Evaluation of the adaptogenic potential exerted by ginsenosides Rb1 and Rg1 against oxidative stress-mediated neurotoxicity in an in vitro neuronal model

Ginseng (Panax sp.) is a drug with multiple pharmacological actions that has been largely used in traditional medicines for the treatment of many health problems. In the therapy of neurodegenerative disorders, it has been employed due to its capacity to strengthen mental processes by enhancing cognitive performance and psychological function. Current work aimed at evaluating the adaptogenic potential of Rb1 and Rg1 against oxidative-stress mediated degeneration in a model of nervous cells. Oxidative stress and mitochondrial dysfunction were achieved by exposing SH-SY5Y cells to the mitochondrial complex I inhibitor rotenone. The cytoprotective activity of pre-treatments with ginsenosides Rb1 and Rg1 against rotenone was assessed by determining biochemical markers regarding oxidative stress (ROS scavenging, glutathione and lipid peroxidation levels, SOD activity and Nrf2 activation) and apoptosis-related alterations (mitochondrial membrane potential, calcium levels, aconitase activity and pro/antiapoptotic proteins). Their capacity to cross the blood brain barrier was also estimated. At their optimal doses, ginsenosides Rb1 and Rg1 significantly ameliorated redox status within the cells; they reduced ROS and TBARS levels and improved the glutathione system, as well as they enhanced SOD activity and Nrf2 pathway activation. They protected neuronal cells against MMP loss, calcium homeostasis disruption and aconitase inhibition. Consequently, apoptotic cell death was attenuated by the pre-treatment with ginsenosides, as evidenced by the reduction in caspase-3 and Bax, and the increase in Bcl-2 expressions; also, lower levels of cytochrome C were found in the cytosol. Poor BBB permeation was demonstrated for both ginsenosides. In conclusion, ginsenosides Rb1 and Rg1 exhibit neuroprotective potential which is achieved, at least in part, via mitochondrial protection and the plausible involvement of Nrf2 pathway activation. Our results contribute to validate the traditional use of ginseng for cognitive-enhancing purposes and provide basis to encourage further research on the potential of ginsenosides in the treatment of neurodegenerative diseases.