Toxicity evaluation of natural and synthetic phenanthrenes in aquatic systems

Seven natural 9,10-dihydrophenanthrenes were isolated from the common reed Juncus effusus by means of chromatographic processes and identified by spectroscopic means. Furthermore, mimics of natural isolated compounds were synthesized to try to evaluate the influence of functional groups on the dihydrophenanthrene skeleton. Syntheses of compounds were based on the cross-coupling of 1-(2-iodo-5-methoxy)phenyl-ethanol with variously substituted iodobenzenes by zerovalent nickel. All the chemicals were tested to evaluate their effects on freshwater organisms from different trophic levels. Toxicity tests were performed on reducers (the bacterium Escherichia coli); producers (the alga Raphidocelis subcapitata, previously known as Selenastrum capricornutum); and consumers including a rotifer (Brachionus calyciflorus), a cladoceran (Daphnia pulex), and an anostracan (Thamnocephalus platyurus). Results suggested no one organism was uniquely sensitive to the chemicals tested. Toxicity depended on the kind and position of substituents on the aromatic skeleton.