Antiviral isocoumarins from the roots and stems of Nicotiana tabacum

Three new isocoumarin derivatives, tabaisocoumarins A-C (1-3), together with other three known phenolic compounds (4-6), were isolated from the leaves of Nicotiana tabacum. Compound 2 exhibited anti-TMV activity with inhibition rate of 33.8%, which is higher than that of positive control, ningnanmycin.