxydopamine

Abstract

Carnosic acid, a diterpene of Rosemarinus officinalis leaves extract (RE), has potent antioxidant activity in vitro. The dopaminergic connection of substantia nigra pars compacta to the hippocampus might be affected by oxidative stress which caused cognitive impairment observed in the early phase of Parkinson's disease (PD). Adult male Wistar rats were lesioned bilaterally by intra-nigral injection of 6-OHDA, and divided into six groups: four groups that orally given RE containing 40% of carnosic acid, at doses of 25, 50 and 100 mg/kg (treated rats) and distilled water (H2O), once daily for a period of 14 days before and after the injury. There were also two another groups as control rats which injected by normal saline and untreated lesion group. The injured animals were evaluated for their spatial memory performance by Morris Water Maze test. Lesioned rats showed significant increase in escape latency, as compared with control group. Two weeks after injury, tissue samples were collected from the hippocampus. Levels of catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), malondialdehyde (MDA) and reactive oxygen species (ROS) were determined. There were significant increase of SOD, GPX and CAT enzymes activities in RE50 treated group as compared to lesioned rats. We found a significant decrease of ROS in RE50 treated group as compared to Lesioned rats. These findings provide evidence that 50mg/kg of RE decreased oxidative damage of the hippocampus induced by 6-OHDA and serve as potential candidate for the treatment of PD.