Evaluation of mushroom dietary fiber (nonstarch polysaccharides) from sclerotia of Pleurotus tuber-regium (Fries) Singer as a potential antitumor agent

Mushroom dietary fiber or nonstarch polysaccharides (NSPs) that were solubl e in hot alkali and belonged to the beta -glucan type were isolated from th e sclerotia: of an edible mushroom, Pleurotus tuber-regium. The mushroom NS Ps were further separated into a number of fractions [hot alkali extracts ( HAEs)] with weight-average molecular weights (R) ranging from 1 x 10(4) to 42.2 x 104. The HAE fractions [with M-w of (5.8-17.1) x 10(4)] administered intraperitoneally at a dose of 20 mg/kg of body weight to BALB/c mice impl anted with solid tumor Sarcoma 180 were found to be effective in inhibiting tumor proliferation with an inhibition ratio of greater than or equal to 5 0%. In vitro experiments using human tumor cell lines HL-60 and HepG2 had s hown that HAE fractions with M-w of (5.8-42.2) X 104 also had antiprolifera tive activity at three different. concentrations (50, 100, and 200 mug/mL) toward the tumor cell lines tested. All HAE fractions did not inhibit the g rowth of a normal kidney cell line (Vero) from monkey. It is therefore post ulated that the antitumoral effect of NSPs from the sclerotia of P. tuber-r egium is probably host-mediated and cytocidal.