Citrantifidiene and citrantifidiol, bioactive metabolites produced by Trichoderma citrinoviride with potential antifeedant activity towards aphids

Two novel metabolites with potential antifeedant activity were isolated from cultures of the fungus T. citrinoviride strain ITEM 4484 grown in solid-state fermn. on sterile rice kernels. The producing strain was identified at species level by sequence anal. of the internal transcribed spacer regions ITS-1 and ITS-2 of the nuclear rDNA and a fragment of the translation elongation factor gene TEF-1???. Fractionation by column chromatog. and TLC of the culture org. ext., followed by feeding preference tests on the aphid pest Schizaphis graminum (Rondani), allowed the purifn. of 5.8 and 8.9 mg/kg of culture of 2 bioactive metabolites, which were named citrantifidiene (I) and citrantifidiol (II). I and II, whose structures were detd. by spectroscopic methods (NMR and MS) are a sym. disubstituted hexa-1,3-dienyl ester of acetic acid and a tetrasubstituted cyclohexane-1,3-diol, resp. The pure metabolites influenced the feeding preference of S. graminum restraining individuals from feeding on wheat leaves dipped in 5% aq. MeOH soln. contg. 0.57 mg/mL of I or 0.91 mg/mL of II.