Toxicology in Vitro 21 (2007) 41–52 www.elsevier.com/locate/toxinvit 0887-2333/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.tiv.2006.07.018 Protective eVect of -glucan extracted from Saccharomyces cerevisiae, against DNA damage and cytotoxicity in wild-type (k1) and repair-deWcient (xrs5) CHO cells Rodrigo Juliano Oliveira a , Renata Matuo a , Ariane Fernanda da Silva a , Hevenilton José Matiazi b , Mário Sérgio Mantovani a,¤ , Lúcia Regina Ribeiro c a Departamento de Biologia Geral, Universidade Estadual de Londrina (UEL), Londrina, PR, Brazil b Departamento de Tecnologia de Alimentos e Medicamentos, Universidade Estadual de Londrina (UEL), Londrina, PR, Brazil c Departamento de Biologia Celular, Universidade Estadual Paulista (UNESP), Rio Claro, SP, Brazil Received 18 May 2006; accepted 29 July 2006 Available online 25 August 2006 Abstract A large number of functional foods, including those that contain -glucan, have been shown to prevent the development of cancer and other chronic diseases. The aim of the present study was to elucidate its mechanism of action, as well as to understand its eVects as an antigenotoxic, anticlastogenic agent, and to determine its capacity to preserve cell viability. The investigation was carried out in the CHO- k1 and CHO-xrs5 cell lines. The cytokinesis-blocked micronucleus assay indicated that the diVerent doses of -glucan examined (5, 10, 20 and 40 g/ml) did not show clastogenic eVects. In the CHO-k1 cell line, a chemopreventive eVect could be observed in all the protocols tested: pre-treatment (% reduction of 35.0–57.3), simultaneous treatment (simple – 5 reduction of 19.7–55.6 and with pre-incubation – of 42.7–56.4) and post-treatment (% reduction of 17.9–37.6). This Wnding indicates mechanisms of action involving desmutagenesis and bio- antimutagenesis, albeit the latter having a lesser role. However, in the repair-deWcient CHO-xrs5 cells, -glucan did not show a protective eVect with post-treatment (% reduction of 2.96), thus supporting the involvement of bioantimutagenesis. The comet assay in CHO-k1 cells demonstrated that -glucan has neither a genotoxic nor an antigenotoxic eVect. Cell viability tests indicated that -glucan preserves cell viability in both cell lines, preventing apoptotic events. These Wndings suggest that -glucan, when present in foods, could provide them with nutraceutical characteristics and act as a dietary supplement, or that -glucan could be used in new drug development.  2006 Elsevier Ltd. All rights reserved. Keywords: -Glucan; CHO-xrs5 cells; CHO-k1; Comet assay; Cytokinesis-blocked micronucleus test 1. Introduction Studies have pointed out that an increased intake of nat- ural foods is directly related to a decreased risk for the development of cancer and other diseases (Weisburger, 2000; Ferrari and Torres, 2002). Therefore, investigations in toxicologic genetics are aimed at determining the genotoxic and clastogenic eVects of xenobiotics, as well as to search for new substances that have chemoprotective eVects or that can mitigate the adverse eVects of harmful xenobiotics. Among the components of these diets are some products that comprise the class of dietary Wbers such as cereals, mainly oats and barley, mushrooms, algae and yeasts. In general, Wbers can be sources of -glucan. -Glucan is one of the components present in large quantities in the cell wall of various organisms, and in the case of fungi it consists of a linear central skeleton of D-glucose molecules linked in the -(1 ! 3) position, containing side chains of various lengths that are made up -1 ! 6 linkages and that occur at diVerent intervals along the central skeleton. Extraction provides a suspension of -1,3 polyglucose particles (Di Luzio et al., 1979). The localization of this polysaccharide is the intermediate layer of the cell wall of yeasts which is * Corresponding author. Tel.: +55 43 3371 4417; fax: +55 43 3371 4527. E-mail address: biomsm@uel.br (M.S. Mantovani).