Indiana University-Purdue University Indianapolis (IUPUI) / Current Mycobacterium tuberculosis (Mtb) treatments suffer from an increase in antibiotic resistance strains and the lack of efficacy against latent state tuberculosis, thus novel approaches targeting different mechanisms of action are needed. One strategy to target Mtb is to target protein homeostasis pathways by inhibiting molecular chaperones, in particular, GroEL/ES (HSP60/10) chaperonin systems. Mtb has two homologs of GroEL, of which GroEL1 is not essential, but is important for cytokine-dependent granuloma formation, and GroEL2 is essential for survival and the likely canonical housekeeping chaperonin. Another strategy to target Mtb is to target the protein tyrosine phosphatase B (PtpB) virulence factor that Mtb secretes into host cells to help evade immune responses. Thus, we envisioned that this analog series might also be capable of inhibiting Mtb PtpB along with GroEL. By developing compound 1 inhibitors that could act on all of GroEL1, GroEL2, and PtpB, we could have an antibiotic candidate that targets all stages of tuberculosis: actively replicating bacteria, bacteria evading host cell immune response, and granuloma formation in latent disease. In the Johnson lab, previous studies explored GroEL/ES inhibitors, with compound 1 being one of the most potent inhibitors, inhibiting both Trypanosoma brucei and Staphylococcus aureus proliferation. In the present study, we have screened previously developed compound 1 analogs, as well as a series of newly synthesized analogs that we term “half-molecules”. In this study, our results indicated two potential avenues to explore for future research. The first is a series of carboxyl-bearing compound 1 inhibitors, compounds 2m-o, 2m-m, and 2m-p, which act solely on Mtb PtpB phosphatase activity without inhibiting GroEL. The second is a series of compound 1 inhibitors (e.g. 20R and 20L) that are able to inhibit both the PtpB phosphatase and GroEL/ES chaperonin system. Thus, this exploratory study showed the possibility of pursuing such a polypharmacological antibiotic strategy against Mtb infections and with further optimization, such dual-targeting GroEL/ES and PtpB inhibitors could be effective against all stages of tuberculosis.

Alloys, intermetallic compounds and multi-metal oxides are generally made by traditional solid-state methods that often require melting or grinding/pressing powders followed by high temperature annealing (> 1000 degrees C) for days or weeks. The research presented here takes advantage of the fact that nanoparticles have a large fraction of their atoms on the surface making them highly reactive and their small size virtually eliminates the solid-solid diffusion process as the rate limiting step. Materials that normally require high temperatures and long annealing times become more accessible at relatively low-temperatures because of the increased interfacial contact between the nanoparticle reactants. Metal nanoparticles, formed via reduction of metal salts in an aqueous solution and stabilized by PVP (polyvinylpyrrolidone), were mixed into nanoparticle composites in stoichometric proportions. The composite mixtures were then annealed at relatively low temperatures to form alloy and intermetallic compounds at or below 600 degrees C. This method was further extended to synthesizing multi-metal oxide systems by annealing metal oxide nanoparticle composites hundreds of degrees lower than more traditional methods. Nanoparticles of Pt (supported or unsupported) were added to a metal salt solution of tetraethylene glycol and heated to obtain alloy and intermetallic nanoparticles. The supported intermetallic nanoparticles were tested as catalysts and PtPb/Vulcan XC-72 showed enhanced catalytic activity for formic acid oxidation while Pt3Sn/Vulcan XC-72 and Cu3Pt/y-Al2O3 catalyzed CO oxidiation at lower temperatures than supported Pt. Intermetallic nanoparticles of Pd were synthesized by conversion chemistry methods previously mentioned and were supported on carbon and alumina. These nanoparticles were tested for Suzuki cross-coupling reactions. However; the homocoupled product was generally favored. The catalytic activity of Pd3Pb/y-Al2O3 was tested for the Heck reaction and gave results comparable to Pd/y-Al2O3 with a slightly better selectivity. Conversion chemistry techniques were used to convert Pt nanocubes into Ptbased intermetallic nanocrystals in solution. It was discovered that aggregated clusters of Pt nanoparticles were capable of converting to FePt3; however, when Pt nanocubes were used the intermetallic phase did not form. Alternatively, it was possible to form PtSn nanocubes by a conversion reaction with SnCl2.