7-Deoxy-desulfo-cylindrospermopsin and 7-deoxy-desulfo-12-acetylcylindrospermopsin: Two new cylindrospermopsin analogs isolated from a Thai strain of Cylindrospermopsis raciborskii

•A Thai strain of Cylindrospermopsis raciborskii was investigated for toxin production.•Two new analogs of cylindrospermopsin were isolated from C. raciborskii.•These additions bring the total number of cylindrospermopsin analogs from 3 to 5.•Structure comparisons to known toxins suggest these new analogs will be toxic as well. As environmental changes such as eutrophication lead to increased size and frequency of cyanobacterial blooms, research into the toxins produced by these blooms becomes increasingly important. One of the common toxins produced by cyanobacterial blooms is cylindrospermopsin (1), a potent inhibitor of protein synthesis. To date, only two additional analogs of cylindrospermopsin have been isolated, namely 7-epicylindrospermopsin (2) and 7-deoxy-cylindrospermopsin (3). This report details the isolation and structure determination of an additional two new analogs, 7-deoxy-desulfo-cylindrospermopsin (4) and 7-deoxy-desulfo-12-acetylcylindrospermopsin (5). These are the first new analogs of cylindrospermopsin to be reported in over a decade. Based on their structural features, it is likely that these new analogs also possess the harmful biological activities displayed by the rest of the cylindrospermopsin family.