Studies on 3'-quaternary ammonium cephalosporins. II. Synthesis and antibacterial activity of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-cephalospori n derivatives bearing various quaternary ammonium methyl groups at the 3 position

Studies on 3'-quaternary ammonium cephalosporins--IV. Synthesis and antibacterial activity of 3'-(2-alkyl-3-aminopyrazolium) cephalosporins related to FK037

The synthesis and in vitro antibacterial activity of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido] cephalosporins bearing various 2-alkyl-3-aminopyrazolium groups at the 3-position are described. Antibacterial activity against MRSA was affected by the nature of the substituent at the 2-position on the 3'-aminopyrazolium groups. Among the cephalosporins prepared in this study, 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-[3-am ino-2-(2 -hydroxyethyl)-pyrazolio]methyl-3-cephem-4-carboxylate sulfate (23e, FK037) showed extremely potent broad-spectrum activity against both Gram-positive bacteria including MRSA, and Gram-negative bacteria including Pseudomonas aeruginosa. In particular, the in vivo activity against MRSA of FK037 was the highest of all the beta-lactam antibiotics tested.

Novelties in the field of parenteral cephem antibacterials since 1993

There is still considerable interest in cephem antibacterial agents. In fact, there are a significant number of patents submitted for this antibacterial class. All the new cephem derivatives, independent of which group they belong to (III to V), possess a 2-amino-5-thiazolyl or a 5-amino-2-thiadiazolyl ring with an oxime group (at position 7 of the cephem nucleus). At position 3, they have a C-3' quaternary ammonium moiety. Research has focused on the following structural modifications: the nature of the oxime residues and the charged azolium heterocycle, and the addition of the vinylogous chain. The aim of researchers is to increase the overall activity of these compounds against Gram-negative bacilli, including against isolates producing type 1 beta-lactamases or extended spectrum beta-lactamases (Enterobacteriaceae). Non-fermentative Gram-negative bacilli are now included in the first screening process, in addition to Pseudomonas aeruginosa. Extensive research is ongoing with the aim of solving the MRSA problem. New promising entities have been reported.

Studies on 3'-quaternary ammonium cephalosporins--III. Synthesis and antibacterial activity of 3'-(3-aminopyrazolium) cephalosporins

The synthesis and in vitro antibacterial activity of 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]cephalos porins bearing N-mono or dialkyl and carbamoyl aminopyrazolium, and five- or six-membered rings fused to the 3-aminopyrazolium methyl groups at the 3-position, are described. Aminopyrazolium methyl cephalosporins (23e, f, i), with fused saturated and unsaturated rings were especially effective against Staphylococcus strains compared to 3-amino-2-methylpyrazolium methyl cephalosporin (1). Among the cephalosporins prepared in this work, 7 beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-(4,5, 6, 7-tetrahydro-1-pyrazolo[1,5-a]pyrimidinio)methyl-3-cephem-4-carbox ylate (23f) showed a good balance of antibacterial activity against both Gram-positive bacteria including Staphylococcus aureus and Gram-negative bacteria including P. aeruginosa. An imidazopyrazolium group at the 3-position in, for example, cephalosporin (23i) was particularly effective for improving antibacterial activity against MRSA.