Light-Activated Compounds

The presently-disclosed subject matter includes light-activated ruthenium compounds. In some embodiments the compounds release one or more ligands when exposed to light, and in specific embodiments the light includes a wavelength of about 500 nm to about 1000 nm. The present compounds can also comprise an overall charge, wherein the overall charge can be a positive overall charge or a negative overall charge. Further still, embodiments include methods of treating cancer in a subject by administering a compound and then exposing a site of the subject to light

Altered Backbone and Side-Chain Interactions Result in Route Heterogeneity during the Folding of Interleukin-1b (IL-1b)

Deletion of the b-bulge trigger-loop results in both a switch in the preferred folding route, from the functional loop packing folding route to barrel closure, as well as conversion of the agonist activity of IL-1b into antagonist activity. Conversely, circular permutations of IL-1b conserve the functional folding route as well as the agonist activity. These two extremes in the folding-functional interplay beg the question of whether mutations in IL-1b would result in changes in the populations of heterogeneous folding routes and the signaling activity. A series of topologically equivalent water-mediated b-strand bridging interactions within the pseudosymmetric b-trefoil fold of IL-1b highlight the backbone water interactions that stabilize the secondary and tertiary structure of the protein. Additionally, conserved aromatic residues lining the central cavity appear to be essential for both stability and folding. Here, we probe these protein backbone-water molecule and side chain-side chain interactions and the role they play in the folding mechanism of this geometrically stressed molecule. We used folding simulations with structure-based models, as well as a series of folding kinetic experiments to examine the effects of the F42W core mutation on the folding landscape of IL-1b. This mutation alters water-mediated backbone interactions essential for maintaining the trefoil fold. Our results clearly indicate that this perturbation in the primary structure alters a structural water interaction and consequently modulates the population of folding routes accessed during folding and signaling activity

Characterization of a Drosophila Alzheimer's Disease Model: Pharmacological Rescue of Cognitive Defects

Transgenic models of Alzheimer's disease (AD) have made significant contributions to our understanding of AD pathogenesis, and are useful tools in the development of potential therapeutics. The fruit fly, Drosophila melanogaster, provides a genetically tractable, powerful system to study the biochemical, genetic, environmental, and behavioral aspects of complex human diseases, including AD. In an effort to model AD, we over-expressed human APP and BACE genes in the Drosophila central nervous system. Biochemical, neuroanatomical, and behavioral analyses indicate that these flies exhibit aspects of clinical AD neuropathology and symptomology. These include the generation of Aβ40 and Aβ42, the presence of amyloid aggregates, dramatic neuroanatomical changes, defects in motor reflex behavior, and defects in memory. In addition, these flies exhibit external morphological abnormalities. Treatment with a γ-secretase inhibitor suppressed these phenotypes. Further, all of these phenotypes are present within the first few days of adult fly life. Taken together these data demonstrate that this transgenic AD model can serve as a powerful tool for the identification of AD therapeutic interventions

High resolution measurement of membrane receptor endocytosis

We present a new approach to quantify the half-life of membrane proteins on the cell surface, through tagging the protein with the photoconvertible fluorescent protein, Dendra2. Upon exposure to 405 nm light, Dendra2 is photoconverted from green to red emission. Total internal reflection fluorescence microscopy (TIRF) is applied to limit visualization of fluorescence to proteins located on the plasma membrane. Conversion of Dendra2 works as a pulse chase experiment through monitoring only the population of protein that has been photoconverted. As the protein is endocytosed the red emission decreases due to the protein leaving the TIRF field of view. This method is not impacted by the insertion of new protein into the plasma membrane as newly synthesized protein only exhibits green emission. We used this approach to determine the half-life of ENaC on the plasma membrane illustrating the high temporal resolution capability of this technique compared to current methods

Photochemical and Photobiological Properties of Pyridyl-pyrazol(in)e-Based Ruthenium(II) Complexes with Sub-micromolar Cytotoxicity for Phototherapy

The discovery of new light-triggered prodrugs based on ruthenium (II) complexes is a promising approach for photoactivated chemotherapy (PACT). The light-mediated activation of "strained" Ru(II) polypyridyl complexes resulted in ligand release and produced a ligand-deficient metal center capable of forming covalent adducts with biomolecules such as DNA. Based on the strategy of exploiting structural distortion to activate photochemistry, biologically active small molecules were coordinated to a Ru(II) scaffold to create light-triggered dual-action agents. Thirteen new Ru(II) complexes with pyridyl-pyrazol(in)e ligands were synthesized, and their photochemical reactivity and anticancer properties were investigated. Isomeric bidentate ligands were investigated, where "regular" ligands (where the coordinated nitrogens in the heterocycles are linked by C-C atoms) were compared to "inverse" isomers (where the coordinated nitrogens in the heterocycles are linked by C-N atoms). Coordination of the regular 3-(pyrid-2-yl)-pyrazol(in)es to a Ru(II) bis-dimethylphenanthroline scaffold yielded photoresponsive compounds with promising photochemical and biological properties, in contrast to the inverse 1-(pyrid-2-yl)-pyrazolines. The introduction of a phenyl ring to the 1N-pyrazoline cycle increased the distortion in complexes and improved ligand release upon light irradiation (470 nm) up to 5-fold in aqueous media. Compounds 1-8, containing pyridyl-pyrazol(in)e ligands, were at least 20-80-fold more potent than the parent pyridyl-pyrazol(in)es, and exhibited biological activity in the dark, with half-maximal inhibitory concentration (IC50) values ranging from 0.2 to 7.6 μM in the HL60 cell line, with complete growth inhibition upon light irradiation. The diversification of coligands and introduction of a carboxylic acid into the Ru(II) complex resulted in compounds 9-12, with up to 146-fold improved phototoxicity indices compared with complexes 1-8

Coordination of Hydroxyquinolines to a Ruthenium Bis-dimethyl-phenanthroline Scaffold Radically Improves Potency for Potential as Antineoplastic Agents

A series of ruthenium coordination complexes containing hydroxyquinoline ligands were synthesized that exhibited radically improved potencies up to 86-fold greater than clioquinol, a known cytotoxic compound. The complexes were also >100-fold more potent than clioquinol in a tumor spheroid model, with values similar to currently used chemotherapeutics for the treatment of solid tumors. Cytotoxicity occurs through rapid processes that induce apoptosis but appear to be mediated by cell-cycle independent mechanisms. The ruthenium complexes do not inhibit the proteasome at concentrations relevant for cell death, and contrary to previous reports, clioquinol and other hydroxyquinoline compounds do not act as direct proteasome inhibitors to induce cell death

Strained Ruthenium Complexes Are Potent Light-Activated Anticancer Agents

Strained ruthenium (Ru) complexes have been synthesized and characterized as novel agents for photodynamic therapy (PDT). The complexes are inert until triggered by visible light, which induces ligand loss and covalent modification of DNA. An increase in cytotoxicity of 2 orders of magnitude is observed with light activation in cancer cells, and the compounds display potencies superior to cisplatin against 3D tumor spheroids. The use of intramolecular strain may be applied as a general paradigm to develop light-activated ruthenium complexes for PDT applications

Design of Cytochrome P450 1B1 Inhibitors <i>via</i> a Scaffold-Hopping Approach

Cytochrome P450 1B1 (CYP1B1) is a potential drug target in cancer research that is overexpressed in several solid tumors but is present only at low levels in healthy tissues. Its expression is associated with resistance to common chemotherapeutics, while inhibitors restore efficacy to these drugs in model systems. The majority of CYP1B1 inhibitors are derived from a limited number of scaffolds, and few have achieved outstanding selectivity against other human CYPs, which could impede clinical development. This study explores a new chemical space for CYP1B1 inhibitors using a scaffold-hopping approach and establishes 2,4-diarylthiazoles as a promising framework for further development. From a small library, compound 15 emerged as the lead, with picomolar CYP1B1 inhibition, and over 19,000-fold selectivity against its relative, CYP1A1. To investigate the activity of 15, molecular dynamics, optical spectroscopy, point mutations, and traditional structure–activity relationships were employed and revealed key interactions important for the development of CYP1B1 inhibitors