Abstract

The current research assessed the anxiolytic activity of the methanol extract of leaves of Manilkara zapota (MEMZ) using behavioural models and neurotransmitter estimation in mice. The preliminary phytochemical screening showed the presence of alkaloids, flavonoids, saponins, triterpenoids, glycosides, and tannins in the extract. The results obtained in the elevated plus maze model showed that MEMZ (100 and 200 mg/kg) significantly (p < 0.01) increased the number of entry and time spent in open arms and decreased in the closed arms, indicating dose- and time-dependent anxiolytic effects. MEMZ (200 mg/kg) also produced a significant decrease in the anxiety index (AI), with AI decreasing from 0.45 to 0.10 by the end of the 21-day experimental duration in comparison to the standard anxiolytic Diazepam (2 mg/kg, p < 0.05 vs. control). In the light-dark transition model, the MEMZ-treated group spent a greater time in the light chamber, implying the treatment reduced anxiety, similar to the Diazepam group. Neurochemical analysis of brain homogenates showed a significant and dose-dependent increase in γ-aminobutyric acid (GABA) and a corresponding decrease in serotonin levels in mice receiving MEMZ treatment. The dose of 200 mg/kg MEMZ increased GABA to 34.42 μg/ml and reduced serotonin to 44.52 μg/ml levels, values not significantly different from Diazepam (p > 0.05). These results offer support for the potential use of MEMZ leaf extract as a natural anxiolytic. Additional studies are necessary to ascertain its mechanism of action and clinical utilization.

Key words: Diazepam, Elevated plus maze, Light dark model, MEMZ, GABA, Serotonin.