Structure-activity relationships of novel 2-substituted quinazoline antibacterial agents

High-throughput screening of in-house compound libraries led to the discovery of a novel antibacterial agent, compound 1 (MIC: 12-25 microM against S. pyogenes). In an effort to improve the activity of this active compound, a series of 2-substituted quinazolines was synthesized and evaluated in several antibacterial assays. One such compound (22) displayed improved broad-spectrum antibacterial activity against a variety of bacterial strains. This molecule also inhibited transcription/translation of bacterial RNA, suggesting a mechanism for its antibiotic effects. Structure-activity relationship studies of 22 led to the synthesis of another 24 compounds. Although some of these molecules were found to be active in bacterial growth assays, none were as potent as 22. Compound 22 was tested for its ability to cure a systemic K. pneumonia infection in the mouse and displayed moderate effects compared with a control antibiotic, gentamycin.

Deconvolution of combinatorial libraries for drug discovery: experimental comparison of pooling strategies

An experimental evaluation of several different pooling strategies for combinatorial libraries was conducted using a library of 810 compounds and an enzyme inhibition assay (phospholipase A2). The library contained compounds with varying degrees of activity as well as inactive compounds. The compounds were synthesized in groups of three and pooled together in various formats to realize different pooling strategies. With one exception, all iterative deconvolution strategies and position scanning resulted in identification of the same compound. The results are in good agreement with the predicted outcome from theoretical and computational methods. These data support the tenet that active compounds for pharmaceutically relevant targets can be successfully identified from combinatorial libraries organized in mixtures.

Sequence specific inhibition of human type II phospholipase A2 enzyme activity by phosphorothioate oligonucleotides

Phosphorothioate oligonucleotides were identified which directly inhibited human type II phospholipase A2 (PLA2) enzyme activity in a sequence specific manner. The minimum pharmacophore common to all oligonucleotides which inhibited PLA2 enzyme activity consisted of two sets of three or more consecutive guanosine residues in a row. These oligonucleotides appear to form G quartets resulting in the formation of oligonucleotide aggregates. Additionally, a phosphorothioate backbone was required to be effective inhibitors of type II PLA2. The activity of one oligodeoxynucleotide, IP 3196 (5'-GGGTGGGTATAGAAGGGCTCC-3') has been characterized in more detail. IP 3196 inhibited PLA2 enzyme activity when the substrate was presented in the form of a phospholipid bilayer but not when presented in the form of a mixed micelle with anionic detergents. Human type II PLA2 was 50-fold more sensitive to inhibition by IP 3196 than venom and pancreatic type I enzymes. These data demonstrate that phosphorothioate oligonucleotides can specifically inhibit human type II PLA2 enzyme activity in a sequence specific manner.