Fungicidal Activity of 3'-Substituted-3-Stilbenols

Abstract

Summary Twenty 3′-substituted-3-stilbenols were synthesized and tested for fungicidal activity (agar plate IC50 values) against two brown-rot fungi rot Gloeophyllum trabeum and Postia placenta and one white-rot fungus Trametes versicolor. Compounds synthesized were eight trans-3-X-3′-stilbenols (X = OMe, Me, Cl, OH, OPr, OBu, OOct, and O-p-Tol), three cis-3-X-3′-stilbenols (X = OMe, Me, Cl), three 3-hydroxy-α-(3-X-phenyl)cinnamic acids (X = OMe, Me, Cl), and six multisubstituted-3′-substituted-3-stilbenols (3′,4-diOMe, 3′-Me-4-OMe, 3′-Cl-4-OMe, 3′-OH-4-OMe, 3′-Cl-4-OMe-4′-OH, and 3′-Cl-4′-OH). The three cinnamic acids and 3′-OOct showed low to no activity against all three fungi. Most of these 3′-substituted-3-stilbenols (15 of 20) had fungicidal activity against the white-rot fungus T. versicolor, in contrast to earlier studies on 3′-substituted-4-stilbenols which were inactive against T. versicolor. These 3′-substituted-3-stilbenols also had fungicidal activity against G. trabeum and P. placenta, with the latter fungus having a parabolic lipophilic Quantitative Structure Activity Relationship (QSAR). 3′-O-p-Tol-3-stilbenol was the most active against T. versicolor and fifth most active against P. placenta of the twenty 3′-substituted-3-stilbenols examined here.