Cytotoxic ent-Abietane-type diterpenoids from the roots of Euphorbia ebracteolata

Euphoroids A–C (1–3), three new ent-abietane-type diterpenoids, together with ten known analogues (4–13) were obtained from the roots of Euphorbia ebracteolata. The structures of these compounds were determined by extensive spectroscopic data analysis, including UV, HRESIMS, 1D-, and 2D-NMR data. The inhibitory effects of compounds 1–13 on human cancer cells were determined using the MTT assay. The results revealed that new compounds 2 and 3 showed moderate cytotoxic activities against human cancer cell lines. Especially, compound 3 displayed selective cytotoxic effect agains cancer cell lines.     

Diterpenoids from the roots of Euphorbia ebracteolata and their anti-tuberculosis effects

Euphorbia ebracteolata was a natural medicine for the treatment of tuberculosis. The present work has performed the investigation of bioactive chemical substances from the roots of E. ebracteolata. Using various chromatographic techniques, 15 compounds were obtained from the roots of E. ebracteolata. On the basis of widely spectroscopic data analyses, the isolated compounds were determined to be diterpenoids, including rosane derivatives (1–12), isopimarane (13), abietane (14), and lathyrane (15), among which compounds 1–4, and 9 were undescribed previously. The inhibitory effects of isolated diterpenoids against Mycobacterium tuberculosis were evaluated using an Alamar blue cell viability assay. And two rosane-type diterpenoids 3 and 8 displayed moderate inhibitory effects on with the MIC values of 18 μg/mL and 25 μg/mL, respectively. For the potential inhibitor 3, the inhibitory effect against the target enzyme GlmU was evaluated, which displayed a moderate inhibitory effect with the IC₅₀ 12.5 μg/mL. Therefore, the diterpenoids from the roots of E. ebracteolata displayed anti-tuberculosis effects, which would be pay more attentions for the anti-tuberculosis agents.     

Crystal structure of human enterovirus 71 3C protease

Human enterovirus 71 (EV71) is the major pathogen that causes hand, foot and mouth disease that particularly affects young children. Growing hand, foot and mouth disease outbreaks were observed worldwide in recent years and caused devastating losses both economically and politically. However, vaccines or effective drugs are unavailable to date. The genome of EV71 consists of a positive sense, single-stranded RNA of ∼ 7400 bp, encoding a large precursor polyprotein that requires proteolytic processing to generate mature viral proteins. The proteolytic processing mainly depends on EV71 3C protease (3C^pro) that possesses both proteolysis and RNA binding activities, which enable the protease to perform multiple tasks in viral replication and pathogen-host interactions. The central roles played by EV71 3C^pro make it an appealing target for antiviral drug development. We determined the first crystal structure of EV71 3C^pro and analyzed its enzymatic activity. The crystal structure shows that EV71 3C^pro has a typical chymotrypsin-like fold that is common in picornaviral 3C^pro. Strikingly, we found an important surface loop, also denoted as β-ribbon, which adopts a novel open conformation in EV71 3C^pro. We identified two important residues located at the base of the β-ribbon, Gly123 and His133, which form hinges that govern the intrinsic flexibility of the ribbon. Structure-guided mutagenesis studies revealed that the hinge residues are important to EV71 3C^pro proteolytic activities. In summary, our work provides the first structural insight into EV71 3C^pro, including a mobile β-ribbon, which is relevant to the proteolytic mechanism. Our data also provides a framework for structure-guided inhibitor design against EV71 3C^pro.     

Three new diterpenes with cytotoxic activity from the roots of Euphorbia ebracteolata Hayata

From the roots of Euphorbia ebracteolata Hayata, three new diterpenes, Ebracteolatas A–C, based on the rosane (1–2) and lathyrane (3) skeleton, were isolated together with four known ones (4–7). Their structures and relative configurations were elucidated on the basis of spectroscopic methods, especially 2D NMR techniques. Compounds 1, 6, and 7 exhibited moderate cytotoxic effects against five cancer cell lines.     

Expression and purification of enterovirus type 71 polyprotein P1 using Pichia pastoris system

Enterovirus type 71(EV71) causes severe hand-foot-and-mouth disease (HFMD) resulting in hundreds of deaths of children every year; However, currently, there is no effective treatment for EV71. In this study, the EV71 poly-protein (EV71-P1 protein) gene was processed and cloned into the eukaryotic expression vector pPIC9k and then expressed in Pichia pastoris strain GS115. The EV71 P1 protein with a molecular weight of 100 kD was produced and secreted into the medium. The soluble EV71 P1 protein was purified by column chromatography with a recovery efficiency of 70%. The result of the immunological analysis showed that the EV71 P1 protein had excellent immunogenicity and could stimulate the production of EV71-VP1 IgG antibody in injected rabbits. We suggest that EV71-P1 protein is an ideal candidate for an EV71 vaccine to prevent EV71 infection.     

Virucidal activity and the antiviral mechanism of acidic polysaccharides against Enterovirus 71 infection in vitro

Enterovirus 71 (EV71) is the predominant pathogen for severe hand, foot, and mouth disease (HFMD) in children younger than 5 years, and currently no effective drugs are available for EV71. Thus, there is an urgent need to develop new drugs for the control of EV71 infection. In this study, LJ04 was extracted from Laminaria japonica using diethylaminoethyl cellulose-52 with 0.4 mol/l NaCl as the eluent, and its virucidal activity was evaluated based on its cytopathic effects on a microplate. LJ04 is composed of fucose, galactose, and mannose and mainly showed good virucidal activity against EV71. The antiviral mechanisms of LJ04 were the direct inactivation of the virus, the blockage of virus binding, disruptions to viral entry, and weak inhibitory activity against the nonstructural protein 3C. The two most important findings from this study were that LJ04 inhibited EV71 proliferation in HM1900 cells, which are a human microglia cell line, and that LJ04 can directly inactivate EV71 within 2 hr at 37°C. This study demonstrates for the first time the ability of a polysaccharide from L. japonica to inhibit viral and 3C activity; importantly, the inhibition of 3C might have a minor effect on the antiviral effect of LJ04. Consequently, our results identify LJ04 as a potential drug candidate for the control of severe EV71 infection in clinical settings.     

Genetic analysis of the P1 region of human enterovirus 71 strains and expression of the 55 F strainVP1 protein

Enterovirus 71 (EV71) is a member of the Entero-virus genus of the Picornaviridae family and is the major cause of Hand,foot,and mouth disease (HFMD) in children.Different strains from Gansu were clone...     

Optimize the interactions at S4 with efficient inhibitors targeting 3C proteinase from enterovirus 71

Enterovirus 71 (EV71) is the causative agent of hand, foot and mouth disease and can spread its infections to the central nervous and other systems with severe consequences. The replication of EV71 depends on its 3C proteinase (3C^pro), a significant drug target. By X‐ray crystallography and functional assays, the interactions between inhibitors and EV71 3C^pro were evaluated. It was shown that improved interactions at S4 for the substrate binding could significantly enhance the potency. A new series of potent inhibitors with high ligand efficiency was generated for developing antivirals to treat and control the EV71‐associated diseases. Copyright © 2016 John Wiley & Sons, Ltd.     

A mammalian cell-based reverse two-hybrid system for functional analysis of 3C viral protease of human enterovirus 71

Although several cell-based reporter assays have been developed for screening of viral protease inhibitors, most of these assays have a significant limitation in that numerous false positives can be generated for the compounds that are interfering with reporter gene detection due to the cellular viability. To improve, we developed a mammalian cell-based assay based on the reverse two-hybrid system to monitor the proteolytic activity of human enterovirus 71 (EV71) 3C protease and to validate the cytotoxicity of compounds at the same time. In this system, the GAL4 DNA binding domain (M3) and transactivation domain (VP16) were fused, in-frame, with 3C or 3C(mut). The 3C(mut) was an inactivated protease with mutations at the predicted catalytic triad. The reporter plasmid contains a secreted alkaline phosphatase (SEAP) gene under the control of GAL4 activating sequences. We demonstrated that M3-3C-VP16 failed to turn on the expression of SEAP due to the separation of M3 and the VP16 domains by self-cleavage of 3C. In contrast, SEAP expression was induced by the M3-3C(mut)-VP16 fusion protein or the M3-3C-VP16 in cells treated with AG7088, a potent inhibitor of human rhinoviruses (HRVs) 3C protease. Potentially, this protease detection system should greatly facilitate anti-EV71 drug discovery through a high-throughput screening.     

ANXA2 Facilitates Enterovirus 71 Infection by Interacting with 3D Polymerase and PI4KB to Assist the Assembly of Replication Organelles

Virologica Sinica - Similar to that of other enteroviruses, the replication of enterovirus 71 (EV71) occurs on rearranged membranous structures called replication organelles (ROs)....     

Interactome analysis of the EV71 5′ untranslated region in differentiated neuronal cells SH‐SY5Y and regulatory role of FBP3 in viral replication

Enterovirus 71 (EV71), a single‐stranded RNA virus, is one of the most serious neurotropic pathogens in the Asia‐Pacific region. Through interactions with host proteins, the 5′ untranslated region (5′UTR) of EV71 is important for viral replication. To gain a protein profile that interact with the EV71 5′UTR in neuronal cells, we performed a biotinylated RNA‐protein pull‐down assay in conjunction with LC–MS/MS analysis. A total of 109 proteins were detected and subjected to Database for Annotation, Visualization and Integrated Discovery (DAVID) analyses. These proteins were found to be highly correlated with biological processes including RNA processing/splicing, epidermal cell differentiation, and protein folding. A protein–protein interaction network was constructed using the STRING online database to illustrate the interactions of those proteins that are mainly involved in RNA processing/splicing or protein folding. Moreover, we confirmed that the far‐upstream element binding protein 3 (FBP3) was able to bind to the EV71 5′UTR. The redistribution of FBP3 in subcellular compartments was observed after EV71 infection, and the decreased expression of FBP3 in host neuronal cells markedly inhibited viral replication. Our results reveal various host proteins that potentially interact with the EV71 5′UTR in neuronal cells, and we found that FBP3 could serve as a positive regulator in host cells.     

VP4 protein from human rhinovirus 14 is released by pressure and locked in the capsid by the antiviral compound WIN

Rhinoviruses are the major causative agents of the common cold in humans. Here, we studied the stability of human rhinovirus type 14 (HRV14) under conditions of high hydrostatic pressure, low temperature, and urea in the absence and presence of an antiviral drug. Capsid dissociation and changes in the protein conformation were monitored by fluorescence spectroscopy, light scattering, circular dichroism, gel filtration chromatography, mass spectrometry and infectivity assays. The data show that high pressure induces the dissociation of HRV14 and that this process is inhibited by WIN 52084. MALDI-TOF mass spectrometry experiments demonstrate that VP4, the most internal viral protein, is released from the capsid by pressure treatment. This release of VP4 is concomitant with loss of infectivity. Our studies also show that at least one antiviral effect of the WIN drugs involves the locking of VP4 inside the capsid by blocking the dynamics associated with cell attachment.     

细胞膜转运分子ABCC3和SLC7A7在肠道病毒A71型感染中作用的初步研究

肠道病毒A71型(enterovirus A71,EV-A71)是导致手足口病(hand-foot-mouth disease,HFMD)的主要病原体之一,目前对其治疗尚无特异高效的抗病毒药物.研究表明,细胞膜转运相关分子参与病毒的入侵、复制以及感染性子代病毒颗粒的释放.为寻找宿主中可有效抑制EV-A71感染的细胞膜转...     

Induction of dystrophin Dp71 expression during neuronal differentiation: opposite roles of Sp1 and AP2α in Dp71 promoter activity

In this study, we delineated the molecular mechanisms that modulate Dp71 expression during neuronal differentiation, using the N1E‐115 cell line. We demonstrated that Dp71 expression is up‐regulated in response to cAMP‐mediated neuronal differentiation of these cells, and that this induction is controlled at promoter level. Functional deletion analysis of the Dp71 promoter revealed that a 5′‐flanking 159‐bp DNA fragment that contains Sp1 and AP2 binding sites is necessary and sufficient for basal expression of this TATA‐less promoter, as well as for its induction during neuronal differentiation. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that Sp1 and AP2α bind to their respective DNA elements within the Dp71 basal promoter. Overall, mutagenesis assays on the Sp1 and AP2 binding sites, over‐expression of Sp1 and AP2α, as well as knock‐down experiments on Sp1 and AP2α gene expression established that Dp71 basal expression is controlled by the combined action of Sp1 and AP2α, which act as activator and repressor, respectively. Furthermore, we demonstrated that induction of Dp71 expression in differentiated cells is the result of the maintenance of positive regulation exerted by Sp1, as well as of the loss of AP2α binding, which ultimately releases the promoter from repression.     

Complete sequence analyses of enterovirus 71 strains from fatal and non-fatal cases of the hand,foot and mouth disease outbreak in Singapore (2000)

Enterovirus 71 (EV71) is a major aetiological agent of hand, foot and mouth disease (HFMD). In recent years, several outbreaks in East Asia were associated with neurological complications and numerous deaths. An outbreak in Singapore in October 2000 afflicted thousands of children, resulting in four fatal cases from three of whom EV71 was isolated. The genomes of two representative EV71 strains isolated from a fatal case and a surviving patient were completely sequenced, and their nucleotide and amino acid sequences compared with known EV71 strains. The two outbreak strains were classified under genogroup B, together with those previously isolated in Singapore, Malaysia and Japan. Comparative sequence analysis of the two Singapore strains revealed 99% nucleotide similarity, while their deduced amino acid sequences were almost identical except for residue 1506 in the 3A non-structural region. Given that the outbreak involved closely related genetic variants of EV71, the broad spectrum of disease severity may be attributed to critical factors such as varying viral inoculation doses or differing host immune responses following infection, but is less likely to be due to the emergence of EV71 strains with heightened virulence.     

Identification of a human monoclonal Fab with neutralizing activity against H3N2 influenza A strain from a newly constructed human Fab library

A combinatorial Fab library was constructed in pComb3H phagemid vectors, using RNA from peripheral blood lymphocytes of a healthy volunteer who had recovered from an influenza A virus infection. The library contained approximately 1.3 x 10(8)E. coli transformants. Bio-panning was carried out against an influenza vaccine containing components of influenza A/New Caledonia/20/99 (H1N1), A/Panama/2007/99 (H3N2), and B/Shandong/7/97 for the enrichment of phages displaying human Fab specific to the viral proteins. E. coli transformed with IF1A11, 1 of 94 randomly selected clones, displayed a human Fab antibody molecule (FabIF1A11) with efficient neutralizing activity against H3N2 influenza A virus strains. The purified FabIF1A11 demonstrated neutralizing activity against A/Okayama/6/01 (H3N2) and A/Kitakyushu/159/93 (H3N2) with 50% plaque reduction neutralization titers of 0.11 microg/ml (2.2 nM) and 1.4 microg/ml (28 nM) respectively. However, FabIF1A11 did not show neutralizing activity against the influenza A virus strain A/USSR/77 (H1N1) or the influenza B virus strain B/Kanagawa/73, even at a concentration of 20 microg/ml (400 nM). The Kd of FabIF1A11 was calculated as 3.6 x 10(-9) M. FabIF1A11 was estimated to recognize a conformational epitope on the hemagglutinin of A/Okayama/6/01 (H3N2). The human monoclonal Fab product FabIF1A11 may have potential as a therapeutic or short-term prophylactic molecule for humans with influenza A H3N2 infection.     

Three new constituents from the roots of Erythrina variegata and their antibacterial activity against methicillin-resistant Staphylococcus aureus

Two new isoflavonoids, eryvarins V and W (1 and 2, resp.), and a new chromen-4-one derivative, eryvarin X (3), along with three known isoflavonoids, 4-6, were isolated from the roots of Erythrina variegata. Their structures were established by spectroscopic analyses. Compound 1 is a rare naturally occurring isoflavanone which possesses a OH group at C(3). Among the new compounds 1-3, 2 exhibited a potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains.     

Outbreak of central nervous system disease associated with hand,foot, and mouth disease in Japan during the summer of 2000: detection and molecular epidemiology of enterovirus 71

Few outbreaks of the serious enterovirus 71 (EV71) infections, which affect the central nervous system (CNS), had been reported in Japan before 2000. During June through August 2000, a patient died of pulmonary edema caused by brainstem encephalitis accompanied by EV71-induced hand, foot, and mouth disease (HFMD), and many patients complicated by serious CNS disease, including paralysis, were hospitalized in a restricted area in Hyogo Prefecture, Japan (K-area). During the same period, endemics of HFMD were reported in other areas in Hyogo Prefecture, where EV71 was isolated from HFMD patients, but few patients developed aseptic meningitis. The isolations of EV71 from K-area patients were difficult with the use of Vero cells, so the strains were isolated by use of GL37 cells; Vero cells, however, could isolate EV71 strains from other areas in Hyogo Prefecture. We sequenced VP4 coding regions of these EV71 isolates and found that the isolates from K-area had the same sequence, which, except for one isolate, was different from the sequences of EV71 strains isolated from other areas of Hyogo Prefecture. Although these results were not enough to state that EV71 from K-area was a virulent strain, it seemed reasonable to conclude that serious CNS diseases in K-area were caused by EV71 because it was the only infectious agent detected in the inpatients of K-area.     

青蒿提取物抗单纯疱疹病毒活性研究

用细胞病变效应(CPE)法证明了青蒿水提物具有抗单纯疱疹病毒Ⅱ型(HSV—2)活性,通过初步分离纯化得到抗HSV—2活性的有效成分。用MTT法研究了青蒿水提物和有效成分的细胞毒性和抗HSV—2活性,CC50分别为5．29mg／ml和4,94mg／ml,IC50分别为1．45mg／ml和0．128mg／ml,TI分别为3．65和38．6。以0．5mg／ml的无环鸟苷(ACV)作为阳性对照,结果显示有效成分在体外可以明显抑制HSV—2的致细胞病变作用,效果与ACV相当。