Purification and characterization of a lectin with antiproliferative activity toward cancer cells from the dried fruit bodies of Lactarius flavidulus

Abstract The isolation of a dimeric 29.8-kDa lectin (LFL) from dried Lactarius flavidulus fruit bodies is reported herein. The chromatographic procedure utilized comprised anion-exchange chromatography on DEAE-cellulose, cation-exchange chromatography on CM-cellulose, anion-exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The hemagglutinating activity of LFL was inhibited by a variety of simple sugars, such as lactose, p -nitrophenyl α- d -glucopyranoside, p -nitrophenyl β- d -glucopyranoside and inositol, and by the polysaccharide inulin. The activity of LFL was stable up to 40 °C. There was a precipitous drop in activity when the temperature was elevated to 50 °C. Hemagglutinating activity was retained when LFL was exposed to 6.25–12.5 mM HCl and NaOH. The activity was potently inhibited by Fe 2+ and Fe 3+ ions, and slightly inhibited by Al 3+ and Mn 2+ ions. LFL suppressed the proliferation of hepatoma (HepG2) and leukemic (L1210) cells with an IC 50 of 8.90 and 6.81 μM, respectively. It inhibited the activity of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) with an IC 50 of 5.68 μM. However, LFL did not exhibit antifungal activity.