Terpestacin, a toxin produced by Phoma exigua var. heteromorpha, the causal agent of a severe foliar disease of oleander (Nerium oleander L.)

Since 1987, several cytochalasins were isolated from Phoma exigua var. heteromorpha, the causal agent of foliar blight disease of oleander (Nerium oleander L.), and chemically and biologically characterised. During the purification process of a large-scale production of cytochalasins A and B, necessary to continue the study on their anticancer activity, a metabolite having a different carbon skeleton compared to that of cytochalasans, was isolated. It was identified as terpestacin, a well-known toxic fungal stestertepenoid, isolated for the first time from P. exigua var. heteromorpha, by spectroscopic investigation (essentially 1D and 2D H-1 and C-13-NMR and ESI MS) and optical methods in comparison with the literature data. Terpestacin and some its derivatives (including a natural one, fusaproliferin) were prepared and tested for their biological activity. Terpestacin and fusaproliferin had some inhibitory effects on seed germination of Phelipanche ramosa, whereas none of the compounds caused phytotoxic effects on weed leaves. [GRAPHICS] .

Automated summary

Since 1987, cytochalasins and terpestacin were isolated from Phoma exigua var. heteromorpha and studied for their chemical and biological properties, showing inhibitory effects on the seed germination of Phelipanche ramosa.