ABSTRACT
Antibiotic resistance is a worldwide threat due to the decreasing supply of new antimicrobials. Novel targets and innovative strategies are urgently needed to generate pathbreaking drug compounds. NAD kinase (NADK) is essential for growth in most bacteria, as it supports critical metabolic pathways. Here, we report the discovery of a new class of antibacterials that targets bacterial NADK. We generated a series of small synthetic adenine derivatives to screen those harboring promising substituents in order to guide efficient fragment linking. This led to NKI1, a new lead compound inhibiting NADK that showed in vitro bactericidal activity against Staphylococcus aureus. In a murine model of infection, NKI1 restricted survival of the bacteria, including methicillin-resistant S. aureus. Collectively, these findings identify bacterial NADK as a potential drug target and NKI1 as a lead compound in the treatment of staphylococcal infections.
Subject(s)
Anti-Bacterial Agents/pharmacology , Phosphotransferases (Alcohol Group Acceptor)/antagonists & inhibitors , Staphylococcal Infections/drug therapy , Staphylococcus aureus/drug effects , Adenine/chemistry , Adenine/pharmacology , Animals , Binding Sites , Cell Line , Crystallography, X-Ray , Female , Humans , Methicillin-Resistant Staphylococcus aureus/drug effects , Mice , Mice, Inbred BALB C , Microbial Sensitivity Tests , Small Molecule Libraries , Staphylococcus aureus/enzymology , Structure-Activity RelationshipABSTRACT
Increased resistance of pathogens to existing antibiotics necessitates the search for novel targets to develop potent antimicrobials. Biosynthetic pathways of several cofactors important for bacterial growth, such as nicotinamide adenine dinucleotide phosphate (NADP), have been proposed as a promising source of antibiotic targets. Nicotinamide adenine dinucleotide kinases (NADK; EC 2.7.1.23) are attractive for inhibitor development, since they catalyze the phosphorylation of NAD to NADP, which is an essential step of NADP metabolism. We previously synthesized diadenosine derivatives that inhibited NADK from two human pathogens, Listeria monocytogenes and Staphylococcus aureus, in the micromolar range. They behave as NAD mimics with the 5',5'-diphosphate group substituted by a 8,5' thioglycolic bridge. In an attempt to improve inhibitory potency, we designed new NAD mimics based on a single adenosine moiety harboring a larger derivatization attached to the C8 position and a small group at the 5' position. Here we report the synthesis of a series of 8-thioalkyl-adenosine derivatives containing various aryl and heteroaryl moieties and their evaluation as inhibitors of L. monocytogenes NADK1, S. aureus NADK and their human counterpart. Novel, sub-micromolar inhibitors of LmNADK1 were identified. Surprisingly, most LmNADK1 inhibitors demonstrated a high selectivity index against the close staphylococcal ortholog and the human NADK. Structural characterization of enzyme-inhibitor complexes revealed the original binding mode of these novel NAD mimics.
Subject(s)
Adenosine/chemistry , Adenosine/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Listeria monocytogenes/enzymology , Phosphotransferases (Alcohol Group Acceptor)/antagonists & inhibitors , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Adenosine/metabolism , Amino Acid Sequence , Enzyme Inhibitors/metabolism , Humans , Molecular Docking Simulation , Phosphotransferases (Alcohol Group Acceptor)/chemistry , Protein Binding , Protein Conformation , Ribose/chemistry , Staphylococcus aureus/enzymology , Structure-Activity RelationshipABSTRACT
The 2'-deoxynucleoside 5'-phosphate N-hydrolase 1 (DNPH1) has been proposed as a new molecular target for cancer treatment. Here, we describe the synthesis of a series of novel 6-aryl- and 6-heteroarylpurine riboside 5'-monophosphates via Suzuki-Miyaura cross-coupling reactions, and their ability to inhibit recombinant rat and human DNPH1. Enzymatic inhibition studies revealed competitive inhibitors in the low micromolar range. Crystal structures of human and rat DNPH1 in complex with one nucleotide from this series, the 6-naphthylpurine derivative, provided detailed structural information, in particular regarding the possible conformations of a long and flexible loop wrapping around the large hydrophobic substituent. Taking advantage of these high-resolution structures, we performed virtual docking studies in order to evaluate enzyme-inhibitor interactions for the whole compound series. Among the synthesized compounds, several molecules exhibited significant in vitro cytotoxicity against human colon cancer (HCT15, HCT116) and human promyelocytic leukemia (HL60) cell lines with IC50 values in the low micromolar range, which correlated with in vitro DNPH1 inhibitory potency.
Subject(s)
Drug Design , Molecular Targeted Therapy , N-Glycosyl Hydrolases/antagonists & inhibitors , Nuclear Proteins/antagonists & inhibitors , Proto-Oncogene Proteins/antagonists & inhibitors , Purine Nucleotides/chemical synthesis , Purine Nucleotides/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Chemistry Techniques, Synthetic , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/metabolism , Enzyme Inhibitors/pharmacology , Humans , Molecular Docking Simulation , N-Glycosyl Hydrolases/chemistry , N-Glycosyl Hydrolases/metabolism , Nuclear Proteins/chemistry , Nuclear Proteins/metabolism , Protein Conformation , Proto-Oncogene Proteins/chemistry , Proto-Oncogene Proteins/metabolism , Purine Nucleotides/chemistry , Purine Nucleotides/metabolism , Rats , Structure-Activity RelationshipABSTRACT
A simple and versatile dendrimer based platform to deliver therapeutic agents at temperatures within the physiological range, is reported. Lipoic acid conjugated at the periphery of the thermosensitive dendrimer formulations undergoes slow and sustained release at 37-42 °C, and rescues the cells from oxidative stress and a pro-inflammatory endotoxic agent.
