Hypericin as a non-antioxidant inhibitor of NF-κB

NF-κB is a transcription factor involved in immune and inflammatory responses. Here we show that micromolar concentrations of hypericin inhibited the PMA- and TNF-α-induced activation of NF-κB in HeLa and TC10 cells, respectively. In contrast, NF-κB activated by H₂O₂ was not influenced by hypericin, indicating a pathway-specificity of hypericin. Hyperforin and a Hypericum perforatum extract standardised on 0.15% hypericin and 5% hyperforin were not active at pharmacologically relevant concentrations. The PMA/TNF-α-induced transcription of a reporter gene, which is under the control of the NF-κB-dependent IL-6 promoter, was strongly reduced by preincubation with hypericin.