New compounds from Japanese oak wilt disease-associated fungus Raffaelea quercivora

Abstract

Two new compounds, a new lactone, quercilactone A (1), and (17R)-hydroxynafuredin (5), as well as five known compounds, scytalone (2), 3S,4R-hydoxy-scytalone (3), nafuredin (4), (+)-(3R,5R)-3-hydroxy-5-decanolide (6) and 3-ethyl-4-hydroxy-6-methyl-2H-pyran-2-one (7), were isolated from Raffaelea quercivora, a fungus that causes Japanese oak wilt disease. The structures of these compounds were determined by 1D and 2D NMR spectroscopic analyses. The absolute configuration at C-17 of 5 was determined to be R by the modified Mosher’s method. Compounds 1, 2, and 7 exhibited weak phytotoxic activity in lettuce seedlings at a concentration of 100 μg mL⁻¹.

Graphical Abstract

Keywords:

• Japanese oak wilt
• Quercus crispula
• Raffaelea quercivora
• quercilactone A
• scytalone
• nafuredin
• phytotoxicity

Acknowledgments

The authors thank Dr. Takako Aboshi in Yamagata University for MS experimental supports.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was mainly supported by MEXT KAKENHI Grant Number 16K07766 (Y. S) and by Universitas Padjadjaran, Indonesia, ALG Grant-2020 (U. S).