Carvotacetones (1–7) isolated from Sphaeranthus africanus were screened for their antimycobacterial and efflux pump (EP) inhibitory potential against the mycobacterial model strains Mycobacterium smegmatis mc² 155, Mycobacterium aurum ATCC 23366, and Mycobacterium bovis BCG ATCC 35734. The minimum inhibitory concentrations (MICs) of the carvotacetones were detected through high-throughput spot culture growth inhibition (HT-SPOTi) and microbroth dilution assays. In order to assess the potential of the compounds 1 and 6 to accumulate ethidium bromide (EtBr) in M. smegmatis and M. aurum, a microtiter plate-based fluorometric assay was used to determine efflux activity. Compounds 1 and 6 were analyzed for their modulating effects on the MIC of EtBr and the antibiotic rifampicin (RIF) against M. smegmatis. Carvotacetones 1 and 6 had potent antibacterial effects on M. aurum and M. bovis BCG (MIC ≤ 31.25 mg/L) and could successfully enhance EtBr activity against M. smegmatis. Compound 1 appeared as the most efficient agent for impairing the efflux mechanism in M. smegmatis. Both compounds 1 and 6 were highly effective against M. aurum and M. bovis BCG. In particular, compound 1 was identified as a valuable candidate for inhibiting mycobacterial efflux mechanisms and as a promising adjuvant in the therapy of tuberculosis or other non-tubercular mycobacterial infections.

中文翻译：

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非洲空壳草中的香芹酮对分枝杆菌的抗菌和外排泵抑制活性。

从Sphaeranthus africanus中分离出香芹酮 ( 1–7 )，筛选其对分枝杆菌模型菌株耻垢分枝杆菌mc ² 155、金分枝杆菌ATCC 23366 和牛分枝杆菌BCG ATCC 35734 的抗分枝杆菌和外排泵 (EP) 抑制潜力。通过高通量斑点培养物生长抑制 (HT-SPOTi) 和微肉汤稀释测定法检测香芹酮丙酮 (MIC)。为了评估化合物1和6在耻垢分枝杆菌和金黄色分枝杆菌中积累溴化乙锭(EtBr)的潜力，使用基于微量滴定板的荧光测定来测定外排活性。分析了化合物1和6对 EtBr 和抗生素利福平 (RIF) 针对耻垢分枝杆菌的 MIC 的调节作用。香芹酮1和6对金黄色分枝杆菌和牛分枝杆菌BCG具有有效的抗菌作用(MIC ≤ 31.25 mg/L)，并能成功增强 EtBr 对耻垢分枝杆菌的活性。化合物1似乎是损害耻垢分枝杆菌外排机制的最有效药物。化合物1和6对金分枝杆菌和牛分枝杆菌BCG均高度有效。特别是，化合物1被确定为抑制分枝杆菌流出机制的有价值的候选者，并作为治疗结核病或其他非结核分枝杆菌感染的有前途的佐剂。