39 research outputs found
Synthesis and Activity of N‐Benzyl Pseudopeptides HIV Protease Inhibitors.
No full textA series of N-benzyl pseudopeptides was designed, synthesized and tested as HIV-1 protease inhibitors. The ability of the new compounds containing N-benzyl hydroxyalkylamino acid core structure to inhibit HIV replication in cell culture is comparable to their capacity to inhibit the isolated enzyme, a result compatible with good pharmacokinetic properties of these derivatives. The pseudotripeptide Fmoc-Leu-N(Bzl)Hse-Met-NH-tBu was the best inhibitor of the series (IC50=170 nM) showing promising inhibition of viral replication (ED50=52 nM). All new compounds exhibit high enzymatic resistance and stability against cell cultures and plasma enzymes
Cytotoxic T lymphocyte epitope analogues containing cis- or trans-4-aminocyclohexanecarboxylic acid residues
No full textIn order to improve the immunotherapeutical potential of H-Cys-Leu-Gly-Gly-Leu-Leu-Thr-Met-Val-OH (CLG) peptide, an Epstein-Barr virus (EBV) subdominant epitope derived from the membrane protein LMP2, we have synthesized and tested CLG analogues containing cis- and/or trans-4-aminocyclohexanecarboxylic acid (ACCA) replacing Gly-Gly and/or Thr-Met dipeptide units. All pseudopeptides were tested for metabolic stability and for their capacity to bind HLA-A2 molecules and to sensitize target cells to lysis. All new compounds exhibited higher enzymatic resistance compared to the original CLG and some trans-ACCA-derivatives were able to associate HLA-A2 and to efficiently stimulate CTL responses directed against the CLG natural epitope
Symmetry-based inhibitors of HIV-1 protease. Design, synthesis and preliminary structure-activity studies of acylated 2,3-diamino-1-hydroxypropanes and 2,4 diamino-1-hydroxybutanes
No full textTwo series of peptidomimetics containing a novel C2 pseudosymmetrical hydroxyalkyldiamino core structure were prepared from amino acid starting materials and tested for inhibitory activity against the HIV-1 protease (HIV-1 Pr) and the virus in cell culture. In the 2,3-diamino-1-hydroxypropane series, compound 6a, containing P1/P1I benzyl and P2/P2I Fmoc substituents, displayed modest HIV-1 Pr inhibition (IC50 = 430 nM). The corresponding 2,4-diamino-1-hydroxybutane derivative (6b) was the best inhibitor of the series (IC50 = 160 nM). Interestingly, 6a and 6b showed satisfactory inhibition of HIV replication in cell culture (ED50 = 340 and 110 nM, respectively), a result which suggests good cell membrane penetration by this class of compounds
HIV-1 protease inhibitors containing an N-hydroxyamino acid core structure
No full textTwo series of peptidomimetics containing an N-hydroxyamino acid core structure were prepared by mixed solution solid-phase synthesis and tested for inhibitory activity against the human immunodeficiency virus (HIV-1) protease (Pr) and the virus in cell culture. In general, N-hydroxy Gly containing pseudopeptides displayed modest HIV Pr inhibition (IC50≥930 nM). In the N-hydroxy Phe derivatives, Fmoc-Phe-ψ[CO–N(OH)]-Phe-Pro-NHtBu was the best inhibitor of the series (IC50=144 nM) showing satisfactory inhibition of HIV replication in cell culture (ED50=98 nM) and remarkable stability against cell culture and plasma enzymes
Peptide analogues of a subdominant epitope expressed in EBV-associated tumors: synthesis and immunological activity
No full textH-Cys-Leu-Gly-Gly-Leu-Leu-Thr-Met-Val-OH (CLG) peptide is an EBV subdominant epitope that represents the target of HLA-A2 restricted CTL responses. The CLG peptide has low affinity for HLA-A2 and does not produce stable complexes, both factors that determine weak CTL responses. In contrast, the [Tyr(1), Ala(3)]CLG (YLA) analogue showed high affinity for HLA-A2 molecules and efficiently stimulated CLG-specific CTL precursors. Nevertheless, this modified epitope showed low enzymatic stability. To further improve the immunotherapeutical potential of this "improved epitope", we have synthesized and tested YLA analogues containing different modifications next to the scissile peptide bond. Among the analogues we found three peptides, with higher enzymatic resistance, that efficiently stimulate CTL responses. These peptides may be used for EBV-specific immunotherapies
Synthesis and activity of new acylated diaminohydroxyalkanes as human immunodeficiency virus protease inhibitors
No full textA 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
The lifespan of major histocompatibility complex class I/peptide complexes determines the efficiency of cytotoxic T‐lymphocyte responses
No full textMajor histocompatibility complex (MHC)/peptide association and stability are determined by
specific amino acid interactions between peptide antigens and the MHC groove, and are regarded
as a critical feature in ensuring efficient monitoring by T cells. In this investigation we examined
the relationship between MHC/peptide stability and the immunostimulatory capacity of MHC/
peptide complexes. For this purpose we compared synthetic peptide analogues derived from the
immunodominant HLA-A11-presented IVTDFSVIK (IVT) epitope, for their capacity to reactivate
IVT-specific memory cytotoxic T-lymphocyte (CTL) responses. The analogues differentiated from
the wild-type epitope by single amino acid substitution at position 2. All peptides showed similar
affinity for HLA-A11 molecules and were recognized by IVT-specific CTL clones, but induced
HLA-A11 complexes at the cell surface with different lifespan. This model offered the possibility
of comparing the capacity of an immunogenic epitope to stimulate a unique population of T-cell
precursors depending on the lifespan of its presentation at the cell surface. We demonstrated that
stable HLA-A11/peptide complexes efficiently stimulate IVT-specific CTL responses, while HLAA11/
peptide complexes with short lifespan do not. The precise identification of the role of amino
acid residues in the formation of stable MHC/peptide complexes may be relevant for the design
of wild-type-derived epitopes with high immunogenicity. These analogues may have important
applications in the immunotherapy of infectious diseases and immunogenic tumours
Benthic foraminifera for the ecological status assessment of tourist marinas
No full textLiving benthic foraminifera were investigated in three tourist marinas of the Central Adriatic in order to test the suitability of these organisms for a quick and cost-effective assessment of the ecological quality status (EcoQS). Local high concentrations of biocidal metals (Cu, Zn, Cr, Sn, Ni and Pb) were measured in the sediments nearby the boathouse areas, i.e. where the careening activity takes place, suggesting that the accumulation of current and past antifouling residues is the main source of pollution in these particular maritime spaces. Factors such as the capacity of the marina, its shape as well as the location of the boathouse area concur to the degree of antifouling residues accumulation. Foraminifera responded to the different environmental conditions and to metal contamination in terms of abundance and species composition. At the boathouse stations these organisms were scarcely numerous and no living specimen was observed in the most polluted sediments. Three categories of indices were tested based on: (1) the percentages of abnormal tests, (2) biodiversity and (3) the sensitive-tolerant species occurrence (i.e. Foram-AMBI). The most diverse assemblage was observed at intermediate metal levels and seemed to be influenced by other environmental factors such as the presence of submerged vegetation that likely provides additional resources and increased heterogeneity. Unexpectedly, the station with the lowest metal levels was characterized by the least biodiverse assemblage. Notwithstanding, among the few species observed, at this site the dominant one was the sole species encountered in the present study that is recognized as sensitive, i.e. Ammonia parkinsoniana. Consequently, while the diversity indices provided very low values, Foram-AMBI outputs indicated the presence of an assemblage not exclusively dominated by opportunistic taxa. This result suggests a complementarity of these two categories of indices that should be taken into account for an accurate EcoQS assessment of tourist marinas
Design of dimeric peptides obtained from a subdominant Epstein-Barr virus LMP2-derived epitope
No full textThe latent membrane protein 2 (LMP2) is expressed in EBV-associated tumours. LMP2 is a target of HLA-A2 restricted EBV-specific CTL responses and consequently it may represent a good target for specific CTL-based immunotherapies. However, the efficacy of such therapy is limited by the poor immunogenicity of the protein that induces weak cytotoxic T lymphocyte (CTL) responses directed against the CLGGLLTMV (CLG) epitope. Indeed, the CLG peptide presents low affinity for HLA-A2 and does not produce stable complexes. Therefore we synthesized and tested CLG-dimeric analogues with the purpose of characterizing new compounds with the capacity to bind HLA-A2 molecules. By these studies we have identified a few peptides which, compared to the natural epitope, showed higher affinity for HLA-A2 molecules and superior capacity to form a complex. These dimeric peptides may have the potential to induce efficient CTL responses directed to the natural epitope
Deubiquitinating Enzymes in Coronaviruses and Possible Therapeutic Opportunities for COVID-19
No full textFollowing the outbreak of novel severe acute respiratory syndrome (SARS)-coronavirus (CoV)2, the majority of nations are struggling with countermeasures to fight infection, prevent spread and improve patient survival. Considering that the pandemic is a recent event, no large clinical trials have been possible and since coronavirus specific drug are not yet available, there is no strong consensus on how to treat the coronavirus disease 2019 (COVID-19) associated viral pneumonia. Coronaviruses code for an important multifunctional enzyme named papain-like protease (PLP), that has many roles in pathogenesis. First, PLP is one of the two viral cysteine proteases, along with 3-chymotripsin-like protease, that is responsible for the production of the replicase proteins required for viral replication. Second, its intrinsic deubiquitinating and deISGylating activities serve to antagonize the hosts immune response that would otherwise hinder infection. Both deubiquitinating and deISGylating functions involve the removal of the small regulatory polypeptides, ubiquitin and ISG15, respectively, from target proteins. Ubiquitin modifications can regulate the innate immune response by affecting regulatory proteins, either by altering their stability via the ubiquitin proteasome pathway or by directly regulating their activity. ISG15 is a ubiquitin-like modifier with pleiotropic effects, typically expressed during the host cell immune response. PLP inhibitors have been evaluated during past coronavirus epidemics, and have showed promising results as an antiviral therapy in vitro. In this review, we recapitulate the roles of PLPs in coronavirus infections, report a list of PLP inhibitors and suggest possible therapeutic strategies for COVID-19 treatment, using both clinical and preclinical drugs.Funding agencies: The Department of Defense Ovarian Cancer Research Program GrantOC160377, the Minnesota Ovarian Cancer Alliance, the Randy Shaver Cancer Research Funds and the NIH grant1R01GM130800-01A1 to Martina Bazzaro. This work was supported by the Swedish Research Council to PadraigD’Arcy. This work was supported by Rotary Club Forlì to Valentino Clemente.</p
