Screening and isolation of antinematodal metabolites againstBursaphelenchus xylophilus produced by fungi

Sixty crude cultural filtrates of thirty fresh water fungi individually grown in both Potato Dextrose broth and GPC broth were assayedin vitro for antinematodal activity againstBursaphelenchus xylophilus (Steiner et Buhrer) Nickle using immersion test. Filtrates fromCamposporium quercicola YMF1.01300,Periconia digitata YMF1.00948,Caryospora callicarpa YMF1.01026 grown in both PDB and GPC broth, and the cultural filtrate ofMelanospora zamiae YMF1.00948 grown in PDB were found to be pathogenic to the tested nematodes. The degree of activity varied with the fungal species, length of exposure time, and media composition. From a nematicidal cultural extract ofCaryospora callicarpa YMF1.01026, four known naphthalenones were isolated and identified as 4,8-dihydroxy-3,4-dihydronaphthalen-1(2H)-one (1), 4,6-dihydroxy-3,4-dihydronaphthalen-1(2H)-one (2), 4,6,8-trihydroxy-3,4-dihydronaphthalen-1(2H)-one) (3), 3,4,6,8-tetrahydroxy-3,4-dihydronaphthalen-1(2H)-one (cis-4-hydroxyscytalone) (4) by NMR and MS analysis. All four metabolites showed noticeable biological activity againstB. xylophilus nematode. This is the first published report of these compounds affecting plant-parasitic nematodes.