Effect of nasal administration of quercetin liposomes on neurodegeneration in an animal model of AD. Quercetin liposomes attenuated the degeneration of neurons and cholinergic neurons in the hippocampus, promoted the elevation of superoxide dismutase, catalase, and glutathione peroxidase activities and induced the reduction in malondialdehyde in the hippocampus. Here, CAT is linked to Alzheimer disease.