Citrantifidiene and Citrantifidiol: Bioactive Metabolites Produced by Trichoderma citrinoviride with Potential Antifeedant Activity toward Aphids

Abstract

Two novel metabolites with potential antifeedant activity were isolated from cultures of the fungus Trichoderma citrinoviride strain ITEM 4484 grown in solid-state fermentation on sterile rice kernels. The producing strain was identified at species level by sequence analysis 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-1alpha. Fractionation by column chromatography and TLC of the culture organic extract, followed by feeding preference tests on the aphid pest Schizaphis graminum (Rondani), allowed the purification of 5.8 and 8.9 mg/kg of culture of two bioactive metabolites, which were named citrantifidiene and citrantifidiol ( 1 and 2). Citrantifidiene and citrantifidiol, whose structures were determined by spectroscopic methods (NMR and MS) are a symmetrical disubstituted hexa-1,3-dienyl ester of acetic acid and a tetrasubstituted cyclohexane-1,3-diol, respectively. The pure metabolites influenced the feeding preference of S. graminum restraining individuals from feeding on wheat leaves dipped in 5% aqueous methanol solution containing 0.57 mg/mL of citrantifidiene or 0.91 mg/mL of citrantifidiol.

Bisorbicillinoids Produced by the Fungus Trichoderma citrinoviride Affect Feeding Preference of the Aphid Schizaphis graminum

“…After re-isolation from a single germinated conidium, the strain was maintained in purity in the culture collection of the Institute of Sciences of Food Production, Bari, Italy, with the accession T. citrinoviride ITEM-4484. The strain was identified on the basis of morphological characters and by molecular techniques (sequence analysis 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-1α) as recently reported (Evidente et al 2008).…”

“…Cultures were incubated at 25°C under a photoperiod of 12 h for 4 weeks and then oven-dried and finely ground. One kilogram of dried material was extracted with MeOH-H 2 O (1% NaCl) mixture (55:45 v/v), defatted, and then extracted with CH 2 Cl 2 as reported elsewhere (Evidente et al 2008). The organic extracts were combined, dried (Na 2 SO 4 ), and evaporated under reduced pressure, yielding a brown oil (15 g).…”

“…Extraction and Purification of Fungal Metabolites Metabolites of T. citrinoviride ITEM 4484 were produced in a solid state fermentation as previously reported (Evidente et al 2008). Briefly, the fungus was grown on autoclaved rice kernels brought to 45% moisture.…”

“…The authors also showed that the biological activity of the fungal culture was from the water-methanol extractable of the fungal biomass, thus implying the presence of diffusible metabolites. Recently, two novel metabolites with potential antifeedant activity, citrantifidiene and citrantifidiol, were isolated from the culture extract of Trichoderma citrinoviride strain ITEM-4484 and characterized as a symmetrical disubstituted hexa-1,3-dienyl ester of acetic acid and a tetrasubstituted cyclohexane-1,3-diol, respectively (Evidente et al 2008).…”

Identification and Characterization of Trichoderma citrinoviride Isolated from Mushroom Fly-Infested Oak Log Beds Used for Shiitake Cultivation

“…Thus, to confirm the identity of the fungus DUCC001 at the molecular level, partial translation elongation factor 1α (tef-1α) gene was amplified by PCR with TEF728 and TEF1 primers (Evidente et al, 2008), cloned and sequenced. The resulting sequence of 651 bp was deposited in GenBank (JF700485).…”