"5-Amino-5"-deoxybutirosin, a semisynthetic analogue of butirosin A: antibacterial activity in vitro and in mice.

Aminodeoxybutirosin (AD-BTN), the 5''-amino-5''-deoxy derivative of butirosin (BTN), was synthesized to improve on the antibacterial activity of BTN by preventing bacterial enzymatic phosphorylation at the 5'' position. AD-BTN possesses the spectrum characteristic of BTN and gentamicin (GTM) and was active at low levels in vitro against a wide variety of gram-negative species including Pseudomonas aeruginosa, indole-positive Proteus and Serratia marcescens; its action was bactericidal against both light and heavy inocula, and it was not antagonized by human serum. AD-BTN was as active as GTM against GTM-sensitive P. aeruginosa in vitro and in mice, and was markedly improved over BTN. AD-BTN retained the good activity of the parent compound against other gram-negative pathogens. Whereas GTM minimal inhibitory concentrations were elevated 35-fold against GTM-resistant P. aeruginosa in vitro, the minimal inhibitory concentration of AD-BTN was only doubled. At 6.3 mug/ml, AD-BTN inhibited 68% of 82 isolates insusceptible to that concentration of GTM. In murine toxicity tests AD-BTN was about one-third to one-half as toxic as GTM.