| Bioactivity | Isoniazid (INH) is a prodrug and must be activated by a bacterial catalase-peroxidase enzyme KatG. Isoniazid is bactericidal to rapidly dividing mycobacteria and has anti-tuberculostatic activity[1][2][3][4]. |
| Invitro | Isoniazid (INH) is a prodrug and must be activated by a bacterial catalase-peroxidase enzyme that in M. tuberculosis is called KatG[1]. KatG couples the isonicotinic acyl with NADH to form isonicotinic acyl-NADH complex. This complex binds tightly to the enoyl-acyl carrier protein reductase known as InhA, thereby blocking the natural enoyl-AcpM substrate and the action of fatty acid synthase. This process inhibits the synthesis of mycolic acid, required for the mycobacterial cell wall. A range of radicals are produced by KatG activation of isoniazid, including nitric oxide, which has also been shown to be important in the action of another antimycobacterial prodrug PA-824[2][3]. Isoniazid is bactericidal to rapidly dividing mycobacteria, but is bacteriostatic if the mycobacteria are slow-growing[4]. |
| Name | Isoniazid |
| CAS | 54-85-3 |
| Formula | C6H7N3O |
| Molar Mass | 137.14 |
| Transport | Room temperature in continental US; may vary elsewhere. |
| Storage | 4°C, protect from light *In solvent : -80°C, 6 months; -20°C, 1 month (protect from light) |