Dimeric C34 Derivatives Linked through Disulfide Bridges as New HIV-1 Fusion Inhibitors

C34, a 34-mer fragment peptide, is contained in the HIV-1 envelope protein gp41. A dimeric derivative of C34 linked through a disulfide bridge at its C terminus was synthesized and found to display potent anti-HIV activity, comparable with that of a previously reported PEGylated dimer of C34REG. The reduction in the size of the linker moiety for dimerization was thus successful, and this result might shed some light on the mechanism of the suppression of six-helix bundle formation by these C34 dimeric derivatives. Addition of a Gly-Cys(CH₂CONH₂)-Gly-Gly motif at the N-terminal position of a C34 monomeric derivative significantly increased the anti-HIV-1 activity. This moiety functions as a new pharmacophore, and this might provide a useful insight into the design of potent HIV-1 fusion inhibitors.     

吲哚席夫碱类衍生物的合成及其抗HIV-1活性研究

设计、合成吲哚席夫碱类衍生物并研究其抗HIV-1活性。以3-吲哚甲醛衍生物为原料,在碱催化下与芳香胺发生缩合反应合成吲哚席夫碱类化合物,并采用通过 MTT 法测试了目标化合物在MT-4 细胞内的抗 HIV-1病毒株的活性。 合成了32个吲哚席夫碱类衍生物,其结构均通过1H NMR和MS加以确证。初步的生物活性结果测试表明,所合成的吲哚席夫碱类化合物对HIV-1均有优秀的抑制活性,并具有广谱的抗HIV-1活性。其中化合物31 (EC50 = 0.06 mol/L)展现出了最强的抗HIV-1活性,与阳性药物地拉韦啶 (DLV, EC50 = 0.57 mol/L)相当;同时,化合物31具有非常低的毒性,选择指数 (SI)高达2500,明显高于地拉韦啶 (DLV, SI = 1272.9)和依法韦仑 (EFV, SI = 321)。将吲哚和席夫碱两个药效团,能够得到高效、低毒的HIV-1逆转录酶抑制剂,为今后发展新型的HIV-1抑制剂提供了新思路。     

Design,Synthesis, and Evaluation of WC5 Analogues as Inhibitors of Human Cytomegalovirus Immediate‐Early 2 Protein,a Promising Target for Anti‐HCMV Treatment

Although human cytomegalovirus (HCMV) infection is mostly asymptomatic for immunocompetent individuals, it remains a serious threat for those who are immunocompromised, in whom it is associated with various clinical manifestations. The therapeutic utility of the few available anti‐HCMV drugs is limited by several drawbacks, including cross‐resistance due to their common mechanism of action, i.e., inhibition of viral DNA polymerase. Therefore, compounds that target other essential viral events could overcome this problem. One example of this is the 6‐aminoquinolone WC5 , which acts by directly blocking the transactivation of essential viral Early genes by the Immediate‐Early 2 (IE2) protein. In this study, the quinolone scaffold of the lead compound WC5 was investigated in depth, defining more suitable substituents for each of the scaffold positions explored and identifying novel, potent and nontoxic compounds. Some compounds showed potent anti‐HCMV activity by interfering with IE2‐dependent viral E gene expression. Among them, naphthyridone 1 was also endowed with potent anti‐HIV activity in latently infected cells. Their antiviral profile along with their innovative mechanism of action make these anti‐HCMV quinolones a very promising class of compounds to be exploited for more effective antiviral therapeutic treatment.     

Double Variational Binding—(SMILES) Conformational Analysis by Docking Mechanisms for Anti-HIV Pyrimidine Ligands

Variational quantitative binding–conformational analysis for a series of anti-HIV pyrimidine-based ligands is advanced at the individual molecular level. This was achieved by employing ligand-receptor docking algorithms for each molecule in the 1,3-disubstituted uracil derivative series that was studied. Such computational algorithms were employed for analyzing both genuine molecular cases and their simplified molecular input line entry system (SMILES) transformations, which were created via the controlled breaking of chemical bonds, so as to generate the longest SMILES molecular chain (LoSMoC) and Branching SMILES (BraS) conformations. The study identified the most active anti-HIV molecules, and analyzed their special and relevant bonding fragments (chemical alerts), and the recorded energetic and geometric docking results (i.e., binding and affinity energies, and the surface area and volume of bonding, respectively). Clear computational evidence was also produced concerning the ligand-receptor pocket binding efficacies of the LoSMoc and BraS conformation types, thus confirming their earlier presence (as suggested by variational quantitative structure-activity relationship, variational-QSAR) as active intermediates for the molecule-to-cell transduction process.     

Imidazolidinones and Imidazolidine-2,4-diones as Antiviral Agents

Imidazolidinones and imidazolidine-2,4-diones are important classes of heterocyclic compounds that possess potent activities against several viruses such as dengue virus, enterovirus, hepatitis C virus (HCV), and human immunodeficiency virus (HIV). The first imidazolidinone derivative as an anti-HIV agent was reported in 1996. Imidazolidinones inhibit HIV aspartic protease activity, and also act as CCR5 co-receptor antagonists. Significant effort has been devoted to the design of various imidazolidinone analogues that are active against drug-resistant HIV strains, with fewer side effects. Different scaffolds have been designed through both rational drug design strategies and computer-aided drug design. Imidazolidinones have been found to be potent against HIV, and preclinical studies are currently in progress. There are some reports of imidazolidinones as having both anti-HCV and anti-dengue virus activity, and more research has yet to be done along these lines. These compounds inhibit NS3 serine protease of HCV, and NS2B-NS3 protease of dengue virus. Pyridyl-imidazolidinones possess very specific and potent activity against human enterovirus 71 (EV71) by targeting the EV71 capsid protein VP1, and inhibiting viral adsorption and/or viral RNA uncoating.     

An Expeditious and Metal‐Free Synthetic Route towards Quinolones,Naphthyridones and Benzonaphthyridones

An efficient, two‐step synthetic strategy has been developed to access the quinolone, naphthyridone and benzonaphthyridone classes of chemotherapeutic agents from Baylis–Hillman adducts. The method involves tandem aza‐Michael addition, S_NAr cyclisation followed by oxidation of the resulting 4‐hydroxy‐1,2,3,4‐tetrahydroquinoline or 4‐hydroxy‐1,2,3,4‐tetrahydro‐1,8‐naphthyridine derivative using IBX, and works well with substrates having a wide variety of substitution pattern.

     

Chemical synthesis and expression of the HIV-1 Rev protein

The HIV-1 Rev protein is responsible for shuttling partially spliced and unspliced viral mRNA out of the nucleus. This is a crucial step in the HIV-1 lifecycle, thus making Rev an attractive target for the design of anti-HIV drugs. Despite its importance, there is a lack of structural, biophysical, and quantitative information about Rev. This is mainly because of its tendency to undergo self-assembly and aggregation; this makes it very difficult to express and handle. To address this knowledge gap, we have developed two new highly efficient and reproducible methods to prepare Rev in large quantities for biochemical and structural studies: 1) Chemical synthesis by using native chemical ligation coupled with desulfurization. Notably, we have optimized our synthesis to allow for a one-pot approach for the ligation and desulfurization steps; this reduced the number of purification steps and enabled the obtaining of desired protein in excellent yield. Several challenges emerged during the design of this Rev synthesis, such as racemization, reduced solubility, formylation during thioester synthesis, and the necessity for using orthogonal protection during desulfurization; solutions to these problems were found. 2) A new method for expression and purification by using a vector that contained an HLT tag, followed by purification with a Ni column, a cation exchange column, and gel filtration. Both methods yielded highly pure and folded Rev. The CD spectra of the synthetic and recombinant Rev proteins were identical, and consistent with a predominantly helical structure. These advances should facilitate future studies that aim at a better understanding of the structure and function of the protein.     

Highly potent HIV inhibition: engineering a key anti-HIV structure from PSC-RANTES into MIP-1 beta/CCL4

The HIV coreceptor CCR5 is a validated target for both the prevention and therapy of HIV infection. PSC-RANTES, an N-terminally modified analogue of one of the natural chemokine ligands of CCR5 (RANTES/CCL5), is a potent inhibitor of HIV entry into target cells. Here, we set out to engineer the anti-HIV activity of PSC-RANTES into another natural CCR5 ligand (MIP-1beta/CCL4), by grafting into it the key N-terminal pharmacophore region from PSC-RANTES. We were able to identify MIP-1beta/CCL4 analogues that retain the receptor binding profile of MIP-1beta/CCL4, but acquire the very high anti-HIV potency and characteristic inhibitory mechanism of PSC-RANTES. Unexpectedly, we discovered that in addition to N-terminal structures from PSC-RANTES, the side chain of Lys33 is also necessary for full anti-HIV potency.     

C3—氯代头孢烯酸及其衍生物的合成

C3-氯代头孢烯酸类衍生物头孢克洛2001年在美国的销售额超过8千万美元,位居抗生素类药物销售额第二位.而我国由于没有母核供应,只能进口国外原料药进行分装.C3-氯代头孢母核的合成方法有两种青霉素扩环和7-ACA改造.青霉素扩环法操作复杂、收率低、难以实现工业化.文章详细分析了以7-ACA为原料合成C3-氯代头孢母核的各步反应.     

人类免疫缺陷病毒抗体EIA检测试剂质控参考品的建立

以国际抗－HIV质控参考品为参比，用亚塔、阿克苏、UBI、普生、万芬等国内外试剂对41份执－HIV阳性和阴性人血浆进行筛查，并进一步以免疫印迹法确证，建立了我国第一代抗－HIV检测试剂质控参考品，其中包括阳性、阴性、灵敏度和精密性参考品。用本品对91批次国产试剂进行检测并与国外试剂进行对比，证明有较好的分辨力。在此基础上制定出我国抗－HIV检测试剂质量标准，此标准及参考品已获国家批准。     

Proposal and evaluation of a new norm index-based QSAR model to predict pEC50 and pCC50 activities of HEPT derivatives☆

The search and development of anti-HIV drugs is currently one of the most urgent tasks of pharmacological studies.In this work,a quantitative structure–activity relationship(QSAR) model based on some new norm indexes,was obtained to a series of more than 150 HEPT derivatives(1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine) to find their pEC_(50)(the required effective concentration to achieve 50% protection of MT-4 cells against the cytopathic effect of virus) and pCC_(50)(the required cytotoxic concentration to reduce visibility of 50% mock infected cell) activities.The model efficiencies were then validated using the leave-one-out cross validation(LOO-CV) and yrandomization test.Results indicated that this new model was efficient and could provide satisfactory results for prediction of pEC_(50) and pCC_(50) with the higher R_(train)~2 and the higher R_(test)~2.By using the leverage approach,the applicability domain of this model was further investigated and no response outlier was detected for HEPT derivatives involved in this work.Comparison results with reference methods demonstrated that this new method could result in significant improvements for predicting pEC_(50) and pCC_(50) of anti-HIV HEPT derivatives.Moreover,results shown in this present study suggested that these two absolutely different activities pEC_(50) and pCC_(50) of anti-HIV HEPT derivatives could be predicted well with a totally similar QSAR model,which indicated that this model might have the potential to be further utilized for other biological activities of HEPT derivatives.     

Glu659Leu substitution of recombinant HIV fusion inhibitor C52L induces soluble expression in Escherichia coli with equivalent anti-HIV potency

The C-peptides used to prevent HIV infection, such as T20 and C34, are chemically synthesized, making them costly drugs. The sensitivity of peptides to protease also restricts their clinical application. We showed previously that C52L, a recombinant peptide produced in bacteria, is a potent anti-HIV C-peptide, although most of the peptide accumulates in inclusion bodies. Here we applied leucine and glutamine scanning mutagenesis to the heptad-repeat of C52L to produce an optimized variant of C52L that is potent and soluble when expressed in bacteria. We present that the substitution of Asn656 and Glu659 with leucine (peptide L14 and L15, respectively) can increase the helical content of this peptide. These substitutions also result in soluble expression. We measured the inhibitory activities of these mutant peptides against laboratory-adapted HIV-1 strains and found that L15 and its parental peptide C52L have equivalent anti-HIV activities. Moreover, L15 was found to be more stable to proteinase K digestion than C52L. Thus, we show that the L15 peptide can be expressed in a soluble state and exhibits potent anti-HIV activity. This peptide may be further developed as an anti-HIV therapeutic and/or microbicide for the prevention of HIV sexual transmission.     

抗HIV靶向治疗制剂的研究进展

抗HIV靶向治疗是利用特异性的运载工具,将可杀伤HIV-1感染靶细胞的生物活性弹头选择性地运送到感染靶细胞部位,通过与靶细胞相结合后内化,杀灭体内残存病毒颗粒和潜伏感染细胞,并修复机体免疫系统,恢复机体正常免疫功能。将靶向治疗作为艾滋病(AIDS)治疗的辅助和补充手段,正成为AIDS一种新型的治疗方法。本文就抗HIV靶向治疗的运载工具及生物活性弹头的研究进展作一综述。     

新型萘环衍生物类液晶的研究进展

新型的萘环衍生物类液晶化合物具有优越的物理性能,是近年来显示用液晶材料研究的热点领域。综述了萘环衍生物类液晶对混合液晶物理性能的影响。大量文献数据表明其可加宽混合液晶的向列相温度范围;增大介电各向异性;降低阈值电压以及调节适宜的双折射率,适用于超扭曲向列型(STN型),薄膜晶体管型(TFT型)等高性能液晶材料。     

A liquid‐like multiwalled carbon nanotube derivative and its epoxy nanocomposites

Multiwall carbon nanotubes (MWCNTs) with liquid‐like behavior at room temperature were prepared with sulfonic acid terminated organosilanes as corona and tertiary amine as canopy. The liquid‐like MWCNT derivative had low viscosity at room temperature (3.89 Pa s at 20°C) and exhibited non‐Newtonian shear‐thinning behavior. The weight fraction of MWCNT in the derivative was 16.72%. The MWCNT derivative showed very good dispersion in organic solvents, such as ethanol and acetone. The liquid‐like MWCNT derivative was incorporated into epoxy matrix to investigate the mechanical performance of the nanocomposites and the distribution of MWCNTs in the matrix. When the liquid‐like MWCNT derivative content was up to 1 wt %, the flexural strength and impact toughness of composites were 12.1 and 124% higher than the pure epoxy matrix, respectively. Transmission electron microscope (TEM) confirmed the very good dispersion of the liquid‐like MWCNT derivative in epoxy matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2217–2224, 2013     

Cellular localisation of antitumoral 6-alkyl thymoquinones revealed by an alkyne-azide click reaction and the streptavidin-biotin system

The subcellular distribution and accumulation of thymoquinone 1, a natural anticancer agent, has hitherto been unknown. We prepared 6-(dec-9-ynyl)thymoquinone 3, an alkyne-labelled derivative with anticancer activity similar to that of its parent compound 1. Alkyne 3 was seen, after a Huisgen-type click reaction with 3-azido-7-hydroxycoumarin, to accumulate in distinct compartments of the nuclei of PtK(2) potoroo kidney cells, and in adjoining regions that were stained with an antibody specific for the Golgi apparatus. In contrast, a biotinlabelled thymoquinone 4 seemed to accumulate across the entire cell nucleus upon visualisation with streptavidin; but this was less easily traceable because of co-staining of other structures such as mitochondria. In conclusion, for small drug-like molecules, visualisation by alkyne-azide cycloaddition seems to be superior to conventional visualisation by the biotin-streptavidin system.     

单基团保护法制备三氯蔗糖的研究

三氯蔗糖是蔗糖的一种衍生物,是目前己知被发现的一种甜度极高、味觉特性最好的蔗糖三氯衍生物,口感与蔗糖相似,其研究及应用都有着广阔的前景。从工业化的角度出发,在讨论甜味剂三氯蔗糖的各种合成方法的基础上展开了研究。     

Release of Omega-3 Fatty Acids by the Hydrolysis of Fish Oil Catalyzed by Lipases Immobilized on Hydrophobic Supports

The release of omega-3 fatty acids by the mild enzymatic hydrolysis of sardine oil was studied. The derivatives of different lipases physically adsorbed on hydrophobic porous supports Hydrophobic Lipase Derivatives (HLD) were tested. These immobilized lipases can only hydrolyze oil molecules partitioned into the aqueous phase of a biphasic reaction system. HLD biocatalysts were compared to other enzyme derivatives that were obtained by very mild covalent immobilization on CNBr-activated Sepharose Cyanogen bromide Lipase Derivatives (CNLD) that behave almost identically to soluble enzymes (CNLD). In general, HLD biocatalysts were found to be more active and more selective for the release of eicosapentaenoic acid (EPA) than CNLD. The most interesting biocatalyst was the HLD derivative of Yarrowia lipolytica lipase, which was found to be sevenfold more active and tenfold more selective than CNLD. On the other hand, the most active (but non-selective) derivative was the HLD of Pseudomonas fluorescens lipase (PFL). The activity of this derivative was 0.6 International Units under non-optimal reaction conditions. High-loaded PFL derivatives could be very interesting for the release of mixtures of EPA and docosahexaenoic acid. Hydrophobic supports promote the interfacial activation of lipases, similar to the interaction promoted by oil drops on soluble enzymes. The most effective overactivation obtained in this work ranged from 6- to 20-fold. The hydrolytic process was carried out under very mild conditions (pH 7.0 and 25 °C), and all lipase derivatives remained fully active for at least 15 days under these conditions.