7-epicylindrospermopsin, a toxic minor metabolite of the cyanobacterium Aphanizomenon ovalisporum from Lake Kinneret, Israel

A toxic minor metabolite, 7-epicylindrospermopsin (1), was isolated from a culture of the cyanobacterium Aphanizomenon ovalisporum isolated from Lake Kinneret in Israel. Homonuclear and inverse-heteronuclear 2D NMR techniques, as well as HRMS and comparison of the NMR data with model compounds, enabled the structure determination of the new compound. Four polymethoxy-1-alkenes, 3-6, were isolated from the lipophilic extract of the cyanobacterium as well.