Study On Secondary Metabolites And Biological Activities Of Two Species Of Pittosporum

The secondary metabolites and their anti-neuroinflammatory activity of two plants of the genus Pittosporum,Pittosporum qinlingense Y.Ren et X.Li and Pittosporum heterophyllum were studied.The natural products were purified by conventional natural product separation and extraction methods,such as positive phase silica gel,reversed phase silica gel,Sephadex LH-20,HPLC and so on.In addition,the sturctures of the compounds were identified by1D,2D NMR,high resolution mass spectrometry（HRESIMS）,IR,UV,CD,and by single-crystal X-ray crystallographic.The anti-neuroinflammatory activity of the compounds was determined by LPS-induced mouse microglia BV-2 inflammation model,and the mechanism of the anti-neuroinflammatory activity was further discussed by Western-blot and computer simulation of the interaction between the compounds and proteins.In the end,35 compounds were isolated and identified from the two species,among which 16 novel sesquiterpenoid glycosides were identified.A total of 25 compounds were determined from P.qinlingense,among which 16 were novel compounds.The compounds were mainly susquiterpene aglycones,which aglycone were main aromadendrane-skeleton.The glycosides are mainly fucose,and other glycosides are glucose and arabose.The glycosyl were generally substituent.In addition,three known sesquiterpenes and one triterpene have been elucidated.For anti-neuroinflammatory activity,the results showed that the activity of the sesquiterpene glycosides was significantly better than that of the positive control queretin at 10μM,and the IC₅₀ of five compounds was about5μM,which showed significant anti-LPS-induced NO release activity in BV-2 cells.Computer simulation of the compounds and i NOS showed that the compounds interact with i NOS strongly,which was consistent with the test results.In addition,Western-blot showed that the expressions of COX-2 and i NOS,two proteins closely related to inflammation,were significantly reduced in administration group,and showing a dose-dependent pattern.The expressions of the two proteins in the high concentration group were equivalent to those in the control group.In particular,compound 17 and 18 significantly reduced the expression of COX-2 in the low concentration group,which was almost the same as that in the control.Ten known compounds including one sesquiterpene and nine neolignan were isolated and identified from the P.heterophyllum.The great difference of secondary metabolites between P.qinlingense and P.heterophyllum indicates that different growth environments have great influence on the production of secondary metabolites.Therefore,combining the relationship between growing environment and secondary metabolites,or the specific functions of secondary metabolites in plants could be used as the breakthrough point for the study of natural products of plants.