Synthesis and optimization of furano[3,2-d]pyrimidines as selective spleen tyrosine kinase (Syk) inhibitors

Development of In Silico Models for Predicting Potential Time-Dependent Inhibitors of Cytochrome P450 3A4

Cytochrome P450 3A4 (CYP3A4) is one of the major drug metabolizing enzymes in the human body and metabolizes ∼30-50% of clinically used drugs. Inhibition of CYP3A4 must always be considered in the development of new drugs. Time-dependent inhibition (TDI) is an important P450 inhibition type that could cause undesired drug-drug interactions. Therefore, identification of CYP3A4 TDI by a rapid convenient way is of great importance to any new drug discovery effort. Here, we report the development of in silico classification models for prediction of potential CYP3A4 time-dependent inhibitors. On the basis of the CYP3A4 TDI data set that we manually collected from literature and databases, both conventional machine learning and deep learning models were constructed. The comparisons of different sampling strategies, molecular representations, and machine-learning algorithms showed the benefits of a balanced data set and the deep-learning model featured by GraphConv. The generalization ability of the best model was tested by screening an external data set, and the prediction results were validated by biological experiments. In addition, several structural alerts that are relevant to CYP3A4 time-dependent inhibitors were identified via information gain and frequency analysis. We anticipate that our effort would be useful for identification of potential CYP3A4 time-dependent inhibitors in drug discovery and design.

Crystal Structures of Spleen Tyrosine Kinase in Complex with Two Novel 4-Aminopyrido[4,3-d] Pyrimidine Derivative Inhibitors

Spleen tyrosine kinase (SYK) is a cytosolic non-receptor protein tyrosine kinase. Because SYK mediates key receptor signaling pathways involving the B cell receptor and Fc receptors, SYK is an attractive target for autoimmune disease and cancer treatments. To date, representative oral SYK inhibitors, including fostamatinib (R406 or R788), entospletinib (GS-9973), cerdulatinib (PRT062070), and TAK-659, have been assessed in clinical trials. Here, we report the crystal structures of SYK in complex with two newly developed inhibitors possessing 4-aminopyrido[4,3-D]pyrimidine moieties (SKI-G-618 and SKI-O-85). One SYK inhibitor (SKI-G-618) exhibited moderate inhibitory activity against SYK, whereas the other inhibitor (SKI-O-85) exhibited a low inhibitory profile against SYK. Binding mode analysis indicates that a highly potent SYK inhibitor might be developed by modifying and optimizing the functional groups that interact with Leu377, Gly378, and Val385 in the G-loop and the nearby region in SYK. In agreement with our structural analysis, one of our SYK inhibitor (SKI-G-618) shows strong inhibitory activities on the β-hexosaminidase release and phosphorylation of SYK/Vav in RBL-2H3 cells. Taken together, our findings have important implications for the design of high affinity SYK inhibitors.