Structure-activity relationship expansion and microsomal stability assessment of the 2-morpholinobenzoic acid scaffold as antiproliferative phosphatidylcholine-specific phospholipase C inhibitors

Dysregulation of choline phospholipid metabolism and overexpression of phosphatidylcholine-specific phospholipase C (PC-PLC) is implicated in various cancers. Current known enzyme inhibitors include compounds based on a 2-morpholino-5-N-benzylamino benzoic acid, or hydroxamic acid, scaffold. In this work, 81 compounds were made by modifying this core structure to explore the pharmacophore. Specifically, these novel compounds result from changes to the central ring substitution pattern, alkyl heterocycle and methylation of the N-benzyl bridge. The anti-proliferative activity of the synthesised compounds was assessed against cancer cell lines MDA-MB-231 and HCT116. PC-PLC_BC enzyme inhibition was also assessed, and the development of a pharmacokinetic profile was initiated using a microsomal stability assay. The findings confirmed the optimal pharmacophore as a 2-morpholino-5-N-benzylamino benzoic acid, or acid derivative, scaffold, and that this family of molecules demonstrate a high degree of stability following treatment with rat microsomes. Additionally, benzylic N-methylated compounds were the most biologically active compounds, encouraging further investigation into this region of the pharmacophore.