Neuroprotective effects of tenuigenin in a SH-SY5Y cell model with 6-OHDA-induced injury.

Tenuigenin, an active component of Polygala tenuifolia root extracts, has been shown to provide antioxidative and anti-aging effects in Alzheimer's disease, as well as to promote proliferation and differentiation of neural progenitor cells. However, the effects of tenuigenin on Parkinson's disease remain unclear. In the present study, SH-SY5Y cells were utilized to determine the effects of tenuigenin on 6-hydroxydopamine (6-OHDA)-induced injury. Results showed that 1.0 × 10⁻¹-10 μM tenuigenin significantly promoted cell viability and reduced cell death. In addition, tenuigenin protected mitochondrial membrane potential (MMP) against 6-OHDA damage and significantly increased glutathione and superoxide dismutase expression. At the mRNA level, tenuigenin resulted in down-regulation of caspase-3, but up-regulation of tyrosine hydroxylase expression in 6-OHDA damaged cells. These results suggested that tenuigenin provides neuroprotection to dopaminergic neurons from 6-OHDA-induced damage. The neuroprotective mechanisms might involve antioxidative effects, maintenance of mitochondrial function, and regulation of caspase-3 and tyrosine hydroxylase expression and activity. Tenuigenin could provide a novel antioxidative strategy for Parkinson's disease.