Effects of erythromycin base and erythromycin esters on protein synthesis in vivo in Escherichia coli.

The inhibitory effects on protein synthesis in vivo of erythromycin base and several erythromycin esters have been determined. An experimental method was used, especially suited for studies on short-lived antibiotics causing low levels of inhibition. Most of the tested derivatives were 2-3% as active as erythromycin base while a split product of erythromycin, anhydroerythromycin, was 4% as effective.