Neuroprotective and Antiamnesic Effects ofMitragyna inermisWilld (Rubiaceae) on Scopolamine-Induced Memory Impairment in Mice

Abstract

Aim. To assess memory improvement and neuroprotective and antioxidant effects ofMitragyna inermis(M. inermis) leaf decoction on the central nervous system.Methodology. Leaf decoction ofM. inermiswas tested on learning and memory in normal and scopolamine-induced cognitive impairment in mice using memory behavioral tests such as the Morris water maze, object recognition task, and elevated plus maze. Oxidative stress enzymes—catalase, superoxide dismutase, and the thiobarbituric acid reactive substance, a product of lipid peroxidation—were quantified. In each test, mice 18 to 25 g were divided into groups of 5.Results. The extract reversed the effects of scopolamine in mice. The extract significantly increased discrimination index in the object recognition task test and inflexion ratio in the elevated plus maze test. The times spent in target quadrant in MWM increased while the transfer latency decreased in mice treated byM. inermisat the dose of 196.5 mg/kg. The activity levels of superoxide dismutase and catalase were significantly increased, whereas the thiobarbituric acid reactive substance was significantly decreased after 8 consecutive days of treatment withM. inermisat the dose of 393 mg/kg.Conclusion. These results suggest thatM. inermisleaf extract possess potential antiamnesic effects.