Synthetically Tuning the 2-Position of Halogenated Quinolines: Optimizing Antibacterial and Biofilm Eradication Activities via Alkylation and Reductive Amination Pathways.
Akash Basak, Yasmeen Abouelhassan, Verrill M Norwood, Fang Bai, Minh Thu Nguyen, Shouguang Jin, Robert W Huigens
Author Information
Akash Basak: Department of Chemistry, University of Florida, 1600 SW Archer Road, Gainesville, FL, 32610, USA.
Yasmeen Abouelhassan: Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, 1345 Center Drive, Gainesville, FL, 32610, USA.
Verrill M Norwood: Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, 1345 Center Drive, Gainesville, FL, 32610, USA.
Fang Bai: Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL, 32610, USA.
Minh Thu Nguyen: Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, 1345 Center Drive, Gainesville, FL, 32610, USA.
Shouguang Jin: Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL, 32610, USA.
Robert W Huigens: Department of Chemistry, University of Florida, 1600 SW Archer Road, Gainesville, FL, 32610, USA. rhuigens@cop.ufl.edu.
Agents capable of eradicating bacterial biofilms are of great importance to human health as biofilm-associated infections are tolerant to our current antibiotic therapies. We have recently discovered that halogenated quinoline (HQ) small molecules are: 1) capable of eradicating methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE) and vancomycin-resistant Enterococcus faecium (VRE) biofilms, and 2) synthetic tuning of the 2-position of the HQ scaffold has a significant impact on antibacterial and antibiofilm activities. Here, we report the chemical synthesis and biological evaluation of 39 HQ analogues that have a high degree of structural diversity at the 2-position. We identified diverse analogues that are alkylated and aminated at the 2-position of the HQ scaffold and demonstrate potent antibacterial (MIC≤0.39 μm) and biofilm eradication (MBEC 1.0-93.8 μm) activities against drug-resistant Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecium strains while demonstrating <5 % haemolysis activity against human red blood cells (RBCs) at 200 μm. In addition, these HQs demonstrated low cytotoxicity against HeLa cells. Halogenated quinolines are a promising class of antibiofilm agents against Gram-positive pathogens that could lead to useful treatments against persistent bacterial infections.
