Synthesis and antimicrobial activities of some new quinolonyl-3'-penicillin and 4'-cephalosporin derivatives.

A number of quinolonyl-3'-penicillin and 4'-cephalosporin derivatives have been synthesised incorporating imino group of fluoroquinolone antibacterials, viz. norfloxacin and ciprofloxacin, into carboxylic acid group of a number of semisynthetic penicillins and cephalosporins via their mixed anhydride, thereby forming an amide linkage at 3 and 4 position of the penicillin and cephalosporin component, respectively. The structure of these compounds was confirmed by spectral data and elemental analysis. The antibacterial activity of the compounds in vitro were investigated against some bacterial strains by agar plate diffusion method. While most of the compounds showed broad spectrum activity, compounds VIa and VIb exhibited higher activity against Ps. aeruginosa, K. pneumoniae and S. aureus than that of norfloxacin suggesting a dual mode of action. No untoward reaction was observed during toxicity studies of the compounds upto 1 g/kg body weight by oral route in albino mice.