Two new triterpenes from Duchesnea indica

Two new triterpenes,2α,3β-dihydroxyurs-12-en-18,19-epoxy-28-oic acid(1)and 18,19-seco,2α,3α-dihydroxyl-19-oxo-urs-11, 13(18)-dien-28-oic acid(2)were isolated from the herbaceous part of Duchesnea indica.Their structures were elucidated by spectroscopic analysis,including 2D NMR technique.The isolated compounds exhibited moderate cytotoxic activities against HeLa and L929 cell lines.     

Electroanalysis and simultaneous determination of dopamine and epinephrine at poly(isonicotinic acid)-modified carbon paste electrode in the presence of ascorbic acid

A carbon paste electrode modified with electropolymerized fills of isonicotinic acid was developed.The modified electrode shows excellent electrocatalytic activity toward the oxidation of both dopamine(DA)and epinephrine(EP).Separation of the reduction peak potentials for dopamine and epinephrine was about 357 mV in pH 5.3 phosphate buffer solution(PBS)and the character was used for the detection DA and EP simultaneously.The peak currents increase linearly with DA and EP concentration over the range of 8.0×10-5 to 7.0×10-4 mol/L and 5.0×10-6 to 1.0×10-4 mol/L with detection limits of 2 × 10-5 and 1×10-6 mol/L,respectively.The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid(AA).     

Synthesis of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives from curcuminoids

Series of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives were synthesized in acceptable to good yields by treatment of the curcuminoids with aqueous ammonia,the mechanism was proposed.By modification of the primary products,total 13 new compounds were obtained.The structures of all products were elucidated by spectroscopy analysis including HR-MS,~1H NMR and ~(13)C NMR.     

Two new ent-kaurane diteroenoids from Isodon excisoides

Two new ent-kaurane diterpenoids taihangexcisoidesin A and B(1 and 2),were isolated from the EtOAc extract of the leaves of Isodon excisoides.Their structures were determined on the basis of spectroscopic methods.     

Rh(Ⅱ) and Zn(Ⅱ) co-catalyzed multi-component reaction for the synthesis of vicinal diols

Oxonium ylide intermediates generated fromα-diazocarbonyl compounds and water were trapped by Zn(Ⅱ)-activatedα-dicarbonyl compounds.The reaction gaveα,β-dihydroxyl acid derivatives in moderate yield.     

Structure-based design,synthesis of novel inhibitors of Mycobacterium tuberculosis FabH as potential anti-tuberculosis agents

Mycobacterium tuberculosis FabH,an essential enzyme in mycolic acids biosynthetic pathway,is an attractive target for novel anti-tuberculosis agents.Structure-based design,synthesis of novel inhibitors of mtFabH was reported in this paper.A novel scaffold structure was designed,and 12 candidate compounds that displayed favorable binding with the active site were identified and synthesized.     

Determination of sulfur anions by ion chromatography-postcolumn derivation and UV detection

A novel method for determination of formaldehyde sulfoxylate,sulfite,thiocyanate,and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed.All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0mL/min.The postcolumn derivation solution was 0.24%iodine in 0.2%phosphate acid and the detection wavelength was set at 288 nm...     

Preparation of novel chiral stationary phase based on click chemistry for ligand exchange chromatography

Click chemistry was applied to immobilize L-proline derivative onto azide-modified silica gel to give a novel chiral stationary phase(denoted as click-CSP) for ligand exchange chromatography.The developed protocol combines the benefits of operational simplicity,exceptionally mild conditions and high surface loadings.The enantioselectivityαof some DL-amino acids on the click-CSP were found to be in the range from 1.13 to 3.46.The chromatographic resolutions of some DL-amino acids and the stability study f...     

β-Cyclodextrin promoted oxidation of aldehydes to carboxylic acids in water

A facile,efficient and substrate-selective oxidation of aldehydes to carboxylic acids with NaClO catalyzed byβ-cyclodextrin in water has been developed.A series of aldehydes which could form inclusion complex withβ-cyclodextrin(β-CD)were oxidized selectively with excellent yields.     

Molecular modeling of epsilon RNA from hepatitis B virus

An initial model of the HBV epsilon RNA was built by the Biopolymer module of InsightⅡ.While its three-dimensional structure was obtained through structure optimization based on molecular dynamics simulation,the two active sites were found.A comparison with the experimental result indicated that the active sites may be the binding sites of the epsilon RNA in the RT-epsilon interaction.The result will be helpful to further discussion about the mechanism of RT-epsilon interaction and the study of HBV genom...