Anti-Mycobacterial Activity of Tamoxifen Against Drug-Resistant and Intra-Macrophage Mycobacterium tuberculosis

Recently, it has become a struggle to treat tuberculosis with the current commercial anti-tuberculosis drugs because of the increasing emergence of multidrug-resistant (MDR) tuberculosis and extensively drug-resistant (XDR) tuberculosis. We evaluated here the anti-mycobacterial activity of tamoxifen, known as a synthetic anti-estrogen, against eight drug-sensitive or resistant strains of Mycobacterium tuberculosis (TB), and the active intracellular killing of tamoxifen on TB in macrophages. The results showed that tamoxifen had anti-tuberculosis activity against drug-sensitive strains (MIC, 3.125-6.25 mu g/ml) as well as drug-resistant strains (MIC, 6.25 to 12.5 mu g/ml). In addition, tamoxifen profoundly decreased the number of intracellular TB in macrophages in a dose-dependent manner.