In the present work, methanolic, ethanolic and boiled water extracts of Suillus collinitus were chemically characterized and further submitted to evaluation of their bioactive properties (antioxidant potential and cytotoxic activity in tumor cell lines). Phenolic acids and sugars were chromatographically identified and quantified in the methanolic and boiled water extracts, respectively. S. collinitus ethanolic extract gave the highest antioxidant activity. Nevertheless, regarding cell growth inhibition, the methanolic extract was the most potent one, particularly in MCF-7 cells (GI50 25.2±0.2µg/ml). Moreover, the GI50 concentration induced a G1 cell cycle arrest, with a concomitant decrease in the percentage of cells in the S phase. Furthermore, it caused an increase in the percentage of apoptotic cells, from 6.0±0.2% in untreated cells, to 15.3±2.0% in cells treated with the GI50 concentration and to 16.3±2.0% in cells treated with 2×GI50 concentration. In addition, 48 h treatment with the GI50 concentration caused a strong increase in the levels of p53, p21, and cleaved PARP, together with a decrease in Bcl-2 and XIAP. Results indicate that Suillus collinitus may be a promising source of bioactive compounds. Particularly, its methanolic extract appears to have a p53-mediated effect on the normal cell cycle distribution and apoptosis induction in a human breast tumor cell line.
