Abstract:
The association of the abnormal metabolism of choline-containing phospholipids with various cancers has resulted in the identification of enzymes involved in the phosphocholine cycle as potential therapeutic targets. Phosphatidyl-choline specific phospholipase C (PC-PLC) plays a role in this cycle, in the hydrolysis of phosphocholine, and has been implicated in many signalling processes, demonstrating overexpression in various tumours and providing a viable target for inhibition of cancer cell growth. Preliminary hit compounds have been identified through virtual high throughput screening as inhibitors of the PC-PLC enzyme, and shown inhibition of the enzyme in vitro through the Amplex Red Bioassay. The aim of this project was to synthesise various novel analogues of 2-morpholinobenzoic acids in order to determine structure activity relationships and improve enzyme inhibition. Three different series of 2-morpholinobenzoic acid derivatives were synthesised; 4-morpholinobenzylanilines were synthesised as two separate series, with di-substitution of the benzylic ring making up one series, and mono-substitution, along with one example of tri-substitution, making up the other. The third series consisted of 4-(piperidin-1-yl)benzylaniline derivatives. Additional synthesised compounds involved modifications of the aniline ring and amine group; 5-(benzylamino)-2-morpholinobenzoic acid and its methyl ester analogue methyl 5-(benzylamino)-2-morpholinobenzoate, N-(4-morpholinophenyl)benzamide, N-benzoyl-N-(4-morpholinophenyl)benzamide and 4-methyl-N-(4-morpholinophenyl)benzenesulfonamide. In all, a total of 52 novel analogues were synthesised in the duration of this project. Synthesised compounds, along with analogues available in the laboratory, were analysed using molecular modelling docking studies with GOLD software. Additionally, these compounds underwent biological testing at the Auckland Cancer Society Research Centre (ACSRC) to determine the strength of enzyme inhibition and their anti-proliferative effects. The studies of both molecular modelling and experimental assays allowed the comparison of the two processes, to determine the accuracy of docking insights into activity. A large number of the tested compounds showed significant improved inhibitory activity over the currently only well-documented PC-PLC inhibitor, D609. The findings give preliminary insight into the structure activity relationships of novel classes of PC-PLC inhibitors.