4-Methoxycinnamaldehyde (p-Methoxycinnamaldehyde) is an active ingredient of Agastache rugosa.4-Methoxycinnamaldehyde has cytoprotective activity against respiratory syncytial virus (RSV) in human laryngeal carcinoma cell lines, and helps to control disease induced by RSV infection, with an IC50 of approximately 0.055 μg/mL. The IC50 was about 0.055 μg/mL.

4-Methoxycinnamaldehyde could effectively inhibit cytopathic effect of RSV (p<0.0001) with an estimated IC(50) of 0.055microg/ml and a selectivity index (SI) of 898.2. 4-Methoxycinnamaldehyde (0.03microg/ml) could inhibit viral entrance by interfering viral attachment (IC(50) of 0.06microg/ml; p<0.0001) and internalization (IC(50) of 0.01microg/ml; p<0.0001). 4-Methoxycinnamaldehyde significantly increased the basal production of IFN (p=0.0015), but not the virus-induced IFN production. In conclusion, 4-Methoxycinnamaldehyde might be helpful to manage the disease induced by RSV infection.[1]