etters

Abstracts / Toxicology L

ingredients of diverse physical–chemical categories, sensitivity,specificity and accuracy of the defined predictive model were 85%,86% and 86% respectively. These results confirmed the validationperformances and demonstrated the usefulness of the tiered strat-egy MTT + IL1 alpha as a decision making tool for skin irritancyhazard identification for this set of chemicals. The EPISKIN modelis currently used in basic and screening studies of large number ofchemical ingredients. The aim is to assess the real performances andusefulness of the in vitro methods in order to concretely determinethe applicability domains and the remaining gaps acknowledgingthe fact that the industry is facing a wide chemical–physical diver-sity of ingredients.

doi:10.1016/j.toxlet.2008.06.443

V53Doxorubicin induces apoptosis and necrosis in rat cortical neu-rons through a concentration-biphasic manner

Miguel Lopes 1,∗, Andreas Meisel 2, Felix Carvalho 1, Maria de Lour-des Bastos 1

1 Faculty of Pharmacy, University of Porto, Porto, Portugal, 2 ChariteFaculty of Medicine, Charite Campus Mitte, Department ofExperimental Neurology and Center for Stroke Research, Berlin,Germany

Doxorubicin (DOX) is an anthracycline anticancer drug consideredto be a first line choice in the treatment of breast cancer, childhoodsolid tumours, soft tissue sarcomas and aggressive lymphomas.Neurotoxicity of this drug has not been a subject of high concerndue to the poor permeability of this drug through the Blood–Brain-Barrier (BBB). Nevertheless, several modified delivery systems havebeen recently developed to circumvent this obstacle and use DOX asan effective agent against brain tumours. This approach brings newconcerns, related to the possible toxic effects to non-target neu-rons. The aim of this work was to investigate the mode of cell deathinduced by DOX in cortical neurons and characterise some molec-ular and biochemical features of its toxicity in this cellular model.To achieve this aim several parameters were analysed namely lac-tate dehydrogenase release, caspase activity, metabolic activity,DNA fragmentation, expression of apoptotic genes and correspon-dent proteins and markers of oxidative stress. The obtained resultsshowed that DOX is neurotoxic to serum-free cultures of corticalneurons in a biphasic concentration manner: For concentrations up

to 0.5 �M, cell death follows an apoptotic pattern, while for higherconcentrations apoptosis is inhibited and necrosis becomes domi-nant. Apoptosis induced by DOX in our model can occur via differentpathways. It is expected that the obtained information from thiswork can provide new clues about the mechanisms of DOX neu-rotoxicity that may be of great value for preventing its effects innon-target cells.

doi:10.1016/j.toxlet.2008.06.444

V54In vitro evaluation of the anti-neoplastic action of novel nucle-oside analogs

Gina Manda 1,∗, Ionela Victoria Neagoe 1, Monica Neagu 1, CarolinaConstantin 1, Eleonora Codorean 1, Constantin Tanase 2

1 Victor Babes National Institute of Pathology, Bucharest, Romania,2 National Institute for Chemical–Pharmaceutical Research andDevelopment, Bucharest, Romania

180S (2008) S32–S246 S111

We developed a panel of preliminary tests to evaluate in vitro theanti-neoplastic action of nucleoside analogs.

Novel nucleoside analogs: ent-T, ent-C, ent-5-FU. Pyrimidinebases (thymine, cytosine, 5-fluorouracil) were linked to an enan-tiomeric bicyclo[2.2.1]heptane key intermediate. 5-FU was used asstandard chemotherapeutic.

Cells: human T lymphoblasts (Jurkat) and neoplastic monocytes(U937), cultivated for 48 h. Cellular tests: viability/multiplication-tetrazolium salt (MTS) reduction test; membrane integrity: LDHreduction test; apoptosis-annexin V/propidium iodide test; cellcycle-flow cytometry with Vybrant orange; nucleoside metabolism(uridine, thymidine)-uptake of tritium-labeled nucleosides.

Experimental results indicated that ent-T and ent-C exert cyto-toxic effects on Jurkat cells and cytostatic ones on U937. Nucleosideuptake was inhibited even at non-toxic concentrations. Decreaseof thymidine uptake was associated with a decrease of viable cellscounts and only partly correlated with cells in the cell cycle S-phase. ent-C had no major effects on tumor cells multiplication,but tended to inhibit uridine uptake particularly by Jurkat cells.Increased apoptosis of Jurkat, but not U937 cells, was also observed.5-FU had a significant cytotoxic action on both types of tumor cells,but did not affect uridine uptake. At moderate and high concen-trations, 5-FU stimulated thymidine uptake (cell cycle arrest in theS-phase). 5-FU induced significant apoptosis and necrosis of bothJurkat and U937 tumor cells.

The applied protocol allowed us to establish that ent-T and ent-5-FU exert anti-neoplastic action, especially on Jurkat cells. Theyinterfere with uridine and thymidine metabolism even at non-toxicconcentrations, by mechanisms that may be partly independent ofRNA/DNA synthesis.

doi:10.1016/j.toxlet.2008.06.445

V55In vitro genotoxicity assessment of non-photoactivated hyper-icin

Eva Miadokova 1,2,∗, Ivan Chalupa 1,2, Viera Vlckova 1,2, AndreaSevcovicova 1,2, Eliska Galova 1,2, Daniel Vlcek 1,2, MarcelaKopaskova 1,2, Alena Hercegova 1,2

1 Department of Genetics, Faculty of Natural Sciences, ComeniusUniversity, Bratislava, Slovakia, 2 Cancer Research Institute, SlovakAcademy of Sciences, Bratislava, Slovakia

Hypericin is a naturally occurring substance with various medic-inal applications. Despite of photoactivated hypericin is slightlyphotogenotoxic, insufficient attention has been paid to the geno-toxic effect assessment of non-photoactivated hypericin. In thisstudy genotoxicity of non-photoactivated hypericin was evaluatedin different in vitro model systems: Salmonella typhimurium/Amesassay, Saccharomyces cerevisiae assay, Chlamydomonas reinhardtiiassay and chromosomal aberration assay, using three mammaliancell lines: HepG2, V79 and VH10 with different levels of metabo-lizing enzymes. It was not genotoxic in the Ames assay. Though,it was not protective against 9-aminoacridine, it slightly reduced2-aminoanthracene-induced mutagenicity in S. typhimurium TA97.In the yeast S. cerevisiae assay hypericin did not increase thefrequency of mitotic crossing-over, total aberrants and furtherchanges at the ade2 locus, number of convertants at the trp5locus, and number of revertants at the ilv1 locus. After combinedapplication with 4-nitroquinoline-1-oxide it statistically signifi-cantly, enhanced the number of revertants at the ilv1 locus at thehighest concentration used. Hypericin was not mutagenic in theC. reinhardtii assay, but it reduced toxicity and mutagenicity ofmethylmethane sulfonate after their combined application. Due to