Antifungal compounds from Zuccagnia punctata leaves active against cereal ear

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

Tucumán

Congreso; VII Congreso Argentino de Microbiología General; 2011

Sociedad Argentina de Microbiología General

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 tha the ethanolic leaf extracts from Zuccagn ia 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 brot h 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 layer chromatography (TLC) and visualized under short and long wave UV light, and afte r spraying with FeCl3 NP-PEG, and vanillin-sulphuric acid . The detected bands were scraped from the TLC plates and assayed by bioautography. TLC visualization reagents, UV-Vis spectrophotometric analysis and gas chromatography coupled to massspectrometry indicated that the most fungi toxic 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.