HMOX1 and Alzheimer disease: In vivo AD experiments have indicated that this compound decreases neurotoxicity and improves cognitive function by activating Nrf2/HO-1 and BDNF.15, 16, 17 Catechin also has diverse molecular mechanisms in AD pathways, and have shown been shown to have a high ability to cross the blood–brain barrier, increase antioxidation, and inhibit lipid peroxidation by increasing Nrf2 protein expression.18