Danoprevir for the Treatment of Hepatitis C Virus Infection: Design, Development, and Place in Therapy.

On June 8, 2018, an NS3/4A protease inhibitor called danoprevir was approved in China to treat the infections of HCV genotype (GT) 1b - the most common HCV genotype worldwide. Based on phase 2 and 3 clinical trials, the 12-week regimen of ritonavir-boosted danoprevir (danoprevir/r) plus peginterferon alpha-2a and ribavirin offered 97.1% (200/206) of sustained virologic response at post-treatment week 12 (SVR12) in treatment-naïve non-cirrhotic patients infected with HCV genotype 1b. Adverse events such as anemia, fatigue, fever, and headache were associated with the inclusion of peginterferon alpha-2a and ribavirin in the danoprevir-based regimen. Moreover, drug resistance to danoprevir could be traced to amino acid substitutions (Q80K/R, R155K, D168A/E/H/N/T/V) near the drug-binding pocket of HCV NS3 protease. Despite its approval, the clinical use of danoprevir is currently limited to its combination with peginterferon alpha-2a and ribavirin, thereby driving its development towards interferon-free, ribavirin-free regimens with improved tolerability and adherence. In the foreseeable future, pan-genotypic direct-acting antivirals with better clinical efficacy and less adverse events will be available to treat HCV infections worldwide.

Design, synthesis, and biological evaluation of novel 5-Alkyl-6-Adamantylmethylpyrimidin-4(3H)-ones as HIV-1 non-nucleoside reverse-transcriptase inhibitors.

A series of novel 5-alkyl-6-Adamantylmethylpyrimidin-4(3H)-ones bearing various substituents at the C-2 position of the pyrimidinone ring were synthesized using a facile route and evaluated for their anti-HIV activity in MT-4 cells. The biological results demonstrated that the majority of the newly designed compounds possessed moderate efficiency in inhibiting the replication of the wild-type (WT) HIV-1 strain (IIIB ) with EC50 values in the range from 0.10 to 5.39 µm. Among them, 5b1 and 5b3 proved to be the two most active inhibitors against WT HIV-1 with EC50 values of 0.10 and 0.12 µm, respectively, which were more active than nevirapine (NVP) in the same assay. In addition, HIV-1 reverse-transcriptase (RT) inhibition assay indicated that the representative compound 5b1 showed affinity to WT HIV-1 RT, and inhibited the activity of RT with an IC50 value superior to the reference drug NVP. Moreover, the preliminary structure-activity relationship (SAR) and the molecular modeling analysis of these new derivatives are also discussed.

Hybrid chemistry. Part 4: Discovery of etravirine-VRX-480773 hybrids as potent HIV-1 non-nucleoside reverse transcriptase inhibitors.

A novel series of etravirine-VRX-480773 hybrids were designed using structure-guided molecular hybridization strategy and fusing the pharmacophore templates of etravirine and VRX-480773. The anti-HIV-1 activity and cytotoxicity was evaluated in MT-4 cell cultures. The most active hybrid compound in this series, N-(2-chlorophenyl)-2-((4-(4-cyano-2,6-dimethylphenoxy)pyrimidin-2-yl)thio)acetamide 3d (EC50=0.24 , SI>1225), was more potent than delavirdine (EC50=0.66 µM, SI>67) in the anti-HIV-1 in vitro cellular assay. Studies of structure-activity relationships established a correlation between anti-HIV activity and the substitution pattern of the acetanilide group.

Synthesis and Biological Evaluation of a Series of 2-((1-substituted-1H-1,2,3-triazol-4-yl)methylthio)-6-(naphthalen-1-ylmethyl)pyrimidin-4(3H)-one As Potential HIV-1 Inhibitors.

A series of novel S-DABO derivatives with the substituted 1,2,3-triazole moiety on the C-2 side chain were synthesized using the simple and efficient CuAAC reaction, and biologically evaluated as inhibitors of HIV-1. Among them, the most active HIV-1 inhibitor was compound 4-((4-((4-(2,6-dichlorobenzyl)-5-methyl-6-oxo-1,6-dihydropyrimidin-2-ylthio)methyl)-1H-1,2,3-triazol-1-yl)methyl)benzenesulfonamide (B5b7), which exhibited similar HIV-1 inhibitory potency (EC50  = 3.22 µm) compared with 3TC (EC50  = 2.24 µm). None of these compounds demonstrated inhibition against HIV-2 replication. The preliminary structure-activity relationship (SAR) of these new derivatives was discussed briefly.

Design, synthesis, and biological evaluation of novel 3,5-disubstituted-1,2,6-thiadiazine-1,1-dione derivatives as HIV-1 NNRTIs.

On the basis of structural features, binding mode, and structure-activity relationship studies of two pyrimidine-derived non-nucleoside reverse-transcriptase inhibitors, DABOs, and diaryl pyrimidines, a novel class of 1,2,6-thiadiazine-1,1-dione derivatives were rationally designed using the strategies of bioisosterism and molecular hybridization, synthesized, and evaluated for their anti-HIV activity in MT4 cell cultures. Three compounds were found to have moderate activity against HIV-1 replication with EC50 values ranging from 23 to 32 µm. To further confirm the binding target, compound IIg was selected to conduct an HIV-1 reverse-transcriptase inhibitory assay. In addition, preliminary structure-activity relationship analysis among the newly synthesized compounds was discussed, and the binding mode of the active compound IIg was rationalized by molecular docking and physicochemical studies.

Selective anti-herpesvirus agents.

This review article focuses on the anti-herpesvirus agents effective against herpes simplex virus, varicella-zoster virus and cytomegalovirus, which have either been licensed for clinical use (idoxuridine, trifluridine, brivudin, acyclovir, valaciclovir, valganciclovir, famciclovir and foscarnet) or are under clinical development (CMX001 [the hexadecyloxypropyl prodrug of cidofovir], the helicase-primase inhibitor BAY 57-1293 [now referred to as AIC316], FV-100 [the valine ester of Cf 1743] and the terminase inhibitor letermovir [AIC246]).

Antivirals: past, present and future.

Vaccination is possible to prevent infections with some viruses: hepatitis B virus (HBV), varicella-zoster virus (VZV), influenza A and B viruses, Yellow fever virus and poliovirus; but not for others: human immunodeficiency virus (HIV), hepatitis C virus (HCV), herpes simplex virus (HSV), cytomegalovirus (CMV), and most hemorrhagic fever viruses (HFV) (except for Yellow fever virus). Antiviral therapy is obviously needed to control those infections that are not amenable to prophylaxis by vaccination, but is also highly desirable for those infections where vaccination has not been implemented or did not fulfill its premises for complete protection.

Antimicrobial, anti-TB, anticancer and anti-HIV evaluation of new s-triazine-based heterocycles.

BACKGROUND: The acquirement of resistance by microorganisms to the antimicrobial arsenal is a threat to public health. A recent WHO report estimated that 1.3 million HIV-negative people and 0.38 million HIV-positive people died from TB in 2009. Various forms of cancer account for a high percentage of deaths in both women (breast cancer) and men (prostate cancer). RESULTS & DISCUSSION: In vitro activity assessment of newly constructed s-triazines against a panel of microorganisms including bacteria, fungi and Mycobacteria demonstrated that the compounds are of immense attraction for impending drug discovery. They were further examined for in vitro activity against breast cancer and prostate cancer cell lines, as well as HIV-1 (III(B)) and HIV-2 (ROD) viral strains. Proposed structural confirmation studies by IR, (1)H NMR, (13)C NMR, (19)F NMR spectroscopy and elemental analysis were in accordance. CONCLUSION: Activity profiles of the products may contribute considerably to future drug-discovery studies.

Synthesis, antiviral activity and cytotoxicity evaluation of Schiff bases of some 2-phenyl quinazoline-4(3)H-ones.

A new series of 3-(benzylideneamino)-2-phenylquinazoline-4(3H)-ones were prepared through Schiff base formation of 3-amino-2-phenyl quinazoline-4(3)H-one with various substituted carbonyl compounds. Their chemical structures were elucidated by spectral studies. Cytotoxicity and antiviral activity were evaluated against herpes simplex virus-1 (KOS), herpes simplex virus-2 (G), vaccinia virus, vesicular stomatitis virus, herpes simplex virus-1 TK- KOS ACVr, para influenza-3 virus, reovirus-1, Sindbis virus, Coxsackie virus B4, Punta Toro virus, feline corona virus (FIPV), feline herpes virus, respiratory syncytial virus, influenza A H1N1 subtype, influenza A H3N2 subtype, and influenza B virus. Compound 2a showed better antiviral activity against the entire tested virus.

Cytotoxicity of natural compounds isolated from the seeds of Garcinia afzelii.

The new compounds guttiferone O ( 1) and 3-methoxycheffouxanthone ( 2) have been isolated from the seeds of Garcinia afzelii Engl., together with nine known compounds: 2-hydroxy-1,7-dimethoxyxanthone ( 3), smeathxanthone A ( 4), 1,5-dihydroxyxanthone ( 5), 1,6-dihydroxy-5-methoxyxanthone ( 6), cheffouxanthone ( 7), 1,3,5-trihydroxyxanthone ( 8), smeathxanthone B ( 9), isoxanthochymol ( 10) and guttiferone E ( 11). Their structures were elucidated by means of 1D and 2D-NMR techniques. All the isolates showed high cytotoxic activity and were found inactive when tested against HIV and influenza viruses.

Synthesis and studies of new 2-(coumarin-4-yloxy)-4,6-(substituted)-S-triazine derivatives as potential anti-HIV agents.

Novel 2-(coumarin-4-yloxy)-4,6-(substituted)-s-triazine derivatives i. e., diaryltriazine (DATA) are reported as novel non-nucleoside reverse transcriptase inhibitors (NNRTIs), were synthesized and their activities against human immunodeficiency virus HIV-1 (III-B), HIV-2 (ROD), and the double RT mutant HIV-1 (K103N and Y181C) were assessed. Modifications at positions 4 and 6 of the coumarinyl-triazine scaffold generated interesting derivatives displaying good to moderate anti-HIV activity against selected HIV strains as compared to nevirapine and efavirenz. The synthesized compounds were characterized by FTIR, (1)H-NMR, and mass spectral data together with elemental analysis.

Structural modifications of DAPY analogues with potent anti-HIV-1 activity.

A novel series of diarylpyrimidine analogues (DAPYs) featuring a naphthyl moiety at the C4 position were designed, with all compounds exhibiting strong activity against wild-type HIV-1.A novel series of diarylpyrimidine analogues (DAPYs) featuring a naphthyl moiety at the C4 position were synthesized and evaluated for their in vitro activity against HIV in MT-4 cells. All compounds exhibited strong activity against wild-type HIV-1. The most active compound showed activity against wild-type HIV-1 with an EC(50) value of 2.35 nM and against the double mutant strain (K103N+Y181C) with an EC(50) value of 6.6 microM, with a selectivity index greater than 60 000 against wild-type HIV-1. Additionally, some compounds also showed activity against HIV-2 (EC(50)=5.82 microM).

Structure-activity relationships for dipeptide prodrugs of acyclovir: implications for prodrug design.

A series of water-soluble dipeptide ester prodrugs of the antiviral acyclovir (ACV) were evaluated for their chemical stability, cytotoxicity, and antiviral activity against several strains of Herpes Simplex-1 and -2, vaccinia, vesicular stomatitis, cytomegalovirus and varicella zoster viruses. ACV dipeptide esters were very active against herpetic viruses, independently of the rate at which they liberate the parent drug. Their minimum cytotoxic concentrations were above 100 microM and the resulting MCC/EC(50) values were lower than those of ACV. When comparing the reactivity of Phe-Gly esters and amides (ACV, zidovudine, paracetamol, captopril and primaquine) in pH 7.4 buffer it was found that the rate of drug release increases with drug's leaving group ability. Release of the parent drug from Phe-Gly in human plasma is markedly faster than in pH 7.4 buffer, thus suggesting that the dipeptide-based prodrug approach can be successfully applied to bioactive agents containing thiol, phenol and amine functional groups.

1,2,3-Thiadiazole thioacetanilides as a novel class of potent HIV-1 non-nucleoside reverse transcriptase inhibitors.

A novel series of 1,2,3-thiadiazole thioacetanilide (TTA) derivatives have been designed, synthesized and evaluated for its anti-HIV activities in MT-4 cells. Some derivatives proved to be highly effective in inhibiting HIV-1 replication at nanomolar concentrations. Among them, 2-[4-(2,4-dichlorophenyl)-1,2,3-thiadiazol-5-ylthio]-N-(2-nitrophenyl)acetamide 7d2 was identified as the most promising compound (EC(50)=0.059+/-0.02 microM, CC(50)>283.25 microM, SI>4883). The structure-activity relationship (SAR) of these novel structural congeners is discussed.

Emerging antiviral drugs.

Foremost among the newly described antiviral agents that may be developed into drugs are, for the treatment of human papilloma virus (HPV) infections, cPrPMEDAP; for the treatment of herpes simplex virus (HSV) infections, BAY 57-1293; for the treatment of varicella-zoster virus (VZV) infections, FV-100 (prodrug of Cf 1743); for the treatment of cytomegalovirus (CMV) infections, maribavir; for the treatment of poxvirus infections, ST-246; for the treatment of hepatitis B virus (HBV) infections, tenofovir disoproxil fumarate (TDF) (which in the meantime has already been approved in the EU); for the treatment of various DNA virus infections, the hexadecyloxypropyl (HDP) and octadecyloxyethyl (ODE) prodrugs of cidofovir; for the treatment of orthomyxovirus infections (i.e., influenza), peramivir; for the treatment of hepacivirus infections (i.e., hepatitis C), the protease inhibitors telaprevir and boceprevir, the nucleoside RNA replicase inhibitors (NRRIs) PSI-6130 and R1479, and various non-nucleoside RNA replicase inhibitors (NNRRIs); for the treatment of human immunodeficiency virus (HIV) infections, integrase inhibitors (INIs) such as elvitegravir, nucleoside reverse transcriptase inhibitors (NRTIs) such as apricitabine, non-nucleoside reverse transcriptase inhibitors (NNRTIs) such as rilpivirine and dapivirine; and for the treatment of both HCV and HIV infections, cyclosporin A derivatives such as the non-immunosuppressive Debio-025.

Dipeptide derivatives of AZT: synthesis, chemical stability, activation in human plasma, hPEPT1 affinity, and antiviral activity.

5'-O-Dipeptide ester prodrugs of antiviral zidovudine (AZT) were designed to target the human intestinal oligopeptide transporter, hPEPT1, and were evaluated for their stability at pH 7.4 in buffer and in human plasma, affinity toward hPEPT1, cytotoxicity, and antiretroviral activity. The dipeptide esters of AZT undergo cyclization in buffer at pH 7.4 to release the parent drug at a rate that depends on the size of the side chains of the peptide carrier; the prodrug is considerably more stable if bulky beta-branched amino acids such as Ile and Val are present, particularly as C-terminal residues. Incubation in human plasma showed that most of the dipeptide esters of AZT release the parent drug through two aminopeptidase-mediated pathways: 1) stepwise cleavage of each of the amino acids and 2) direct cleavage of the dipeptide-drug ester bond. However, the plasma hydrolysis of Gly-Gly-AZT and Phe-Gly-AZT showed only direct cleavage of the dipeptide-drug ester bond. Substrate half-lives in plasma were again remarkably high when hydrophobic beta-branched amino acids (Val, Ile) were present. The esters were also good substrates for the intestinal oligopeptide transporter hPEPT1 in vitro, with Val-Gly-AZT and Val-Ala-AZT presenting the highest affinity toward the transporter (IC(50): 0.20 and 0.15 mM, respectively). The AZT dipeptide esters were assayed against the IIIB and ROD strains of HIV, and their cytotoxicity was evaluated in MT-4 cells. The selectivity index of the prodrugs was two- to threefold higher than that of AZT for all compounds analyzed. These results point to the potential of dipeptide-based carriers for the development of effective antiviral drug-delivery systems. Val-Ala-AZT appears to combine chemical stability with good affinity for the hPEPT1 transporter and an improved cytotoxicity/antiretroviral index relative to AZT.

Tetrazolium-based colorimetric assay for the detection of HIV replication inhibitors: revisited 20 years later.

Since its first description 20 years ago, the tetrazolium-based colorimetric (MTT) assay using MT-4 cells for the detection of anti-HIV compounds has been widely used. This method, which remains popular, provides more information than more recently developed methods and, therefore, represents a useful methodology on its own or in combination with other screening systems. The replication of HIV in MT-4 cells is usually monitored 5 d after infection; therefore, this protocol can be divided into three steps: the infection (at day 0), an incubation period (5 d) and the evaluation (at day 5). The long-standing and intensive use of the MTT method has taught users of the limitations and, equally importantly, the unexpected advantages of the MT-4/MTT assay. The use of this method can be extended to antiviral testing of compounds against other cyto-destructive viruses.

Synthesis of some novel thiourea derivatives obtained from 5-[(4-aminophenoxy)methyl]-4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thiones and evaluation as antiviral/anti-HIV and anti-tuberculosis agents.

As a continuation of our previous efforts on N-alkyl/aryl-N'-[4-(4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thione-5-yl)phenyl]thioureas 1-19 and N-alkyl/aryl-N'-[4-(3-aralkylthio-4-alkyl/aryl-4H-1,2,4-triazole-5-yl)phenyl]thioureas 20-22, a series of novel 5-[(4-aminophenoxy)methyl]-4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thiones 23-26 and several related thioureas, N-alkyl/aryl-N'-{4-[(4-alkyl/aryl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)methoxy]phenyl}thioureas 27-42 were synthesized for evaluation of their antiviral potency. Structures of the synthesized compounds were confirmed by the use of (1)H NMR, (13)C NMR and HR-MS data. All compounds 1-42 were evaluated in vitro against HIV-1 (IIIB) and HIV-2 (ROD) strains in MT-4 cells, as well as other selected viruses such as HSV-1, HSV-2, Coxsackie virus B4, Sindbis virus and Varicella-zoster virus using HeLa, Vero, HEL and E6SM cell cultures, and anti-tuberculosis activity against Mycobacterium tuberculosis H37Rv. Compounds 4 and 5 showed weak activity against HSV-1, HSV-2 and TK(-) HSV, whereas eight compounds showed marginal activity against Coxsackie virus B4. The most active derivative in this series was compound 38 which showed moderate protection against Coxsackie virus B4 with an MIC value of 16 microg/ml and a selectivity index of 5. This compound was also active against thymidine kinase positive Varicella-zoster virus (TK(+) VZV, OKA strain) with an EC(50) value of 9.9 microg/ml. Compound 38 was the most active compound with 79% inhibition against M. tuberculosis H37Rv.

Cinnamacrins A-C, cinnafragrin D, and cytostatic metabolites with alpha-glucosidase inhibitory activity from Cinnamosma macrocarpa.

Two new monomeric and two new dimeric drimane sesquiterpenes, cinnamacrins A-C (1-3) and cinnafragrin D (4), along with bemadienolide (5), capsicodendrin (6), cinnamodial (7), cinnamolide (8), isopolygodial (9), and delta-tocotrienol (10), were isolated from Cinnamosma macrocarpa. The structures of the new compounds were determined by physical, chemical, and spectroscopic evidence. Capsicodendrin (6) and/or cinnamodial (7) are the major compounds in C. fragrans and C. macrocarpa, which are both widely used in Malagasy traditional medicine. The cytostatic activity as well as alpha-glucosidase inhibition and antiviral activities of the major constituents 6 and 7 and the compounds previously isolated from C. fragrans were evaluated.

The novel C-5 aryl, alkenyl, and alkynyl substituted uracil derivatives of L-ascorbic acid: synthesis, cytostatic, and antiviral activity evaluations.

The novel C-5 substituted uracil derivatives of l-ascorbic acid were synthesized by coupling of 5-iodouracil-4,5-didehydro-5,6-dideoxy-l-ascorbic acid with unsaturated stannanes under Stille reaction conditions. The new compounds were evaluated for their antitumoral and antiviral activities. Among all compounds evaluated the 5-propynyl substituted uracil derivative of l-ascorbic acid (7) exhibited the most pronounced cytostatic activities against all examined tumor cell lines (IC(50): 0.2-0.78 microM). However, this compound was also cytotoxic to human normal fibroblasts WI 38. The 5-(phenylethynyl)uracil-2,3-di-O-benzylated l-ascorbic acid derivative (4) exhibited an albeit slight (IC(50): 55-108 microM), but selective inhibitory effect toward all tumor cell lines except for cervical carcinoma (HeLa), pancreatic carcinoma (MiaPaCa-2), laryngeal carcinoma (Hep-2), and colon carcinoma (SW 620), and no cytotoxicity to normal human fibroblast (WI 38). Compound 7 showed some, not highly specific, inhibitory potential against vesicular stomatitis virus, Coxsackie B4 virus, and Sindbis viruses (EC(50): 1.6 microM).