Antifungal compounds from Zuccagnia punctata leaves active against cereal ear ot pathogens

JIMÉNEZ, C.M.; SGARIGLIA, M.A.; SOBERÓN, J.R.; SAMPIETRO, D.A.; VATTUONE, M.A.

San Miguel de Tucumán

Congreso; VII Congreso Argentino de Microbiologia General SAMIGE del Bicentenario; 2011

SAMIGE

Argentina is both an important cereal producer and consumer. Diseases restrict the grain yields, specially ear rotting and grain mold caused by Fusarium species. These fungi also contaminate grains with mycotoxins which are a serious risk for human and animal health. We showed that the ethanolic leaf extracts from Zuccagnia punctata Cav. have antifungal activity against several phytopathogenic fungi, including Fusarium species. The aim of this work was to isolate and identify the bioactive compounds responsible for the antifungal activity of leaf extracts from Z. punctata . The dry residue of the ethanolic leaf extract from Z. punctata was sequentially extracted with diethyl ether, ethyl acetate, and methanol. The obtained extracts were dried and assayed by the microdilution broth method on strains of Fusarium species isolated from cereals of Argentina (F. thapsinum, F. verticillioides, F. graminearum sensu stricto, F. subglutinans and F. bothii). Diethyl ether extract was the most fungitoxic. Their constituents were separated by thin la yer chromatography (TLC) and visualized under short and long wave UV light, and after spraying with FeCI" NP-PEG, and vanillin -sulphuric acid . The detected bands were scraped from the TLC plates and assayed by bioautography. TLC visualization reagents, UVNis spectrophotometric analysis and gas chromatography coupled to mass spectrometry indicated that the most fungitoxic band was constituted by the known 2 ' , 4 ' -dihydroxy-chalcone and a new compound (2', 6 ' dihydroxy-4' -methoxy-chalcone). Further research is in progress to determine the antifungal activity of these compounds alone, in mixtures and as additives of commercial fungicides.