Two New Antibacterial Naphthoquinones from a Cigar Tobacco-Derived Endophytic Fusarium solani

In this study, two new (1 and 2), together with five known (3–7) naphthoquinones were isolated from the cigar tobacco-derived endophytic Fusarium solani. Their structures were determined by means of HR-ESI-MS and extensive 1D and 2D NMR spectroscopic studies. The new compounds were evaluated for antibacterial activities against Pseudomonas syringae (the main pathogenic sources of tobacco angular leaf spot disease). Interestingly, compounds 1 and 2 exhibited inhibitory effects with MIC50 values of 6.8 and 5.9 μg/mL, respectively. These rates are lower than that of the positive control (agricultural streptomycin, with MIC50 of 2.2 μg/mL).