Effect of glabridin from Glycyrrhiza glabra on learning and memory in mice.

Glabridin was isolated from the roots of Glycyrrhiza glabra and its effects on cognitive functions and cholinesterase activity were investigated in mice. Glabridin (1, 2 and 4 mg kg (-1), P. O.) and piracetam (400 mg kg (-1), i. p.), a clinically used nootropic agent, were administered daily for 3 successive days to different groups of mice. The higher doses (2 and 4 mg kg (-1), P. O.) of glabridin and piracetam significantly antagonized the amnesia induced by scopolamine (0.5 mg kg (-1), I. P.) in both the elevated plus maze test and passive avoidance test. Furthermore, glabridin (2 and 4 mg kg (-1), P. O.) and metrifonate (50 mg kg (-1), I. P.), used as a standard drug, both remarkably reduced the brain cholinesterase activity in mice compared to the control group. Therefore, glabridin appears to be a promising candidate for memory improvement and it will be worthwhile to explore the potential of glabridin in the management of Alzheimer patients.