Selectivity of PEG/Salt Aqueous Two-Phase System Enhanced by Surfactant@MWCNT Composites.

Aqueous two-phase systems (ATPS) are considered a new type of green separation system, but their low selectivity to target molecules limits their practical application. In this study, we used surfactant@MWCNT as an adjuvant to improve the selectivity of PEG/(NH4)2SO4 ATPS. The surfactants used include Triton X-100 (TX-100), Tween 80, sodium dodecyl sulfate (SDS), sodium dodecyl benzenesulfonate (SDBS), and bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT). Nine aromatic compounds, including syringic acid, vanillin, tryptophan, phenylalanine, tyrosine, mandelic acid, theophylline, theobromine, and cephalexin, were selected as model extracts. The results showed that the use of the surfactant@MWCNT composite as an adjuvant significantly improved the selectivity of the ATPS toward syringic acid among the nine extracts. Moreover, the selectivity of the ATPS for syringic acid with the TX-100/MWCNT composite as the adjuvant is better than that with the Tween 80/MWCNT composite as the adjuvant, followed by that with the anionic surfactant/MWCNT composite as the adjuvant. The enhanced selectivity of ATPS by the surfactant/MWCNT composite is ascribed to the spatial effect and the electrostatic and hydrophobic interactions between the extract and the surfactant adsorbed on the MWCNT.

Ion Exchange-mediated 3D Cross-linked ZIF-L Superstructure for Flexible Electrochemical Energy Storage.

Metal-organic frameworks (MOFs) are considered as a promising candidate for advancing energy storage owing to their intrinsic multi-channel architecture, high theoretical capacity, and precise adjustability. However, the low conductivity and poor structural stability lead to unsatisfactory rate and cycling performance, greatly hindering their practical application. Herein, we propose a sea urchin-like Co-ZIF-L superstructure using molecular template to induce self-assembly followed by ion exchange method, which shows improved conductivity, successive channels, and high stability. The ion exchange can gradually etch the superstructure, leading to the reconstruction of Co-ZIF-L with three-dimensional (3D) cross-linked ultrathin porous nanosheets. Moreover, the precise control of Co to Ni ratios can construct effective micro-electric field and synergistically enhance the rapid transfer of electrons and electrolyte ions, improving the conductivity and stability of CoNi-ZIF-L. The Co6.53Ni-ZIF-L electrode exhibits a high specific capacity (602 F g-1 at 1 A g-1) and long cycling stability (95.3% retention after 4,000 cycles at 5 A g-1). The Co6.53Ni-ZIF-L//AC asymmetric flexible supercapacitor employing gel electrolyte also exhibits excellent cycling stability (93.3% retention after 4000 cycles at 5 A g-1). This discovery provides valuable insights for electrode material selection and energy storage efficiency improvement.

Adsorption Mechanism of Benzene Derivatives by Pagoda[n]arenes.

Despite the widespread use in industrial production, benzene derivatives are harmful to both human beings and the environment. The control of these substances has become an important subject of scientific research. This study introduces a new approach for adsorption and separation of benzene derivatives utilizing pagoda[n]arene based supramolecular materials. Density functional theory calculations were employed to investigate the molecular recognition mechanism of benzene derivatives by pagoda[4]arenes and pagoda[5]arenes (Pa[4]As and Pa[5]As). Results indicate that Pa[4]As and Pa[5]As can effectively accommodate benzene derivatives through non-covalent interactions, leading to the formation of stable host-guest complexes. Additionally, molecular dynamics simulations revealed that both crystalline and non-crystalline supramolecular aggregates of Pa[4]As and Pa[5]As possess the ability to adsorb benzene derivatives and maintain the stability of the adsorption. Moreover, increasing the temperature causes benzene derivatives to desorb from the adsorbing aggregates, and thus the material can be reutilized.

Efficacy of High-Frequency Repetitive Transcranial Magnetic Stimulation at 10 Hz in Fibromyalgia: A Systematic Review and Meta-analysis.

OBJECTIVE: The purpose of this review was to systematically assess the effectiveness of 10-Hz repetitive transcranial magnetic stimulation (rTMS) in fibromyalgia. DATA SOURCES: We searched PubMed, Cochrane Library, Embase, Web of Science, and Ovid databases as of November 6, 2021. STUDY SELECTION: The inclusion criteria for this review were randomized controlled trials of 10-Hz rTMS for fibromyalgia, exploring the effects of 10-Hz rTMS on pain, depression, and quality of life in patients with fibromyalgia. DATA EXTRACTION: Data extraction was performed independently by 2 evaluators according to predefined criteria, and the quality of the included literature was assessed using the Cochrane Bias Risk Assessment Tool. The measurement outcomes include visual analog scale, Hamilton Depression Rating Scale, and Fibromyalgia Impact Questionnaire, and so on. DATA SYNTHESIS: A total of 488 articles were screened, and the final 7 selected high-quality articles with 217 patients met our inclusion criteria. Analysis of the results showed that high-frequency transcranial magnetic stimulation at 10 Hz was significantly associated with reduced pain compared with sham stimulation in controls (standardized mean difference [SMD]=-0.72; 95% confidence interval [CI], -1.12 to -0.33; P<.001; I2=46%) and was able to improve quality of life (SMD=-0.70; 95% CI, -1.00 to -0.40; P<.001; I2=15%) but not improve depression (SMD=-0.23; 95% CI, -0.50 to 0.05; P=.11; I2=33%). In addition, a subgroup analysis of pain conducted based on stimulation at the primary motor cortex and dorsolateral prefrontal cortex showed no significant difference (SMD=-0.72; 95% CI, -1.12 to -0.33; P=.10; I2=62%). CONCLUSIONS: Overall, 10-Hz rTMS has a significant effect on analgesia and improved quality of life in patients with FMS but did not improve depression.

Polyoxometalate-Cyclodextrin-Based Cluster-Organic Supramolecular Framework for Polysulfide Conversion and Guest-Host Recognition in Lithium-sulfur Batteries.

Developing polyoxometalate-cyclodextrin cluster-organic supramolecular framework (POM-CD-COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM-CD-COSF crystalline structure produced through the self-assembly process of a Krebs-type POM, [Zn2 (WO2 )2 (SbW9 O33 )2 ]10- , and two ß-CD units. The as-prepared POM-CD-COSF-based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm-2 ) to mitigate the polysulfide shuttle effect in lithium-sulfur batteries. The designed Li-S batteries equipped with the POM-CD-COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li+ diffusion through the supramolecular channel of ß-CD, efficient polysulfide-capture ability by the dynamic host-guest interaction of ß-CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li-S batteries.

Bifunctional monomer oligomers-based composite molecularly imprinted membranes for the electrochemical monitoring of Sudan I.

Herein, we developed a highly sensitive electrochemical sensor for the trace detection of Sudan I (SDI) dye based on composite molecularly imprinted membranes (MIMs). The pentenyl (lipoic acyl)-isoleucyl-chitosan oligosaccharide (P(L)ICO) and pentenyl-asparaginyl-chitosan oligosaccharide (PASCO) served as bifunctional monomer oligomers. After deposition of gold nanoparticles on a glassy carbon electrode (GCE) surface, a P(L)ICO layer successfully self-assembled on the surface. Subsequently, the primary MIM was polymerised on the electrode surface by using SDI as a template, PASCO as a functional monomer oligomer, and ethylene glycol dimethacrylate as a cross-linking agent. Electrochemical polymerisation was then conducted in an N,N'-methylenebisacrylamide solution. After eluting the SDI molecules from the composite MIMs, the fabricated SDI-MIM(PM)/Fn-Au/GCE demonstrated specific adsorption of SDI. Under optimal conditions, the constructed sensor exhibited a linear relationship between decreasing peak current and SDI concentration from 0.02 to 3.5 µM with a low detection limit of 4 nM (S/N = 3). As a proof of concept, SDI-MIM(PM)/Fn-Au/GCE was also applied to detect SDI in chili powder samples, with recoveries ranging from 96.8 to 106.6%.

Unravelling the effects of complexation of transition metal ions on the hydroxylation of catechol over the whole pH region.

Catechol pollutants (CATPs) serving as chelating agents could coordinate with many metal ions to form various CATPs-metal complexes. Little information is available on the effects of complexation of metal ions on CATPs degradation. This work presents a systematical study of •OH-mediated degradation of catechol and catechol-metal complexes over the whole pH range in advanced oxidation processes (AOPs). Results show that the pH-dependent complexation of metal ions (Zn2+, Cu2+, Ti4+ and Fe3+) promotes the deprotonation of catechol under neutral and even acidic conditions. The radical adduct formation (RAF) reactions are both thermodynamically and kinetically favorable for all dissociation and complexation species, and OH/O- group-containing C positions are more vulnerable to •OH attack. The kinetic results show that the complexation of the four metal ions offers a wide pH range of effectiveness for catechol degradation. At pH 7, the apparent rate constant (kapp) values for different systems follow the order of catechol+Ti4+ ≈ catechol+Zn2+ > catechol+Cu2+ > catechol+Fe3+ > catechol. The mechanistic and kinetic results would greatly improve our understanding of the degradation of CATPs-metal and other organics-metal complexes in AOPs. The toxicity assessment indicates that the •OH-based AOPs have the ability for decreasing the toxicity and increasing the biodegradability during the processes of catechol degradation.

Embedding Cobalt Atom Clusters in CNT-Wired MoS2 Tube-in-Tube Nanostructures with Enhanced Sulfur Immobilization and Catalyzation for Li-S Batteries.

Lithium-sulfur batteries are one of the most promising next-generation energy storage systems. The efficient interconversion between sulfur/lithium polysulfides and lithium sulfide is a performance-determining factor for lithium-sulfur batteries. Herein, a novel strategy to synthesize a unique tube-in-tube CNT-wired sulfur-deficient MoS2 nanostructure embedding cobalt atom clusters as an efficient polysulfide regulator is successfully conducted in Li-S batteries. It is confirmed that encapsulating MWCNTs into hollow porous sulfur-deficient MoS2 nanotubes embedded with metal cobalt clusters not only can accelerate electron transport and confine the dissolution of lithium polysulfide by physical/chemical adsorption, but also can catalyze the kinetics of polysulfide redox reactions. Based on DFT calculations, in situ spectroscopic techniques, and various electrochemical studies, catalytic effects of CNT/MoS2 -Co nanocomposite in Li-S battery are deeply investigated for the first time. The CNT/MoS2 -Co composite cathode exhibits a very remarkable rate capability (641 mAh g-1 at 5.0 C) and excellent cycling stability (capacity decay rate of 0.050% per cycle at 5.0 C) even at high sulfur mass loading of 3.6 mg cm-2 . More crucially, CNT/MoS2 -Co tube-in-tube nanostructures present a superior specific capacity of 650 mAh g-1 in a Li-S pouch cell at 0.2 C (4.0 mg cm-2 ).

Construction of Polyfunctionalized 2,4-Dioxa-8-azaspiro[5.5]undec-9-enes and 2,4,8-Triazaspiro[5.5]undec-9-enes via a Domino [2+2+2] Cycloaddition Reaction.

The three-component reaction of α,ß-unsaturated N-arylaldimines, dialkyl but-2-ynedioates, and 2-arylidene Meldrum acids in DCM at room temperature gave mixtures of cis/trans-11-aryl-7-styryl-2,4-dioxa-8-azaspiro[5.5]undec-9-enes in satisfactory yields. The similar three-component reaction with 2-arylidene-N,N'-dimethylbarbituric acids afforded cis-11-phenyl-7-styryl-2,4,8-triazaspiro[5.5]undec-9-enes as major products. On the other hand, the three-component reaction of N-arylaldimines, dialkyl but-2-ynedioates, and 2-arylidene Meldrum acids or 2-arylidene-N,N'-dimethylbarbituric acids afforded cis/trans-isomeric spirocompounds in satisfactory yields with high diastereoselectivity. This domino [2+2+2] cycloaddition reaction proceeded with sequential nucleophilic addition of N-arylaldimine to an electron-deficient alkyne, Michael addition, and annulation process. The stereochemistry of all cis/trans isomeric spirocompounds was clearly elucidated by the determination of 33 single-crystal structures. The diastereoselectivity of the three-component reaction was correlated by DFT calculations.

Ozonolysis of Permethrin in the Atmosphere: Mechanism, Kinetics, and Evaluation of Toxicity.

Pyrethroid, a pesticide widely used worldwide, could mimic, block, or synergize the effects of endogenous hormones in humans or mammals after entering into the atmosphere and after being sprayed and applied in large quantities. This research aims to study the mechanism, kinetics, and eco-toxicity evaluation of the ozonolysis of permethrin (PER)-one of the typical pyrethroid (type I) pesticides. Existing experimental studies only predicted that ozonolysis of PER could generate a cycloperoxy analogue of PER (IM13-1-11), and the reaction mechanism has not yet been completed. To make up for the lack of experimental results, the 13 primary reaction pathways of PER and ozone, as well as the subsequent reactions of Criegee intermediates with small molecules such as NOx, COx, SO2, and O2, have been studied to propose new reaction paths by quantum chemical calculations in this work. We calculated the total reaction rate constant of PER and ozone at 298 K and 1 atm based on the calculated thermodynamic data and the transition state theory (TST), which was compared with the experimental values to prove the reliability of our results. Based on the quantitative structure and activity relationship, we predicted the acute and chronic toxicity of PER and its products of ozonolysis to three representative organisms-fish, daphnia, and green algae to avoid animal experiments. The results show that ozonolysis products of PER are still extremely harmful to the environment and should be taken seriously, although the products have less toxicity than PER.

Theoretical Study of Ozonation of Methylparaben and Ethylparaben in Aqueous Solution.

Parabens are widely employed in toothpaste, cosmetics, textiles, beverages, and preservatives, causing a serious environmental concern because they are endocrine-disrupting compounds (EDCs). As one of the highly reactive oxidants, ozone has a great effect on EDC removal. To understand the degradation and transformation of parabens in the aquatic environment and their toxicity to aquatic organisms, the degradation reaction of parabens initiated by O3 was studied meticulously using quantum chemical calculations. The degradation process includes multiple initial reaction channels and consequent degradation pathways of the Criegee intermediates. Through thermodynamic data, the rate constants were computed using the transition state theory (TST). At a temperature of 298 K and a pressure of 1 atm, the calculated rate constants were 3.92 and 3.94 M-1 s-1 for methylparaben (MPB) and ethylparaben (EPB), respectively. The rate constants increased as the temperature increased or as the length of the alkyl chain on the benzene ring increased. Through the ecotoxicity assessment procedure, the ecotoxicity of parabens and the products in the degradation process can be assessed. Most degradation byproducts are either less toxic or nontoxic. Some byproducts are still harmful, such as oxalaldehyde (P2) and ethyl 2,3-dioxopropanoate (P10). Furthermore, the ecological toxicity of parabens increased with augmentation of the alkyl chain on the benzene ring. The effect of the alkyl chain length on the benzene ring in the compound cannot be ignored.

Ozonation of diclofenac in the aqueous solution: Mechanism, kinetics and ecotoxicity assessment.

The pharmaceutical and personal care products (PPCPs) in aquatic environment have aroused more interest recently. Many of them are hard to degrade by the typical biological treatments. Diclofenac (DCF), as a significant anti-inflammatory drug, is a typical PPCP and widely existed in water environment. It is reported that DCF has adverse effects on aquatic organisms. This work aims to investigate the mechanism, kinetics and ecotoxicity assessment of DCF transformation initiated by O3 in aqueous solution, and provide a solution to the degradation of DCF. The O3-initiated oxidative degradations of DCF were performed by quantum chemical calculations, including thirteen primary reaction pathways and subsequent reactions of the Criegee intermediates with H2O, NO and O3. Based on the thermodynamic data, the kinetic parameters were calculated by the transition state theory (TST). The total reaction rate constant of DCF initiated by O3 is 2.57 × 103 M-1 s-1 at 298 K and 1 atm. The results show that the reaction rate constants have a good correlation with temperature. The acute and chronic toxicities of DCF and its degradation products were evaluated at three different trophic levels by the ECOSAR program. Most products are converted into less toxic or harmless products. Oxalaldehyde (P3) and N-(2,6-dichlorophenyl)-2-oxoacetamide (P6) are still harmful to the three aquatic organisms, which should be paid more attention in the future.

Theoretical investigation on the contribution of HO, SO4- and CO3- radicals to the degradation of phenacetin in water: Mechanisms, kinetics, and toxicity evaluation.

Indirect oxidation induced by reactive free radicals, such as hydroxyl radical (HO), sulfate radical (SO4-) and carbonate radical (CO3-), plays an important or even crucial role in the degradation of micropollutants. Thus, the coadjutant degradation of phenacetin (PNT) by HO, SO4- and CO3-, as well as the synergistic effect of O2 on HO and HO2 were studied through mechanism, kinetics and toxicity evaluation. The results showed that the degradation of PNT was mainly caused by radical adduct formation (RAF) reaction (69% for Г, the same as below) and H atom transfer (HAT) reaction (31%) of HO. For the two inorganic anionic radicals, SO4- initiated PNT degradation by sequential radical addition-elimination (SRAE; 55%), HAT (28%) and single electron transfer (SET; 17%) reactions, while only by HAT reaction for CO3-. The total initial reaction rate constants of PNT by three radicals were in the order: SO4- > HO > CO3-. The kinetics of PNT degradation simulated by Kintecus program showed that UV/persulfate could degrade target compound more effectively than UV/H2O2 in ultrapure water. In the subsequent reaction of PNT with O2, HO and HO2, the formation of mono/di/tri-hydroxyl substitutions and unsaturated aldehydes/ketones/alcohols were confirmed. The results of toxicity assessment showed that the acute and chronic toxicity of most products to fish increased and to daphnia decreased, and acute toxicity to green algae decreased while chronic toxicity increased.

Degradation of prosulfocarb by hydroxyl radicals in gas and aqueous phase: Mechanisms, kinetics and toxicity.

Prosulfocarb (PSC) is a thiocarbamate herbicide mainly used in winter cereals and a relevant aerosol precursor under OH radicals (OH) photooxidation conditions. We investigated the environmental risks, mechanisms, kinetics and products for the PSC withOH by employing theoretical chemical calculations. Two reaction types of H-abstraction andOH-addition reactions were taken into account. Whether in the atmosphere or aqueous particles, the most favorable pathway was the H-abstraction in the N-alkyl groups close to nitrogen atom. Subsequent reactions of primary intermediates were considered at different conditions. The total rate constants were determined as 2.62 × 10-10 cm3 molecule-1 s-1 and 4.96 × 10-11 cm3 molecule-1 s-1 at 298 K in atmosphere and aqueous particles, respectively. In natural water with theOH concentration of 10-15-10-18 mol l-1, the half-lives (t1/2) of PSC in theOH-initiated reactions were calculated as t1/2 = 2.40 × 104-2.40 × 107 s. With regard to the influence on human health and the ecosystem, oxidized products of PSC were estimated to be mutagenicity negative and had no obvious bioaccumulation potential. The aquatic toxicity of PSC and its degradation products was evaluated and the assessment results showed that the degradation of PSC was a toxicity-reduced process but they were still at toxic and harmful levels.

Mechanisms and Kinetic Parameters for the Gas-Phase Reactions of 3-Methyl-3-buten-2-one and 3-Methyl-3-penten-2-one with Ozone.

Ozonolysis of unsaturated ketones is a common atmospheric chemical process that plays a significant role in controlling the atmospheric budget of OH and O3, organic acids, and secondary organic aerosols (SOA). In this work, the detailed reaction mechanism and rate coefficients for the reactions of O3 with two unsaturated ketones, 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2-one (MPO332), were investigated by using density functional theory (DFT) and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The results indicate that the major products are butanedione and formaldehyde for MBO332, and butanedione and acetaldehyde for MPO332. Possible reaction mechanism and thermodynamic parameters of some complex stable Criegee intermediates (SCIs) RR'COO were also be investigated in this study. Some organic peroxides can be regarded as the main products for the further reactions of SCIs. The rate constants calculated with O3 are 2.59 × 10-16 cm3 molecule-1 s-1 and 2.28 × 10-16 cm3 molecule-1 s-1 for MBO332 and MPO332 at 298 K and 1 atm. The total rate constant is negatively correlated with temperature (200-400 K) and positively correlated with pressure. The atmospheric half-lives of MBO332 and MPO332 based on O3 are estimated.

Controllable Supramolecular Chiral Twisted Nanoribbons from Achiral Conjugated Oligoaniline Derivatives.

The fabrication of supramolecular chiral nanostructures from achiral materials without the need of pre-existing chirality is a major challenge associated with the origin of life. Herein, supramolecular chiral twisted nanoribbons of achiral oligoaniline derivatives were prepared via simply performing the chemical oxidation of aniline in an alcohol/water mixed solvent. In particular, the supramolecular chirality of the twisted nanoribbons could be controlled by facilely tuning the alcohol content in the mixed solvent. A tetra-aniline derivative C24H20O3N4 was attested to be the major component of the obtained nanoribbons. The main driving forces for the assembly of the oligoaniline derivative into twisted nanoribbons might be the π-π stacking and hydrogen bonding interactions among the chains which could be modulated by the alcohol content in the mixed solvent. The single-handed twisted nanoribbons could be used to separate chiral phenylalanine from a racemic mixture. Thus, it is highly anticipated that the supramolecular chirality endows π-conjugated molecules with potential application in chiral recognition.

Ionic S(N)i-Si Nucleophilic Substitution in N-Methylaniline-Induced Si-Si Bond Cleavages of Si2Cl6.

N-Methylaniline-induced Si-Si bond cleavage of Si2Cl6 has been theoretically studied. All calculations were performed by using DFT at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) levels. An ionic SN i-Si nucleophilic substitution mechanism, which is a newly found nucleophilic substitution in silicon-containing compounds, is proposed in the N-methylaniline-induced Si-Si bond cleavage in Si2Cl6. Unlike general S(N)i-Si nucleophilic substitutions that go through a pentacoordinated silicon transition state, ionic nucleophilic substitution goes through a tetracoordinated silicon transition state, in which the Si-Si bond is broken and siliconium ions are formed. Special cleavage of the Si-Si bond is presumably due to the good bonding strength between Si and N atoms, which leads to polarization of the Si-Si bond and eventually to heterolytic cleavage. Calculation results show that, in excess N-methylaniline, the final products of the reaction, including (NMePh)(3-n) SiHCl(n) (n=0-2) and (NMePh)(4-n) SiCl(n) (n=2-3), are the Si-Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic S(N)i-Si nucleophilic substitution mechanism can also be employed to describe the amination of chlorosilane by N-methylaniline. The suggested mechanisms are consistent with experimental data.

EGFL7-overexpressing epidermal stem cells promotes fibroblast proliferation and migration via mediating cell adhesion and strengthening cytoskeleton.

Epidermal growth factor (EGF)-like family members mediate a wide range of biological activities including cell proliferation and migration. Increasing evidence indicated that EGF plays an important role in the process of wound healing by stimulating fibroblast motility. The aim of this study was to see whether EGF-like domain 7 (EGFL7)-overexpressing epidermal stem cells (EGFL7-ESCs) would promote fibroblast proliferation and migration. We found that mRNA and protein levels of EGFL7 expression were significantly increased in EGFL7-ESCs. The protein expression of EGFL7 was significantly elevated in conditioned media (CM) of EGFL7-ESCs compared to ESCs CM or vector-ESCs CM. The cell count and cell viability of EGFL7-ESCs CM-treated fibroblasts were also significantly increased compared to control. In addition, EGFL7-ESCs CM-treated fibroblasts showed elevated migration compared with control. Moreover, the expressions of ß1-integrin, ß-tubulin, ß-actin, and Vimentin were increased, while that of E-cadherin was decreased in EGFL7-ESCs CM-treated fibroblasts. These results indicate that EGFL7-ESCs contribute towards promoting fibroblast migration through enhancing cell adhesion, strengthening cytoskeleton, and reducing intercellular aggregation. These findings suggest that the stimulating effect of EGFL7-ESCs on fibroblast proliferation and migration may provide a useful strategy for wound healing.

Molecular diversity of the three-component reaction of α-amino acids, dialkyl acetylenedicarboxylates and N-substituted maleimides.

The one-pot three-component reaction of secondary α-amino acids, including proline, thiazolidine-4-carboxylic acid, and piperidine-2-carboxylic acid sarcosine with dialkyl acetylenedicarboxylate and N-substituted maleimides in refluxing ethanol afforded functionalized pyrrolo[3,4-a]pyrrolizines, pyrrolo[3',4':3,4]pyrrolo[1,2-c]thiazoles, pyrrolo[3,4-a]indolizines and octahydropyrrolo[3,4-c]pyrroles in good yields and with high diastereoselectivity. On the other hand, the similar three-component reaction containing primary α-amino acids, such as glycine, alanine, phenylalanine and leucine, with N-substituted maleimides and two molecules of dialkyl acetylenedicarboxylate obtained the corresponding hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl)maleates.

[The anti-apoptotic effect of cytoplasmic alpha-fetoprotein in hepatoma cells induced by all-trans retinoic acid involves activation of the PI3K/AKT signaling pathway].

OBJECTIVE: To explore the effect of alpha-fetoprotein (AFP) on transduction of the PI3K/ AKT signal in hepatocellular carcinoma cells and the role played by AFP in resistance to cytotoxicity of all-trans retinoic acid (ATRA). METHODS: The effects of ATRA of human liver cancer cells was assessed using the BEL-7402 cell line with the MTT assay (to evaluate proliferation), microscopy (to evaluate morphology), flow cytometry (to evaluate apoptosis), laser confocal microscopy and coimmunoprecipitation (co-IP; to evaluate co-localization and interaction of AFP with PTEN), Western blotting (to evaluate expression of phosphorylated-protein kinase B (pAKT) and Src, and RNA interference (RNAi)-mediated knockdown of AFP. Finally, application of the PI3K-specific inhibitor Ly294002 was used to monitor the influence of AFP in transduction of the PI3K signal pathway. RESULTS: The human hepatoma cell line BEL-7402 were resistant to ATRA cytotoxicity. PTEN and AFP co-localized in the cytoplasm, and co-IP indicated that AFP interacts with PTEN in BEL-7402 cells.RNAi knockdown of AFP expression led to reduced growth of BEL-7402 cells.BEL-7402 cells transfected with AFP-short interfering (si)RNA vectors showed enhanced sensitivity to ATRA and reduced expression of pAKT(Ser473) and Src; Ly294002 reduced the role of AFP in stimulating expression of pAKT(Ser473) and Src. CONCLUSION: AFP can activate transduction of the PI3K/AKT signal, and expression of AFP in hepatoma cells is a pivotal event for resisting ATRA-induced apoptosis.