Synthesis and biological evaluation of dihydrofuran-fused perhydrophenanthrenes as a new anti-influenza agent having novel structural characteristic

Dihydrofuran-fused perhydrophenanthrenes were synthesized by means of o-quinodimethane chemistry with high generality and stereoselectivity, and found to exhibit potent anti-influenza activity. These compounds exerted an inhibitory effect on various strains of influenza virus growth, including influenza A and B, with a concentration dependent manner, and direct cytotoxicity was low. Several biological experiments suggested that these new drugs affected a virus replication process before mRNA synthesis stage. Novel rigid cage-type of structural characteristic of the compounds has not been found in hitherto anti-influenza drugs, and will provide new basis and motif for exploring promising and unprecedented anti-influenza agents.     

Synthesis of dihydrofuran-fused perhydrophenanthrenes having a phenolic hydroxyl group as a novel anti-Alzheimer's disease agent

As a part of our research program on developing novel anti-Alzheimer's disease medicines, several dihydrofuran-fused perhydrophenanthrenes (DFs) possessing a phenolic hydroxyl group were found to exhibit potent dendritic and axonal regeneration activities. Introduction of a methoxy group into the perhydrophenanthrene skeleton was successfully achieved via a PhI(OAc)(2)-mediated phenolic oxidation of a benzocyclobutene nucleus and subsequent tandem intramolecular electrocyclic reactions based on o-quinodimethane chemistry. We could reveal that a new methoxy derivative having a phenolic hydroxyl group exerted the most significant effects on the dendritic and axonal extensions in the damaged neurons, among DFs examined in this study.     

Synthesis and anti-influenza virus activity of 7-O-alkylated derivatives related to zanamivir

A series of 7-alkyl ether derivatives related to zanamivir were synthesized using direct alkylation of the C-7 alcohol of sialic acid. Alkyl ether moiety of less than 12 carbons in length showed low nanomolar inhibitory activity against influenza A virus sialidase. Furthermore, their moiety improved influenza A virus plaque reduction activity compared to zanamivir. However, removal of the 8,9-diol of the 7-O-alkyl derivatives resulted in loss of antiviral potency. This result suggests that 8,9-diol must play an important role in binding with both influenza A and B virus sialidases.     

Synthesis and anti-influenza activity of aminoalkyl rupestonates

A series of aminoalkyl rupestonates were designed and synthesized by reacting rupestonic acid with 1,ω-dibromoalkanes, followed by amination. All of the new compounds were bioassayed in vitro to determine their activities against influenza A (H3N2, H1N1) and B viruses. The results showed that compounds 5a-5g, which each contain a 1H-1,2,4-triazolyl moiety, were found to be the most potent set of compounds. Compound 5g was demonstrated to possess the highest inhibitory activity against influenza H3N2 and H1N1, with IC(50) values of 0.97 and 0.42 μM, respectively. Our results also indicated that compounds 2g, 3g, 4g and 5g, which contain ten-CH(2)-unit spacers between the rupestonic acid and amino functional groups, were the most potent inhibitors of influenza H1N1 among the synthesized compounds. Unfortunately, most of the synthesized compounds did not show an obvious activity against influenza B; the only exceptions were compounds 5d and 5f, which had IC(50) values of 17.3 and 3.2 μM, respectively. Compounds 4g and 5g were potent inhibitors of influenza H1N1, and they might be potentially developed as new lead anti-influenza virus compounds. Further studies of the mechanism of action are underway.     

Synthesis, conformational characteristics and anti-influenza virus A activity of some 2-adamantylsubstituted azacycles

The broad-spectrum antiviral activity of 2-(2-adamantyl)piperidines 11, 13a,b, and 15, 3-(2-adamantyl)pyrrolidines 27, 21a-g and 2-(2-adamantylmethyl)piperidines 30, 32a-c, and 35a-d was examined. Several compounds in the new series were potent against influenza A H(3)N(2) virus. When 1-aminoethyl pharmacophore group of 2-rimantadine 4 (2-isomer of rimantadine) is included into a saturated nitrogen heterocycle, see compound 11, potency was retained. The diamine derivatives 21e-g and particularly 35a-c possessing three pharmocophoric groups, that is, the adamantyl and the two amine groups, exhibited high potency. The new compounds did not afford specific activity at non-toxic concentrations against any of the other viruses tested. According to NMR spectroscopy and molecular mechanics calculations it is striking that the parent structures 11 and 27 adopt a fixed trans conformation around C2-C2' bond. In the parent amines, which proved to be active compounds, the distance between nitrogen and adamantyl pharmacophoric groups was different; N-C2' distance is 3.7, 3.8 A for 27, 30 and 2.5 A for 11 suggesting that M2 receptor site can accommodate different in size and orientation lipophilic cages.     

Synthesis and anti-influenza virus evaluation of triterpene-sialic acid conjugates

We are interested in new non-natural glycosides with sialic acid conjugates and their biological activities. We report the synthesis of eleven non-natural occurring glycosides, which are triterpene (glycyrrhetinic acid and its derivatives)-sialic acid conjugates, and their inhibitory activities against influenza virus sialidases and influenza virus multiplication in MDCK host cells. Deoxoglycyrrhetol-sialic acid conjugates (6d and 6e) and oleanolic acid-sialic acid conjugates (7d and 7e) showed strong inhibitory activities against three subtypes of influenza virus sialidases. These four compounds (6d, 6e, 7d and 7e) showed clear inhibition to influenza virus multiplication but not to MDCK host cell survival.     

Design and synthesis of 1,2-annulated adamantane piperidines with anti-influenza virus activity

1–2 Annulated adamantane piperidines 4, 6, 16, 17, 19, 23 and 25 were synthesized and evaluated for anti-influenza A virus activity. The stereoelectronic requirements for optimal antiviral potency were investigated. Piperidine 23 proved to be the most active of the compounds tested against influenza A virus, being 3.5-fold more active than amantadine, equipotent to rimantadine and 15-fold more potent than ribavirin. It is noteworthy that piperidine 23 displayed one of the highest selectivity indexes (SI > 732) among aminoadamantanes or other cage structure amines tested till now.     

Synthesis and anti-influenza virus activity of 4-guanidino-7-substituted Neu5Ac2en derivatives

Substitution of 7-OH by small hydrophobic groups on zanamivir resulted in the retaining of low nanomolar inhibitory activities against not only influenza A virus sialidase but also influenza A virus in cell culture. These compounds were prepared by treatment of the corresponding 7-substituted sialic acids derived from 4-modified N-acetyl-D-mannosamine (ManNAc) using enzyme-catalyzed aldol condensation.     

Pyrazole compound BPR1P0034 with potent and selective anti-influenza virus activity

Background

Influenza viruses are a major cause of morbidity and mortality around the world. More recently, a swine-origin influenza A (H1N1) virus that is spreading via human-to-human transmission has become a serious public concern. Although vaccination is the primary strategy for preventing infections, influenza antiviral drugs play an important role in a comprehensive approach to controlling illness and transmission. In addition, a search for influenza-inhibiting drugs is particularly important in the face of high rate of emergence of influenza strains resistant to several existing influenza antivirals.

Methods

We searched for novel anti-influenza inhibitors using a cell-based neutralization (inhibition of virus-induced cytopathic effect) assay. After screening 20,800 randomly selected compounds from a library from ChemDiv, Inc., we found that BPR1P0034 has sub-micromolar antiviral activity. The compound was resynthesized in five steps by conventional chemical techniques. Lead optimization and a structure-activity analysis were used to improve potency. Time-of-addition assay was performed to target an event in the virus life cycle.

Results

The 50% effective inhibitory concentration (IC₅₀) of BPR1P0034 was 0.42 ± 0.11 μM, when measured with a plaque reduction assay. Viral protein and RNA synthesis of A/WSN/33 (H1N1) was inhibited by BPR1P0034 and the virus-induced cytopathic effects were thus significantly reduced. BPR1P0034 exhibited broad inhibition spectrum for influenza viruses but showed no antiviral effect for enteroviruses and echovirus 9. In a time-of-addition assay, in which the compound was added at different stages along the viral replication cycle (such as at adsorption or after adsorption), its antiviral activity was more efficient in cells treated with the test compound between 0 and 2 h, right after viral infection, implying that an early step of viral replication might be the target of the compound. These results suggest that BPR1P0034 targets the virus during viral uncoating or viral RNA importation into the nucleus.

Conclusions

To the best of our knowledge, BPR1P0034 is the first pyrazole-based anti-influenza compound ever identified and characterized from high throughput screening to show potent (sub-μM) antiviral activity. We conclude that BPR1P0034 has potential antiviral activity, which offers an opportunity for the development of a new anti-influenza virus agent.     

流感泰得在小鼠模型中抗流感病毒活性研究

为了在动物整体水平评价流感泰得（ｆｌｕｔｉｄｅ,ＦＴ）抗流感病毒活性,建立了流感病毒感染小鼠实验模型,并测定了ＦＴ在小鼠模型中的抗病毒活性和对小鼠的急性毒性作用。结果表明,流感病毒Ａ／京防／８６－１（Ｈ１Ｎ１）和Ａ／沪防／９３－９（Ｈ３Ｎ２）在小鼠体内连续传代６次时即对小鼠具有感染性,表现为小鼠体重下降,小鼠肺脏湿重增加并能检测到很高的病毒滴度。在小鼠模型中ＦＴ具有较高的抗病毒活性,表现在ＦＴ能明     

Comparison of the anti-influenza virus activity of cyclopentane derivatives with oseltamivir and zanamivir in vivo

Cyclopentane derivatives, designated as BCX-1812, BCX-1827, BCX-1898, and BCX-1923, were tested in parallel with oseltamivir carboxylate and zanamivir for the in vivo activity in mice infected with A/Turkey/Mas/76 X A/Beijing/32/92 (H6N2) influenza virus. The compounds were tested orally and intranasally at different dose levels. BCX-1812, BCX-1827, and BCX-1923 showed more than 50% protection at 1mg/kg/day dose level on oral treatment. The intranasal treatment was 100% effective even at 0.01 mg/kg/day for all four compounds. On comparison with oseltamivir carboxylate and zanamivir, these four cyclopentane derivatives have shown equal or better efficacies. The synthesis of two new compounds, BCX-1898 and BCX-1923, is also described.     

Synthesis and biological evaluation of novel bisheterocycle-containing compounds as potential anti-influenza virus agents

A series of novel 4,2-bisheterocycle tandem derivatives consisting of a methyloxazole and thiazole subunit were synthesized. Many compounds were found to inhibit human influenza A virus. Several analogues exhibited moderate biological activity and could serve as leads for further optimizations for antivirus research.     

Comparison of anti-influenza virus activity and pharmacokinetics of oseltamivir free base and oseltamivir phosphate

Influenza viruses are major human respiratory pathogens that cause high morbidity and mortality worldwide. Currently, prophylactic vaccines and therapeutic antiviral agents are used to prevent and control influenza virus infection. Oseltamivir free base (OSV-FB), a modified generic antiviral drug of Tamiflu (oseltamivir phosphate, OSV-P), was launched in the Republic of Korea last year. Here, we examine the bioequivalence of these two compounds by assessing their antiviral efficacy in infected cells and in a mouse model. It was observed that both antivirals showed comparable efficacy against 11 different influenza A and B viruses in vitro. Moreover, in mice infected with influenza A virus (mouse-adapted A/Puerto Rico/8/34), they showed a dose-dependent therapeutic activity and alleviated infection-mediated reductions in body weight, leading to significantly better survival. There was histopathological disappearance of virus-induced inflammatory cell infiltration of the lung after oral treatment with either antiviral agent (at 10 mg/kg). Pharmacokinetic analysis also exhibited similar plasma concentrations of the active drug, oseltamivir carboxylate, metabolised from both OSV-B and OSV-P. This is the first report showing bioequivalence of OSV-FB to its phosphate salt form in the mouse system. The free base drug has some beneficial points including simple drug formulation process and reduced risk of undesirable cation-phosphate precipitation within solution. The long term stability of OSV-FB requires further monitoring when it is provided as a national stock in readiness for an influenza pandemic.     

Design,synthesis and anti-influenza A virus activity of novel 2,4-disubstituted quinazoline derivatives

Four 2,4-disubstituted quinazoline series containing various amide moieties were designed and synthesized as new anti-influenza A virus agents using the strategies of bio-isosterism and scaffold hopping. Many of them exhibit potent in vitro anti-influenza A virus activity and low cytotoxicity (CC₅₀: >100 μM). Particularly, compounds 10a5 and 17a show better activity (IC₅₀: 3.70–4.19 μM) and higher selective index (SI: >27.03, >23.87, respectively) against influenza A/WSN/33 virus (H1N1), opening a new direction for quinazoline derivatives in anti-influenza A virus field.     

Synthesis of a novel side-chain to side-chain cyclized enkephalin analogue containing a carbonyl bridge

A novel type of cyclic opiod peptide analogue, cyclo(N^ϵ,N^ϵ′-carbonyl- D -Lys²,Lys⁵)enkephalinamide, was prepared from a linear precursor peptide. The peptide was synthesized on the Merrifield resin and also by a combination of the solid-phase technique and the classical method in solution. In both cases the cyclization was performed by reaction of bis(4-nitrophenyl)carbonate with the free side-chain amino groups of the two lysine residues. The described method permits the convenient preparation of novel peptide analogues cyclized via a ureido group incorporating the side-chain amino groups of two α,ω-diamino acid residues. The cyclic enkephalin analogue containing a 21-membered ring structure showed preference for μ over δ opioid receptors in opioid bioassays in vitro. © 1997 European Peptide Society and John Wiley & Sons, Ltd.     

RNA聚合酶——抗流感病毒的新靶点

RNA聚合酶是由PA、PB1和PB2三个亚基构成的蛋白质复合物,在流感病毒基因组的转录复制过程中发挥着重要作用。随着研究的不断深入,RNA聚合酶已经成为抗流感病毒药物重要的靶点。本文介绍了RNA聚合酶各个亚基结构、功能以及RNA聚合酶抑制剂的研究进展。     

Synthesis of 2-(2-adamantyl)piperidines and structure anti-influenza virus A activity relationship study using a combination of NMR spectroscopy and molecular modeling

The 2-(2-adamantyl)piperidines 13 and 15a-c were synthesized and evaluated for anti-influenza virus A and B activity. The parent N-H compound 13 was 3–4 times more active than amantadine and rimantadine against H₂N₂ influenza A. N-alkylation of 13 resulted in derivatives 15a-c that were devoid of biological activity. This dramatic reduction in biological activity may be attributed to the different conformational properties between N-H and N-alkyl piperidines, as deduced from the combination of computational chemistry and NMR spectroscopy.     

Concise synthesis of dideoxy-epigallocatechin gallate (DO-EGCG) and evaluation of its anti-influenza virus activity

Dideoxy-epigallocatechin gallate (DO-EGCG) (2), a simplified analog of naturally occurring EGCG (1), was efficiently prepared by directly introducing a ketone group at C3 and successive reduction to the sec-alcohol with 2,3-cis stereochemistry. Compound 2 showed potent anti-influenza virus activity, indicating that the hydroxyl substituents on the A-ring are not crucial for anti-influenza virus activity.     

Spiro[pyrrolidine-2,2'-adamantanes]: synthesis,anti-influenza virus activity and conformational properties

Synthetic spiro[pyrrolidine-2,2'-adamantanes] 2, 3, 11, 15, 12, 16, 18, 20 were evaluated in vitro and found to be active anti-influenza virus A compounds; the effect of the position of C-Me pyrrolidine ring substituent on antiviral activity was examined. Pyrrolidine 5-Me substitution appears to be optimal for H(2)N(2) strain activity. From the four different possible protonated conformers, experimental observation using NMR spectroscopy and molecular mechanics calculations demonstrated only a pair of conformers A(+)H (N-Me (ps-ax), C-Me (ps-eq)) and B(+)H ((N-Me ps-ax, C-Me ps-ax)) which can contribute to the biological activity of C-Me, N-Me protonated derivatives 15(+)H, 16(+)H and 20(+)H. The relative populations were calculated from NMR spectra. For compounds 15(+)H and 20(+)H conformer A(+)H (cis dimethyl orientation) is the major one whereas a similar population of conformers A(+)H and B(+)H (trans dimethyl orientation) was observed for compound 16(+)H. Since this new series is characterized by a lipophilic part, that is the pyrrolidine ring, in addition to adamantane, that can interact with influenza A M2 protein, an ultimate future goal would be the in vitro mapping of M2 lipophilic pocket.     

siRNA在抗流感病毒感染中的研究进展

季节性流感和全球性大流感的危害已普遍受到社会各界的关注,而目前的流感治疗药物和流感疫苗在使用上存在一定局限性。siRNA及其介导的RNAi过程自发现以来,其高度特异性和强选择性被广泛应用于抗流感病毒感染的研究中,为流感病毒的防治提供了新思路。而随着研究的深入,siRNA仍面临巨大挑战。对siRNA在抗流感病毒感染中的研究进展进行了综述。