Three new prenylated xanthones from Comastoma pedunculatum and their anti-tobacco mosaic virus activity

•Three new (1–3) xanthones were isolated from Comastoma pedunculatum.•Three known (4–6) xanthones were also obtained from the title plant.•1–6 were evaluated for their anti-TMV activities.•1–6 showed weak anti-TMV activity with IC50 values ranging from 122.7 to 242.9μM.