Xanthones from the herb of <i>Swertia elata</i> and their anti-TMV activity

<p>Two new xanthones (<b>1</b>–<b>2</b>), together with four known ones (<b>3</b>–<b>6</b>), were isolated from whole herb of <i>Swertia elata</i>. Their structures were elucidated by spectroscopic methods including extensive 1D- and 2D-NMR techniques. Their anti-tobacco mosaic virus (anti-TMV) activity test revealed that <b>1</b>–<b>6</b> showed weak anti-TMV activities with inhibition rate in the range of 15.2–28.8% at the concentration of 20 μM.