Durhamycin A, a potent inhibitor of HIV Tat transactivation.

Tat is a small HIV protein essential for both viral replication and the progression of HIV disease. In our efforts to discover Tat inhibitors from natural product screening of microbial fermentation extracts, we discovered durhamycin A (1) as a potent inhibitor (IC(50) = 4.8 nM) of Tat transactivation. Detailed NMR and MS/MS studies were utilized to elucidate the structure of 1 as a new member of the aureolic acid family of antibiotics. It consists of tetrasaccharide and disaccharide moieties attached to the aglycone, which is hitherto unknown in the aureolic acid family. Three other novel analogues, durhamycin B (2), compound (3), and the aglycone (4), were also discovered or chemically prepared that were less potent than durhamycin A.