Discovery of Benzodiazepine-Based Inhibitors of the E2 Enzyme UBCH10 from a Cell-Based p21 Degradation Screen.

p21Cip1 (p21) is a universal cyclin-dependent kinase (CDK) inhibitor that halts cell proliferation and tumor growth by multiple mechanisms. The expression of p21 is often downregulated in cancer cells as a result of the loss of function of transcriptional activators, such as p53, or the increased degradation rate of the protein. To identify small molecules that block the ubiquitin-mediated degradation of p21 as a future avenue for cancer drug discovery, we have screened a compound library using a cell-based reporter assay of p21 degradation. This led to the identification of a benzodiazepine series of molecules that induce the accumulation of p21 in cells. Using a chemical proteomic strategy, we identified the ubiquitin-conjugating enzyme UBCH10 as a cellular target of this benzodiazepine series. We show that an optimized benzodiazepine analogue inhibits UBCH10 ubiquitin-conjugating activity and substrate proteolysis by the anaphase-promoting complex.

Size-Reduced Macrocyclic Analogues of [Pyr1]-apelin-13 Showing Negative Gα12 Bias Still Produce Prolonged Cardiac Effects.

We previously reported a series of macrocyclic analogues of [Pyr1]-apelin-13 (Ape13) with increased plasma stability and potent APJ agonist properties. Based on the most promising compound in this series, we synthesized and then evaluated novel macrocyclic compounds of Ape13 to identify agonists with specific pharmacological profiles. These efforts led to the development of analogues 39 and 40, which possess reduced molecular weight (MW 1020 Da vs Ape13, 1534 Da). Interestingly, compound 39 (Ki 0.6 nM), which does not activate the Gα12 signaling pathway while maintaining potency and efficacy similar to Ape13 to activate Gαi1 (EC50 0.8 nM) and ß-arrestin2 recruitment (EC50 31 nM), still exerts cardiac actions. In addition, analogue 40 (Ki 5.6 nM), exhibiting a favorable Gα12-biased signaling and an increased in vivo half-life (t1/2 3.7 h vs <1 min of Ape13), produces a sustained cardiac response up to 6 h after a single subcutaneous bolus injection.

Mild and Diazo-Free Synthesis of Trifluoromethyl-Cyclopropanes Using Sulfonium Ylides.

The synthesis of several 1,1-disubstituted trifluoromethyl-cyclopropanes (TFCPs), known as tert-butyl bioisosteres, has been achieved from the reaction between trifluoromethylalkenes and unstabilized sulfonium ylides in yields of ≤97%. This method offers practical access to this cyclopropyl moiety of pharmacological interest, employing a commercially available reagent at low temperatures. The synthesis of cyclopropanes bearing other electron-withdrawing groups as well as trisubstituted TFCPs was also accomplished.