In male rats Wistar strain the effect of pleuran (b-1,3-D glucan isolated from Pleurotus ostreatus) on the antioxidant state of the organism was investigated as well as the development of precance- rous lesions, foci of aberrant crypts (ACF) on the large intestine of the rat. Diets with 10 % pleuran or with 10 % cellulose, as compared with a cellulose-free diet markedly reduced the content of conjugated dienes in red blood cells and liver, and pleuran in particular to half the levels in the large intestine. Similarly both diets reduced the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) (and conversely increased the catalase activity) in erythrocytes. As compared with the cellulose diet, pleuran increased the activities of SOD, GSH- PX, glutathione reductase and glutathione transferase in the liver. In all animals on the cellulose- free diet ACF developed in the large intestine. Under the influence of the cellulose diet and more markedly after the intake of pleuran, their incidence declined to 60 %. The mean number of the most frequent small ACF, as well as the total number of ACF was highest in animals on the cellulose-free diet, lower on the diet with cellulose and statistically lowest (by more than 50 %) on the diet with pleuran.

        Key words: pleuran (b-glucan from Pleurotus ostreatus) – dimethyl hydrazine – antioxidant state – foci of aberrant crypts – large intestine