Suppression of BK virus replication and cytopathic effect by inhibitors of prokaryotic DNA gyrase

Nalidixic acid and oxolinic acid, two antibacterial agents known to inhibit bacterial DNA gyrase, are shown to suppress the replication, as well as the cytopathic effect, of BK virus in Vero cell cultures. The inhibition of virus replication was detectable at day 4 post infection in cultures which had been continuously exposed to drugs at concentrations as low as 0.02 to 0.04 mM of nalidixic acid and 0.2 mM of oxolinic acid. These active concentrations are inferior to plasma levels attained in the course of clinical use of the drugs for antibacterial chemotherapy. Also, under these circumstances, no cytotoxicity occurred. The inhibition of development of cytopathology and of virus-induced cell death was demonstrable in cultures treated for 12 days with the drugs. Under these circumstances of prolonged action, oxolinic acid proved to be slightly cytotoxic in that virus inhibitory doses reduced the viability of normal cells. No alterations in the topological conformation of the viral genome or accumulation of end products of viral DNA replication were detected. However, accumulation of viral DNA form I at 48 h post infection suggests that the drugs act through a mechanism involving DNA topoisomerase.     

Identification of novel virus inhibitors by influenza A virus specific reporter cell based screening

As influenza viruses have developed resistance towards current drugs, it is urgent to find potential novel antiviral inhibitors. Here we generated an influenza virus reporter cell line in which the luciferase gene was driven by the influenza virus promoter and screened a small compound library (NCI Diversity Set II). Ten compounds were identified to have inhibitory activity against influenza A virus H1N1. Among them, four compounds blocked influenza virus replication through inhibiting the activity of vRNP. The compound NSC 335506 inhibited HA-mediated membrane fusion. It showed the inhibitory activity against H1N1, H9N2 and H5N1 subtype but not H3N2. Our results demonstrated that influenza virus reporter cell is a very useful tool to identify novel inhibitors against influenza A virus.     

Cardiac chloride channels: physiology, pharmacology and approaches for identifying novel modulators of activity

Drugs that block cardiac cation channels have been marketed as the therapeutic answer to cardiac arrhythmia. However, such molecules have been only moderately successful at improving the survival of cardiac patients, and so new targets have been needed for future antiarrhythmic agents. This article outlines the properties and roles of Cl(-) channels, which are one of these new targets, and describes an approach for identifying novel CI(2) channel modulators.     

Phosphonylmethoxyalkylpurines and -pyrimidines as inhibitors of African swine fever virus replication in vitro

Several phosphonylmethoxyalkylpurine and -pyrimidine derivatives related to (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine [(S)-HPMPA] and 9-(2-phosphonylmethoxyethyl)adenine (PMEA) were evaluated as inhibitors of African swine fever virus (ASFV) replication in Vero cells. (S)-HPMPA has previously been shown to inhibit ASFV replication at a minimum inhibitory concentration (MIC) of 0.01 microgram/ml with a selectivity index of 15000. Of the new compounds tested, the following emerged as the most potent and selective inhibitors of ASFV replication: the cyclic phosphonate of (S)-HPMPA [(S)-cHPMPA] with an MIC of 0.2 microgram/ml and a selectivity index of 2500, the 2,6-diaminopurine analogue of (S)-HPMPA [(S)-HPMPDAP] with an MIC of 0.5 microgram/ml and a selectivity index of 1400, and the cytosine [(S)-HPMPC] and guanine [(RS)-HPMPG] analogues with an MIC of 1 microgram/ml and a selectivity index of 600-700.     

新型β-内酰胺酶抑制剂的合成及其活性研究

摘要：阿维巴坦是一种β-内酰胺酶抑制剂,最近与β-内酰胺酶抗生素头孢他啶联用被批准用于治疗复杂性腹腔感染和复杂 性尿路感染。它的成功案例鼓励了许多同系物的发展,其基础是其特殊的二氮杂环辛烷骨架。本文设计合成一系列新型具有二 氮杂环辛烷骨架的β-内酰胺酶抑制剂1~6,对β-内酰胺酶抑制剂1~6与头孢他啶抗生素联合使用时产生的抑菌活性进行了研究。 研究结果表明,与头孢他啶抗生素联用时对产生TEM-1、AmpC和KPC-2 3种β-内酰胺酶耐药菌表现出抑菌活性,使头孢他啶的 抑菌活性增强了2~4倍。     

A facile method to screen inhibitors of protein-protein interactions including MDM2-p53 displayed on T7 phage

Protein-protein interactions are essential in many biological processes including cell cycle and apoptosis. It is currently of great medical interest to inhibit specific protein-protein interactions in order to treat a variety of disease states. Here, we describe a facile multiwell plate assay method using T7 phage display to screen for candidate inhibitors of protein-protein interactions. Because T7 phage display is an effective method for detecting protein-protein interactions, we aimed to utilize this technique to screen for small-molecule inhibitors that disrupt these types of interaction. We used the well-characterized interaction between p53 and MDM2 and an inhibitor of this interaction, nutlin 3, as a model system to establish a new screening method. Phage particles displaying p53 interacted with GST-MDM2 immobilized on 96-well plates, and the interaction was inhibited by nutlin 3. Multiwell plate assay was then performed using a natural product library, which identified dehydroaltenusin as a candidate inhibitor of the p53-MDM2 interaction. We discuss the potential applications of this novel T7 phage display methodology, which we propose to call 'reverse phage display'.     

A novel class of geldanamycin derivatives as HCV replication inhibitors targeting on Hsp90: synthesis, structure-activity relationships and anti-HCV activity in GS4.3 replicon cells

A novel class of geldanamycin (GA) derivatives as hepatitis C virus (HCV) replication inhibitors has been synthesized and their anti-HCV activities were evaluated in GS4.3 HCV replicon cells. Most of the synthesized compounds demonstrated potential activities against HCV in vitro. Substitution with an aliphatic cyclic group (2b) and polar phosphate group (2f) at the 17 position of GA resulted in more potent inhibitory activity. The configurations of the tetrahydrofurfurylamino (THFM) substituents obviously affected their antiviral activities. The 2b with a 2'-(R)-THFM group at the 17 position showed much potent activity and higher selectivity than its 2'-(S) and 2'-(R, S) epimers. In the tested GA derivatives, 2b and 2f show the most potential leading compounds for development of novel anti-HCV agents.     

A cell-based, microplate colorimetric screen identifies 7,8-benzoflavone and green tea gallate catechins as inhibitors of the hepatitis C virus

We describe a cell-based, microplate colorimetric screen for anti-hepatitis C virus (HCV) drugs that exploits the HCV-JFH1 viral culture system. Antiviral activity was assessed by measuring protection against the HCV-JFH1-induced cytopathic effect (CPE) in Huh7.5.1 cells using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) viability assay. The use of serum-free medium substantially sensitized Huh7.5.1 cells to HCV-induced CPE, causing sufficient cell death to perform colorimetric assays for anti-HCV activity in 96-well plates. As a proof of concept, we carried out a pilot screen of an inhibitor library and identified cyclosporin A and tamoxifen, two compounds with reported anti-HCV activity. Using the assay, we discovered the anti-HCV properties of the plant flavonoids epigallocatechin gallate (EGCG) and 7,8-benzoflavone (α-naphthoflavone). Other gallate-type catechins and flavones also displayed anti-HCV activity, but 5,6-benzoflavone (β-naphthoflavone), flavanone, and non-gallate catechins were inactive. EGCG apparently acted mainly on HCV entry, although it may also block other steps. In contrast, 7,8-benzoflavone was presumed to inhibit later stages of the HCV life cycle. This assay is simple, reliable and cost-effective; does not require any specially engineered cell lines or viruses; and should be useful in the identification of compounds with anti-HCV activity.     

A novel series of potent and selective ketone histone deacetylase inhibitors with antitumor activity in vivo

Histone deacetylase (HDAC) inhibitors offer a promising strategy for cancer therapy, and the first generation HDAC inhibitors are currently in the clinic. Entirely novel ketone HDAC inhibitors have been developed from the cyclic tetrapeptide apicidin. These compounds show class I subtype selectivity and levels of cellular activity comparable to clinical candidates. A representative example has demonstrated tumor growth inhibition in a human colon HCT-116 carcinoma xenograft model comparable to known inhibitors.     

Synthesis and antiallergic activity of a novel series of 5-lipoxygenase inhibitors

A series of novel substituted [[(phenoxymethyl)phenyl]amino]oxoalkanoic acid esters have been synthesized. These compounds were tested in vitro for their ability to inhibit the synthesis of 5-hydroxyeicosatetraenoic acid and leukotriene (LT) B4 from rat polymorphonuclear leukocytes (PMN) and in vivo as inhibitors ovalbumin- (OA) and LTD4-induced bronchospasm in the guinea pig. Compounds 5-12 and 25 had IC50's between 1 and 5.6 microM in the rat PMN 5-lipoxygenase assay. Compounds 1, 3, and 16 inhibited OA-induced bronchoconstriction (61%, 64%, and 57%, respectively), but only 1 showed activity against LTD4-induced bronchoconstriction. When tested against LTD4-induced contraction of isolated guinea pig tracheal spiral strips, 1 was a competitive inhibitor with a pKB of 4.94.     

Synthesis and anti-influenza virus activity of novel pyrimidine derivatives.

Efficient synthetic routes of 2-amino-4-(omega-hydroxyalkylamino)pyrimidine derivatives were investigated in relation to the anti-influenza virus activity of these compounds. The derivatives in which cyclobutyl and cyclopentyl groups were introduced to the beta-position of the aminoalkyl group (especially the cyclobutyl group substituted by a phenylalkyl group at the 3'-position) resulted in improved antiviral potency: i.e. an average 50% effective concentration for inhibition of plaque formation (EC50, microM) of 0.1-0.01 microM for both types A and B influenza virus. The antiviral efficacies were in the order of amino group > hydroxyiminomethyl group > halogen substitution at the 5-position, and chlorine or methoxy group > hydrogen at the 6-position of the pyrimidine ring. The antiviral indices of these compounds were 2-6 with respect to the 50% inhibitory concentration for cell proliferation (IC50, microM) for growing cells, but > 500 to > 10(4) with respect to the IC50 for stationary cells, indicating that these compounds may be efficacious for the topical treatment of influenza virus infection.     

新型吲哚胺2,3-双加氧酶1抑制剂的合成及活性研究

目的设计合成2类1H-吲唑类新化合物,并测试其吲哚胺2,3-双加氧酶1(IDO1)抑制活性。方法以肿瘤免疫关键调控蛋白IDO1作为靶标,依据IDO1活性位点的关键药效团特征,利用合理药物设计方法,以前期研究获得的高活性化合物作为先导化合物,设计合成了2类1H-吲唑类衍生物,并测试其体外IDO1酶抑制活性。采用分子对接软件DOCK6进行分子对接模拟并分析化合物的构效关系。结果与结论合成了5个1H-吲唑类衍生物,均表现出不同程度的IDO1抑制活性,其中化合物2a和3b的抑制活性较好,在100μmol·L~(-1)时的抑制率均为69%。构效关系和分子对接研究显示,4位连接基团的结构对化合物活性影响很大,1H-吲唑类化合物还有很大结构优化空间,极具开发潜力,可为靶向IDO1的肿瘤免疫治疗提供候选化合物。     

Effect of novel modulators of protein kinase C activity upon chemotherapy-induced differentiation and apoptosis in myeloid leukemic cells

Modulation of protein kinase C (PKC) activity has been demonstrated to either prevent or enhance drug-induced apoptosis in various tissue types. We tested four novel modulators of PKC activity in comparison to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) for the capability to affect differentiation, cell cycle progression and apoptosis in the human myeloid leukemia cell lines U937 and HL-60. Farnesyl thiotriazole (FTT) and N-(n-heptyl)-5-chloro-1-naphthalenesulfonamide (SC-10) are both direct activators of PKC, whereas 6-(2-(4-[(4-fluorophe-nyl)phenylmethylene]-1-piperidinyl)ethyl)-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-one (R59022) and [3-[2-[4-(bis-(4-fluorophenyl)methylene]piperidin-1-yl)ethyl]-2,3-dihydro-2-thioxo-4(1H)-quin-azolinone (R59949) are diacyl glycerol kinase inhibitors that activate PKC by enhancing the levels of the endogenous ligand diacyl glycerol. U937 cells displayed a slight reduction in the number of cells in G(2)/M cell cycle phase after exposure to FTT, SC-10, R59022 and R59949, respectively. In contrast, HL-60 cells demonstrated a largely unaltered cell cycle distribution. Whereas TPA treatment resulted in a strong induction of p21(WAF/CIP1), c-Fos and c-Jun levels, neither one of the novel PKC activators altered expression of these proteins. Consequently, we tested the ability of the activators to cause membrane translocation of PKC. While TPA treatment resulted in translocation of the PKC isoforms alpha, delta and epsilon, SC-10 and FTT failed to induce alterations in the PKC content of the membrane and cytosolic fractions, respectively. Expression of the beta(2)-integrin CD11c that is induced during TPA-mediated differentiation remained unaltered after exposure to SC-10 and was partly reduced after treatment with FTT. To further investigate the effect of these activators upon apoptosis in leukemic cells, HL-60 and U937 cells were treated with 1-beta-D-arabinofuranosylcytosine (Ara-C) or etoposide (VP-16). Whereas TPA strongly reduced apoptosis in Ara-C- or VP-16-treated U937 cells, little if any reduction was observed after pretreatment with either FTT, SC-10, R59022 or R59949, respectively, in these cells. In contrast, TPA enhanced apoptosis in Ara-C- or VP-16-treated HL-60 cells. Interestingly, FTT and SC-10 demonstrated a protective effect in Ara-C-treated HL-60 cells. Taken together, these data suggest that the novel PKC activators FTT, SC-10, R59022 and R59949 exhibit modest biological effects upon leukemic blast cells, and are not capable of enhancing the apoptotic response of these cells to cytotoxic drugs.     

自噬相关蛋白ATG4B抑制剂的虚拟筛选及体外活性测定

目的通过计算机虚拟筛选和体外活性测定,筛选自噬相关蛋白ATG4B的特异性小分子抑制剂。方法基于ATG4B蛋白的晶体结构(PDB ID:2CY7)找出合适的对接口袋;用分子对接方法对SPECS数据库20万化合物进行虚拟筛选并确定候选化合物;用荧光共振能量转移方法(FRET)检测候选化合物对ATG4B的体外抑制活性并对其特异性进行验证。结果确定受体蛋白2CY7的site 5为最适的对接口袋;分子对接后经综合分析选择并购买30个代表性化合物做进一步活性测定。活性测定结果显示,AG-690/10400046能有效抑制ATG4B蛋白的活性,而对半胱氨酸蛋白酶家族的另一成员caspase-3无酶切抑制作用。结论建立了一种ATG4B蛋白抑制剂的虚拟筛选方法。筛选得到的化合物AG-690/10400046具有明显的体外抑制活性,为后续ATG4B抑制剂的生理功能研究奠定基础。     

Synthesis and activity of new acylated diaminohydroxyalkanes as human immunodeficiency virus protease inhibitors

A series of HIV-1 protease inhibitors based on the lead compound Pc (IC50 = 165 nmol/l) with structural modifications at P1/P1' substituents or with a lengthening at its core unit were synthesized from amino acid starting materials. All analogues were less active than Pc against the protease.