7,8 And 9-substituted tetracycline compounds

A 7-, 8- or 9-substituted tetracycline compound of the formula:

• wherein:
• R4 and R4′ are each methyl;
• R5 is hydrogen or hydroxyl;
• R6 and R6′ are each independently hydrogen, methyl, or hydroxyl;
• R7 is hydrogen, lower alkenyl, lower alkynyl, phenyl, halophenyl, acyl, phenylalkynyl, heteroaryl, or dimethylamino;
• and
• R8 is hydrogen, phenyl, nitrophenyl, halo, or lower alkynyl;
• and R9 is hydrogen, amino, acetamide, or lower alkynyl;
• and provided that at least one of R7, R8, or R9 is not hydrogen;
• and pharmaceutically acceptable salts thereof.