Ethionamide(2-ethylthioisonicotinamide) is an antibiotic used in the treatment of tuberculosis. Target: Antibacterial Ethionamide is a second-line antitubercular agent that inhibits mycolic acid synthesis. It also may be used for treatment of leprosy. Ethionamide is a prodrug. It is activated by the enzyme EthA, a mono-oxygenase in Mycobacterium tuberculosis, and binds NAD+ to form an adduct which inhibits InhA in the same way as isoniazid. Expression of the ethA gene is controlled by EthR, a transcriptional repressor. It is understood that improving ethA expression will increase the efficacy of ethionamide and so EthR inhibitors are of great interest to co-drug developers. The action may be through disruption of mycolic acid [1, 2].

• [1]. Vannelli, T.A., A. Dykman, and P.R. Ortiz de Montellano, The antituberculosis drug ethionamide is activated by a flavoprotein monooxygenase. J Biol Chem, 2002. 277(15): p. 12824-9.

  [2]. Quemard, A., G. Laneelle, and C. Lacave, Mycolic acid synthesis: a target for ethionamide in mycobacteria? Antimicrob Agents Chemother, 1992. 36(6): p. 1316-21.