A new lectin with highly potent antihepatoma and antisarcoma activities from the oyster mushroom Pleurotus ostreatus.

A dimeric lectin, composed of subunits with a molecular weight of 40 and 41 kDa, respectively, and demonstrating similarity in N-terminal sequence to each other and to Aleuria aurantia lectin, was isolated from fresh fruiting bodies of the edible mushroom Pleurotus ostreatus. The lectin was unadsorbed on DEAE-cellulose in 10 mmol/L phosphate buffer (pH 7.5), subsequently adsorbed on CM-cellulose in 10 mmol/L NH(4)OAc (pH 5.4), and came off in the first peak from a Superose 12 column during fast protein liquid chromatography. The lectin was acid-labile, alkali-labile, and heat-labile. Its hemagglutinating activity was sensitive to inhibition by CaCl(2), MgCl(2), MnCL(2) and FeCl(3) and potentiation by AlCl(3). Melibiose, lactose, d-galactose, alpha-methyl-d-galactopyranoside, N-acetylneuraminic acid, raffinose, and inulin were capable of inhibiting its hemagglutinating activity, with melibiose being the most potent. The lectin exerted potent antitumor activity in mice bearing sarcoma S-180 and hepatoma H-22. Survival in these mice was prolonged and body weight increase reduced after lectin treatment. Copyright 2000 Academic Press.