Effects of Quercetin Encapsulated Liposomes via Nasal Administration: A Novel Cognitive Enhancer

Problem statement: 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 ^L (dose = 20 ^g), 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.