Quercetin also increased the activity of GPx, SOD, and CAT in traumatic brain injury [63], decreased the elevated MMP-9 level [64], and also activated the brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), and PI3K/Akt signaling pathway in cerebral focal ischemia [65]. Here, BDNF is linked to brain injury.