Antifungal metabolites from the roots of Diospyros virginiana by overpressure layer chromatography.

A preparative overpressure layer chromatography (OPLC) method was successfully used for the separation of two new natural compounds, 4-hydroxy-5,6-dimethoxynaphthalene-2-carbaldehyde (1) and 12,13-didehydro-20,29-dihydrobetulin (2) together with nine known compounds, including 7-methyljuglone (3), diospyrin (4), isodiospyrin (5), shinanolone (6), lupeol (7), betulin (8), betulinic acid (9), betulinaldehyde (10), and ursolic acid (11) from the acetone extract of the roots of Diospyros virginiana. Their identification was accomplished by 1D- and 2D-NMR spectroscopy and HR-ESI-MS methods. All the isolated compounds were evaluated for their antifungal activities against Colletotrichum fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and P. viticola using in vitro micro-dilution broth assay. The results indicated that compounds 3 and 5 showed high antifungal activity against P. obscurans at 30 μM with 97.0 and 81.4% growth inhibition, and moderate activity against P. viticola (54.3 and 36.6%). It appears that an optimized OPLC system offers a rapid and efficient method of exploiting bioactive natural products.