Modulatory effects of the addition of argan and olive oils on oxidative and nitrosative stress induced in Tetrahymena pyriformis

Virgin Argan Oil (VAO) is extracted from the fruits of the Moroccan endemic species argan [Argania spinosa (L.) Skeels]. It is known for its richness in polyunsaturated fatty acids and its unique composition in tocopherols conferring a panoply of pharmacological properties, documented in several studies. The aim of this study was to investigate the potential protective effect of VAO against oxidative and nitrosative stress induced in cells of the model species Tetrahymena pyriformis. As a comparison, well-known Virgin Olive Oil (VOO) from Olea europaea L. was used instead. Both oils were subjected to a preliminary analysis of phytochemicals and properties of interest. Oxidative stress in T. pyriformis cells was induced by hydrogen peroxide (H2O2) at 350µM, whereas sodium nitroprusside (SNP) nitrosative stress was induced using a 1mM concentration. Neither of these concentrations caused relevant changes in cell viability. The level of reactive oxygen species (ROS) was evaluated in the cell cultures by using H2-DCFDA dye. The activity and cell localization of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX) was evaluated as well as the levels of glutathione (GSH) and the malondialdehyde (MDA) generated after lipid peroxidation. Finally, the presence and localization of intracellular lipid droplets was assessed by using Nile red. The treatment of cultures with H2O2 produced significant increases in the activity of CAT, SOD and GPX and in the level of GSH, as also did the SNP treatment. MDA level was increased by both the treatments. VAO and VOO treatment were found to protect T. pyriformis from oxidative stress and increased cells defense in nitrosative stress. In another hand VAO and VOO decreased significantly MDA level increased by H2O2 treatment and failed after SNP treatment. The quantification of fluorescence signal obtained from immunolocalization of antioxidant enzymes confirmed the results obtained after the evaluation of their activities. Interestingly the level of ROS and the number of lipid droplets increased by H2O2 treatment was significantly decreased by VAO and VOO co-treatments. VAO and VOO represent strong antioxidants, playing an important role in protecting cells against oxidative stress.