[Show abstract][Hide abstract] ABSTRACT: This study reports the synthesis, antibacterial evaluation and nature of fluorine–rRNA contacts revealed by an X-ray co-crystal structure of a series of 4′-deoxy-4′-fluoro B-neomycin analogs. 4′-Deoxyfluorination improves the inhibition profile towards resistant enzymes and renders equally potent antibiotics compared to the parent neomycin B. The 4′-deoxy-4′-fluoro-4′-epi neomycin analogs showed a preferential inhibition over the 4′-deoxy-4′-fluoro neomycin counterpart against the strains of P. aeruginosa carrying a chromosomal APH(3′)-IIb enzyme, known to inactivate the parent aminoglycoside. To the best of our knowledge, this is the first example of a neighboring-group aminoglycoside-modifying enzyme evasion by fluorine substitution. A unique F-G1491 stacking was observed in a co-crystal structure of 4′-deoxy-4′-fluoro-4′-epi neomycin with a bacterial ribosomal RNA A-site.
Chemical Science 08/2014; 5(12). DOI:10.1039/C4SC01626B · 9.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aminoglycoside antibiotics are pseudosaccharides decorated with ammonium groups that are critical for their potent broad-spectrum antibacterial activity. Despite over three decades of speculation whether or not modulation of pKa is a viable strategy to curtail aminoglycoside kidney toxicity, there is a lack of methods to systematically probe amine-RNA interactions and resultant cytotoxicity trends. This study reports the first series of potent aminoglycoside antibiotics harboring fluorinated N1-hydroxyaminobutyryl acyl (HABA) appendages for which fluorine-RNA contacts are revealed through an X-ray cocrystal structure within the RNA A-site. Cytotoxicity in kidney-derived cells was significantly reduced for the derivative featuring our novel β,β-difluoro-HABA group, which masks one net charge by lowering the pKa without compromising antibacterial potency. This novel side-chain assists in evasion of aminoglycoside-modifying enzymes, and it can be easily transferred to impart these properties onto any number of novel analogs.
ACS Chemical Biology 07/2014; 9(9). DOI:10.1021/cb5003416 · 5.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Deoxygenation of the diol groups in rings A and D of neomycin in combination with the introduction of an N1-(l)-HABA group in the 2-deoxystreptamine subunit (ring B) leads to a novel and potent antibiotic (1) with activity against strains of S. aureus carrying known aminoglycoside resistance determinants, as well as against an extended panel of Methicillin-resistant S. aureus isolates (n = 50). Antibiotic 1 displayed >64 fold improvement in MIC50 and MIC90 against this MRSA collection when compared to the clinically relevant aminoglycosides amikacin and gentamicin. The synthesis was achieved in six steps and 15% overall yield.Keywords: Aminoglycoside; antibiotics; deoxygenation; MRSA; enzymatic modification; resistance; neomycin analogues
[Show abstract][Hide abstract] ABSTRACT: ACHN-490 is a neoglycoside, or "next-generation" aminoglycoside (AG), that has been identified as a potentially useful agent to combat drug-resistant bacteria emerging in hospitals and health care facilities around the world. A focused medicinal chemistry campaign produced a collection of over 400 sisomicin analogs from which ACHN-490 was selected. We tested ACHN-490 against two panels of Gram-negative and Gram-positive pathogens, many of which harbored AG resistance mechanisms. Unlike legacy AGs, ACHN-490 was active against strains expressing known AG-modifying enzymes, including the three most common such enzymes found in Enterobacteriaceae. ACHN-490 inhibited the growth of AG-resistant Enterobacteriaceae (MIC(90), ≤4 μg/ml), with the exception of Proteus mirabilis and indole-positive Proteae (MIC(90), 8 μg/ml and 16 μg/ml, respectively). ACHN-490 was more active alone in vitro against Pseudomonas aeruginosa and Acinetobacter baumannii isolates with AG-modifying enzymes than against those with altered permeability/efflux. The MIC(90) of ACHN-490 against AG-resistant staphylococci was 2 μg/ml. Due to its promising in vitro and in vivo profiles, ACHN-490 has been advanced into clinical development as a new antibacterial agent.
[Show abstract][Hide abstract] ABSTRACT: Nosocomial infections caused by multi-drug resistant (MDR) Gram-negative bacteria are on the increase, often with few or no therapeutic options for treatment. Historically, a successful approach to generate novel antibiotics has been the chemical modification of existing classes, addressing deficiencies such as resistance mechanisms, safety profile or pharmacokinetic parameters. Aminoglycosides (AGs) represent one of the five clinically-used classes (AGs, β-lactams, quinolones, tetracyclines and sulfonamides) with activity against Gram-negative bacteria.
A summary of the AG patent literature between the beginning of 2005 and February 2010 with the main focus on novel AG analogs with potential for therapeutic activity against MDR Gram-negative pathogens.
Overview of the patent literature in the aminoglycoside field during the past 5 years including an assessment of the therapeutic potential for the derivatives described.
A few companies and academic groups have recently reawakened the dormant field of AG antibiotics, successfully applying novel technologies. So far, this has yielded one clinical candidate, ACHN-490, currently undergoing a Phase II evaluation in complicated urinary tract infections.