Lewis acid-catalyzed asymmetric synthesis of complex chiral-fluorinated aminoesters via addition of acyclic silyl dienolates to α-fluoroalkyl sulfinylimines

<p>A Lewis acid-catalyzed asymmetric addition reaction of β-methyl- or γ-methyl-substituted acyclic silyl dienolates <b>2</b> with α-fluoroalkylsulfinylimines <b>1</b> furnished complex fluorinated aminoesters in high yield under stereocontrol. Two different transition states were proposed to explain the observed selectivity.</p

AgBF₄ catalyzed regio- and stereoselective synthesis of <i>trans</i> α-vinyl-β-amino esters via asymmetric addition of siyl dienolate to sulfinylimines

<p>AgBF₄ catalyzed Mannich-type reactions of siyl dienolate with chiral aryl-substituted (<i>S</i>)-<i>N</i>-<i>tert</i>-butanesulfinylimines has been developed. A class of chiral <i>trans</i> α-vinyl-β-amino esters was obtained in moderate to excellent yields (up to 93%), good diastereoselectiveties (up to 92:8 dr), and complete α-site regioselectivity.</p

Iron-catalyzed aerobic oxidative phosphonation of <i>N</i>-aryl tetrahydroisoquinolines

<p></p> <p>We report herein a novel and efficient method for iron-catalyzed aerobic oxidative phosphonation of <i>N</i>-aryl tetrahydroisoquinolines for the synthesis of biologically interesting α-aminophosphonates. This new C–P bond formation reaction features the employment of a sustainable and cost-effective iron salt [Fe(NO₃)₃·9H₂O] as catalyst, the utilization of air as environmental-benign oxidant, as well as the user-friendly open-flask reaction conditions.</p

Manganese-Catalyzed Aerobic Oxytrifluoromethylation of Styrene Derivatives Using CF₃SO₂Na as the Trifluoromethyl Source

A mild and practical protocol for manganese-catalyzed aerobic oxytrifluoromethylation of olefinic bonds of styrene derivatives using CF₃SO₂Na (Langlois’ reagent) as the CF₃ source is described. A distinguishing feature of this method is the generation of trifluoromethyl radicals from CF₃SO₂Na using the simple manganese salt/O₂ system. The reaction proceeds under ambient conditions, free of added peroxide initiators, and provides moderate to good selectivities for alcohol versus ketone product

Design, synthesis and biological evaluation of 3-fluoroalkenyloxindole ring-fused 3-trifluoromethyloxindoles obtained from indoline-2,3-diones and difluoromethylene phosphabetaine

<p></p> <p>A wide variety of multi-substituted 3-fluoroalkenyloxindole ring-fused 3-trifluoromethyloxindoles were obtained in good yields by the reaction of indoline-2,3-diones with difluoromethylene phosphabetaine. Their biological activities against human prostate cancer cells <b>PC-3</b> and human Breast cancer cells <b>MCF-7</b> have been preliminarily demonstrated, using MTT-based assays with the commercially available standard drug Paclitaxel as a positive control. Several compounds exhibited comparable <i>in vitro</i> inhibitory activities against human prostate cancer cells <b>PC-3</b> and human Breast cancer cells <b>MCF-7</b> to Paclitaxel. These results indicate that 3-fluoroalkenyloxindole ring-fused 3-trifluoromethyloxindoles may be potential lead compounds for further biological screening.</p

Investigation of the roles of ERK, JNK, and PKC in the regulation of miR-21 expression upon HCV infection.

<p>(A) Huh7 cells were co-transfected with miPPR21 and pCMV-NS5A (<i>left panel</i>) or pCMV-NS3/4A (<i>right panel</i>) for 24 h, and then signal pathway specific inhibitors (20 µM each) were then added, as indicated. The cells were lysed and luciferase activity was measured. (B) Cells were transfected with pCMV-NS5A (<i>left panel</i>) or pCMV-NS3/4A (right panel) for 24 h, and then treated with the signal pathway inhibitors (20 µM each) as indicated. The phosphorylation and total protein levels of c-Jun (<i>left panel</i>) and c-Fos (<i>right panel</i>) were determined by Western blot (<i>upper panel</i>), and miR-21 expression was measured by qPCR (<i>lower panel</i>). (C) Huh7 cells were co-transfected with miPPR21 and dominant-negative mutants of ERK1 (mERK1), ERK2 (mERK2), JNK (mJNK) or control vectors at different concentrations, as indicated and the resultant luciferase activities were measured. All experiments were repeated at least three times with similar results. Bar graphs represent the means ± SD, n = 3.</p

Determination of the expression of miR-21 during HCV infection in hepatocytes.

<p>(<i>A</i>) Human Huh7 hepatocytes were infected with or without HCV (MOI = 1) for different times as indicated. The expression of miR-21 was measured by qPCR and normalized to the expression of U6 in each sample. Results are standardized to 1 in uninfected cells. (<i>B</i>) Human Huh7 hepatocytes were infected with or without HCV at different MOIs, as indicated, for 12 h, and expression miR-21 was determined by qPCR. Data are presented as the meansSD (n = 3) from one representative experiment. Similar results were obtained in three independent experiments.</p

Proposed model for the activation of miR-21 expression upon HCV infection and the role of miR-21 in the regulation of the antiviral activity of type I IFN.

<p>During HCV infection, the virus is first recognized by TLRs and RIG-1, which in turn activates MyD88 and IRAK1 to initiate IFN-α synthesis, resulting in the activation of ISGs and the inhibition of HCV replication. In addition, miR-21 expression is activated during HCV infection through two signaling pathways: the PKCε/JNK/c-Jun pathway and the PKCα/ERK/c-Fos pathway. The HCV NS5A protein activates PKCε to enhance the expression of JNK and c-Jun, while the HCV NS3/4A complex stimulates PKCα to promote the production of ERK and c-Fos. The two subunits (c-Jun and c-Fos) of AP-1 join together to recognize the miR-21 promoter and activate the expression of miR-21, which represses the expression of MyD88 and IRAK1 via imperfect base pairing between miR-21 and the 3′UTR of MyD88 and IRAK1. The reduction in MyD88 and IRAK1 causes a reduction of type-I IFN production and ISG expression that might contribute to viral pathogenesis and virus propagation.</p

miR-21 suppresses HCV-triggered type I IFN production.

<p>(A) Human Huh7 hepatocytes (0.5 ml, 2×10⁵ cells) were transfected with control miRNA (miR-ctrl) or miR-21 mimics (<i>left</i>), and control inhibitor (ctrl) or miR-21 inhibitor (<i>right</i>), as indicated at a final concentration of 50 nM. RNA was isolated 48 h post-transfection, and miR-21 expression was measured by qPCR and normalized to U6 snRNA. Results are standardized to 1 in control cells. (B) Huh7 hepatocytes were infected with or without HCV (MOI = 1) for different times as indicated. IFN-α mRNA levels (<i>left</i>) were determined by qPCR and normalized to the expression of GAPDH in each sample. IFN-α secretion into the cell culture medium (<i>right</i>) was measured by ELISA. (<i>C</i> and <i>D</i>) Huh7 hepatocytes were transfected with miR-21 mimics or control RNA (<i>C</i>), miR-21 inhibitor or control inhibitor (<i>D</i>), as indicated. After 48 h, the cells were transfected with FL-J6/JFH5′C19Rluc2AUbi (0.1 µg) for the indicated time. IFN-α mRNA levels were determined by qPCR, and IFN-α secretion into the medium was measured by ELISA. Data are shown as the meansSD (n = 3) from one representative experiment. Similar results were obtained in three independent experiments. **, p<0.01; *, p<0.05.</p

miR-21 regulates components of the Toll-like receptor 7 signaling cascade.

<p>Huh7 hepatocytes were transfected with miR-21 mimics or control RNA, miR-21 inhibitor or control inhibitor (final concentration, 50 nM). After 48 h, MyD88, IRAK1, IRAK4, and TRAF6 mRNA levels were determined by qPCR (<i>A</i>, <i>B</i>, <i>C</i>, and <i>D</i>) and RT-PCR (<i>E</i> and <i>F</i>), respectively. Data are presented as the meansSD (n = 3) from one representative experiment. Similar results were obtained in three independent experiments. **, p<0.01; *, p<0.05.</p