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Cyclobutyl nucleoside analogues containing guanine and 8-azaguanine (compounds 5-10) were prepared from (1R,cis)-3-aminomethyl-2,2-dimethylcyclobutylmethanol (1). All were evaluated as antiviral and antitumoral agents in a variety of assay systems. Compounds 6 and 7 showed a noteworthy activity against a respiratory syncytial virus and compound 10 was moderately active against vaccinia virus. Only compound 5 showed some cytostatic activity.
There are now exactly 20 anti-HIV drugs licenced (approved) for clinical use, and > 30 anti-HIV compounds under (pre)clinical development. The licensed anti-HIV drugs fall into five categories: nucleoside reverse transcriptase inhibitors (NRTIs: zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir and emtricitabine); nucleotide reverse transcriptase inhibitors (NtRTIs: tenofovir disoproxil fumarate); non-nucleoside reverse transcriptase inhibitors (NNRTIs: nevirapine, delavirdine and efavirenz); protease inhibitors (PIs: saquinavir, indinavir, ritonavir, nelfinavir, amprenavir, lopinavir, atazanavir and fosamprenavir); and fusion inhibitors (FIs: enfuvirtide). The compounds that are currently under clinical (Phase I, II or III) or preclinical investigation are either targeted at the same specific viral proteins as the licensed compounds (i.e., reverse transcriptase [NRTIs: PSI-5004, (-)-dOTC, DPC-817, elvucitabine, alovudine, MIV-210, amdoxovir, DOT; NNRTIs: thiocarboxanilide, UC-781, capravirine, dapivirine, etravirine, rilpivirine], protease [PIs: tipranavir, TMC-114]) or other specific viral proteins (i.e., gp120: cyanovirin N; attachment inhibitors: AIs, such as BMS-488043; integrase: L-870,812, PDPV-165; capsid proteins: PA-457, alpha-HCG); or cellular proteins (CD4 downmodulators: CADAs; CXCR4 antagonists: AMD-070, CS-3955; CCR5 antagonists: TAK-220, SCH-D, AK-602, UK-427857). Combination therapy is likely to remain the gold standard for the treatment of AIDS so as to maximise potency, minimise toxicity and diminish the risk for resistance development. Ideally, pill burden should be reduced to once-daily dosing so as to optimise the patient's compliance and reduce the treatment costs.
Interferon induction by poly(rI).poly(rC) in primary rabbit kidney and mouse L-929 cell cultures was markedly increased if the cells were previously treated with homologous interferon. This priming effect has been established with different times of exposure of the cells to poly(rI).poly(rC), and was most pronounced for short pulses of contact of the polynucleotide with the cells (10 s, 1 min). Treatment of the cells with pancreatic ribonuclease immediately after their exposure to poly(rI).poly(rC) brought about a relatively greater reduction of the interferon response in interferon-primed cells than it did in unprimed cell cultures. Priming of the cells with interferon did not increase cell-binding of poly(rI).poly(rC), whether this cell-binding was measured quantitatively (by radioactivity, upon exposure of the cells to radiolabeled polymer) or qualitatively (by antiviral activity, by assaying the cell extract for virus plaque reduction). Similarly, interferon priming did not alter the sensitivity of cell-associated poly(rI).poly(rC) to extraneous ribonuclease treatment. Finally, priming with interferon did not decrease the rate of degradation of cell-bound poly(rI).poly(rC) by cellular nucleases nor did it increase the anti-nuclease potency of the cells. The exact mechanism by which previous exposure of the cells to interferon enhances subsequent interferon production, induced by either synthetic polynucleotides or viruses, has not yet been resolved.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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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.
