ABSTRACT
In 2014, a published report of the high-throughput screen of>42,000 kinase inhibitors from GlaxoSmithKline against T. brucei identified 797 potent and selective hits. From this rich data set, we selected NEU-0001101 (1) for hit-to-lead optimization. Through our preliminary compound synthesis and SAR studies, we have confirmed the previously reported activity of 1 in a T. brucei cell proliferation assay and have identified alternative groups to replace the pyridyl ring in 1. Pyrazole 24 achieves improvements in both potency and lipophilicity relative to 1, while also showing good in vitro metabolic stability. The SAR developed on 24 provides new directions for further optimization of this novel scaffold for anti-trypanosomal drug discovery.
Subject(s)
Drug Design , Pyrazoles/chemical synthesis , Quinazolinones/chemistry , Trypanocidal Agents/chemical synthesis , Cell Line , Cell Proliferation/drug effects , Humans , Pyrazoles/pharmacology , Pyrazoles/therapeutic use , Quinazolinones/chemical synthesis , Quinazolinones/pharmacology , Quinazolinones/therapeutic use , Structure-Activity Relationship , Trypanocidal Agents/pharmacology , Trypanocidal Agents/therapeutic use , Trypanosoma brucei brucei/drug effects , Trypanosoma brucei brucei/growth & development , Trypanosomiasis, African/drug therapyABSTRACT
Ruthenium complexes of the general formula [Ru(CO)(H)(L2)(L'2)][PF6] (L2 = trans-2PPh3, L' = η2-4,4'-dicarboxybipyridine (1); L2 =trans-2Ph2PCH2CH2COOH, L'2 = bipyridine (2); L2 = Ph2PCHCHPPh2, L' = η2-5-amino-1,10-phenanthroline (3); L2 = trans-2PPh3, L'2 = η2-4-carboxaldehyde-4'-methylbipyridine (4)) have been shown to have longer emission lifetimes and higher quantum yields in solution compared with more symmetrical molecules such as [Ru(bpy)3][Cl]2. Compound 4 is obtained as a mixture with the corresponding acetal, 4'. These less symmetrical complexes have been covalently immobilized on the surface of silica polyamine composites, and their photophysical properties have been studied. The surface-bound complexes have been characterized by solid-state CPMAS 13C, 31P, and 29Si NMR, UV-vis, and FT-IR spectroscopies. Excited-state lifetime studies revealed that, in general, the lifetimes of the immobilized complexes are 1.4 to 8 times longer than in solution and are dependent on particle size (300-500 µm versus 10-20 nm average diameter silica gels), polymer structure (linear poly(allylamine) versus branched poly(ethylenimine)), and the type of surface tether. One exception to this trend is the previously reported complex [Ru(bpy)2(5-amino-1,10-phenanthroline)][PF6]2 (5), where only a slight increase in lifetime is observed. Only minor changes in emission wavelength are observed for all the complexes. This opens up the possibility for enhanced heterogeneous electron transfer in photocatalytic reactions.
