A New Phytotoxic Nonenolide from Phoma herbarum

Abstract

Reinvestigation of the fermentation broth and mycelium of the fungus Phoma herbarum led to the isolation of a new phytotoxic nonenolide, namely, (7R,9R)-7-hydroxy-9-propyl-5-nonen-9-olide, which was designated with the trivial name herbarumin III (3). The known compounds herbarumins I (1) and II (2) were also obtained. The structure of 3 was elucidated by spectroscopic methods and molecular modeling. Compounds 1-3 interacted with bovine-brain calmodulin and inhibited the activation of the calmodulin-dependent enzyme cAMP phosphodiesterase.

Relationships between the stereochemistry and biological activity of fungal phytotoxins

“…119 The relative configuration of the chiral carbons of stagonolides B-F as depicted in the structural formulas was determined by comparing the 3 J H,H spin systems observed with those of herbarumin I and/or putaminoxin, for which the absolute stereochemistry was independently determined. 168,169 The relative configuration assigned to stagonolides B-E is in full agreement with the NOE effects observed in the NOESY spectra and with the inspection of Dreiding models. 166 (-)-Stagonolide F appears to be a diastereomer of aspinolide A, a fungal metabolite isolated with other nonenolides and polyketides from Aspergillus ochraceus Wilh.…”

“…The latter observation can be connected with a change of propyl group at C-9 in stagonolide to a methyl group in stagonolide C. These results confirm that modifications at the C(2)À ÀC(4) moiety of the nonenolide ring induces a decrease or total loss of phytotoxicity. Furthermore, stagonolides C-F differ from the phytotoxic herbarumins I-III 168 or putaminoxins, nonenolides produced by Phoma putaminum, 169,171,172 pathogenic for the pasture weed Erigeron annus, in having a methyl group at C-9 instead of an n-propyl group, which appears to be an important structural feature for the latter two groups of phytotoxins. The functionality and conformation of the nonenolide ring are important for the activity of putaminoxins as well as closely related pinolidoxins, which are phytotoxic nonenolides isolated from cultures of Ascochyta pinodes Jones, a fungal pathogen for pea (Pisum sativum L.).…”

Métodos de preparação de lactonas de anel médio

“…Há poucos anos, Rivero-Cruz et al 9,10 isolaram do fungo Phoma herbarum três lactonas de 10 membros, que chamaram de herbaruminas (Figura 2). Estas lactonas mostraram atividade fitotóxica significativa na inibição da germinação e do crescimento de mudas de Amaranthus hypochondriacus, o que as torna potenciais herbicidas.…”

Enantioselective Synthesis of Herbarumin III by Using a Chelation‐Controlled Reduction

“…-Natural lactones with a medium ring size between eight to eleven [1] are attracting the attention of several groups because of their significant biological importance, but their syntheses are challenging. The phytotoxic lactone herbarumin III (1) was isolated by Mata and co-workers from the fermentation broth and mycelium of the fungus Phoma herbarum along with herbarumin I (2) and II (3) [2]. The structure of 1 was elucidated by spectroscopic methods combined with molecular modeling.…”