Antibacterial action of amphipathic derivatives of isoniazid against the Mycobacterium avium complex

The antibacterial action of amphipathic derivatives of isoniazid (INH) as compared to the parent hydrophilic molecule was determined against the bacteria of the Mycobacterium avium complex (MAC) using a 7H11 agar-dilution method. The results obtained showed a higher activity of 1-isonicotinyl-2-palmitoyl hydrazine and 1-isonicotinyl-2-(12 hydroxy dodecanoyl) hydrazine as compared to INH. However, when one mannose residue was terminally attached to the fatty acid chain of the latter, it lost its anti-MAC activity. 1-isonicotinyl-2-D-galacturonic acid hydrazone (but not hydrazine) also showed increased activity against MAC. Although pristinamycin was shown to bind to M. avium surface lipids, the INH-pristinamycin derivative was not more active than INH alone. These findings are discussed in respect to a proposed mechanism of diffusion across a lipid barrier.