Cholinergic‑Enhancing and Antioxidant Effect of Vigna subterranea (L.) Verdc. (Fabaceae) Landrace Aqueous Extract on Scopolamine‑Induced Amnesia in Male Swiss Mice

Background: Currently, no drug effectively curbs down the progression of Alzheimer’s disease (AD), and thus early prevention is important. Objectives: The present study was conducted to investigate the protective effects of the aqueous extract of Vigna subterranea seed landrace on amnesia induced by scopolamine in mice. Materials and Methods: V. subterranea aqueous extract (100, 200, and 400 mg/kg BW) was administered by gavage for 9 consecutive days and memory impairment was induced by repeated intraperitoneal injection of scopolamine (1.5 mg/kg). The Y‑maze (YM), Morris water maze (MWM), novel object recognition paradigm (NOR), and the T maze™ were used to assess learning, memory, and retention. Superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) levels, and acetyclcholine esterase activity were also evaluated in the mouse hippocampi homogenates. Results: V. subterranea aqueous extract (400 mg/kg) significantly increased the percentage of spontaneous alternation in the YM task and decreased escape latency in the MWM. Moreover, this dose brought about a significant improvement in the time spent in the preferred TM arm and discrimination index in the NOR tasks despite repeated scopolamine injection. Additionally, low acetylcholine esterase levels, reduced lipid peroxidation (MDA), but increased antioxidant enzyme (CAT and SOD) activity were observed in hippocampi homogenate of mice pretreated with the extract. A protective action against hippocampal cell damage was also evident. Conclusion: This finding suggests that the aqueous extract of V. subterranea seed landrace may improve learning and memory.