Synthesis, Plasmodium falciparum Inhibitory Activity, Cytotoxicity and Solubility of N2,N4-Disubstituted Quinazoline-2,4-diamines.

BACKGROUND: Despite the development of extensive control strategies and treatment options, approximately 200 million malaria cases, leading to approximately 450,000 deaths, were reported in 2015. Due to issue of disease resistance, additional drug development efforts are needed to produce new, more effective treatments. Quinazoline-2,4-diamines were identified as anti-parasitic compounds over three decades ago and have remained of interest to date in industry and academia.

OBJECTIVE: An anti-malarial SAR evaluation of previously unreported N2,N4-disubstituted quinazoline-2,4-diamines have been undertaken in this study. We been synthesized and evaluated new derivatives against P. falciparum in our attempt to better characterize their biological activity and overall physical properties.

METHOD: The synthesis of N2,N4-disubstituted quinazoline-2,4-diamines inhibitors is reported along with activities in a radioactive labeled hypoxanthine incorporation assay against the f Plasmodium falciparum (Pf.) K1 strain. In addition, cytotoxicity was determined in the A549 and Vero cell lines using an MTT based. The aqueous solubility of key compounds were assessed at pH 7.4 using a shake flask-based approach.

RESULTS: We identified compounds 1 and 6p as sub µM inhibitors of P. falciparum, having equivalent anti-malarial activity to Chloroquine. Compounds 1 and 6m are low µM inhibitors of P. falciparum with improved cytotoxicity profiles. Compound 6m displayed the best balance between P. falciparum Inhibitory activity (2 µM) and cytotoxicity, displaying >49 fold selectivity over A549 and Vero cell lines.

CONCLUSION: Twenty one N2,N4-Disubstituted Quinazoline-2,4-diamines have been prepared in our group and characterized in terms of their antimalarial activity, cytotoxicity and physical properties. Compounds with good activity and reasonable selectivity over mammalian cell lines have been identified. SAR analyses suggest further exploration is are necessary to improve the balance of P. falciparum Inhibitory activity, cytotoxicity and solubility.