A number of 9-acylamino and 9-sulfonylamino derivatives of minocycline have been synthesized for structure–activity relationship studies. These compounds showed activity against both tetracycline-susceptible and tetracycline-resistant strains. Many of the 9- sulfonylamino derivatives exhibited improved antibacterial activity against a number of tetracycline-and minocycline-resistant Gram-positive pathogens.
