In silico and in vitro evaluation of potential agonistic and antagonistic estrogenic and androgenic activities of pure cyanotoxins, microcystin-LR and cylindrospermopsin

The potential endocrine disruption activity of cyanotoxins, particularly their effects on estrogen and androgen receptors (ER, AR), remains poorly understood. In the present study, the potential agonistic/antagonistic estrogenic and androgenic activities of MC-LR and CYN have been determined for the first time with validated OECD Test Guidelines No. 455 and 458, respectively. The data show that only MC-LR demonstrated weak estrogenic agonistic effects (LogPC₁₀ value of -9.85 M), while both toxins displayed antagonistic effects on the ER, with LogIC₃₀ values of -4.4 and -6.4 for MC-LR and CYN, respectively. In addition, neither MC-LR nor CYN exhibited agonistic/antagonistic activities in AR. Docking studies revealed potential interactions between both toxins and AR, with CYN showing a higher predicted affinity for this receptor. In vivo studies, particularly those investigating androgen disruption, are warranted to confirm the endocrine disrupting potential of MC-LR and CYN.