Two New Isobenzofurans from the Roots of Yunnan Local Sun Cured Tobacco and Their Bioactivities

Two new isobenzofurans, 5-(methoxymethyl)-2,2-dimethyl-2 H -furo[3,4-h]chromen-7(9 H )-one ( 1 ) and 5-(2-methoxyethyl)-2,2-dimethyl-2 H -furo[3,4-h]chromen-7(9 H )-one ( 2 ), together with two known isobenzofurans ( 3 and 4 ), were isolated from the roots of Yunnan local sun cured tobacco. Their structures were determined by means of HR-ESI-MS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1–4 were tested for their anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity. The results revealed that compound 4 showed strong inhibition with IZD of 16.5 ± 2.2. Compounds 1–3 also showed good inhibition with IZD of 13.6 ± 2.0, 14.0 ± 2.3, and 11.8 ± 1.6 mm, respectively. Compounds 1–4 were also tested for their antioxidant activity, and they showed good antioxidant activity with IC 50 value of 4.38, 4.57, 4.46, and 4.28 μg/mL, respectively.