Studies of tylosin derivatives effective against macrolide-resistant strains: Synthesis and structure-activity relationships

Abstract

The 4“-O-substituted tylosin derivatives were prepared by selective esterification of the 4“-OH, and relationships between the substituent groups and antimicrobial activity against macrolide-resistant strains were examined. Introduction of branched-chain aliphatic acyl groups such as 2-methoxyisovaleryl or 4-methylvaleryl group afforded derivatives with good antibacterial activity; MIC values were 12.5 μg/ml against Staphylococcus aureus MS-8710. MIC values of tylosin, erythromycin and josamycin against this strain were 800 or more. Further improved activity was obtained by introduction of aromatic groups such as phenyl-thioacetyl, phenylsulfonylacetyl, 4-nitrophenylacetyl, 4-nitrophenylsulfonyl and phenylethanesulfonyl groups; MIC values were 6.25μg/ml. These derivatives had also an improved antimycoplasmal activity; MIC values were 0.08 against macrolide-resistant strains of Mycoplasma gallisepticum. MIC values of tylosin against these strains were from 2.5 to 10 μg/ml. Introduction of the groups described above into the 4“-OH was confirmed to increase the uptake by a resistant strain. © 1982, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.