title: Pyrenophoric acids B and C, two new phytotoxic sesquiterpenoids produced by Pyrenophora semeniperda.
abstract: Two new phytotoxic sesquiterpenoid acids, named pyrenophoric acids B and C, were isolated together with the related pyrenophoric and abscisic acids from solid Bromus tectorum (cheatgrass) seed culture of the seed pathogen Pyrenophora semeniperda. This fungus has been proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum), a Eurasian annual grass that has become invasive in rangelands and is also a serious agricultural weed in the western U.S. Pyrenophoric acids B and C were characterized by spectroscopic methods (NMR and HR ESIMS) as (2Z,4E)-5-[(1R*,4R*,6R*)-1,4-dihydroxy-2,2,6-trimethylcyclohexyl]-3-methylpenta-2,4-dienoic and (2Z,4E)-5-[(1S*,3S*,4R*,6S*)-3,4-dihydroxy-2,2,6-trimethylcyclohexyl]-3-methylpenta-2,4-dienoic acids, respectively. Cytochalasins A, B, F, and Z3, as well as deoxaphomin and pyrenophoric acid, all previously isolated from P. semeniperda grown on wheat seed, were also isolated from cheatgrass seed culture. In a cheatgrass seedling bioassay at 10(-3) M, pyrenophoric acid B showed higher coleoptile toxicity than pyrenophoric acid, while pyrenophoric acid C showed lower phytotoxicity. Abscisic acid was by far the most active compound.
authors.affiliation: Department of Plant and Wildlife Sciences, Brigham Young University , Provo, Utah 84601, United States.
authors.forename: Marco
authors.initials: M
authors.lastname: Masi
authors.forename: Susan
authors.initials: S
authors.lastname: Meyer
authors.forename: Alessio
authors.initials: A
authors.lastname: Cimmino
authors.forename: Suzette
authors.initials: S
authors.lastname: Clement
authors.forename: Beth
authors.initials: B
authors.lastname: Black
authors.forename: Antonio
authors.initials: A
authors.lastname: Evidente
mesh_terms: D001203:Ascomycota / Q000737:chemistry / Q000378:metabolism*; D031724:Bromus / Q000187:drug effects*; D015394:Molecular Structure; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D014118:Toxins, Biological / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity
chemical_list: D012717:Sesquiterpenes; D014118:Toxins, Biological; C000589573:pyrenophoric acid
keywords: Bromus tectorum; Pyrenophora semeniperda; cytochalasins; mode of action; pyrenophoric acids B and C; sesquiterpenoids