Antibiotics from gliding bacteria, XLII. Chemical modification of sorangicin A and structure — Activity relationship I: Carboxyl and hydroxyl group derivatives

The synthesis of selectively protected sorangicin A derivatives and their application in the modification of the hydroxyl groups and the carboxyl group in sorangicin A ( 1 ) is described. Esters, amides, and sorangicins modified at the hydroxyl groups were prepared and their activities against Staphylococcus aureus, Escherichia coli , and their in vitro inhibition of RNA polymerase were examined. Although no sorangicin A derivatives with superior biological activity were observed, some derivatives completely retained their antibiotic activity or were slightly improved in their activity with certain strains.