Development of a C6 Glioma Cell Model System to Assess Effects of Cathodic Passively Balanced Electrical Stimulation on Responses to Neurotransmitters: Implications for Modulation of Intracellular Nitric Oxide, Chloride, and Calcium Ions.

This research focused on the development of an astrocyte cell model system (C6 glioma) for the assessment of molecular changes in response to cathodic passively balanced pulsed electrical stimulation at a rate of 50 Hz (60 µs duration, 0.15 mA intensity). Cells treated with selected neurotransmitters (glutamate, adenosine, D-serine, and γ-aminobutyric acid) were monitored (using specific fluorescent probes) for changes in levels of intracellular nitric oxide, calcium ions, and/or chloride. ES exerted an inhibitory effect on NO, increased calcium and had no effect on chloride. Using this model, cells can be assessed qualitatively and quantitatively for changes and these changes can be correlated with the putative molecular effects that electrical stimulation has on astrocytes and their role in glia-mediated diseases. This model system allows for faster and cheaper experiments than those involving animal models due to the potential to easily vary the conditions, reduce the number of variables (especially problematic in animal models), and closely monitor the cellular effects.

A Dual-Pronged Approach: A Ruthenium(III) Complex That Modulates Amyloid-ß Aggregation and Disrupts Its Formed Aggregates.

Alzheimer's disease (AD) is a devastating neurological disorder for which soluble oligomers of the peptide amyloid-ß (Aß) are now recognized as the neurotoxic species. Metal-based therapeutics are uniquely suited to target Aß, with ruthenium-based (Ru) complexes emerging as propitious candidates. Recently, azole-based Ru(III) complexes were observed to modulate the aggregation of Aß in solution, where the inclusion of a primary amine proximal to the ligand coordination site improved the activity of the complexes. To advance these structure-activity relationships, a series of oxazole-based Ru complexes were prepared and evaluated for their ability to modulate Aß aggregation. From these studies, a lead candidate, Oc, emerged that had superior activity relative to its azole predecessors in modulating the aggregation of soluble Aß and diminishing its cytotoxicity. Further evaluation of Oc demonstrated its ability to disrupt formed Aß aggregates, resulting in smaller amorphous species. Because altering both sides of the aggregation equilibrium for Aß has not been previously suggested for metal-based complexes for AD, this work represents an exciting new avenue for improved therapeutic success.

Leishmania tarentolae novel responses to Bi3+-doped strontium aluminum oxyfluorides.

Novel therapeutics for the treatment of leishmaniasis are of interest as the disease not only is becoming more prevalent, but drug resistance is increasing in certain regions of the world. Reported here is the use of Bi3+-doped strontium aluminum oxyfluoride phosphors and protease inhibitors to test in vitro inhibitory activity against cultured promastigote Leishmania tarentolae and effects on L. tarentolae secreted acid phosphatase (SAP) activity. Cell viability did not significantly decrease in the presence of 50 µM anti-perovskite compounds, implying limited cytotoxicity. Yet SAP activity did increase in the cell free preparations with time in the presence of strontium compounds. Of interest was the observation that cell free SAP activity did not increase in the presence of protease inhibitors with or without added strontium compounds. Since secreted proteases may play a role in the maturation of Leishmania SAP and thus be involved with parasite-host infection establishment, this is in further need of evaluation. Nitric oxide production on day 4 post-addition of the strontium compounds was evaluated and showed an approximately 50% decrease in NO production in the presence of two test compounds relative to DMSO control cells. This is the first report of anti-perovskite compound inhibition of NO production by Leishmania.

Importance of Hydrogen Bonding: Structure-Activity Relationships of Ruthenium(III) Complexes with Pyridine-Based Ligands for Alzheimer's Disease Therapy.

Alzheimer's disease (AD) is the most common form of dementia, where one of the pathological hallmarks of AD is extracellular protein deposits, the primary component of which is the peptide amyloid-ß (Aß). Recently, the soluble form of Aß has been recognized as the primary neurotoxic species, making it an important target for therapeutic development. Metal-based drugs are promising candidates to target Aß, as the interactions with the peptide can be tuned by ligand design. In the current study, 11 ruthenium complexes containing pyridine-based ligands were prepared, where the functional groups at the para position on the coordinated pyridine ligand were varied to determine structure-activity relationships. Overall, the complexes with terminal primary amines had the greatest impact on modulating the aggregation of Aß and diminishing its cytotoxicity. These results identify the importance of specific intermolecular interactions and are critical in the advancement of metal-based drugs for AD therapy.

Synthesis of Polycyclic Ether-Benzopyrans and In Vitro Inhibitory Activity against Leishmania tarentolae.

Construction of a focused library of polycyclic ether-benzopyrans was undertaken in order to discover new therapeutic compounds that affect Leishmania growth and infectivity. This is especially of interest since there are few drug therapies for leishmaniasis that do not have serious drawbacks such high cost, side effects, and emerging drug resistance. The construction of these polycyclic ether-benzopyrans utilized an acetoxypyranone-alkene [5+2] cycloaddition and the Suzuki-Miyaura cross-coupling. The multi-gram quantity of the requisite aryl bromide was obtained followed by effective Pd-catalyzed coupling with boronic acid derivatives. Compounds were tested in vitro using the parasitic protozoan, Leishmania tarentolae. Effects of concentration, time, and exposure to light were evaluated. In addition, the effects on secreted acid phosphatase activity and nitric oxide production were investigated, since both have been implicated in parasite infectivity. The data presented herein are indicative of disruption of the Leishmania tarentolae and thus provide impetus for the development and testing of a more extensive library.