TH and Parkinson disease: Tenuigenin (Table 1), the main active component of Polygala tenuifolia (Figure 2), improves the survival rate of tyrosine hydroxylase-immunoreactive neurons, reduces dopamine content in the substantia nigra, and abolishes the production of TNF-α and IL-1β in the lipopolysaccharide- (LPS-) induced PD model [182] (Figure 3).