Antibacterial activity, cytotoxicity and Lipid II binding of BAS00127538 derivatives.

<p>Antibacterial activity, cytotoxicity and Lipid II binding of BAS00127538 derivatives.</p

Towards Development of Small Molecule Lipid II Inhibitors as Novel Antibiotics

<div><p>Recently we described a novel di-benzene-pyrylium-indolene (BAS00127538) inhibitor of Lipid II. BAS00127538 (<i>1-Methyl-2</i>,<i>4-diphenyl-6-((1E</i>,<i>3E)-3-(1</i>,<i>3</i>,<i>3-trimethylindolin-2-ylidene)prop-1-en-1-yl)pyryl-1-ium) tetrafluoroborate</i> is the first small molecule Lipid II inhibitor and is structurally distinct from natural agents that bind Lipid II, such as vancomycin. Here, we describe the synthesis and biological evaluation of 50 new analogs of BAS00127538 designed to explore the structure-activity relationships of the scaffold. The results of this study indicate an activity map of the scaffold, identifying regions that are critical to cytotoxicity, Lipid II binding and range of anti-bacterial action. One compound, 6jc48-1, showed significantly enhanced drug-like properties compared to BAS00127538. 6jc48-1 has reduced cytotoxicity, while retaining specific Lipid II binding and activity against <i>Enterococcus spp</i>. <i>in vitro</i> and <i>in vivo</i>. Further, this compound showed a markedly improved pharmacokinetic profile with a half-life of over 13 hours upon intravenous and oral administration and was stable in plasma. These results suggest that scaffolds like that of 6jc48-1 can be developed into small molecule antibiotic drugs that target Lipid II.</p></div

<i>In vitro</i> drug-like properties of 6jc48-1.

<p><i>In vitro</i> drug-like properties of 6jc48-1.</p

Pharmacokinetics of 6jc48-1 <i>in vivo</i>.

<p>Compound was administered at 2.5 mg/kg (IV) or 5 mg/kg (PO) to male CD1 mice (n = 3) in 10% DMSO and 50% PEG 400 in PBS. Half-life was determined by measuring the plasma concentration of compound by LC/MS/MS at the time points indicated.</p

<i>In vivo</i> efficacy of 6jc48-1 in murine sepsis.

<p>Spleen samples were collected from vehicle-treated, ampicillin (300 mg/kg) treated or 6jc48-1 (100 mg/kg) treated animals at 20 h post-infection with 5 x 10⁸ CFU/animal of <i>E</i>. <i>faecalis</i> EF1509. * One animal treated with compound did not survive.</p

Models of BAS00127538 and 6jc48-1 in complex with a Lipid II analog.

<p>The compounds are shown in CPK atom colored format, with the Br atoms for 6jc48-1 shown as vdW spheres, and the Lipid II is in licorice representation with atom type coloring with the N-acetylglucoseamine sugars shown in blue. The phosphate (Phos), sugars (GlcNAc) and pentapeptide (Peptide) are indicated. The upper and lower panels are approximately 180° rotations of the two complexes. (C) Chemical structure of <i>de novo</i> synthesized BAS00127538 and the 6jc-48-1 derivative.</p

Activity of 6jc48-1 against <i>Enterococcus spp</i>.

<p>Activity of 6jc48-1 against <i>Enterococcus spp</i>.</p

Pharmacokinetic properties of 6jc48-1.

<p>Pharmacokinetic properties of 6jc48-1.</p

MMS analysis of 6jc48-1.

<p>The effects of 6jc48-1 (MIC 4 μg/ml) and Jc-67 (BAS00127538) (MIC 2 μg/ml) on the macromolecular synthetic pathways for DNA, Cell wall, protein, and lipid.</p