Two New Isoindole Alkaloids from Aspergillus fumigatus as Potential Activators for Tobacco Powdery Mildew

To further explore powdery mildew (caused by Golovinomyces cichoracearum ) natural products, an extract from the fermentation of endophytic Aspergillus fumigatus was investigated. As a result, six isoindole alkaloid derivatives ( 1–6 ) were isolated. Among them, two compounds ( 1 and 2 ) were newly discovered and the activity evaluation of the purified compounds 1–6 against G. cichoracearum was studied. The results revealed that compounds 1–6 demonstrated obvious anti- G. cichoracearum activities for cigar tobacco in the range of 40.6% ± 5.4 to 66.5% ± 4.9 at a concentration of 250 μg/mL, respectively. However, these rates are lower than that of positive control. By isolating and structurally identifying the above isoindole alkaloids, new materials conducive to improving the utilization of N. tabacum -derived fungi could be developed for screening anti-powdery mildew drugs.