Synthesis, characterization, in vitro SAR study, and preliminary in vivo toxicity evaluation of naphthylmethyl substituted bis-imidazolium salts.

A series of novel bis-imidazolium salts was synthesized, characterized, and evaluated in vitro against a panel of non-small cell lung cancer (NSCLC) cells. Two imidazolium cores were connected with alkyl chains of varying lengths to develop a structure activity relationship (SAR). Increasing the length of the connecting alkyl chain was shown to correlate to an increase in the anti-proliferative activity. The National Cancer Institute's NCI-60 human tumor cell line screen confirmed this trend. The compound containing a decyl linker chain, 10, was chosen for further in vivo toxicity studies with C578BL/6 mice. The compound was well tolerated by the mice and all of the animals survived and gained weight over the course of the study.

Synthesis and Characterization of Cobalt(II) N,N'-Diphenylazodioxide Complexes.

Removal of chloride from CoCl2 with TlPF6 in acetonitrile, followed by addition of excess nitrosobenzene, yielded the eight-coordinate cobalt(II) complex salt [Co{Ph(O)NN(O)Ph}4](PF6)2, shown by single-crystal X-ray analysis to have a distorted tetragonal geometry. The analogous treatment of the bipyridyl complex Co(bpy)Cl2 yielded the mixed-ligand cobalt(II) complex salt [Co(bpy){Ph(O)NN(O)Ph}2](PF6)2, whose single-crystal X-ray structure displays a trigonal prismatic geometry, similar to that of the iron(II) cation in the previously known complex salt [Fe{Ph(O)NN(O)Ph}3](FeCl4)2. The use of TlPF6 to generate solvated metal complex cations from chloride salts or chlorido complexes, followed by the addition of nitrosobenzene, is shown to be a useful synthetic strategy for the preparation of azodioxide complex cations with the noncoordinating, diamagnetic PF6 - counteranion. Coordination number appears to be more important than d electron count in determining the geometry and metal-ligand bond distances of diphenylazodioxide complexes.

Synthesis, characterization, in vitro SAR and in vivo evaluation of N,N'bisnaphthylmethyl 2-alkyl substituted imidazolium salts against NSCLC.

Alkyl- and N,N'-bisnaphthyl-substituted imidazolium salts were tested in vitro for their anti-cancer activity against four non-small cell lung cancer cell lines (NCI-H460, NCI-H1975, HCC827, A549). All compounds had potent anticancer activity with 2 having IC50 values in the nanomolar range for three of the four cell lines, a 17-fold increase in activity against NCI-H1975 cells when compared to cisplatin. Compounds 1-4 also showed high anti-cancer activity against nine NSCLC cell lines in the NCI-60 human tumor cell line screen. In vitro studies performed using the Annexin V and JC-1 assays suggested that NCI-H460 cells treated with 2 undergo an apoptotic cell death pathway and that mitochondria could be the cellular target of 2 with the mechanism of action possibly related to a disruption of the mitochondrial membrane potential. The water solubilities of 1-4 was over 4.4mg/mL using 2-hydroxypropyl-ß-cyclodextrin as a chemical excipient, thereby providing sufficient solubility for systemic administration.

Synthesis, anti-proliferative activity, SAR study, and preliminary in vivo toxicity study of substituted N,N'-bis(arylmethyl)benzimidazolium salts against a panel of non-small cell lung cancer cell lines.

A series of N,N'-bis(arylmethyl)benzimidazolium salts have been synthesized and evaluated for their in vitro anti-cancer activity against select non-small cell lung cancer cell lines to create a structure activity relationship profile. The results indicate that hydrophobic substituents on the salts increase the overall anti-proliferative activity. Our data confirms that naphthylmethyl substituents at the nitrogen atoms (N1(N3)) and highly lipophilic substituents at the carbon atoms (C2 and C5(C6)) can generate benzimidazolium salts with anti-proliferative activity that is comparable to that of cisplatin. The National Cancer Institute's Developmental Therapeutics Program tested 1, 3-5, 10, 11, 13-18, 20-25, and 28-30 in their 60 human tumor cell line screen. Results were supportive of data observed in our lab. Compounds with hydrophobic substituents have higher anti-cancer activity than compounds with hydrophilic substituents.

Synthesis, characterization, and in vitro SAR evaluation of N,N'-bis(arylmethyl)-C2-alkyl substituted imidazolium salts.

A series of C2-alkyl substituted N,N'-bis(arylmethyl)imidazolium salts were synthesized, characterized, and tested for their in vitro anti-cancer activity against multiple non-small cell lung cancer cell lines by our group and the National Cancer Institute's-60 human tumor cell line screen to establish a structure-activity relationship. Compounds are related to previously published N,N'-bis(arylmethyl)imidazolium salts but utilize the historical quinoline motif and anion effects to increase the aqueous solubility. Multiple derivatives displayed high anti-cancer activity with IC50 values in the nanomolar to low micromolar range against a panel of non-small cell lung cancer cell lines. Several of these derivatives have high aqueous solubilities with potent anti-proliferative properties and are ideal candidates for future in vivo xenograft studies and have high potential to progress into clinic use.

An NMR-Guided Screening Method for Selective Fragment Docking and Synthesis of a Warhead Inhibitor.

Selective hits for the glutaredoxin ortholog of Brucella melitensis are determined using STD NMR and verified by trNOE and (15)N-HSQC titration. The most promising hit, RK207, was docked into the target molecule using a scoring function to compare simulated poses to experimental data. After elucidating possible poses, the hit was further optimized into the lead compound by extension with an electrophilic acrylamide warhead. We believe that focusing on selectivity in this early stage of drug discovery will limit cross-reactivity that might occur with the human ortholog as the lead compound is optimized. Kinetics studies revealed that lead compound 5 modified with an ester group results in higher reactivity than an acrylamide control; however, after modification this compound shows little selectivity for bacterial protein versus the human ortholog. In contrast, hydrolysis of compound 5 to the acid form results in a decrease in the activity of the compound. Together these results suggest that more optimization is warranted for this simple chemical scaffold, and opens the door for discovery of drugs targeted against glutaredoxin proteins-a heretofore untapped reservoir for antibiotic agents.

Anti-tumor activity of lipophilic imidazolium salts on select NSCLC cell lines.

The anti-tumor activity of imidazolium salts is highly dependent upon the substituents on the nitrogen atoms of the imidazolium cation. We have synthesized and characterized a series of naphthalene-substituted imidazolium salts and tested them against a variety of non-smallcell lung cancer cell lines. Several of these complexes displayed anticancer activity comparable to cisplatin. These compounds induced apoptosis in the NCI-H460 cell line as determined by Annexin V staining, caspase-3, and PARP cleavage. These results strongly suggest that this class of compounds can serve as potent chemotherapeutic agents.