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Tuberculosis is a worldwide health problem that warrants attention given that the current treatment options require a long-term chemotherapeutic period and have reported the development of Mycobacterium tuberculosis ( M. tuberculosis ) multidrug resistant strains. In this study, n -butyl and isobutyl quinoxaline-7-carboxylate 1,4-di- N -oxide were evaluated against replicating and non-replicating H37Rv M. tuberculosis strains. The results showed that seventeen of the twenty-eight derivatives have minimum inhibitory concentration (MIC) values lower than isoniazid (2.92 μM). The most active antimycobacterial agents were T-148 , T-149 , T-163 , and T-164 , which have the lowest MIC values (0.53, 0.57, 0.53, and 0.55 μM respectively). These results confirm the potential of quinoxaline-1,4-di- N -oxide against M. tuberculosis to develop and obtain new and more safety antituberculosis drugs., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Three unique linear oligomeric depsipeptides, designated as cavomycins A-C ( 1 - 3 ), were identified from Streptomyces cavourensis , a gut bacterium associated with the annelid Paraleonnates uschakovi . The structures of these depsipeptides were determined through a combination of spectroscopic methods and chemical derivatization techniques, including methanolysis, the modified Mosher's method, advanced Marfey's methods, and phenylglycine methyl ester derivatization. The unique dipeptidyl residue arrangements in compounds 1 - 3 indicate that they are not degradation products of valinomycin. Compound 2 and its methylation derivative 2a exhibited antiproliferative activity against PANC-1 pancreatic cancer cells with IC 50 values of 1.2 and 1.7 μM, respectively.