1.Novel cephalosporins synthesized by amination of 2,5-dihydroxybenzoic acid derivatives using fungal laccases II.
Mikolasch A1, Niedermeyer TH, Lalk M, Witt S, Seefeldt S, Hammer E, Schauer F, Gesell Salazar M, Hessel S, Jülich WD, Lindequist U. Chem Pharm Bull (Tokyo). 2007 Mar;55(3):412-6.
Sixteen novel cephalosporins were synthesized by amination of 2,5-dihydroxybenzoic acid derivatives with the aminocephalosporins cefadroxil, cefalexin, cefaclor, and the structurally related carbacephem loracarbef using laccases from Trametes sp. or Myceliophthora thermophila. All products inhibited the growth of several Gram positive bacterial strains in the agar diffusion assay, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. The products protected mice against an infection with Staphylococcus aureus lethal to the control animals. Cytotoxicity and acute toxicity of the new compounds were negligible. The results show the usefulness of laccase for the synthesis of potential new antibiotics. The biological activity of the new compounds stimulates intensified pharmacological tests.
2.Biscatecholate-monohydroxamate mixed ligand siderophore-carbacephalosporin conjugates are selective sideromycin antibiotics that target Acinetobacter baumannii.
Wencewicz TA1, Miller MJ. J Med Chem. 2013 May 23;56(10):4044-52. doi: 10.1021/jm400265k. Epub 2013 May 8.
Chemical syntheses and biological evaluation of biscatecholate-monohydroxamate mixed ligand sideromycins utilizing the carbacephalosporin β-lactam antibiotic loracarbef and the fluoroquinolone antibiotic ciprofloxacin are described. The mixed ligand β-lactam sideromycin (1b) had remarkably selective and extremely potent antibacterial activity against the Gram-negative pathogen Acinetobacter baumannii ATCC 17961 (MIC = 0.0078 μM). The antibacterial activity of the β-lactam sideromycin was inversely related to the iron(III) concentration in the testing media and was antagonized by the presence of the competing parent siderophore. These data suggested that active transport of the mixed ligand β-lactam sideromycin across the outer cell membrane of A. baumannii via siderophore-uptake pathways was responsible for the selective and potent antibacterial activity.
3.The effect of four different types of diet on the bioavailability of loracarbef.
Bapujee AT1, Singh T, Ahmed T, Monif T, Saha N, Sharma PL. Eur J Drug Metab Pharmacokinet. 2007 Oct-Dec;32(4):205-11.
This randomized open-label single-dose crossover pharmacokinetic study was carried out to assess the effect of different diets on the bioavailability of loracarbef in 24 healthy male volunteers. A single dose of loracarbef in 200-mg tablet form was administered at 5 different times: after overnight fasting, after two vegetarian (high-fat and low-fat) diets, and following two non-vegetarian (high-fat and low-fat) diets. Serial blood samples were collected up to 10 h post-dose. Serum loracarbef concentrations were determined by a validated high performance liquid chromatographic (HPLC) method. Area under curve (AUC) values were significantly affected only by non-vegetarian diets; however the time to reach maximum serum concentration (Tmax) was prolonged and the maximum serum concentration (Cmax was decreased by all types of meals. The non-vegetarian diets affected the rate of absorption of loracarbef more than the vegetarian diets. The lowest decrease in Cmax was produced by the high-fat vegetarian diet, while the maximum was produced by the low-fat non-vegetarian diet.
4.Syntheses of Siderophore-Drug Conjugates Using a Convergent Thiol-Maleimide System.
Juárez-Hernández RE1, Miller PA, Miller MJ. ACS Med Chem Lett. 2012 Oct 11;3(10):799-803. Epub 2012 Sep 4.
Three siderophore-drug conjugates (sideromycins) were synthesized by preparation of a maleimide linked derivative of the siderophore desferrioxamine B and reacting the corresponding Ga(3+)-complex with freshly prepared thiol-containing antibiotics: loracarbef, ciprofloxacin and nadifloxacin. The conjugates and their synthetic precursors were tested against a broad panel of bacteria and were found to display Gram-positive selective, growth inhibitory activity (µM) indicating that this approach is suitable for the convergent synthesis and screening of novel sideromycins.