Synergic effect of curcumin and its structural analogue (Monoacetylcurcumin) on anti-influenza virus infection

Curcumin (Cur), a polyphenolic compound extracted from spice and common food colourantturmeric, contains versatile bio-activities. Monoacetylcurcumin (MAC), a structuralanalogue of Cur, differs from Cur by acetyl modification, but retains enone groups.Comparative analysis revealed MAC effectively inhibited influenza virus infection (IAV) to asimilar extent as, if not superior to, curcumin. Both compounds mildly reduced viral NAactivity. Surprisingly, unlike Cur, the MAC inhibition of IAV did not occur through theblocking of HA activity. However, MAC strongly dampened Akt phosphorylation, theprerequisite signalling for efficient IAV propagation. A much stronger inhibition effect onIAV infection was observed when MAC treatment was in combination with Cur. Collectively,MAC demonstrated clear antiviral activity, and likely inhibited IAV via multiplemechanisms that were not identical to Cur. Importantly, Cur and MAC in combinationsynergistically inhibited IAV infection.