Research Article Base Excision Repair Pathway Is Involved in the Repair of Lesions Generated by Flavonoid-Enriched Fractions of Pepper Tree ( Schinus terebinthifolius, Raddi) Stem Bark Francisco Napole~ aoT ulio Varela-Barca, 1 Lucymara Fassarella Agnez-Lima, 2 and S  |lvia Regina Batistuzzo de Medeiros 2 * 1 Departamento de Educac ¸a˜o Fı´sica, Faculdade de Educac ¸a˜o Fı´sica, Universidade do Estado do Rio Grande do Norte, Campus Universita ´rio Central, Mossoro ´, Brazil 2 Departamento de Biologia Celular e Gene´tica, Centro de Biocieˆncias, Universidade Federal do Rio Grande do Norte, Campus Universita ´rio, Lagoa Nova, Natal-RN, ZC 59072-970, Brazil Cell-free and bacterial assays indicate that flavo- noid-enriched fractions and the flavonoids of pep- per tree stem bark from Schinus terebinthifolius Raddi have genotoxic rather than antigenotoxic properties. In the present report, we have exam- ined the ability of flavonoid-enriched fractions to damage plasmid DNA and the repair pathways involved in the recognition of these DNA lesions. High concentrations of two flavonoid-enriched fractions were able to break phosphodiester bonds in DNA. In addition, studies using bacterial strains deficient in nucleotide excision repair and base excision repair (BER) enzymes indicated that the flavonoid-enriched fractions generated lesions that were substrates for enzymes belonging to the BER pathway. In addition, in vitro studies indi- cated that the DNA damage produced by the fla- vonoid-enriched fractions was also a substrate for exonuclease III and that the phosphodiester break- age was amplified by copper ions. These results indicate that flavonoids from the pepper tree (Schinus terebinthifolius, Raddi) generate lesions on DNA that are potential targets of FPG and MutY glycosylase from the BER pathway. Chro- matographic and spectral analyses helped to sup- port the hypothesis that the flavonoids of the Bra- zilian pepper tree bark are the main factors involved in the fraction’s damage potential. The isolated flavonoids from Fraction II were also tested in vitro and support the oxidative damage potential of these flavonoids. Environ. Mol. Muta- gen. 48:672–681, 2007. V V C 2007 Wiley-Liss, Inc. Key words: Schinus terebinthifolius; Brazilian pepper tree; flavonoids; genotoxicity INTRODUCTION Flavonoids comprise an important class of low-molecu- lar-weight secondary metabolites ubiquitously distributed in the plant kingdom. Their chemical structure is based on the phenylchromane or flavane ring system, and they are synthesized via the phenylpropanoid cascade [Simo ˜es et al., 1999; Hodek et al., 2002]. On the basis of their structure, flavonoids can be classified into at least eight groups: flavans, flavanones, isoflavanones, flavones, isofla- vones, anthocyanidines, chalcones, and flavolignans. Widely distributed in the leaves, seeds, bark, and the flowers of plants, over 4,000 flavonoids have been identi- fied to date [Costa, 1977; Simo ˜es et al., 1999; Rahua, 2001; Hodek et al., 2002]. The biological and pharmacological properties of flavo- noids cover a wide spectrum, ranging from beneficial to harmful health effects. The literature describes flavonoids as anti-oxidative [Hanasaki et al., 1994], anti-apoptotic [Quadri et al., 2000], anti-inflammatory [Clavin et al., 2007], anti-mutagenic [Wall, 1992], anti-ulcerogenic [Gambhir et al., 1987], and anti-anxiolytic [Baureithel et al., 1997]. However, many other studies indicate that particular flavonoids can also display mutagenic and gen- otoxic activities in bacterial assays [Ertrurk et al., 1984; Starvic et al., 1984; Czeczot et al., 1990; Jurado et al., *Correspondence to: Sı ´lvia Regina Batistuzzo de Medeiros, Departa- mento de Biologia Celular e Gene ´tica, Centro de Biocie ˆncias, Universi- dade Federal do Rio Grande do Norte, Campus Universita ´rio, Lagoa Nova, Natal-RN, ZC 59072-970, Brazil. E-mail: sbatistu@cb.ufrn.br Grant sponsor: CNPq (The National Council for Scientific and Techno- logical Development), Brası ´lia, Brazil. Received 16 February 2007; provisionally accepted 3 July 2007; and in final form 4 July 2007 DOI 10.1002/em.20334 Published online 23 August 2007 in Wiley InterScience (www.interscience. wiley.com). V V C 2007 Wiley-Liss, Inc. Environmental and Molecular Mutagenesis 48:672^681 (2007)