Three New Isobenzofurans from the Root of Yunnan Local Sun Cured Tobacco and Their Bioactivities

Three new isobenzofurans (1-3), together with three known isobenzofurans (4-6) were isolated from the root of Yunnan local sun cured tobacco. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1-4 were tested for their anti-tobacoo mosaic virus (TMV) activities and compounds 1-6 were tested for their cytotoxicity activities. The results revealed that compounds 1-4 showed high anti-TMV activity with inhibition rate of 31.4, 35.2 and 38.8, 29.6%. These rates are close to that of positive control. Compounds 1-6 also showed moderate-to-weak inhibitory activities against some tested human tumor cell lines with IC50 values in the range of 2.6-9.5 mu M.