Oak K. Kim

Small Molecule Inhibitors of LcrF, a Yersinia pseudotuberculosis Transcription Factor, Attenuate Virulence and Limit Infection in a Murine Pneumonia Model

ABSTRACT LcrF (VirF), a transcription factor in the multiple adaptational response (MAR) family, regulates expression of the Yersinia type III secretion system (T3SS). Yersinia pseudotuberculosis lcrF-null mutants showed attenuated virulence in tissue culture and animal models of infection. Targeting of LcrF offers a novel, antivirulence strategy for preventing Yersinia infection. A small molecule library was screened for inhibition of LcrF-DNA binding in an in vitro assay. All of the compounds lacked intrinsic antibacterial activity and did not demonstrate toxicity against mammalian cells. A subset of these compounds inhibited T3SS-dependent cytotoxicity of Y. pseudotuberculosis toward macrophages in vitro. In a murine model of Y. pseudotuberculosis pneumonia, two compounds significantly reduced the bacterial burden in the lungs and afforded a dramatic survival advantage. The MAR family of transcription factors is well conserved, with members playing central roles in pathogenesis across bacterial genera; thus, the inhibitors could have broad applicability.

N-hydroxybenzimidazole inhibitors of the transcription factor LcrF in Yersinia: novel antivirulence agents.

LcrF, a multiple adaptational response (MAR) transcription factor, regulates virulence in Yersinia pestis and Yersinia pseudotuberculosis. In a search for small molecule inhibitors of LcrF, an acrylic amide series of N-hydroxybenzimidazoles was synthesized and the SAR (structure-activity relationship) was examined. Selected test compounds demonstrated inhibitory activity in a primary cell-free LcrF-DNA binding assay as well as in a secondary whole cell assay (type III secretion system dependent Y. pseudotuberculosis cytotoxicity assay). The inhibitors exhibited no measurable antibacterial activity in vitro, confirming that they do not target bacterial growth. These results demonstrate that N-hydroxybenzimidazole inhibitors, exemplified by 14, 22, and 36, are effective antivirulence agents and have the potential to prevent infections caused by Yersinia spp.

N-Hydroxybenzimidazole inhibitors of ExsA MAR transcription factor in Pseudomonas aeruginosa: In vitro anti-virulence activity and metabolic stability.

ExsA is a multiple adaptational response (MAR) transcription factor, regulating the expression of a virulence determinant, the type III secretion system (T3SS) in Pseudomonas aeruginosa. Non-cytotoxic, non-antibacterial N-hydroxybenzimidazoles were identified as effective inhibitors of ExsA-DNA binding, and their potential utility as anti-virulence agents for P. aeruginosa was demonstrated in a whole cell assay. Select N-hydroxybenzimidazole inhibitors were stable in an in vitro human liver microsomal assay.

Synthesis and structure-activity relationship of C-3 quaternary ammonium cephalosporins exhibiting anti-MRSA activities

Abstract A series of cephalosporins bearing C-3 quaternary ammonium groups were prepared and evaluated for their anti-MRSA activity. They exhibit good to excellent in vitro activity (MICs = 1−8 μg/mL) against MRSA.

Synthesis and structure-activity relationship of C-3 benzoyloxymethyl cephalosporins exhibiting anti-MRSA activities

Abstract A series of cephalosporins bearing C-3 benzoyloxymethyl groups were prepared and evaluated for their anti-MRSA activity and plasma stability. They exhibit excellent in vitro activity (MIC = 0.06 ∼2 μg/mL) against MRSA and excellent stability in human plasma.

Patents on β-lactam antibacterials: January 1999 to March 2001

This review summarises patents claiming β-lactam antibacterials published from January 1999 to March 2001. The majority in the patents described in this review disclose chemistry and biological evaluation of novel cephalosporin and carbapenem derivatives. In addition, many patents reporting chemical processes and pharmaceutical formulations of known β-lactam antibiotics have also been published.