Novel Macrocyclic Peptidomimetics Targeting the Polo-Box Domain of Polo-Like Kinase 1.

The polo-box domain (PBD) of Plk1 is a promising target for cancer therapeutics. We designed and synthesized novel phosphorylated macrocyclic peptidomimetics targeting PBD based on acyclic phosphopeptide PMQSpTPL. The inhibitory activities of 16e on Plk1-PBD is >30-fold higher than those of PMQSpTPL. Both 16a and 16e possess excellent selectivity for Plk1-PBD over Plk2/3-PBD. Analysis of the cocrystal structure of Plk1-PBD in complex with 16a reveals that the 3-(trifluoromethyl)benzoyl group in 16a interacts with Arg516 through a π-stacking interaction. This π-stacking interaction, which has not been reported previously, provides insight into the design of novel and potent Plk1-PBD inhibitors. Furthermore, 16h, a PEGlyated macrocyclic phosphopeptide derivative, induces Plk1 delocalization and mitotic failure in HeLa cells. Also, the number of phospho-H3-positive cells in a zebrafish embryo increases in proportion to the amount of 16a. Collectively, the novel macrocyclic peptidomimetics should serve as valuable templates for the design of potent and novel Plk1-PBD inhibitors.

Novel trisaccharide based phospholipids as immunomodulators.

A focused library of novel mannosylated glycophospholipids was synthesized employing imidate coupling and H-phosphate phosphorylation methods. All novel glycophospholipids were evaluated for their receptor interactions by molecular docking studies. Docking studies revealed dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) specific interaction of the glycophospholipid ligand P4 acts, which was further confirmed by in vitro DC-SIGN expression on monocyte-derived dendritic cells (MoDCs). Further, in vitro and in vivo immunomodulatory activity among the six compounds (P1-P6) examined, compound P4 displayed good immunopotentiation and adjuvant properties as indicated by the induced cytokine expression and enhanced ovalbumin (OVA) specific antibody (IgG) titers. Phosphatidylinositol mannosides (PIMs) analogues in the present study enforced the immunomodulatory properties, truncating parent PIMs or tailor-made of PIMs may bring the novel efficacious molecules, which will be useful in vaccine preparation against different diseases.

Design, Synthesis, and Evaluation of Novel 1,2,3-Triazole-Tethered Glycolipids as Vaccine Adjuvants.

A Cu-mediated azide-alkyne click chemistry protocol was employed for the synthesis of a focused library of novel 1,2,3-triazolyl conjugates bearing various carbohydrate-steroid/triterpenoid entities. The immunogenicity of these compounds was examined initially by ex vivo assays. The lead compound 15g was further subjected to in vivo evaluation in BALB/c mice immunized with ovalbumin. These in vivo biological studies revealed an increase in B cell-mediated proliferation, higher expression levels of IL-2, TNF-α, IL-12, and IFN-γ indicating Th1 activation, together with an enhanced OVA-specific antibody (IgG) response compared to alum, affirming adjuvanticity of these glycolipids. The primary indications of response skewed toward Th1 immunity induced by the new triazoyl analogs indicate the potential of these molecules for possible application as adjuvants.