Agropyrenol and agropyrenal, phytotoxins from Ascochyta agropyrina var. nana, a fungal pathogen of Elitrigia repens

A strain of Ascochyta agropyrina var. nana, a fungal pathogen of the perennial weed Elytrigia repens, produced several toxins in a liquid medium, and its primary toxin, named agropyrenol, was characterized as a substituted salicylaldehyde on the basis of its chemical and spectroscopic properties. Its absolute stereochemistiy was determined by Mosher's method. Two other minor metabolites were isolated from the same culture and named agropyrenal and agropyrenone, respectively. They were characterized as a tri-substituted naphthalene carbaldehyde and a pentasubstituted 3H-benzofuranone, respectively, using the same techniques. When assayed on leaves of several weed plants, i.e., Mercurialis annua, Cheno podium album and Setaria viridis, agropyrenol proved to be phytotoxic, causing the appearance of necrotic lesions, agropyrenal was less active, while agropyrenone was inactive. None of the compounds showed antibiotic, fungicidal or zootoxic activity. (C) 2012 Elsevier Ltd. All rights reserved.