Metabolic activation of CaMKII by coenzyme A.

Active metabolism regulates oocyte cell death via calcium/calmodulin-dependent protein kinase II (CaMKII)-mediated phosphorylation of caspase-2, but the link between metabolic activity and CaMKII is poorly understood. Here we identify coenzyme A (CoA) as the key metabolic signal that inhibits Xenopus laevis oocyte apoptosis by directly activating CaMKII. We found that CoA directly binds to the CaMKII regulatory domain in the absence of Ca(2+) to activate CaMKII in a calmodulin-dependent manner. Furthermore, we show that CoA inhibits apoptosis not only in X. laevis oocytes but also in Murine oocytes. These findings uncover a direct mechanism of CaMKII regulation by metabolism and further highlight the importance of metabolism in preserving oocyte viability.

Discovery of novel isoxazolines as anti-tuberculosis agents.

Nitrofuranyl isoxazolines with increased proteolytic stability over nitrofuranyl amides were designed and synthesized leading to discovery of several compounds with potent in vitro anti-tuberculosis activity. However, their in vivo activity was limited by high protein binding and poor distribution. Consequently, a series of non-nitrofuran containing isoxazolines were prepared to determine if the core had residual anti-tuberculosis activity. This led to the discovery of novel isoxazoline 12 as anti-tuberculosis agent with a MIC(90) value of 1.56microg/mL.

Synthesis and evaluation of cyclic secondary amine substituted phenyl and benzyl nitrofuranyl amides as novel antituberculosis agents.

In an ongoing effort to develop new and potent antituberculosis agents, a second-generation series of nitrofuranyl amides was synthesized on the basis of the lead compound 5-nitrofuran-2-carboxylic acid 3,4-dimethoxybenzylamide. The primary design consideration was to improve the solubility and consequently the bioavailability of the series by the addition of hydrophilic rings to the benzyl and phenyl B ring core. The synthesis of 27 cyclic, secondary amine substituted phenyl and benzyl nitrofuranyl amides is described and their activity against Mycobacterium tuberculosis reported. The series showed a strong structure-activity relationship as the benzyl nitrofuranyl amides were significantly more active than similarly substituted phenyl nitrofuranyl amides. Para-substituted benzyl piperazines showed the most antituberculosis activity. Compounds in the series were subsequently selected for bioavailability and in vivo testing. This study led to the successful discovery of novel compounds with increased antituberculosis activity in vitro and a better understanding of the requisite pharmacological properties to advance this class.

Synthesis and evaluation of nitrofuranylamides as novel antituberculosis agents.

In an effort to develop new and more potent therapies to treat tuberculosis, a library of compounds was screened for M. tuberculosis UDP-Gal mutase inhibition. Nitrofuranylamide 1 was identified as a hit in this screen, possessing good antituberculosis activity. This paper describes the synthesis and evaluation of an expanded set of nitrofuranylamides. We have discovered a number of nitrofuranylamides with submicromolar M. tuberculosis MIC values and acceptable therapeutic indexes. The MIC activity did not correlate with UDP-Gal mutase inhibition, suggesting an alternative primary cellular target was responsible for the antituberculosis activity. The compounds were only active against mycobacteria of the tuberculosis complex. On the basis of these results, four compounds were selected for in vivo testing in a mouse model of tuberculosis infection, and of these compounds one showed significant antituberculosis activity.

Synthesis, optimization and structure-activity relationships of 3,5-disubstituted isoxazolines as new anti-tuberculosis agents.

In the course of the development of a potent series of nitrofuranylamide anti-tuberculosis agents, we investigated if the exceptional activity resulted in part from the isoxazoline core and if it possessed any intrinsic anti-tuberculosis activity. This led to the discovery of an isoxazoline ester with appreciable anti-tuberculosis activity. In this study we explored the anti-tuberculosis structure-activity relationship of the isoxazoline ester compound through systematic modification of the 3,5-di-substituted isoxazoline core. Two approaches were used: (i) modification of the potentially metabolically labile ester functionality at the 3 position with acids, amines, amides, reverse amides, alcohols, hydrazides, and 1,3,4-oxadiazoles; (ii) substitution of the distal benzyl piperazine ring in the 5 position of the isoxazoline ring with piperazyl-ureas, piperazyl-carbamates, biaryl systems, piperidines and morpholine. Attempts to replace the ester group at C-3 position of isoxazoline with a variety of bioisosteric head groups led to significant loss of the tuberculosis inhibition indicating that an ester is required for anti-tuberculosis activity. Optimization of the isoxazoline C-5 position produced compounds with improved anti-tuberculosis activity, most notably the piperazyl-urea and piperazyl-carbamate analogs.

Nitrofurans as novel anti-tuberculosis agents: identification, development and evaluation.

During a search for new anti-tuberculosis agents, a screen of a commercially available library provided a hit nitrofuranyl amide. This hit was selected for further development due to its potential as an anti-tuberculosis agent with a novel mechanism of action, and its potential for activity against both actively growing and latent bacteria. This review covers the optimization of this lead and the strategies applied for developing this series into anti-tuberculosis agents. To optimize the hit, a series of libraries were synthesized, producing several compounds that showed increased anti-tuberculosis activity along with a strong structure activity relationship. The most active compounds from the first optimization series showed good in vitro anti-tuberculosis activity and limited in vivo efficacy, but their application was restricted due to solubility problems. Therefore, a second generation optimization library was designed and synthesized in order to increase bioavailability and solubility while maintaining good anti-tuberculosis activity. Hydrophilic cyclic secondary amines were substituted to the core scaffold and a benzyl piperazine substitution was found to be most effective in achieving improved solubility and potent anti-tuberculosis activity. However, bioactivity studies of these 2nd generation leads showed that the in vivo anti-tuberculosis activity of these compounds was limited due to rapid metabolism. Consequently, a 3rd generation of compounds was designed and synthesized in which potential sites of metabolism were blocked.

Synthesis of new and potent analogues of anti-tuberculosis agent 5-nitro-furan-2-carboxylic acid 4-(4-benzyl-piperazin-1-yl)-benzylamide with improved bioavailability.

Previously, the lead compound 5-nitro-furan-2-carboxylic acid 4-(4-benzyl-piperazin-1-yl)-benzylamide was identified in our anti-tuberculosis drug discovery program. Although this compound demonstrated excellent in vitro activity, it did not meet the expected in vivo profiles due to structural features that resulted in rapid metabolic cleavage and poor absorption, which therefore limited its bioavailability. In efforts to increase the bioavailability, a new series of analogues was successfully synthesized using three modification schemes: replacement of the benzyl group on the piperazine C-ring with carbamate and urea functional groups; introduction of a nitrogen atom into the aromatic ring-B; and expansion of the ring-B to a bicyclic tetrahydroisoquinoline moiety. These modifications retained strong activity and in some case gained superior anti-tuberculosis activity, increased absorption, and serum half life.