TLR4 and Parkinson disease: Calycosin, an isoflavone phytoestrogen that is isolated from Astragalus membranaceus, could ameliorate the behavioral abnormalities, reduce pro-inflammatory molecule levels, and maintain TH neuron integrity in the brain of MPTP-induced PD mice by suppressing the expression of TLR2, TLR4, the MAPK pathway, and nuclear NF-kB [163].