thiourea and acetylalanylalanine

A series of thiourea and isothiouronium salt derivatives of the aglycone of teicoplanin was prepared by reaction of the terminal amino group with isothiocyanates, followed by S-alkylation of the thiourea compounds. Unexpectedly, the two classes of derivatives show a similar in vitro antibacterial activity against Gram-positive bacteria. Thiourea compounds, due to the lack of a positively charged N-terminus group, have a 10-fold lower binding constant to Ac-D-Ala-D-Ala, a bacterial cell-wall model, than the parent antibiotic and isothiouronium salt derivatives.

Topics: Anti-Bacterial Agents; Cell Wall; Chromatography, High Pressure Liquid; Dipeptides; Glycopeptides; Isothiuronium; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Molecular Structure; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Structure-Activity Relationship; Teicoplanin; Thiourea