STRUCTURE-ACTIVITY RELATIONSHIP STUDIES ON 4''-O-ACYLTYLOSIN DERIVATIVES: SIGNIFICANCE OF THEIR 23-O-MYCINOSYL AND 4''-O-ACYL MOIETIES IN ANTIMICROBIAL ACTIVITY AGAINST MACROLIDE-RESISTANT MICROBES

Essential roles for both the 23-O-mycinosyl and 4''-O-acyl moieties of 4''-O-acyltylosin derivatives in the expression of antimicrobial activity against multiple macrolide-resistant strains of Staphylococci and mycoplasmas were demonstrated by in vitro comparison of the MICs of erythromycin, josamycin, tylosin and its 3- and 4''-O-acyl derivatives, demycinosyltylosin (DMT) and its 3- and 4''-O-acyl derivatives and 23-modified 3-O-acetyl-4''-O-isovaleryl-DMT derivatives.