Evaluation of antidepressant and nootropic activities of leaf extracts of Rhizophora apiculata

Abstract

Background Rhizophora (R.) apiculata is a traditional mangrove plant having antioxidant, anti-inflammatory, and central analgesic activities. Objective The current study was performed to assess the beneficial neurological activities of the plant using rodent models and also to explore the phytochemical distribution of plant extracts using the hyphenated analytical technique. Materials and methods Ethyl alcohol and aqueous extracts were subjected to phytochemical screening, followed by GC-MS analyses. In experimental studies, the animals were divided into normal, positive control (standard), negative control, and extract-treated groups at three doses of each extract. The tail suspension method and forced swim tests were used as requisite animal models for the evaluation of antidepressant activity. Imipramine was used as the standard drug for the evaluation of antidepressant studies. Nootropic activity was evaluated by using the radial arm maze and Y-maze models. For these studies, scopolamine was used to impair the cognition of the animals and donepezil was used as the standard drug. The results were displayed as mean±standard error mean, and two-way ANOVA was used to analyze statistical significance between the test groups. Results and conclusion Preliminary phytochemical analyses showed that the leaves contain a wide range of secondary metabolites in abundance. As per GC-MS characterization, a few bioactive compounds like 3-O-methyl-D-glucose, desulphosinigrin, 1,25-dihdroxy vitamin D3, and ethyl iso-allocholate were identified. Ethyl alcohol extract (at 300 mg/kg; and 600 mg/kg) and aqueous extract (at 200 mg/kg; and 400 mg/kg) of R. apiculata exhibited antidepressant activity in both models. The plant extracts were proved to have cognition-enhancing activities at tested doses. The results stated that the plant R. apiculata is proved to have antidepressant and cognition-enhancing activities. Thus, it may provide a chance in the therapeutic management of neurological ailments. The effects of leaf constituents on brain neurotransmitter levels and the histology of the brain need to be established by future investigations.