Pharmacological actions of Thespesia populnea relevant to Alzheimer's disease

Thespesia populnea (Malvaceae) is a large tree found in the tropical regions and coastal forests of India. Various parts of T populnea are found to possess useful medicinal properties, such as antifertility, antibacterial, anti-inflammatory, antioxidant, purgative and hepatoprotective activity. The present study was undertaken to investigate the effects of T populnea bark on cognitive functions, total cholesterol levels and cholinesterase activity in mice. A total of 312 mice divided into 52 different groups were employed in the present investigation. The ethanolic extract of T. populnea (TPE) was administered orally in three doses (100, 200 and 400 mg/kg) for 7 successive days to different groups of young and aged mice. The learning and memory parameters were assessed using elevated plus maze and passive avoidance apparatus. TPE (200 and 400 mg/kg, p.o.) showed significant improvement in memory of young and aged mice. TPE also reversed the amnesia induced by scopolamine (0.4 mg/kg, i.p.) and diazepam (I mg/kg, i.p.). Furthermore, TPE reduced significantly the central (brain) cholinesterase activity in mice. TPE exhibited a remarkable cholesterol lowering property comparable to simvastatin (a standard drug) in the present study. Furthermore, we observed that, T populnea bark possessed a powerful memory enhancing activity in mice. Since diminished cholinergic transmission and increased cholesterol levels appear to be responsible for development of amyloid plaques and dementia in Alzheimer patients, TPE may prove to be a useful medicine on account of its multifarious beneficial effects, such as memory improving property, cholesterol lowering, anticholinesterase and anti-inflammatory activity. Therefore, T populnea bark appears to be a promising candidate for improving memory and it would be worthwhile to explore the potential of this plant in the management of Alzheimer patients. (c) 2006 Elsevier GmbH. All rights reserved.