RESUMO
Bisphosphonates are a major class of drugs used to treat osteoporosis, Paget's disease, and cancer. They have been proposed to act by inhibiting one or more targets including protein prenylation, the epidermal growth factor receptor, or the adenine nucleotide translocase. Inhibition of the latter is due to formation in cells of analogs of ATP: the isopentenyl ester of ATP (ApppI) or an AppXp-type analog of ATP, such as AMP-clodronate (AppCCl2p). We screened both ApppI as well as AppCCl2p against a panel of 369 kinases finding potent inhibition of some tyrosine kinases by AppCCl2p, attributable to formation of a strong hydrogen bond between tyrosine and the terminal phosphonate. We then synthesized bisphosphonate preprodrugs that are converted in cells to other ATP-analogs, finding low nM kinase inhibitors that inhibited cell signaling pathways. These results help clarify our understanding of the mechanisms of action of bisphosphonates, potentially opening up new routes to the development of bone resorption, anticancer, and anti-inflammatory drug leads.
Assuntos
Trifosfato de Adenosina/análogos & derivados , Difosfonatos/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Trifosfato de Adenosina/síntese química , Trifosfato de Adenosina/química , Trifosfato de Adenosina/farmacologia , Linhagem Celular Tumoral , Difosfonatos/síntese química , Difosfonatos/química , Humanos , Ligação de Hidrogênio , Modelos Químicos , Pró-Fármacos/síntese química , Pró-Fármacos/química , Pró-Fármacos/farmacologia , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Proteínas Tirosina Quinases/antagonistas & inibidoresRESUMO
There is a growing need for new antibiotics. Compounds that target the proton motive force (PMF), uncouplers, represent one possible class of compounds that might be developed because they are already used to treat parasitic infections, and there is interest in their use for the treatment of other diseases, such as diabetes. Here, we tested a series of compounds, most with known antiinfective activity, for uncoupler activity. Many cationic amphiphiles tested positive, and some targeted isoprenoid biosynthesis or affected lipid bilayer structure. As an example, we found that clomiphene, a recently discovered undecaprenyl diphosphate synthase inhibitor active against Staphylococcus aureus, is an uncoupler. Using in silico screening, we then found that the anti-glioblastoma multiforme drug lead vacquinol is an inhibitor of Mycobacterium tuberculosis tuberculosinyl adenosine synthase, as well as being an uncoupler. Because vacquinol is also an inhibitor of M. tuberculosis cell growth, we used similarity searches based on the vacquinol structure, finding analogs with potent (â¼0.5-2 µg/mL) activity against M. tuberculosis and S. aureus. Our results give a logical explanation of the observation that most new tuberculosis drug leads discovered by phenotypic screens and genome sequencing are highly lipophilic (logP â¼5.7) bases with membrane targets because such species are expected to partition into hydrophobic membranes, inhibiting membrane proteins, in addition to collapsing the PMF. This multiple targeting is expected to be of importance in overcoming the development of drug resistance because targeting membrane physical properties is expected to be less susceptible to the development of resistance.
Assuntos
Anti-Infecciosos/farmacologia , Força Próton-Motriz/efeitos dos fármacos , Desacopladores/farmacologia , Alquil e Aril Transferases/antagonistas & inibidores , Anti-Infecciosos/química , Fenômenos Biofísicos , Clomifeno/farmacologia , Descoberta de Drogas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Humanos , Modelos Moleculares , Simulação de Dinâmica Molecular , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologia , Mycobacterium tuberculosis/crescimento & desenvolvimento , Piperidinas/farmacologia , Quinolinas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/enzimologia , Desacopladores/químicaRESUMO
We show that copper-containing metal-organic nanoparticles (MONPs) are readily synthesized via Cu(II)-mediated intramolecular cross-linking of aspartate-containing polyolefins in water. In situ reduction with sodium ascorbate yields Cu(I)-containing MONPs that serve as highly efficient supramolecular catalysts for alkyne-azide "click chemistry" reactions, yielding the desired 1,4-adducts at low parts per million catalyst levels. The nanoparticles have low toxicity and low metal loadings, making them convenient, green catalysts for alkyne-azide "click" reactions in water. The Cu-MONPs enter cells and perform efficient, biocompatible click chemistry, thus acting as intracellular nanoscale molecular synthesizers.
Assuntos
Alcinos/química , Azidas/química , Nanopartículas/química , Compostos Organometálicos/química , Catálise , Linhagem Celular Tumoral , Química Click , Cobre/química , Humanos , Modelos Moleculares , Conformação MolecularRESUMO
Diamagnetic chemical exchange saturation transfer (CEST) contrast agents offer an alternative to Gd(3+) -based contrast agents for MRI. They are characterized by containing protons that can rapidly exchange with water and it is advantageous to have these protons resonate in a spectral window that is far removed from water. Herein, we report the first results of DFT calculations of the (1) H nuclear magnetic shieldings in 41â CEST agents, finding that the experimental shifts can be well predicted (R(2) =0.882). We tested a subset of compounds with the best MRI properties for toxicity and for activity as uncouplers, then obtained mice kidney CEST MRI images for three of the most promising leads finding 16 (2,4-dihydroxybenzoic acid) to be one of the most promising CEST MRI contrast agents to date. Overall, the results are of interest since they show that (1) Hâ NMR shifts for CEST agents-charged species-can be well predicted, and that several leads have low toxicity and yield good in vivo MR images.
Assuntos
Meios de Contraste/química , Gadolínio/química , Hidroxibenzoatos/química , Imageamento por Ressonância Magnética/métodos , Animais , Espectroscopia de Ressonância Magnética , Camundongos , Teoria QuânticaRESUMO
Overall, 8-mol% yttria-stabilized zirconia (8YSZ), unlike 3YSZ, is optically transparent and stable against low-temperature degradation but has insufficient mechanical properties due to its large grain size. The influence of the grain size of 8YSZ on mechanical properties was investigated to develop an 8YSZ suitable for dental restoration. Modulation of the grain size and relative density was achieved via a two-step sintering (TSS) process, and the corresponding kinetic window was established. The conditions of TSS employed herein yielded a relative density of more than 99% while maintaining a small grain size of 0.75 µm. On the other hand, the highest biaxial strength and the highest total transmittance attained were 833 MPa and 34.6% (1-mm-thick, 39.1% for a 0.5-mm thick sample) in the TSS 8YSZ with a grain size of 1.25 µm. These results suggest that strength has improved only when grain size reduction and increased relative density are achieved at the same time. The results demonstrate that the ceramic processing method has a significant effect on the mechanical and optical properties of 8YSZ needed for dental restoration and provide a new insight that contrasts previous studies focused on the starting material.