Demand for cognitive-enhancing drugs is growing. Numerous
medicinal plants possessing antioxidant activity have received much attention as food supplement to
improve cognitive function. Quercetin is a potent free radical scavenger and antioxidant. However, the
limitations of quercetin: Rapidly metabolized is an obstacle to its use for a cognitive enhancer. In
addition, the burden of blood brain barrier can be overcome by nasal administration and liposomes. In
the present study, we investigated whether nasal administration of quercetin liposomes could
improve spatial memory in healthy adult rats. Approach: Male Wistar rats were pretreated with
quercetin liposomes, containing 0.5 mg of quercetin in 20 µL (dose = 20 µg), via right nasal cavity
once daily continually for 4 weeks. Evaluation of rodent learning and memory was assessed by
Morris water maze test and then all rats were sacrificed for determining the survival and cholinergic
neurons densities in hippocampus. Results: Quercetin liposomes via nasal route treated rats
exhibited a significant improvement in cognitive performance. In addition, nasal administration of
quercetin liposomes also resulted in induced the densities of survival and cholinergic neurons in
hippocampus. However, further researches about the precise underlying mechanism are still
required. Conclusion: Our studies demonstrate that quercetin liposomes via nasal administration
may have a candidate for cognitive enhancer in the future.