Teratogenesis, Carcinogenesis, and Mutagenesis 19:377–384 (1999) © 1999 Wiley-Liss, Inc. Investigation of Genotoxic Activity of Trans-Dehydrocrotonin, a Clerodane Diterpene From Croton cajucara Aniele R. Agner 1 , Maria A.M. Maciel 2 , Angelo C. Pinto 2 , Sônia G.S.R. Pamplona 2 , and Ilce M.S. Cólus 1 * 1 Departamento de Biologia Geral, CCB-UEL-Pr-Brazil, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Campus Universitário, Londrina (Pr), Brazil 2 Instituto de Química, Centro de Tecnologia Bloco A, Universidade Federal do Rio de Janeiro, Rio de Janeiro (RJ), Brazil The genotoxic action of three doses of trans-dehydrocrotonin (t-DCTN), an active ingredient obtained from the bark extracts of an Amazon native plant, Croton cajucara, were examined in Swiss mouse bone marrow cells in vivo, submitted to acute intrap- eritoneal treatment, by micronucleus (MN) and chromosomal aberration (CA) tests. The statistical tests (Anova and Tukey) made to compare the results obtained in each of the three doses of t-DCTN with the negative-control group showed that the frequencies of MN and mitotic index were equal to the negative-control and that the frequencies of CA were lower than that observed in the negative-control. Therefore, based on our results it can be said that t-DCTN is not genotoxic nor cytotoxic to mouse bone marrow cells, submitted to acute intraperitoneal treatment in vivo. Teratogenesis Carcinog. Mutagen. 19:377–384, 1999. © 1999 Wiley-Liss, Inc. Key words: Croton cajucara; t-DCTN; micronucleus; chromosomal aberrations; mitotic index; genotoxicity INTRODUCTION Croton cajucara Benth (Euphorbiaceae family), commonly called “sacaca,” that has been in common use in Amazonia of Brazil, is widely known in traditional phytotherapy [1]. Extracts prepared from the leaves and barks are used extensively Contract grant sponsor: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-(CAPES)-Brazil. *Correspondence to: Ilce M.S. Cólus, Departamento de Biologia Geral-CCB-UEL-Pr-Brazil, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Campus Universitário, CEP 86051-970 Londrina (Pr) Brazil. E-mail: colus@sercomtel.com.br