Cobalt Protoporphyrin IX serves as a potent, specific inducer of heme oxygenase-1 (HO-1) and demonstrates broad-spectrum antiviral effects against Influenza A virus (IAV) [1].

Cobalt protoporphyrin IX demonstrated maximal non-toxic concentration (TC0) of 3.13 μM in both MDCK and RAW264.7 cells after 72 hours [1]. At 2 μM, with a treatment duration ranging from 0 to 24 hours, the compound increased HO-1 intracellular protein levels in a time-dependent manner in these cells [1]. With respect to influenza viruses Empty Cell A/FortMonmouth/1/1947, A/TianjinJinnan/15/2009, A/Wuhan/359/1995, A/FujianTongan/196/2009, and BY/FujianXinluo/54/2006, Cobalt protoporphyrin IX exhibited IC50 values of 0.40 ± 0.16, 0.42 ± 0.15, 0.46 ± 0.19, 0.34 ± 0.05, and 0.64 ± 0.30 μM, respectively [1]. At concentrations ranging from 0.25-2 μM for 18 or 24 hours, the compound inhibited IAV replication by enhancing the IFN response, an antiviral activity that was independent of the catalytic function of HO-1 [1]. Additionally, at 2 μM for 0-6 hours, Cobalt protoporphyrin IX induction of HO-1 antiviral activity may be dependent on the phosphorylation and translocation of IRF3, thereby strengthening the antiviral IFN response [1].