Studies On The Structures And Bioactivities Of Compounds From Ailanthus Altissima

Ailanthus altissima,native to China and naturalized in many temperate regions,is one of the most well-studied deciduous trees of Ailanthus(Simaroubaceae).This plant is resistant to the insect pests,and secreting allelopathic substance all around.The root barks of A.altissima have been used as traditional Chinese medicine for its application of hepatoprotection,hemostasia,and anodyne.Phytochemical investigations into this species have revealed the presence of many kinds of secondary metabolites.The quassinoids and their precursors,triterpenoids,have attracted more attention than other compounds isolated from the plant,due to their broad spectrum of bioactivities,such as antitumor,antivirus,anti-inflammatory,and antifungal effects.However,the study on the secondary metabolites of this plant is not thorough,which is rarely to see in recent 20years.In order to seek for novel secondary metabolites with marked bioactivities from A.altissima,a phytochemical investigation was carried out by our group on the root barks and leaves of the plant.In this paper,we describe the isolation,structural characterization,and biological evaluation of the compounds from this species.The structures of these compounds were elucidated by combination of spectroscopic data interperation(IR,UV,HRESIMS,NMR),electronic circular dichroism data(ECD),and X-ray analysis.Finally,82 compounds were identified from the plant,including 32 triterpenoids,20 quassinoids and 30 compounds of other different types.Among the compounds,there were 10 new triterpenoids(Aa1–Aa7,Aa9,Aa10,and Aa12),7 new quassinoids(Aa33–Aa39),3 new compounds of C₁₃ nor-isoprenoids type(Aa62–64).Compounds Aa1–Aa7 are highly oxygenated apotirucallane-type triterpenoids,which is very rare in A.altissima.Morever,it is uncommom that compound Aa7 possessed a dihydrofuran in its C-17 side chain;Compound Aa33 has a C-seco ring in its skeleton,representing the first example in the C₂₀-skeleton quassinoids;Compounds Aa62 and Aa63 are C₁₃ nor-isoprenoids,which bore two ester rings in their structures.In addition,we have tested the antifungal activities towards four phytopathogenic fungi,Bipolaris sorokinian,Curvularia lunata,Fursarium avenaceum,and Alternaria alternat.The assay results revealed that compound Aa20 had the highest inhibitory effect against C.lunata and B.sorokinian.The inhibitory rate was 38.6%and 43.8%at the concentration of 50?g/mL,respectively,which was higher than the positive control.The bioactivities of the selective quassinoids were tested against the tumor cell lines.The results showed that compound Aa43 was a very cytotoxic one with the ability to induce cell cycle arrest and caspase-dependent apoptosis.However,owing to the cytotoxicity,it has no effect on enhancing the radiosensitivity of A549cells.Finally,we summarized the structure and biological potency of quassinoids from the genus of Ailanthus,Brucea,and Picrasma from 1980 to 2018.The thesis would provide a supplement for the research on bioactivities of chemical constituents as well as structure-activity relationship in A.altissima,a helpful basis for screening new medicines,pharmacology,and chemotaxonomy,and may contribute to utilize and develop the natural resources for our country.