We report the synthesis, biological evaluation, and X-ray structural studies of a series of SARS-CoV-2 Mpro inhibitors based upon the X-ray crystal structure of nirmatrelvir, an FDA approved drug that targets the main protease of SARS-CoV-2. The studies involved examination of various P4 moieties, P1 five- and six-membered lactam rings to improve potency. In particular, the six-membered P1 lactam ring analogs exhibited high SARS-CoV-2 Mpro inhibitory activity.
View Article and Find Full Text PDFIn the development of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drugs, its main protease (M), which is an essential enzyme for viral replication, is a promising target. To date, the M inhibitors, nirmatrelvir and ensitrelvir, have been clinically developed by Pfizer Inc. and Shionogi & Co.
View Article and Find Full Text PDFSARS-CoV-2-BA.4/5-adapted-bivalent-BNT162b2-vaccine (BNT), developed in response to the recent emergence of immune-evasive Omicron-variants, has been given to individuals who completed at least 2-doses of the monovalent-BNT162b2-vaccine (BNT). In the present cohort study, we evaluated neutralization-titers (NTs) against Wuhan-strain (SCoV2) and Omicron-sublineages including BA.
View Article and Find Full Text PDFWe report here the synthesis and biological evaluation of a series of small molecule SARS-CoV-2 PLpro inhibitors. We compared the activity of selected compounds in both SARS-CoV-1 and SARS-CoV-2 PLpro inhibitory and antiviral assays. We have synthesized and evaluated several new structural variants of previous leads against SARS-CoV-2 PLpro.
View Article and Find Full Text PDFThe main protease (M) of SARS-CoV-2 is an attractive target for the development of drugs to treat COVID-19. Here, we report the design, synthesis, and structure-activity relationship (SAR) studies of highly potent SARS-CoV-2 M inhibitors including TKB245 ()/TKB248 (). Since we have previously developed M inhibitors () and (), several hybrid molecules of these previous compounds combined with nirmatrelvir () were designed and synthesized.
View Article and Find Full Text PDFNuclear localization signal (NLS) of HIV-1 integrase (IN) is implicated in nuclear import of HIV-1 preintegration complex (PIC). Here, we established a multiclass drug-resistant HIV-1 variant (HIV) by consecutively exposing an HIV-1 variant to various antiretroviral agents including IN strand transfer inhibitors (INSTIs). HIV was extremely susceptible to a previously reported HIV-1 protease inhibitor, GRL-142, with IC of 130 femtomolar.
View Article and Find Full Text PDFEncouraged by our recent findings that 4'-cyano-deoxyguanosine (2), entecavir analogues 4 and 5 are highly potent anti-hepatitis B virus (HBV) agents, we designed and synthesized 6 having a hybridized structure of 4 and 5. The chiral quaternary carbon portion at the 4'-position, which is substituted by cyano- and 5'-hydroxymethyl groups, was stereospecifically constructed by radical-mediated 5- mode cyclization of 10. The introduction of the fluorine atom into the 6''-position was achieved by radical-mediated stannylation of sulfide ()-11 and subsequent electrophilic fluorination of ()-12.
View Article and Find Full Text PDFCellular senescence is a cellular state with a broad spectrum of age-related physiological conditions that can be affected by various infectious diseases and treatments. Therapy of hepatitis B virus (HBV) infection with nucleos(t)ide analogs [NA(s)] is well established and benefits many HBV-infected patients, but requires long-term, perhaps lifelong, medication. In addition to the effects of HBV infection, the effects of NA administration on hepatocellular senescence are still unclear.
View Article and Find Full Text PDFCurrently, the emergence of drug resistance is an important issue in the treatment of hepatitis B virus (HBV). Recently, our collaborating group developed a novel long-acting anti-HBV drug, E-CFCP. However, until this study, the effects of E-CFCP in the kidney have remained unclarified.
View Article and Find Full Text PDFPotent and biostable inhibitors of the main protease (M) of SARS-CoV-2 were designed and synthesized based on an active hit compound 5h (). Our strategy was based not only on the introduction of fluorine atoms into the inhibitor molecule for an increase of binding affinity for the pocket of M and cell membrane permeability but also on the replacement of the digestible amide bond by a surrogate structure to increase the biostability of the compounds. Compound is highly potent and blocks SARS-CoV-2 infection without a viral breakthrough.
View Article and Find Full Text PDFWe newly generated two human induced pluripotent stem cell (hiPSC)-derived spheroid lines, termed Spheroids_ and Spheroids_, both of which express angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2), which are critical for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Both spheroids were highly susceptible to SARS-CoV-2 infection, and two representative anti-SARS-CoV-2 agents, remdesivir and 5h (an inhibitor of SARS-CoV-2's main protease), inhibited the infectivity and replication of SARS-CoV-2 in a dose-dependent manner, suggesting that these human-derived induced spheroids should serve as valuable target cells for the evaluation of anti-SARS-CoV-2 activity. The hiPSC-derived spheroids we generated are more expensive to obtain than the human cell lines currently available for anti-SARS-CoV-2 drug evaluation, such as Calu-3 cells; however, the spheroids have better infection susceptibility than the existing human cell lines.
View Article and Find Full Text PDFThe design, synthesis, X-ray structural, and biological evaluation of a series of highly potent HIV-1 protease inhibitors are reported herein. These inhibitors incorporate novel cyclohexane-fused tricyclic bis-tetrahydrofuran as P2 ligands in combination with a variety of P1 and P2' ligands. The inhibitor with a difluoromethylphenyl P1 ligand and a cyclopropylaminobenzothiazole P2' ligand exhibited the most potent antiviral activity.
View Article and Find Full Text PDFThe persistence of covalently closed circular DNA (cccDNA) poses a major obstacle to curing chronic hepatitis B (CHB). Here, we used droplet digital PCR (ddPCR) for cccDNA quantitation. The cccDNA-specific ddPCR showed high accuracy with the dynamic range of cccDNA detection from 10 to 10 copies/assay.
View Article and Find Full Text PDFDespite various attempts to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients with COVID-19 convalescent plasmas, neither appropriate approach nor clinical utility has been established. We examined the efficacy of administration of highly neutralizing COVID-19 convalescent plasma (-plasmas) and such plasma-derived IgG administration using the Syrian hamster COVID-19 model. Two -plasmas, which were in the best 1% of 340 neutralizing activity-determined convalescent plasmas, were intraperitoneally administered to SARS-CoV-2-infected hamsters, resulting in a significant reduction of viral titers in lungs by up to 32-fold compared to the viral titers in hamsters receiving control nonneutralizing plasma, while with two moderately neutralizing plasmas (-plasmas) administered, viral titer reduction was by up to 6-fold.
View Article and Find Full Text PDFHere, we report the synthesis, structure-activity relationship studies, enzyme inhibition, antiviral activity, and X-ray crystallographic studies of 5-chloropyridinyl indole carboxylate derivatives as a potent class of SARS-CoV-2 chymotrypsin-like protease inhibitors. Compound exhibited a SARS-CoV-2 3CLpro inhibitory IC value of 250 nM and an antiviral EC value of 2.8 μM in VeroE6 cells.
View Article and Find Full Text PDFWhile there are various attempts to administer COVID-19-convalescent plasmas to SARS-CoV-2-infected patients, neither appropriate approach nor clinical utility has been established. We examined the presence and temporal changes of the neutralizing activity of IgG fractions from 43 COVID-19-convalescent plasmas using cell-based assays with multiple endpoints. IgG fractions from 27 cases (62.
View Article and Find Full Text PDFExcept remdesivir, no specific antivirals for SARS-CoV-2 infection are currently available. Here, we characterize two small-molecule-compounds, named GRL-1720 and 5h, containing an indoline and indole moiety, respectively, which target the SARS-CoV-2 main protease (M). We use VeroE6 cell-based assays with RNA-qPCR, cytopathic assays, and immunocytochemistry and show both compounds to block the infectivity of SARS-CoV-2 with EC values of 15 ± 4 and 4.
View Article and Find Full Text PDFBackground & Aims: While certain nucleos(t)ide reverse transcriptase inhibitors (NRTIs) are efficacious in treating HBV infection, their effects are yet to be optimized and the emergence of NRTI-resistant HBV variants is an issue because of the requirement for lifelong treatment. The development of agents that more profoundly suppress wild-type and drug-resistant HBVs, and that have a long-acting effect, are crucial to improve patient outcomes.
Methods: Herein, we synthesized a novel long-acting 4'-modified NRTI termed E-CFCP.
The design, synthesis, biological evaluation, and X-ray structural studies are reported for a series of highly potent HIV-1 protease inhibitors. The inhibitors incorporated stereochemically defined amide-based bicyclic and tricyclic ether derivatives as the P2 ligands with ()-hydroxyethylaminesulfonamide transition-state isosteres. A number of inhibitors showed excellent HIV-1 protease inhibitory and antiviral activity; however, ligand combination is critical for potency.
View Article and Find Full Text PDFWe designed, synthesized and identified a novel nucleoside derivative, 4'-C-cyano-7-deaza-7-fluoro-2'-deoxyadenosine (CdFA), which exerts potent anti-HBV activity (IC ~26 nM) with favorable hepatocytotoxicity (CC ~56 μM). Southern blot analysis using wild-type HBV (HBV)-encoding-plasmid-transfected HepG2 cells revealed that CdFA efficiently suppresses the production of HBV (IC = 153.7 nM), entecavir (ETV)-resistant HBV carrying L180M/S202G/M204V substitutions (HBV; IC = 373.
View Article and Find Full Text PDFWe designed, synthesized, and characterized a novel nucleoside analog, (1,3,5)-3-(2-amino-6-oxo-1,6-dihydro-9H-purin-9-yl)-5-hydroxy-1-(hydroxymethyl)-2-methylene-cyclopentanecarbonitrile, or 4'-cyano-methylenecarbocyclic-2'-deoxyguanosine (CMCdG), and evaluated its anti-hepatitis B virus (anti-HBV) activity, safety, and related features. CMCdG's activity was determined using quantitative PCR and Southern blotting assays, and its cytotoxicity was determined with a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, while its activity and safety were determined in human liver-chimeric mice infected with wild-type HBV genotype Ce (HBV) and an entecavir (ETV)-resistant HBV variant containing the amino acid substitutions L180M, S202G, and M204V (HBV). CMCdG potently inhibited HBV production in HepG2.
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