Homonojirimycin, an alkaloid from dayflower inhibits the growth of influenza A virus in vitro.

We have previously examined the antiviral effects of total alkaloids from Commelina communis L. (TAC). Here we investigated the active constituents of TAC, responsible for the antiviral effect. Harman, homonojirimycin (HNJ) and 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine were isolated from TAC by HPLC. Only HNJ showed strong antiviral activity against influenza A/PR/8/34 virus (H1N1) as measured by cytopathic effect reduction assay. The results suggest that HNJ is one of the active components of TAC.