TY - JOUR

T1 - Elucidating cylindrospermopsin toxicity via synthetic analogues: An in vitro approach

AU - Murphy, Patrick

AU - Evans, Daniel

AU - Hughes , Jack

AU - Jones, Leigh

AU - Falfushynska, Halina

AU - Horyn, Oksana

AU - Sokolova, Inna

AU - Christensen, Jeppe

AU - Coles, Simon

AU - Rzymskic, Piotr

PY - 2019/11

Y1 - 2019/11

N2 - Cylindrospermopsin (CYN) is an alkaloid biosynthesized by selected cyanobacteria, the cyto- and genotoxic properties of which have been studied extensively by in vitro and in vivo experimental models. Various studies have separately established the role of uracil, guanidine and hydroxyl groups in CYN-induced toxicity. In the present study, we have prepared five synthetic analogues that all possess a uracil group but had variations in the other functionality found in CYN. We compared the in vitro toxicity of these analogues in common carp hepatocytes by assessing oxidative stress markers, DNA fragmentation and apoptosis. All the analogues tested induced generation of reactive oxygen species, lipid peroxidation (LPO) and DNA fragmentation. However, the greatest increase in LPO and increase in caspase-3 activity, an apoptosis marker, was demonstrated by an analogue containing guanidine, hydroxyl and uracil functionalities similar to those found in CYN but lacking the complex tricyclic structure of CYN. We also report a crystal structure of an analogue lacking the hydroxyl group found in CYN which does not show intramolecular H-bonding interactions between the guanidine and the uracil functionalities. The observations made in this work supports the hypothesis that CYN toxicity is a result of an interplay between both of the uracil, hydroxyl and guanidine functional groups.

AB - Cylindrospermopsin (CYN) is an alkaloid biosynthesized by selected cyanobacteria, the cyto- and genotoxic properties of which have been studied extensively by in vitro and in vivo experimental models. Various studies have separately established the role of uracil, guanidine and hydroxyl groups in CYN-induced toxicity. In the present study, we have prepared five synthetic analogues that all possess a uracil group but had variations in the other functionality found in CYN. We compared the in vitro toxicity of these analogues in common carp hepatocytes by assessing oxidative stress markers, DNA fragmentation and apoptosis. All the analogues tested induced generation of reactive oxygen species, lipid peroxidation (LPO) and DNA fragmentation. However, the greatest increase in LPO and increase in caspase-3 activity, an apoptosis marker, was demonstrated by an analogue containing guanidine, hydroxyl and uracil functionalities similar to those found in CYN but lacking the complex tricyclic structure of CYN. We also report a crystal structure of an analogue lacking the hydroxyl group found in CYN which does not show intramolecular H-bonding interactions between the guanidine and the uracil functionalities. The observations made in this work supports the hypothesis that CYN toxicity is a result of an interplay between both of the uracil, hydroxyl and guanidine functional groups.

U2 - 10.1016/j.chemosphere.2019.06.021

DO - 10.1016/j.chemosphere.2019.06.021

M3 - Article

VL - 234

SP - 139

EP - 147

JO - Chemosphere

JF - Chemosphere

SN - 0045-6535

ER -