Cytotoxic steroids from Polyporus umbellatus.

The steroids ergone (1), (22E, 24R)-ergosta-7,22-dien-3β-ol (2), 5α,8α-epidioxy-(22E,24R) -ergosta-6,22-dien-3β-ol (3), ergosta-6,22-dien-3β,5α,6β-triol (4), and polyporusterone B (5) were isolated from Polyporus umbellatus by bioassay-guided approach. They showed potent anticancer activity against HepG2 cells. Ergone displayed remarkable anticancer activity against HepG2, Hep-2, and Hela cancer cells, of which HepG2 cells were the most sensitive. Furthermore, the cytotoxic effects of ergone on normal human cells (HUVEC) were smaller than on cancer cells. The results showed that ergone had more selective cytotoxic activity against cancer cells than against normal cells.