Fungicidal compounds from a marine Ascidian - associated fungus

A marine Ascidian-associated fungus, Trichoderma harzianum, (NIO/BCC2000-51) was assessed for its in vitro antagonistic activity against ten fungal phytopathogens and three food-infesting fungi. Fractionation of the cell-free culture filtrate of T. harzianum (NIO/BCC2000-51) showed its ethyl acetate (EA) fraction to be significantly active against fungal phytopathogens; Macrophomina sp, Pyricularia oryzae, Sclerotium rolfsii, Penicillium piceum, Trichoderma koningii, T. longibrachiatum and a food-infesting fungal pathogen Penicillium griseofulvum. Bioassay guided chemical investigation of the ethyl acetate fraction yielded five compounds (1-5); two α-pyrone derivatives, a phenol, a sesquiterpene and an unsaturated hydroxy fatty acid as methyl ester. Of the five isolated secondary metabolites, compounds 2 and 5 are being reported here for the first time from T. harzianum. Compounds 1 and 4 inhibited the growth of Sclerotium rolfsii causing sclerotium wilt or rot disease in tropical plants. Compound 2 and 5 were significantly effective in inhibiting the growth of Macrophomina sp. causing charcoal rot in cereals. Compound 3 showed moderate activity against plant pathogen Penicillium piceum and food pathogen P. griseofulvum. T. harzianum of the present investigation did not show antagonism towards all the three Aspergillus sp. tested, besides being ineffective against T. atroviride and Chalara sp. Though compounds 1, 3 and 4 are known metabolites of T. harzianum, to the best of our knowledge this is the first report of their antagonistic activity against the pathogens tested.