Ala(O)-actagardine, a new lantibiotic from cultures of Actinoplanes liguriae ATCC 31048

Abstract

The actagardine-producing strain Actinoplanes liguriae ATCC 31048, forms an additional lantibiotic when it is cultured on mannitol and soya meal. The new compound, Ala(O)actagardine (1), has been isolated by solid-phase extraction followed by a two-step chromatographic separation. The molecular formula of 1 is C84H129N21O25S4. Its chemical structure was determined by 2D-NMR analysis and was further confirmed by an amino acid analysis, Edman degradation, acid partial synthesis from actagardine. 1 exhibits a slightly higher biological activity than the parent compound actagardine. The synthetic analogs Lys(O)-actagardine (2) and Ile(O)-actagardine (3) demonstrate also antibacterial activities and emphasize the importance of the N-terminus for further derivatization.