Synthesis and structure-activity relationships evaluation of benzothiazinone derivatives as potential anti-tubercular agents

Bioorg Med Chem Lett. 2013 Sep 1;23(17):4919-22. doi: 10.1016/j.bmcl.2013.06.069. Epub 2013 Jul 4.


N-Alkyl and heterocycle substituted 1,3-benzothiazin-4-one (BTZ) derivatives were synthesized. The anti-mycobacterial activities of these compounds were evaluated by determination of minimal inhibitory concentration (MIC) for Mycobacterium tuberculosis H37Ra and M. tuberculosis H37Rv. It was found that an extended or branched alkyl chain analog could enhance the potency, and activities of N-alkyl substituted BTZs were not affected by either nitro or trifluoromethyl at 6-position. Trifluoromethyl plays an important role in maintaining anti-tubercular activity in the piperazine or piperidine analogs. Compound 8o, which contains an azaspirodithiolane group, showed a MIC of 0.0001 μM against M. tuberculosis H37Rv, 20-fold more potent than BTZ043 racemate. These results suggested that the volume and lipophilicity of the substituents were important in maintaining activity. In addition, compound 8o was nontoxic to Vero cells and orally bioavailable in a preliminary pharmacokinetics study.

Keywords: Benzothiazinone; DprE1; Structure–activity relationships (SAR); Tuberculosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antitubercular Agents / chemical synthesis
  • Antitubercular Agents / chemistry*
  • Antitubercular Agents / pharmacokinetics
  • Antitubercular Agents / pharmacology*
  • Chlorocebus aethiops
  • Humans
  • Mycobacterium tuberculosis / drug effects*
  • Rats
  • Rats, Sprague-Dawley
  • Spiro Compounds / chemical synthesis
  • Spiro Compounds / chemistry*
  • Spiro Compounds / pharmacokinetics
  • Spiro Compounds / pharmacology*
  • Structure-Activity Relationship
  • Thiazines / chemical synthesis
  • Thiazines / chemistry*
  • Thiazines / pharmacokinetics
  • Thiazines / pharmacology*
  • Tuberculosis / drug therapy
  • Vero Cells


  • 2-(2-methyl-1,4-dioxa-8-azaspiro(4.5)dec-8-yl)-8-nitro-6-(trifluoromethyl)-4H-1,3-benzothiazin-4-one
  • Antitubercular Agents
  • Spiro Compounds
  • Thiazines