Identification of a novel selective and potent inhibitor of glycogen synthase kinase-3

Glycogen synthase kinase-3 (GSK-3) is a multitasking protein kinase that regulates numerous critical cellular functions. Not surprisingly, elevated GSK-3 activity has been implicated in a host of diseases including pathological inflammation, diabetes, cancer, arthritis, asthma, bipolar disorder, and Alzheimer's. Therefore, reagents that inhibit GSK-3 activity provide a means to investigate the role of GSK-3 in cellular physiology and pathophysiology and could become valuable therapeutics. Finding a potent inhibitor of GSK-3 that can selectively target this kinase, among over 500 protein kinases in the human genome, is a significant challenge. Thus there remains a critical need for the identification of selective inhibitors of GSK-3. In this work, we introduce a novel small organic compound, namely COB-187, which exhibits potent and highly selective inhibition of GSK-3. Specifically, this study 1) utilized a molecular screen of 414 kinase assays, representing 404 unique kinases, to reveal that COB-187 is a highly potent and selective inhibitor of GSK-3; 2) utilized a cellular assay to reveal that COB-187 decreases the phosphorylation of canonical GSK-3 substrates indicating that COB-187 inhibits cellular GSK-3 activity; and 3) reveals that a close isomer of COB-187 is also a selective and potent inhibitor of GSK-3. Taken together, these results demonstrate that we have discovered a region of chemical design space that contains novel GSK-3 inhibitors. These inhibitors will help to elucidate the intricate function of GSK-3 and can serve as a starting point for the development of potential therapeutics for diseases that involve aberrant GSK-3 activity.

Synthesis of a functionalized oxabicyclo[2.2.1]-heptene-based chemical library

The 7-oxabicyclo[2.2.1]heptene ring system is a common structural motif in many pharmacologically interesting molecules. We recognized the potential to employ this highly oxygenated and conformationally-restricted scaffold in diversity-oriented synthesis to generate a library of non-chiral but topologically complex compounds. Herein, we report the synthesis and biological evaluation of two 96-member tricyclic libraries containing the oxabicyclo[2.2.1]heptene framework using acetal formation as the key step.

Resolution of Methyl Nonactate by Rhodococcus erythropolis under Aerobic and Anaerobic Conditions

[reaction: see text]. An efficient resolution of methyl nonactate is reported by biotransformation in shake flask cultures of Rhodococcus erythropolis. The equilibrium of the reaction redox system can be manipulated by switching from aerobic to anaerobic growth, thereby generating both enantiomers of the target in excellent yield and enantiomeric purity.

Furan-Terminated N-Acyliminium Ion Initiated Cyclizations in Alkaloid Synthesis

A study of the utility of furan-terminated N-acyliminium ion initiated cyclizations for the synthesis of linearly fused alkaloid precursors (Figure 2) is presented. The outcome of the cyclization event depends on the position of furan tether attachment (2 vs 3), tether length, and furan 5-substituent (R = H, CH(3), Ar). 3-Substituted furans cyclized to form 6- and 7-membered ring containing furans 35-38, 50, and 51 in good to excellent yields. 2-Substituted furans closed to form only 6-membered rings; however, the products obtained were a function of the furan 5-substituent. The 5-H furans 17 and 18 led exclusively to the corresponding furans 21 and 22, while the 5-CH(3)-furans 42 and 43 gave only diketone containing compounds 44 and 45. 5-Arylfurans 66-71 provided mixtures of furan- and diketone-containing products 72-83, with the ratio related to the substitution on the phenyl moiety. A preparation of epilupinine 10 is also discussed.

Synthesis of [3H]2-amino-4-phosphonobutyric acid and characterization of its binding to rat brain membranes: a selective ligand for the chloride/calcium-dependent class of L-glutamate binding sites

[3H]2-amino-4-phosphonobutyric acid was synthesized by the conjugate addition of 1-lithio-2-trimethylsilyethyne to diethyl ethynylphosphate followed by catalytic tritiation and hydrolysis. Radiolabelled 2-amino-4-phosphonobutyric acid binds to a distinct class of L-glutamate binding sites and does not exhibit appreciable binding to sites not displaced by L-glutamate. The binding affinity (Kd = 5.1 +/- 0.4 microM) and pharmacological profile correspond to those values obtained from physiological studies of 2-amino-4-phosphonobutyric acid inhibition of synaptic transmission, and to those values obtained in [3H]L-glutamate binding assays. [3H]2-amino-4-phosphonobutyric acid does not exhibit significant binding to the Cl-/Ca2+-independent L-glutamate binding site(s), nor to the Na+-dependent L-glutamate binding site (up to 50 mM Na+). These data provide further evidence that the physiological action of 2-amino-4-phosphonobutyric acid is mediated by the previously described Cl-/Ca2+-dependent L-glutamate binding sites, and provides an assay system which is optimal for the study of these sites.