Structure-activity relationships of globomycin analogues as antibiotics.

Globomycin (1a), a signal peptidase II inhibitor, and its derivatives show potent antibacterial activity against Gram-negative bacteria. The synthesis and antimicrobial activity of novel globomycin analogues are reported. The hydroxyl group in the L-Ser residue was essential for the antimicrobial activity and the length of the alkyl side chain greatly influenced the activity. In addition, derivatives that had a modified cyclic core exhibited weak activity. One of the analogues showed a wider antimicrobial spectrum, effective against not only Gram-negative but also Gram-positive bacteria.