Antiviral flavones from the leaves of Nicotiana tabacum

Three new flavones, tabaflavones A–C (1–3), together with three known flavones (4–6), were isolated from the leaves of Nicotiana tabacum. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1–6 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed compound 1 exhibited moderate anti-TMV activity with inhibition rate of 29.2%, which is close to that of the positive control. The other compounds also showed the anti-TMV activities with inhibition rates in the range of 14.2–20.8%.