Studies On Structural Modifications Of Sapogenin And Their Anti-neurodegenerative Activities

Sasanqua saponin is a major pentacyclic triterpenoid in seeds of Camellia oleifera, composed of three parts which are sapogenin, glycosides and organic acids, and the main active site is sapogenin. The saponin has significant effects of antioxidation, anti-inflammation, analgesia, parahormone, immunomodulation and antitumor. Because of its multi-target effects, and activities of anti-inflammation and analgesia of isolated sapogenin to brain centers are significantly enhanced, the saponin can be used as a prodrug for anti-neurodegenerative. In this paper, the studies on structural modifications of sapogenin and their anti-neurodegenerative activities have been done, trying to discover new medicines for anti-neurodegenerative diseases.Sapogenin was got by purification and hydrolysis from crude sasanqua saponin, and the methods of animation and metallic coordination were used to direct the synthesis of different sapogenin derivatives. At last, the activities of anti-nervedegeneration of sapogenin derivatives were studied, and main methods and results are as follows:(1) Crude saponin was purified respectively by ultrafiltration, reverse osmosis and macroporous resin, and the content of saponin was measured with the method of vanillin-sulfuric acid colorimetry, getting the purity of 95.02%. The sapogenin from alkaline hydrolysis and acid hydrolysis of saponin was purified, and the structure was analysed by UV, IR, 1H NMR.(2) Discovery Studio 2.5 software was used to guide structural transformation of sapogenin which was simulated to dock with dopamine receptor of D3. The structure of a long-chain hydroxyl group substituted with an amino group from successful docking structure was synthesized with the method of the synthesis of primary amines from alcohols and ammonia by heterogeneous nickel catalyst. The purity of the product is 93.29% by HPLC. Amination product purified was characterized by UV, IR, 1HNMR and organic elemental analysis, getting the structural formula of C30H55N5, namely, all of hydroxyl(including aldehyde) of sapogenin are substituted by amino. Then, method of single factor analysis was used to investigate the impact of the concentration of sapogenin, reaction temperature, reaction time on the reaction yield, and the best reaction conditions are concentration of sapogenin is 12.5 mg/mL, reaction temperature is 200, reaction time is 32 h.(3) Fe, Zn, Mn and Cu metal complexes were obtained by the complexation reaction of sapogenin, and the metal complexes were analysed by UV, IR, elemental analysis, determination of metal content and thermal gravimetric analysis. Four metals are complexed with the ligand, but Cu and Mn complexes are unstable, while the complexing abilities of Zn and Fe are strong. Finally, with the characterization, the formula of zinc and iron complexes respectively are Zn(C30H47O5) 3 ? H2 O and Fe(C30H47O5) 4 ? 2H2 O.(4) Particle size of derivatives were measured less than 100 nm by Malvern nanoparticle size analyzer and scanning electron microscopy, showing good nature of the nanoparitcles. Sapogenin and its derivatives have antioxidant activity to some degree in vitro by the DPPH radical scavenging. In this study, the roles of sapogenin and its derivatives were studied by model of injury in mice hippocampus and dopaminergic neurons induced by rotenone. It is found that sapogenin and its derivatives have capacity of improving antioxidant of brain tissue, reducing hippocampal damage and the loss of DA induced by rotenone. Its mechanism of action may be about of increasing the levels of antioxidant enzymes to improve the antioxidant of brain, thus protecting dopaminergic neurons and antagonizing the decrease of DA induced by rotenone. The amination product can decrease the loss of DA, may also because of the interaction with dopamine receptor, reducing the slow degradation of DA.