Abstract: Objective: To study the effects and mechanisms of ethanol extract and its n-butanol-soluble fraction from Herba Portulacae on learning and memory performance in senile mice induced by D-galactose. Method: Mice were randomly divided into 6 groups: control group, model group and n-butanol-soluble fraction treatment (0.5 g/(kg ·d) and 0.25 g/(kg ·d)) groups and ethanol extract treatment groups (1 g/(kg ·d) and 0.5 g/(kg ·d)) groups. Normal saline was given to control group once daily for 42 consecutive days by subcutaneous injection in the neck back, and 1 g/(kg ·d) D-galactose to the other 5 groups using the same administration route before intragastric administration of the same volume of distilled water and corresponding drugs (in aqueous solution) every afternoon during the administration period. Mouse learning and memory performance were tested by step-through test and water maze test, and MDA content and SOD and GSH-Px activities in the brain of senile mice were assayed. Results: Both dosages of n-butanol-soluble fraction could significantly improve mouse learning and memory performance (P <0.01), and the dosage of 0.5 g/(kg ·d) resulted in a significant increase in the activities of SOD and GSH-Px in the brain (P <0.05, P <0.01), and the other dosage significantly decreased MDA content in the brain (P <0.05). Meanwhile, ethanol extract from Herba Portulacae had a highly significant improving effect on mouse learning and memory performance (P <0.01) and significantly reduced MDA content in the brain (P <0.05). Conclusion: From these results, we concluded that ethanol extract and its n-butanol-soluble fraction from Herba Portulacae are capable of significantly improving senile mouse learning and memory performance. The possible mechanisms may be through increasing SOD and GSH-Px activities and decreasing MDA content in the brain. Furthermore, ethanol extract from Herba Portulacae is superior to its n-butanol-soluble fraction.

Key words: Herba Portulacae, learning and memory, MDA, SOD, GSH-Px, senile mouse