Evaluation of the Effect of Moringa peregrina Extract on Learning and Memory: Role of Oxidative Stress

Abstract

Oxidative stress interferes with the functional roles of the hippocampus and results in cognitive decline. Antioxidant supplementation has a cognitive enhancing activity through protecting hippocampus brain cells from the damaging effects of the reactive oxygen species. The dried methanolic extract of the aboveground parts of Moringa peregrina (Forssk.) Fiori (Moringaceae) was hypothesized to have memory-enhancing activity via its antioxidative properties. HPLC and LC-MS methods were used for qualitative analysis of the marker compounds. Six major compounds of the methanolic extract of M. peregrina were identified, namely, rutin, myricetin, α-amyrin, β-amyrin, lupeol acetate, and β-sitosterol. Male Wistar rats were administered via oral gavage three dose levels (50, 100, and 500 mg/kg) of M. peregrina methanolic extract for 2 months. The radial arm water maze (RAWM) was used to test spatial learning and memory. In addition, ELISA was used to analyze the levels of brain-derived neurotrophic factor (BDNF) and to assess the level of some oxidative stress markers. M. peregrina (150 mg/kg) resulted in short- and long-term memory enhancement (P < 0.05). Moreover, M. peregrina administration elevated BDNF levels in the hippocampus (P < 0.05) and caused favorable changes in oxidative stress biomarkers. In particular, an increase in glutathione (GSH), a decrease in oxidized glutathione (GSSG), and an increase in the antioxidant enzyme glutathione peroxidase (GPx) levels in the hippocampus were elicited after treatment with M. peregrina. Taken together, our data show that oral administration of M. peregrina enhances both short- and long-term memory functions via combating oxidative stress and increasing BDNF levels in the hippocampus. Consuming this safe plant may thus help promote spatial learning and improve memory.

Keywords: Antioxidant; Cognition; Hippocampus; Learning; Memory; Moringa peregrina.