Two new ortho benzoquinones from Uncaria rhynchophylla

The present study was designed to determine the chemical constituents of the stems and hooks of Uncaria rhynchophylla. The chemical constituents were isolated and purified from CH_2Cl_2 fraction by chromatography. Their structures were elucidated by spectroscopic analyses. Their cytotoxicity was tested using MTT method. Two new ortho benzoquinones, 3-diethylamino-5-methoxy-1, 2-benzoquinone(1) and 3-ethylamino-5-methoxy-1, 2-benzoquinone(2), together with a known compound isorhynchophyllic acid(3) were isolated from U. rhynchophylla. These compounds were evaluated for their cytotoxicity against cancer cells A549, Hep G2 and A2780. Compounds 1 and 2 were new ortho benzoquinones and showed weak antiproliferative activities on A549, Hep G2 and A2780 cells. Compound 3 significantly inhibited the proliferation of A549, Hep G2 and A2780 cells with IC_(50) values being 5.8, 12.8 and 11.8 μmol·L^(–1), respectively.

Core-shell structured 1,4-benzoquinone@TiO_2 cathode for lithium batteries

Organic carbonyl compounds are considered as promising candidates for lithium batteries due to theirhigh capacity and environmental friendliness, However, they suffer from serious dissolution in the elec-trolyte, leading to fast capacity decay. Here we report core-shell structured 1,4-benzoquinone@titaniumdioxide （BQ@TiO2） composite as cathode for lithium batteries. The composite cathode can deliver a highdischarge capacity of 441.2 mA h/g at 50 mA/g and a high capacity retention of 80.7% after 100 cycles. Thegood cycling performance of BQ@TiO2 composite can be attributed to the suppressed dissolution of BQ,which results from the physical confinement effect of Ti02 shell and the strong interactions between BQand Ti02. Moreover, the combination of ex situ infrared spectra and density functional theory calculationsreveals that the active redox sites of BQ are carbonyl groups. This work provides an alternative way tomitigate the dissolution of small carbonyl compounds and thus enhance their cycling stability.

QSAR modeling of benzoquinone derivatives as 5-lipoxygenase inhibitors

The inhibitors of 5-LOX control the overproduction of pro-inflammatory mediators known as leukotrienes(LTs)and thus have therapeutic relevance in the treatment of various diseases like asthma,rheumatoid arthritis,inflammatory bowel disease and certain types of cancers.This has increased the search for efficient therapeutic agents for protein 5-LOX and this process is now primarily based on QSAR.In this study,we have developed four different quantitative structure and 5-LOX inhibition activity relationship models of benzoquinone derivative by exploiting CoMFA,RF,SVM,and MLR chemometric methods.Performance of the QSAR models was measured by using cross-validation technique as well as through the external test set prediction.RF model outperforms all other models.SVM and MLR models failed due to the poor performance of the external test set prediction.CoMFA model,which shows relatively good performance was used to explore the essential structural regions where the modification was necessary to design a novel scaffold with improved activity.Moreover,molecular docking of all the derivatives to the binding site of 5-LOX was done to show their binding mode and to identify critical interacting residues inside the active site of 5-LOX.The docking result confirms the stability and rationality of the CoMFA model.

Synthesis and Cytotoxicities of Royleanone Derivatives

Carnosic acid was used as starting material to synthesize royleanone derivatives featured C11–C14 para quinone.The importance of C-20 group of royleanone derivatives was verified by the cytotoxicity assay of royleanonic acid,miltionone I and deoxyneocrptotanshinone.Following our synthetic route,15 amide derivatives were synthesized and 8 compounds exhibited moderate cytotoxic activities against three human cancer lines in vitro.

Acute andchronic cytotoxicity and genotoxicity induced by 2,6-dichloro-1,4-benzoquinone in NIH3T3 cells

Objective:This study aimed to evaluate the acute and chronic cytotoxicity and genotoxicity of 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ).Methods:NIH3T3 cells were exposed to 2,6-DCBQ for 3 and 72 h,and relative cell viability was calculated.NIH3T3 cells were treated with different concentrations of 2,6-DCBQ for 24 h.The solvent and positive controls were dimethyl sulfoxide(DMSO)and 0.5μmol/L ethylmethylsulfone,respectively.The values of Olive tail moment were measured by comet assay.NIH3T3 cells were then simultaneously treated with 5μg/mL cytochalasin B and different concentrations of 2,6-DCBQ.The solvent and positive controls were DMSO and 1μmol/L mitomycin C,respectively.Micronucleus rates were calculated after 48 h.Results:The half lethal doses of 2,6-DCBQ in NIH3T3 cells were 64.93μmol/L for 3 hand 13.46μmol/L for 72 h.The values of Olive tail moment in the 7.5 and 10μmol/L groups were significantly higher than those in the solvent control(P<0.05).Moreover,the micronucleus rates in the 10 and 15μmol/L groups were significantly higher than those in the solvent control(P <0.05).The results of comet assay and micronucleus test showed a dose-response relationship.Conclusion:2,6-DCBQ exhibited strong cytotoxicity and induced DNA and chromosomal damage in NIH3T3 cells.

Enhancement of Fenton oxidation for removing organic matter from hypersaline solution by accelerating ferric system with hydroxylamine hydrochloride and benzoquinone

Fenton oxidation is generally inhibited in the presence of a high concentration of chloride ions.This study investigated the feasibility of using benzoquinone（BQ） and hydroxylamine hydrochloride（HA） as Fenton enhancers for the removal of glycerin from saline water under ambient temperature by accelerating the ferric system.It was found that organics removal was not obviously affected by chloride ions of low concentration（less than 0.1 mol/L）,while the mineralization rate was strongly inhibited in the presence of a large amount of chloride ions.In addition,ferric hydrolysis-precipitation was significantly alleviated in the presence of HA and BQ,and HA was more effective in reducing ferric ions into ferrous ions than HA,while the H_2O_2 decomposition rate was higher in the BQ-Fenton system.Electron spin resonance analysis revealed that OH production was reduced in high salinity conditions,while it was enhanced after the addition of HA and BQ（especially HA）.This study provided a possible solution to control and alleviate the inhibitory effect of chloride ions on the Fenton process for organics removal.

Construction of diaminobenzoquinone imines via ferrocene-initiated radical reaction of benzoquinone with amines

A ferrocene-initiated radical reaction of benzoquinone with amines has been successfully developed for the direct access to diaminobenzoquinone imines in high yields,in which the comme rcially available and cheap ferrocene was employed as a radical initiator and TBHP was used as an oxidant.Moreover,this reaction could be achieved with low loading of ferrocene(0.5 mol%).This protocol is highly efficient with good substrate tolera nce and provides a new approach for the construction of benzoquinone imines with potential pharmaceutical interest.

Aerobic Heterogeneous Palladium-Catalyzed Oxidative Allenic C−H Arylation:Benzoquinone as a Direct Redox Mediator between O_(2)and Pd

Transitionmetal-catalyzedaerobicoxidativereactions using molecular oxygen as the terminal oxidant play a significant role in organic synthesis.Benzoquinone(BQ)has been widely used as an electron-transfer mediator(ETM)in biomimetic palladium-catalyzed aerobic oxidative reactions,but always together with an ETM between O_(2) and BQ,such as a macrocyclic metal complex.Herein,we report on a heterogeneous palladium-catalyzed allenic C(sp3)-H arylation with only catalytic amounts of BQ under air without the need of an additional ETM.Arange ofmultisubstituted 1,3-dienes were synthesized under mild reaction conditions.Mechanistic studies reveal the bifunctional role of BQ as a ligand for reductive elimination and as an ETM between Pd(0)and O_(2).This new regime of oxidation has important implications for further development of other transition metal-catalyzed aerobic oxidative reactions.