Rhamnetin Exhibits Anti-Tuberculosis Activity and Protects against Lung Inflammation

Rhamnetin, a natural flavonoid found in cloves and berries has been reported to show anti‐inflammatory activities in lipopolysaccharide‐stimulated RAW264.7 cells and may be a potent inhibitor for extracellular signal‐regulated kinase 1 (ERK1) and c‐Jun N‐terminal kinase. Here, we showed that rhamnetin has antimycobacterial effects on Mycobacterium tuberculosis (MT) H37Rv, multi‐drug‐, and extensively drug‐resistant clinical isolates. We also investigated the effect of rhamnetin on interferon (IFN)‐γ‐stimulated human lung fibroblast MRC‐5 cells, since MT infection causes intensive lung inflammation. Rhamnetin suppressed mRNA levels of tumor necrosis factor‐α, interleukin (IL)‐1β, IL‐6, IL‐12, and matrix metalloproteinase‐1. Furthermore, it inhibited IFN‐γ‐mediated stimulation of ERK1 and p38 mitogen‐activated protein kinase in MRC‐5 cells. These results showed that rhamnetin has potent anti‐tuberculosis activities and effectively suppresses lung inflammation, implying that rhamnetin can be a potent anti‐tuberculosis dietary agent.