Antifungal activity of 8-methoxynaphthalen-1-ol isolated from the endophytic fungus MFLUCC 17-0313 against the plant pathogenic fungus on tomatoes.

Thirty-four endophytic fungal isolates were obtained from the leaves of the medicinal plant , and their antagonistic activities against the growth of the common tomatoes plant pathogenic fungus were initially screened using a dual culture assay. The endophytic fungus MFLUCC 17-0313, which was later molecularly identified as , displayed the highest inhibition percentage (49.98%) in comparison to the others. This fungus was then chosen for further evaluation. Its culture broth and mycelia from a 10 L scale were separated and extracted using ethyl acetate, methanol, and hexane. Each extract was tested for antifungal activity against the same pathogen using a disc diffusion assay. Only the crude hexane extract of fungal mycelium showed antifungal activity. The hexane extract was fractioned using sephadex gel filtration chromatography and each fraction was tested for antifungal activity until the one with the highest inhibition percentage was obtained. The bioactive compound was identified as 8-methoxynaphthalen-1-ol using nuclear magnetic resonance spectroscopy and mass spectrometry. The minimum inhibition concentration of 8-methoxynaphthalen-1-ol was demonstrated at 250 µg/mL against the selected pathogen. Using the leaf assay, the solution of 8-methoxynapthalen-1-ol was tested for phytotoxic activity against and was found to have no phytotoxic effects. These results showed that 8-methoxynaphthalen-1-ol has the potential for controlling the growth of , the cause of Southern blight disease on tomatoes. This study may provide the foundation for future use of this compound as a biofungicide.