Design of selective SRPK1 inhibitors to control the alternative splicing of VEGF-A

Abstract

This thesis is focused on the development of three different scaffolds for the design of potent SRPK1 inhibitors. Chapter 1 discusses a pathway to regulate angiogenesis by controlling, for instance, the alternative splicing of vascular endothelial growth factor (VEGF-A) in pro- and anti-angiogenic isoforms. A detailed literature review on known serine/arginine-rich (SR) inhibitors, such as SPHINX and Purvalanol B is detailed. In Chapter 2, previous established methodologies were used to prepare differentially substituted analogues of SPHINX. A number of these methodologies were extended to yield more efficient synthesis. A large number of analogues were prepared and it was possible to fully elucidate the features required for efficient binding of the SPHINX compounds. Some of the analogues prepared in Chapter 2 have shown to be more potent and selective than the lead molecules. In Chapter 3, the knowledge learned from the investigations with SPHINXes (Chapter 2) was extended to the SRPIN scaffold, for which previously investigated lead compound SRPIN340 was found to weakly inhibit serine/arginine-rich (SR) proteins with an IC50 value of 890 nM. This investigation was focused on developing more potent SRPIN analogues so that they could be used as chemical probes. Within a small library of SRPIN340-related analogues it was possible to access compounds with a very significant increase in biological activity, with some analogues displaying single digit IC50 values. In Chapter Four, in a bid to discover a new scaffold for the SRPK1 project, the purine compound Purvalanol B was investigated to determine whether the Purine scaffold was a viable option. As Purvalanol B is not very potent nor it is selective, methodologies for the selective substitution of the core were established and used to prepare differentially substituted analogues. None of these compounds, however, have shown to be as potent as the SPHINXes or SRPINs. Extensive molecular modeling was carried out in an effort to understand the binding mode of this scaffold and for that reason, it is uncertain whether these compounds are worth pursuing. Full experimental procedures are included in Chapter 5.