Bioassay-guided isolation of cytotoxic constituents from the flowers of Aquilaria sinensis

Bioassay-guided fractionation of the EtOH extract from the flowers of Aquilaria sinensis(Lour.)Spreng.(Thyme-laeaceae)led to the isolation of a new cucurbitane-type triterpenoid,aquilarolide A(1),along with five known compounds(2-6).The structure of 1 was elucidated by extensive 1D and 2D nuclear magnetic resonance(NMR)experiments and mass spectrometry(MS)data and theoretical calculations of its electronic circular dichroism(ECD)spectra.Aquilarolide A,cucurbitacin E(3),cucurbitacin B(4),and 7-hydroxy-6-methoxy-2-[2-(4-methoxyphenyl)ethyl]-4H-1-benzopyran-4-one(6)showed significant cytotoxicity against human lung adenocarcinoma SPC-A-1,human lung squamous cell carcinoma NCI-H520,human lung adenocarcinoma A549,and paclitaxel-resistant A549(A549/Taxol)cell lines.All four active compounds,with IC_(50) values ranging from 0.002 to 0.91μM,had better inhibitory activities against A549/Taxol cells than paclitaxel(IC_(50)=1.80μM).Among them,cucurbitacin E(IC_(50)=0.002μM)is the most active.Further studies are needed to evaluate their in vivo antitumor activities and to clarify their mechanisms.

Neolignans from Selaginella moellendorffii

Two new neolignans selaginellol(1)and selaginellol 4'-O-β-D-glucopyranoside(2),together with seven known compounds(3–9),were isolated from the whole plant of Selaginella moellendorffii.The structures of the new isolates were determined through spectroscopic data analysis.Compounds 1–9,as well as compounds 10–18 previously isolated from the species,were measured for the activity against platelet aggregation induced by ADP or collagen.Three neoligans(8,11,and 12),one flavanone(14),and one alkaloid(16)showed inhibitory activity against ADP-or collagen-induced platelet aggregation as compared with tirofiban.The dihydrobenzofuran neolignans(8,11,and 12)are more potent than the benzofuran neolignan(13)and other types of neolignans(1–7).Glucosidation of the dihydrobenzofuran neolignans(11 and 12)is helpful for the activity.Graphical Abstract Two new neolignans selaginellol(1)and selaginellol 40-O-b-D-glucopyranoside(2)were isolated from the whole plant of Selaginella moellendorffii.Several compounds from this plant showed the activity against platelet aggregation induced by ADP or collagen.

Chemical constituents from heartwoods of Caesalpinia sappan with antiplatelet aggregation activities

Objective:To clarify the active constituents of the heartwoods of Caesalpinia sappan,a traditional Chinese medicine with the functions of promoting blood circulation(Huoxue in Chinese)and removing blood stasis(Quyu in Chinese).Methods:The chemical constituents were isolated and purified by combination of silica gel and Sephadex LH-20 column chromatography,along with semipreparative HPLC.Their chemical structures were established by multiple spectroscopic methods and comparison with literature data.The in vitro antiplatelet aggregation activities were evaluated using mouse platelet induced by AYPGKF-NH2,a gold agonist of protease-activated receptor 4(PAR4).Results:Two new phenols,methyl 2-(4,4’,5’-trihydroxy-2’-(methoxymethyl)biphenyl-2-yloxy)acetate(1)and 1’-methylcaesalpin J(2),together with 24 known compounds(3-26),were isolated from the heartwoods of C.sappan.Among them,sappanchalcone(16)and brazilin(20)showed inhibitory activities against mouse platelet aggregation with IC50 values of 114.8μmol/L and 100.8μmol/L,respectively.Conclusion:Antiplatelet compounds from C.sappan targeting at PAR4 are reported for the first time.