Studies On Chemical Constituents And Bioactivity Of Dasymaschalon Rostratum And Polyalthia Laui

Dasymaschalon rostratum?Dasymaschalon?and Polyalthia laui?Polyalthia?are the arbor plants of Annonaceae,D.rostratum is mainly distributed in Guangdong,Guangxi and Hainan Island,P.laui is the endemic arbor plant growing in Hainan Island.Previous phytochemical investigations on the plants of two genus have afforded various types of compounds,such as alkaloids,diterpenoids,sesquiterpenoids and annonaceous acetogenins,etc.,most of them showed moderate bioactivities.In our ongoing investigation of structural diversity and bioactive natural products from the endemic medicinal plants,and to rationally develop and utilize the plant resources in Hainan Island,a research on the chemical constituents of D.rostratum and P.laui was explored.The study provides theoretical basis for theirs further development and utilization.111 Compounds,including 25 new and 1 new nature products were isolated from these plants through column chromatography over Silica gel,Sephadex LH-20,and semi-preparative HPLC.Their structures were elucidated on the basis of spectroscopic methods including UV,IR,ESI-MS,HR-ESI-MS,CD,1D and 2D NMR,and single crystal X-ray diffraction.The structural types of the isolates include alkaloids,clerodane diterpenoids,sesquiterpenoids,iridoids,phenylpropanoids,steroids and phenolic acids,etc.62 Compounds,including 7 new were isolated from D.rostratum.Compounds 1-3 are new phenylpropanoid derivatives with a polymethyl substituted cyclopentene or cyclohexene conjugated diketone as a substituent,and the similar structures are rare in natural products.Compound 5 is found to be a rarely nitrated aporphine alkaloid,and the absolute configuration of 5 was established by X-ray diffraction analysis.Moreover,compound 33represents the first oxoaporphine N-oxide alkaloid in nature products.The most of isolated compounds were evaluated for their anti-HIV-1,cytotoxic and antibacterial activities.Compounds 10 showed moderate anti-HIV-1 activities with EC₅₀ values 8.10?g/mL,TI>24.7.The most of compounds displayed moderate cytotoxicities against human Hela,MCF-7and A-549 cancer cell lines in the range of IC₅₀ at 18.62-38.51?g/mL.Compound 24exhibited definite antibacterial activities against broad spectrum bacterial,which exhibited activity against B.subtilis,S.aureus and E.coli with MIC values of 0.625?g/mL comparable to those of Ciprofloxacin as positive control.49 Compounds,including 18 new and 1 new nature product were isolated from the roots of P.laui,among them 34 compounds are clerodane diterpenoids which are the characteristics chemical constituents of Polyalthia.Compounds 63-65 are found to be novel ring-opening19-norclerodane diterpenoids,a plausible biogenetic pathway for 63-65 was presented and the absolute configurationof 63 established by X-ray diffraction analysis.Compounds 66-67represent the first norclerodane diterpenoids?17-carbon skeleton?.Moreover,Compounds68-69 are a pair of C16 epimerides with 6/6 ring rearranged to 6/5 ring,the absolute configurations of 68-69 were established by circular dichroism?CD?spectra and X-ray diffraction method,The most of isolated compounds were evaluated for their cytotoxic and antibacterial activities.Many compounds displayed weak cytotoxicities against human Hela,MCF-7 and A-549 cancer cell lines with IC₅₀ values ranged from 18.62 to 38.51?g/mL.Compound 108 exhibited activity against B.subtilis,S.aureus and E.coli with MIC values of 0.625?g/mL.