Study Of Extracts From POLYGALA TENUIFOLIA On Cognitive Improving And Protective Effects Of Neurocytes Damaged

According to the Chinese Materia Medica, the root of Polygala tenuifolia (Chinese name: yuanzhi), is guessed to have a special effect upon the will and mental powers, improving understanding and strengthening the memory.In this thesis, Polygala tenuifolia was choosen as reseach. The dried roots of Polygala tenuifolia were extracted and get the seven parts of extracts of polygala tenuifolia (Ept). The seven parts were screened parallely, EptA3 and EptB2 was located as the active compound.To investigate the effects of Ept on learning and memory, learning and memory impaired mice which are induced by Scopolamine and aged mice were employed. In the Step Down Test, the application of EptA3 100,50,25mg·kg^-1·d^-1 ig for 2 weeks successively, improved the learning and memory disturbance in mice caused by Scopolaminiumbromid.. While the application of EptB2 200,100,50mg·kg^-1·d^-1 i. g. for 4 weeks successively could increase the reference spatial learning and memory of 15 months mices and strengthening the working memory of 17 months mices.In order to investigate the mechanism of EptB2 pharmacological activity, the antioxidation effect and the effect of EptB2 on the activity of MAO-B, acetylcholine esterase (AchE) and monoamine neurotrasmitter's contents were tested. The result showed that EpB2 can inhibite the formation of MDA, improve the activity of SOD and CAT and depress the activity of Ache and MAO-B and improve the contents of monoamine neurotrasmitter's contents.To study the effects of extracts of Polygala Tenuifolia on neurotoxicity induced by glutamine (Glu), H₂O₂ and toxic metabolites of amyloid precursor protein (APP) such as amyloid protein Aβ_25～35 in the PC12 cells and SH-SY5Y cells. The results showed that both the extract of EptA3 and EptB2 could improve proliferation on PC12 cells and SH-SY5Y and significantly reduced cell injuried induced by H₂O₂ (0.15mM), Glu (0.5mM), Aβ_25～35(10μM).We also investigated the effects of EptA3 and EptB2 on neurotoxicity induced by Glu and Aβ_25～35 in primary cultured neurons of rat. The pretreatment of EptA3 (100, 50μg/ml) and EptB2(200, 100μg/ml) significantly reduced cell damaged induced by Glu (0.5mM), Aβ_25～35(10μM).In conclusion, Ept A2 and B3 could reinforce intelligence, improve learning and memory ability by regulating center cholinergic, monoamine: amino acid systems, promoting the activities of CAT and SOD, and attenuating free radical, antagonizing the neurotoxicity of exicitatory amino acid, H₂O₂ and Aβ_25～35, and inhibiting apoptosis of neurons.