Effect of Polygala tenuifolia root extract on scopolamine-induced impairment of rat spatial cognition in an eight-arm radial maze task

Biol Pharm Bull. 2007 Sep;30(9):1727-31. doi: 10.1248/bpb.30.1727.


The effects of Polygala tenuifolia root fractions and the acyl groups of its constituents on the retrieval process of spatial cognition in rats were studied using an eight-arm radial maze task. Oral administration of a precipitate fraction (PTB) obtained by concentration of the n-BuOH-soluble portion from the extract of the roots significantly decreased the number of total errors (TEs) and that of working memory errors (WMEs) at doses of 100 mg/kg and 200 mg/kg. However, it caused no significant decrease in the number of reference memory errors (RMEs). In addition, the saponin-rich fraction (PTBM) obtained by purification of PTB also showed significant decreases in TEs and WMEs at a dose of 100 mg/kg. Among the cinnamic acid derivatives present as the acyl groups in the P. tenuifolia constituents, sinapic acid (SNPA) significantly decreased TEs and WMEs at doses of 10 to 100 mg/kg. These results indicated that P. tenuifolia extracts, PTB and PTBM, and SNPA had a beneficial effect on the memory impairment induced by dysfunction of the cholinergic system in the brain. The memory improvement in the scopolamine-induced memory impairment seen in the radial maze performance was due to improvement in the short-term memory. A contribution of some constituents other than SNPA to the memory improvement was also suggested.

MeSH terms

  • Animals
  • Chromatography, High Pressure Liquid
  • Coumaric Acids / pharmacology
  • Dose-Response Relationship, Drug
  • Male
  • Maze Learning / drug effects*
  • Memory / drug effects
  • Memory, Short-Term / drug effects
  • Muscarinic Antagonists / pharmacology*
  • Parasympathetic Nervous System / drug effects
  • Plant Extracts / pharmacology
  • Plant Roots / chemistry
  • Polygala / chemistry*
  • Rats
  • Rats, Wistar
  • Saponins / pharmacology
  • Scopolamine / antagonists & inhibitors*
  • Scopolamine / pharmacology*
  • Space Perception / drug effects*


  • Coumaric Acids
  • Muscarinic Antagonists
  • Plant Extracts
  • Saponins
  • Scopolamine