Chemical methodology as a source of small-molecule checkpoint inhibitors and heat shock protein 70 (Hsp70) modulators

Chemical biology in stem cell research

Stem cells are offering a considerable range of prospects to the biomedical research including novel platforms for disease models and drug discovery tools to cell transplantation and regenerative therapies. However, there are several obstacles to overcome to bring these potentials into reality. First, robust methods to maintain stem cells in the pluripotent state should be established and factors that are required to direct stem cell fate into a particular lineage should be elucidated. Second, both allogeneic rejection following transplantation and limited cell availability issues must be circumvented. These challenges are being addressed, at least in part, through the identification of a group of chemicals (small molecules) that possess novel activities on stem cell biology. For example, small molecules can be used both in vitro and/or in vivo as tools to promote proliferation of stem cells (self-renewal), to direct stem cells to a lineage specific patterns (differentiation), or to reprogram somatic cells to a more undifferentiated state (de-differentiation or reprogramming). These molecules, in turn, have provided new insights into the signaling mechanisms that regulate stem cell biology, and may eventually lead to effective therapies in regenerative medicine. In this review, we will introduce recent findings with regards to small molecules and their impact on stem cell self-renewal and differentiation.

Progress in Microwave-Aided Chemical Synthesis

The continuing use of microwave (µwave) energy in chemical synthesis has been impressive over the past decade, with many reports incorporating µwave-based reactions. Two of the major benefits of using µwave heating are the remarkable decrease in reaction times and often high yield of products in comparison with classical heating, an ideal technology for synthetic chemists. Herein, we highlight some exciting examples of its recent utility in organic, medicinal, and natural product synthetic endeavours.

High-throughput screening identifies a bisphenol inhibitor of SV40 large T antigen ATPase activity

The authors conducted a high-throughput screening campaign for inhibitors of SV40 large T antigen ATPase activity to identify candidate antivirals that target the replication of polyomaviruses. The primary assay was adapted to 1536-well microplates and used to screen the National Institutes of Health Molecular Libraries Probe Centers Network library of 306 015 compounds. The primary screen had an Z value of ~0.68, signal/background = 3, and a high (5%) DMSO tolerance. Two counterscreens and two secondary assays were used to prioritize hits by EC(50), cytotoxicity, target specificity, and off-target effects. Hits that inhibited ATPase activity by >44% in the primary screen were tested in dose-response efficacy and eukaryotic cytotoxicity assays. After evaluation of hit cytotoxicity, drug likeness, promiscuity, and target specificity, three compounds were chosen for chemical optimization. Chemical optimization identified a class of bisphenols as the most effective biochemical inhibitors. Bisphenol A inhibited SV40 large T antigen ATPase activity with an IC(50) of 41 µM in the primary assay and 6.2 µM in a cytoprotection assay. This compound class is suitable as probes for biochemical investigation of large T antigen ATPase activity, but because of their cytotoxicity, further optimization is necessary for their use in studying polyomavirus replication in vivo.