Antiviral Isocoumarins from a Cigar Tobacco-Derived Endophytic Fungus Aspergillus oryzae

Two new isocoumarins, 5-(2-hydroxyethyl)-7-methoxy-3-(2-oxopropyl)-1H-isocoumarin ( 1 ), 7-methoxy-5-methyl-3-(2-oxopropyl)-1H-isocoumarin ( 2 ), along with four known ones, were isolated from the fermentation products of an endophytic fungus Aspergillus oryzae derived from cigar tobacco. Their structures were elucidated by spectroscopic methods. Compounds 1 and 2 exhibited anti-TMV activities with inhibition rates of 36.2 and 32.8% at a concentration of 20 μmol/mL, respectively, compared with 35.6% for positive control ningnanmycin.