ARS | Publication request: Phyllostictines A-D, Oxazatricycloalkenones Produced by Phyllosticta cirsii, A Potential Mycoherbicide for Cirsium arvense Biocontrol

Submitted to: Tetrahedron
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2007
Publication Date: December 8, 2007
Citation: Evidente, A., Cimmino, A., Andolfi, A., Vurro, M., Zonno, M.C., Cantrell, C.L., Motta, A. 2007. Phyllostictines A-D, Oxazatricycloalkenones Produced by Phyllosticta cirsii, A Potential Mycoherbicide for Cirsium arvense Biocontrol. Tetrahedron. 64:1612-1619.

Interpretive Summary: Cirsium arvense (L.) Scop. (commonly called Canada thistle) is a persistent perennial weed that grows vigorously, forming dense colonies, and spreading by roots growing horizontally that give rise to aerial shoots. It spreads by seed either by wind or as a contaminant in crop seed. Canada thistle is native to south eastern Europe and the eastern Mediterranean area. It has spread to most temperate parts of the world and is considered an important weed all around the world as it infests many habitats such as cultivated fields, roadsides, pastures and rangeland, railway embankments, and lawns. There is no easy method of control, and all methods require follow-up. Although there are no effective biological control organisms available at this time, search for efficacious biocontrol microorganisms and natural herbicides is receiving a renewed interest. Phyllosticta cirsii, a fungal pathogen isolated from Cirsium arvense and proposed as biocontrol agent of this noxious perennial weed, produces in liquid cultures different phytotoxic metabolites with potential herbicidal activity. Four new oxazatricycloalkenones, named phyllostictines A-D, were isolated and characterized using essentially spectroscopic and chemical methods.

Technical Abstract: Phyllosticta cirsii, a fungal pathogen isolated from Cirsium arvense and proposed as biocontrol agent of this noxious perennial weed, produces in liquid cultures different phytotoxic metabolites with potential herbicidal activity. Four new oxazatricycloalkenones, named phyllostictines A-D, were isolated and characterized using essentially spectroscopic and chemical methods. Tested by leaf-puncture assay on the fungal host plant phyllostictine A proved to be highly toxic. The phytotoxicity decreases when both the dimension and the conformational freedom of the macrocyclic ring change, as in phyllostictines B and D, and it is totally lost when also the functionalization of the same ring is modified, as in phyllostictine C. Beside its phytotoxic properties, phyllostictine A has no antifungal activity, an interesting antibiotic activity only against Gram positive bacteria, and a noticeable zootoxic activity when tested at high concentrations. The integrity of the oxazatricycloalkenone system appears to be an important feature to preserve these activities.