A series of amino acid and dipeptide prodrugs of IMB-070593, a fluoroquinolone candidate discovered in our lab, were synthesized and evaluated for their water solubility and then antibacterial activity. Our results reveal that four amino acid prodrugs 4a,b,e,f and two dipeptide prodrugs 4k,l have much greater solubility (>85 mg/mL) than IMB-070593 mesylate (22.5 mg/mL). Compounds 4a and 4k show good in vivo efficacy against MSSA 12-1 (p.o./i.v., 5.32-7.68 mg/kg) and S. pneumoniae12-10 (p.o., 18.39-23.13 mg/kg) which is 1.19-1.50 fold more active than the parent drug.
A series of novel (R)/(S)-7-(3-alkoxyimino-2-aminomethyl-1-azetidinyl)fluoroquinolone derivatives were synthesized and evaluated for their in vitro antibacterial activity against representative strains. Our results reveal that 12 of the target compounds generally show better activity (MIC: <0.008-0.5 μg mL(-1)) against the tested Gram-positive strains including MRSA and MRSE than levofloxacin (LVFX, MIC: 0.125-8 μg mL(-1)). Their activity is similar to that of gemifloxacin (GMFX, MIC: <0.008-4 μg mL(-1)). However, they are generally less active than the two reference drugs against Gram-negative strains. Moreover, against clinical strains of S. aureus including MRSA and S. epidermidis including MRSE, the MIC(50) values (0.06-16 μg mL(-1)) and MIC(90) values (0.5-32 μg mL(-1)) of compounds 16 w, y, and z are 2-8- and 2-16-fold less than LVFX, respectively, and 16 w (MIC(90) range: 0.5-4 μg mL(-1)) was also found to be more active than GMFX (MIC(90) range: 1-8 μg mL(-1)).
The back cover picture shows the structural evolution of fluroqinolone‐derived antibacterial agents—particularly the C‐7 nitrogen heterocycle, which influences the potency, activity spectrum and safety, from piperazine to pyrrolidine and azetidine. Now, derivatives containing a chiral 3‐(alkoxyimino)‐2‐(aminomethyl)azetidine show promise against Gram‐positive strains including methicillin‐resistant Staphylococcus aureus (MRSA). For more details, see the Full Paper by Mingliang Liu et al. on
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