Two New Antifungal Aromatic Sesquiterpenes from the Leaves of Cigar Tobacco

Two new aromatic sesquiterpenes, (1-isopropyl-6-methoxy-3-methylnaphthalen-7-yl)methanol ( 1 ) and 1-isopropyl-6-methoxy-3,7-dimethylnaphthalene ( 2 ), as well as five known ones ( 3–7 ) were isolated from the leaves of cigar tobacco. Their structures were determined mainly using spectroscopic methods, including extensive 1D and 2D NMR techniques. Interestingly, the anti-fungi activity test revealed that compounds 1 and 2 showed potential anti- Golovinomyces cichoracearum (the main pathogen of tobacco powdery mildew disease) activity with inhibition rates of 55.4% ± 4.8, and 76.2% ± 5.1 respectively compared with the negative control. These rates are lower than that of a positive control (with an inhibition rate of 90.5% ± 5.3).