STRUCTURE FUNGICIDAL PROPERTIES OF SOME 3-HYDROXYLATED AND 4-HYDROXYLATED STILBENES AND BIBENZYL ANALOGS

The fungicidal activity of some substituted hydroxylated stilbenes and bibenzyls was measured against three wood-destroying fungi using the agar plate technique. Four 3-hydroxystilbene derivatives and 3-hydroxybibenzyl were active against the white-rot fungus Coriolus versicolor. A tentative structure-activity relationship was proposed for stilbene C. versicolor activity. The previously proposed hypothesis that white-rot extracellular enzymes oxidatively degrade stilbenes which makes white-rot fungi immune to stilbenes may need to be reexamined. No structure-activity relationship was apparent for stilbenes tested against the two brown-rot fungi Gloeophyllum trabeum and Poria placenta. Of the two natural hydroxylated stilbenes studied, pinosylvin was slightly more active against G. trabeum and C. versicolor than pinosylvin monomethyl ether. Surprisingly, neither of these two natural stilbenes showed much activity against the copper-tolerant fungus P. placenta.