Ginsenoside Rd and ginsenoside Re offer neuroprotection in a novel model of Parkinson's disease.

Ginsenosides are the main active constituents of Panax ginseng. Ginsenoside Re is one of the major ginsenosides; whereas hydrolysis products such as Rd appear to have higher biological activity though are present in smaller amounts. Ginsenosides, from their early use in folk medicine to modern studies, appear to exert beneficial actions against aging and even neurodegenerative disorders. Parkinson's disease is a progressive neurodegenerative movement disorder characterized by a profound loss of midbrain dopamine neurons in the substantia nigra pars compacta. Carbon tetrachloride (CCl4) exerts neurotoxic effects when present as an environmental pollutant. As a model compound it was used here to study the impact on primary nigrostriatal dopaminergic nerve cells and to investigate the neuroprotective potential of ginsenosides Rd and Re against this organic solvent. CCl4 (2.5 mM on day 12 in vitro for 48 h) significantly decreased the number of tyrosine hydroxylase (TH+) cells by 51% compared with untreated control cultures, reduced their neuritic lengths, and led to truncated degenerations of cell morphology. Ginsenosides Rd and Re (10 µM) strongly reduced cell loss and degeneration and significantly protected process lengths and numbers of neurites of TH+ cells. The anti-oxidative and anti-inflammatory potential of the cellular supernatant was lowered by CCl4 exposure. Inclusion of ginsenosides inhibited both oxidative stress and inflammation. Therefore the neuroprotective effects of ginsenosides at least partially depend on lowering oxidative stress and anti-inflammation.